Annexe 4 SESSION 1: THE DISTRIBUTION AND NATURE OF RINDERPEST

THE GLOBAL RINDERPEST STATUS IN 1996

Mark Rweyemamu¹

INTRODUCTION

In the last decade of the twentieth century rinderpest continues to cause havoc to the livestock farmers of Africa, the Near East and Asia. The several theatres in which the battle for its control goes on are often thought of as discrete entities, yet, the pattern of recent rinderpest incidents indicates that they are interlinked now, as in the past, by extensive trade in livestock. For example, the Near East and the Arabian Peninsula cannot be freed and maintained free from rinderpest until the disease is eradicated from South Asia and East Africa. Indeed, no continent can be considered free from risk until all foci of persistent infection are eradicated.

Livestock trade may be the key factor in moving rinderpest around the globe but long-term persistence of infection occurs in some areas and the reasons for this must be elucidated. Understanding the factors that favour the long-term maintenance of rinderpest infection, the movement of rinderpest infection out of the areas in which it persists and transfer from one country to another are clearly pre-requisites for eventual global eradication. A global perspective is essential to elaborate a sound epidemiological understanding, in itself an essential pre-requisite for refining eradication strategies to progress from rinderpest control to eradication within coordinated national and regionally-coordinated eradication campaigns.

The account of global rinderpest status presented here is a synthesis of official and informal information combined with the results of EMPRES missions. It can not be definitive but represents a working basis for decision making.

GLOBAL RINDERPEST STATUS

Central, South and South-east Asia

South-east Asia has been free from rinderpest for decades and in South Asia the disease is currently recognised to be present only in Pakistan, Afghanistan, India and Sri Lanka.

Bangladesh, Nepal, Bhutan and most of India are now free from rinderpest but, even as late as the 1980s, rinderpest was widespread throughout the area. Concerted action in the last decade has succeeded in reducing its range considerably; since January 1994 rinderpest has been recognised only in the States of Tamil Nadu, Karnataka and Andrha Pradesh at the southern tip of peninsular India and prospects for eradication by Operation Rinderpest Zero in the near future are good. Nationwide blanket vaccination, followed by zoned withdrawal of vaccination except in state border areas, paved the way for the final stage of intensive vaccination in affected areas, prophylactic vaccination in neighbouring areas and tracking down pockets of residual infection by Operation Village Search. A major factor in accelerating progress has been the recognition that PPR was almost certainly the true cause of the majority of outbreaks of rinderpest-like disease in which only sheep were affected.

Sri Lanka had been free for decades when rinderpest was introduced inadvertently in 1978 by the Indian Peace-keeping Force. Since that time, rinderpest persisted in the troubled north-east of the island. Civil disturbance reduces access to the affected areas and reduces the prospects for eradication. However, extensions of rinderpest from the affected area have been few and there is no evidence for infection since 1994.

¹ Senior Officer, EMPRES, Animal Health Service, Animal Production and Health Division, FAO, Rome; paper prepared jointly with Dr Peter Roeder, Animal Health Officer EMPRES.

In 1993 a rinderpest epidemic in Punjab State stimulated the Pakistan National Authorities to take the bold step of acknowledging the presence of rinderpest in Punjab and Sindh States. Subsequently, in 1994 a separate epidemic appeared in the Northern Areas in the Gilgit and Hunza Valleys. Both epidemics had their origin to the south through trade in cattle and buffaloes. A clearer, yet still incomplete, picture of rinderpest in Pakistan is now emerging.

Rinderpest has been maintained by constant circulation within the Landhi Dairy Colony, and possibly other colonies, which supply milk to Karachi in Sindh State, for many years. The husbandry system practised involves the intensive stall feeding of buffaloes and cattle throughout a lactation. At the end of lactation most cows are slaughtered but a proportion of high yielders (and rinderpest immune cows) are “salvaged” by returning them to their villages for rebreeding, and this is reported to be increasing. This provides a constantly changing population in the colony which continually receives rinderpest-susceptible animals to fuel the rinderpest “fire”. However, it is probable that the disease is widespread and endemic in Sindh State and is constantly reintroduced to the cattle colony from the source villages. This understanding is supported by the recognition of apparently sporadic rinderpest outbreaks throughout Sindh State, at least since 1991, (in early 1994 it was present close to the Iran border) and by the fact that trade in livestock, primarily from the state, has resulted in outbreaks in the Arabian Peninsula over many years. Therefore, it is also possible that the Landhi Colony may be acting as an indicator of infection in the source areas rather than as the main site of persistence. Buffaloes and cattle which have spent their entire lactation in the colony would have had ample opportunity to experience infection and become immune by recovery from infection if not vaccinated; indeed, recognition of the rinderpest immune status of survivors is one of the main reasons for their retention. Therefore, the movement out of the colony is unlikely to present a significant frequent risk of transmission to the areas they go back to if salvaged and the trade in is important in terms of providing a substrate for rinderpest infection maintenance. If all buffaloes and cattle could be immunised before entering the colony the chain of transmission would be broken. Eradication from Sindh State is, thus, a matter of eliminating infection not just from the Landhi Colony but from the entire state.

The epidemic in Punjab State appeared subside but the disease is unlikely to have been eliminated from that area, indeed an outbreak close to Islamabad was recognised in early 1996. Invasion of Afghanistan in mid 1995 resulted from the movement of cattle from central Punjab although these could have originated from further south. Rinderpest certainly overwintered in the Northern Areas of Pakistan after introduction in mid-1994 although it has probably died out in the initial focus because of vaccination and exhaustion of the susceptible population. In late 1995 there were reports of rinderpest in sheep close to Jammu and Kashmir and in 1996 it is uncertain whether or not rinderpest has been eliminated from the Northern Areas. If the control attempts have not eliminated all foci of infection, it is conceivable that rinderpest could linger on for many years spreading from valley to valley as seasonal migrations allow the mixing of their cattle, yaks and small ruminants at high pasture.

Lack of epidemiological information makes it difficult to understand clearly why rinderpest is able to persist in Sindh State (or at least a large part of it) and possibly other states. Clearly the disease has persisted there for a long time as, in recent years, trade from there in cattle and buffalos, which are in great demand as breeding stock and for slaughter, is suspected to have resulted in the movement of rinderpest to trading partners on several occasions. The high demand for Pakistan's genetically-superior buffaloes and cattle, by countries with developing or expanding livestock industries places many in South-East Asia at a low, but none-the-less real, risk of reintroduction. These include Thailand, Vietnam, Laos, Cambodia and the Philippines.

Afghanistan is intimately linked to Pakistan and has itself suffered the ravages of rinderpest in the past. Years of war in the country have left the country depleted of livestock and with an uncertain rinderpest status. Restocking from Pakistan is taking place in several areas in the north-east, east and south-west of the country and there is, or at least was until recently, a lively trade in animals for slaughter from Pakistan; reintroduction of rinderpest was expected and occurred in mid 1995 south-east of Kabul. The Tajikistan authorities believe, although this has not been substantiated, that rinderpest was present in the extreme north of Afghanistan, and possibly on its own territory in 1995; these remote areas are currently severely affected by civil strife. In late 1994 Pakistan announced that it had opened up a new trade route to Central Asia and there is already believed to be some trade of livestock from Pakistan through Afghanistan to Tajikistan, Uzbekistan and possibly farther afield. These southern central Asian republics are clearly at risk from its introduction. The Tajikistan Republic and western China are also at low risk of direct extension from Pakistan.

Available disease intelligence suggests that Kazakhstan, Turkmenistan, Uzbekistan, Kyrgyzstan, Tajikistan (with the possible exception noted above) and the Russian Federation are currently free from rinderpest.

In the past the Indian sub-continent was a major source of infection for neighbouring countries and distant trading partners as far apart as Brazil and the Philippines, but today neither India nor Sri Lanka afford a high risk of transmission to other countries. Pakistan, however, remains a major risk and is of central importance to the Global Rinderpest Eradication Programme.

Rinderpest was confirmed in the Tuva and Chita Republics on the northern border of Mongolia in the winter of 1991/92 indicative of an outbreak in yaks and cattle which spanned the borders. Further outbreaks also appear to have occurred in the same area in 1992/93. There was no indication that the disease persisted there and the Mongolian authorities do not recognise the presence of the disease. These could conceivably be epidemic indicator areas of endemicity in yet undisclosed areas.

West Asia and the Near East

Iran now appears to provide an effective buffer for direct overland transmission between Pakistan/ Afghanistan and the countries of the Near East and should prevent the events of 1969 and earlier being repeated. In that year a pandemic swept through Iran and onwards to the Mediterranean littoral affecting most countries in the region including Turkey. National and international action brought rapid control but left infection persisting in Lebanon from where it emerged again in 1982/83 to infect Syria and Israel. The Levant is now free from infection as are Syria and Jordan. Iran was again invaded from the east in 1981. Although official records are scanty the next major introduction into the region seems to have occurred in 1985 but this time rinderpest was introduced to Iraq with 600 Indian buffaloes conveyed by sea to the port of Basrah or possibly Kuwait. India was the source of the buffaloes but not necessarily the rinderpest virus which could have been contracted by contact with other infected livestock en route. The buffaloes were distributed widely in Iraq and caused a country-wide virgin epidemic which in the Baghdad Alfedelia Dairy Village alone killed half of the 30,000 buffaloes resident there at the time. From then until late 1994, when intensive and repeated vaccination, aided by reorganisation to provide a centrally-controlled line-managed veterinary service, appears finally to have resulted in its elimination, rinderpest was continuously present in the Alfedelia and El Zehab El Abyad dairy villages close to Baghdad. An apparently separate persisting focus of rinderpest infection in the marshes on the Iraq/Iran border close to the Shatt al Arab was disclosed by the detection of rinderpest in buffaloes entering Iran in 1994; an earlier epidemic in Iran in 1987 was also derived from this source. Major demographic changes in this area of Iraq combined with intensive vaccination in 1995 might have eradicated this focus. Rinderpest is known to have persisted until 1994, and might still be persisting, in the northern Governorates of Iraq aided by the instability in the Kurdish areas. Iran was invaded from this source in 1989 and again in 1994.

Recent events in Turkey are enigmatic. The epidemic of 1991 which originated in the east of the country and spread throughout Turkey was preceded by recognition of an outbreak in Georgia and molecular epidemiological evidence indicates that the Georgian virus belonged to the Asiatic lineage including the rinderpest virus which caused outbreaks on the Mongolia-Tuva-Chita Republic border in 1992. The origin of the Georgian outbreak is generally considered to have been Turkey and this is most likely. Rinderpest was again reported in eastern Turkey in 1994 and 1996 but it is unclear whether these related to new introductions or ongoing endemic infection which has persisted since 1991. Sequencing data are accruing which should shed light on the situation if a sufficient number of samples can be obtained for study. In the present circumstances, there can be no certainty that rinderpest is not still being maintained in endemic form in certain remote foci within the country. When reported outbreaks clearly relate to livestock trade through a complex network of livestock exchanges but it has not been demonstrated conclusively that the source is the north of Iraq nor, indeed, outside the country.

Extensive and difficult to control cattle trading, varying in nature and direction with the vagaries of economic conditions in individual countries, such as Iraq's economic decline following the Gulf War and the economic decline and recovery of the CIS Republics, continues to place many countries of the Near East, the CIS Republics themselves and Europe at risk of introduction from persisting foci of infection in the region and possible undisclosed foci further north.

Countries of the Arabian Peninsula present a unique situation. The large demand for fresh meat and live animals combined with the economic strength of most countries generates a massive live cattle import trade. Fortunately most of the cattle are destined for slaughter but on occasions contact with local cattle occurs and prime stock may be diverted for breeding resulting in local epidemics if vaccination coverage is not maintained, as for example in Oman and United Arab Emirates where outbreaks occurred in 1995. Repeated introductions of rinderpest have resulted (e.g. Kuwait, Oman, Saudi Arabia, United Arab Emirates and Yemen), rarely resulting in prolonged outbreaks. The limited virus sequencing data available support the view that the virus introductions originated from South Asia.

The Yemen appeared to be alone in this area in having constituted an area of endemic persistence. Rinderpest was continuously present in that country for more than 23 years despite annual vaccination campaigns and its apparent maintenance appeared at first inspection difficult to explain given the small cattle population, estimated at one million head, and husbandry practices which restrict the majority of cattle to homesteads. In the highland areas cattle are kept in the homestead mainly for milk production, individually or in very small groups. In the lowland areas, such as the Tahama, larger herds are found numbering 10 to 15, occasionally higher. A higher demand for meat is met by imports mainly, but not exclusively, from Africa (Ethiopia, Somalia and Kenya); cattle from South Asia also find their way to Yemen. The Ethiopian cattle present a risk (which is diminishing) as may those from Kenya and southern Somalia, on occasion. Quarantine premises exist for imported cattle at the major ports but it is estimated that only about one third pass through them; the rest are landed at many points along the coast. Imported cattle come into contact with local cattle on arrival, enter markets and a small proportion are retained as breeding stock.

Yemeni farmers customarily change their cows every one to two years. Traders of breeding stock provide them with a service by assembling groups of dairy heifers and cows from the lowlands and take them to the highland areas. They trade the spent cows for higher yielding animals and also purchase young stock from the farmers. The trader with his newly-constituted group then travels on to another village where this process is repeated. As they travel around the country the traders also put their livestock into the numerous markets where they come into contact with those of other traders and those belonging to local farmers who have taken their animal to the market. Unsold cattle return home. The traders then continue their trading from village to village and market to market. Presumably after some time cull animals go for slaughter and salvageable cows and young animals are returned to breeding herds. Thus, there is ample opportunity for disease transmission sufficient to maintain rinderpest infection within the country for protracted periods despite the sedentary husbandry practices. However, an EMPRES mission in 1995 found no evidence for rinderpest presence in the country. It is conceivable that the apparent continuous presence of rinderpest there resulted from repeated reintroductions in traded cattle followed by protracted evolution of epidemics, rather than true endemicity. The two rinderpest viruses from Yemen which have been characterised clearly belong to the Asiatic lineage, suggesting introduction from South Asia in common with the rest of the Arabian Peninsula. This is surprising given the close proximity to the Ethiopian Afar endemic focus and probably indicates that few cattle are traded from this source to Yemen; unofficial trade from the Red Sea coast involves primarily small ruminants. Cattle destined for Yemen through Djibouti and Berbera are probably derived from the Ogaden Region of Ethiopia and northern Somalia which have been free from rinderpest for a considerable time.

The African Continent

Following JP15 which saw the elimination of rinderpest from most of the African continent where it had formerly been present, the disease reemerged in the 1970s to attain again epidemic proportions in the 1980s. There are believed to have been two residual pockets of rinderpest infection; field observations indicate that rinderpest invaded Nigeria from both the east and the west in 1983. This belief is supported by sequencing data which demonstrates clearly that two distinct viruses were present in Nigeria at that time. One source was probably the large pastoral herds in Mauritania/Mali and the other was Ethiopia. Starting in 1975 rinderpest spread progressively from a focus in south-east Ethiopia to envelope the whole country and cross into Sudan in 1977. It took until 1983 for the epidemic to hit eastern Nigeria from Chad at which time rinderpest was entering western Nigeria from another focus which had survived on the Mauritania/Mali border. The combined pandemic involved 18 countries and devastated their cattle populations. The Pan-African Rinderpest Campaign has again reduced the extent of rinderpest infection until only eastern Africa is recognised to be affected. West and Central Africa appear to have been free from rinderpest for several years but this must be verified before it can be accepted and there is no room for complacency while foci of rinderpest exist in East Africa; Nigeria's economic weakness may well be the major reason why rinderpest has failed to recolonise West Africa in recent years.

It is clear that eradication of rinderpest from the African continent is ultimately dependant on eradication of the disease from East Africa where two, or possibly three, independent foci of rinderpest appear to have persisted for many years.

The first covers a large area comprising contiguous areas of the south of Sudan, lowland areas in south-west Ethiopia, north west and west Kenya and north-east and east Uganda. The extensive cattle herds of the related Iteso group of tribes (Karamajong, Turkana etc) have provided a fertile substrate for rinderpest for many decades. The northern boundary of this focus is unclear. A subfocus persisting to the west of Lake Tana on the Ethiopia-Sudan border in the late 1980s and early 1990s could have represented its northernmost extent. However, it is also feasible that this focus was generated from the waves of infection which extended in the past from the north-eastern Ethiopian focus across the highland massif; whatever its origin, current evidence indicates that the focus has been eradicated. From the core in the south of Sudan rinderpest infection spreads repeatedly north along trade routes in Sudan, into the west of Ethiopia and into north-west Kenya. Virus sequencing data indicates that clearly this was the source of outbreaks in Kenya in Marsabit in 1987 and around Nairobi in 1988. This endemic focus is also related to, if not continuous with, the southern Karamoja focus in east Uganda which extends regularly into western Kenya (West Pokot) and probably extended in 1994 into south-east Uganda (Tororo).

The second clearly-defined area lies to the east of the northern Ethiopian highland massif and is occupied by the pastoralist Afar people whose extensive cattle herds range the lowland pastures extending into Eritrea. Transhumant cattle management and raiding bring their cattle herds into contact with those of the neighbouring Kereyu and Issa pastoralists and also the peoples inhabiting the semi-highland areas. Outbreaks in highland areas result from social interaction which involves contract grazing of highland cattle by farmers resident at the highland-lowland interface and by the seasonal trade in draught oxen from the lowlands to the highlands. All available evidence suggests surprisingly that the Afar area had been free from rinderpest until 1976 when infection was introduced along the Rift Valley from south-east Ethiopia. An epidemic ensued followed by endemic maintenance to this day. However, this focus of infection has not been totally isolated. In the late 1980s an epidemic of rinderpest originating in the west of Ethiopia on the Sudan/Ethiopia border spilled across the north of Ethiopia into the Afar country.

In the last half of 1994 some 40 outbreaks occurred in the east of the northern Ethiopian highlands through the trade from the Afar lowlands. Lateral spread was limited and outbreaks were quickly eliminated. Closure of markets, which formed one element of the control measures, resulted in a diversion of trade through markets in the west of the northern highlands and a small number of outbreaks there; these were also quickly eliminated. Eritrea recognised infection in the northern tip of the Afar focus in 1993. Rinderpest occurred in Asmara in trade cattle from Ethiopia Asmara in early 1995 but was quickly identified and eliminated; there was no spread. The Afar focus is yielding to intensive control efforts which have cleared most of the formerly infected area.

The third possible focus has never been clearly defined. In 1975 at a time when most of Africa was free from rinderpest, the disease emerged from south-east Ethiopia. Rinderpest was first recognised in cattle in late 1975 in the southern Rift Valley but its presence had been heralded immediately before when wildlife wardens reported high mortality of Lesser Kudus, giraffe and warthogs to the south-east; mortality was preceded by ocular discharge and keratoconjunctivitis. Reports suggested that the disease had originated on the Somalia border. The disease which was confirmed to be rinderpest spread progressively, northwards along the Rift Valley and then north-east until it entered the Afar country in 1976 as well as west to cross the Sudan border also in 1976. In recent years repeated outbreaks in Arsi and Bale in the south central highlands of Ethiopia suggested spread of rinderpest along cattle trade routes from this conjectured persisting focus of hyperendemic infection in the south-east. However, since the clearance of rinderpest from the southern Afar area, outbreaks in Arsi and Bale have ceased. These observations, together with sequencing data, suggest that the rinderpest in the two areas might have been linked. The connection between Afar and the Arsi/Bale Highlands could well have been traditional systems of migration which link the two areas. Mortality in warthogs occurring in early 1995 close to the suspect area in south-east Ethiopia were investigated and rinderpest was ruled out as the cause. Intensive disease search combined with systematic questionnaire surveys supported by serological investigations indicate that a focus of rinderpest was, in fact, present south of the Bale mountains until 1993 but there is no evidence that it is still present. If this suspected focus of endemic maintenance has in fact been eliminated, then all of the southern border areas of Ethiopia (east of the Omo River) and the Ogaden are free from rinderpest.

The occurrence of rinderpest in the Tsavo National Park of south-east Kenya raises many questions. There is evidence that the epidemic commenced as early as December 1993 with high mortality of Lesser Kudus; spread occurred in a south-westerly direction affecting primarily buffaloes but also other species. In the order of half the buffaloes and the majority of the Lesser Kudus in the area were killed. Disease in cattle appears not to have occurred. Investigations by the Kenyan and Tanzanian authorities seem to have precluded the large game reserves of the Serengeti and Masai Mara-Amboseli as the source of infection. Sequencing data indicate that the virus responsible is distinct from those of the Sudanese and Ethiopian Afar foci and is closely related to 30 year old viruses isolated from wildlife in Kenya and Tanzania. The Kenyan giraffe isolate of 1961 had been associated with a rinderpest epidemic which is suspected to have originated from Somalia. The source of the Tsavo outbreak has not been determined but it is conceivable that it was illegal movements of large mobs of cattle from Garissa (and therefore from Somalia and northeast Kenya) to Mombasa along the eastern border of the park. There is growing evidence to indicate that rinderpest has been present in southern Somalia and north-east Kenya in the last 15 years and certainly rinderpest was confirmed in north-east Kenya in early 1996; only molecular characterisation of the virus present there can resolve this issue but to date this has not proved possible. Until that is done, alternative explanations however unlikely, including long term clandestine maintenance in wildlife, have to be considered. The Kenyan veterinary authorities are leading an intensive disease search programme in the area with the collaboration of the Kenya Wildlife Service and the technical and financial support of the OAU/IBAR, EC and FAO-EMPRES. This work is considered as crucial to the strategy for sustained rinderpest eradication from eastern Africa.

Note: The designation recent indicates areas outside endemic foci where there is clear evidence that rinderpest was present in 1995/96. Some of these may still be harbouring infection. Areas designated as suspect require further epidemiological investigation to define their status; infection might be persisting there.

CURRENT STATUS OF RINDERPEST IN AFRICA

Walter N. Masiga²

1. Introduction

The J.P 15 was reasonably successful in controlling rinderpest in Africa. Mass vaccination campaigns were carried out between 1964 and 1975 and the disease was eradicated from large areas of the continent, but pockets were left in Ethiopia and in the inland delta of the Niger river.

With rinderpest being controlled, the government tended to reduce funding to the State Veterinary Services in real terms. This meant that their ability to control rinderpest as well as other diseases was reduced greatly. When the Pan African Rinderpest Campaign (PARC) was being developed it was realised that as well as controlling rinderpest it was essential to strengthen the veterinary services and place them on a more self sustaining basis.

It is for this reason that some PARC projects have not always been implemented in the way most appropriate for only rinderpest eradication, but also to include restructuring and strengthening livestock services.

Despite these constraints the PARC Campaign has been largely successful in controlling rinderpest in most of Africa. In the early 1980s the disease was present in 20 African countries and during 1995 and 1996 was only reported from three, all in East Africa.

Central and West Africa have been free from the disease for 8 years, with the last outbreak being reported in mid 1988 from the Ghana-Burkina Faso border. A number of countries in West Africa such as Liberia and Sierra Leone have not vaccinated for many years and The Gambia ceased vaccinating in 1988 and is moving down the OIE pathway of freedom from disease.

2. Present Position

Ethiopia

When the Ethiopian PARC project started rinderpest was occurring over much of the country and there was also a war in the northern part of the country.

A very well planned control and eradication programme has been implemented. During the first phase, blanket vaccinations were carried out over most of the country for two consecutive years. This involved vaccinating over 21 million head of cattle using the combined rinderpest/CBPP vaccine. This reduced the incidence of the disease considerably. During phase 2 the veterinary services were strengthened and through clinical and sero-surveillance, the epidemiology and distribution of the disease in the country was better understood. Mass vaccinations were carried out but these were more targeted to the areas more at risk and other parts of the country were not vaccinated. A further 18 million cattle were vaccinated during this phase.

During phase 3 the endemic zones were demarcated and these are the Afar Region in the north east and the south west adjacent to the southern Sudanese border. The disease has not been reported from the previously endemic area west of Lake Tana for over two years. The endemic areas have been surrounded by sanitary cordons and vaccinations in the rest of the country have been stopped. In November 1994 the disease did spread out of the Afar endemic area into the highlands in Tigre. However, with very rapid reaction and probably most importantly, strong political backing, movement control, tracing and vaccination the spread was controlled.

² Director, OAU/IBAR, Nairobi, Kenya.

Following concerted vaccination campaigns in the Afar region using Community Based Animal Health Workers (CBAHWs) and conventional campaigns the disease appears to have been controlled as there have been no reports of the disease in 1996. However, vaccinations and control measures will continue.

The endemic area adjacent to southern Sudan still remains a problem and will remain so while the disease persists in that country. Vaccinations continue in that endemic area and in the sanitary cordon.

During the past year 4.38 million cattle out of a target population of 4.5 million were vaccinated in the endemic and sanitary cordon areas. Vaccinations were not carried out in the rest of the country.

Sudan

Southern Sudan remains a problem. Because of civil strife properly implemented vaccination campaigns cannot be implemented throughout the region. Vaccination campaigns are being carried out by government but this is on a limited scale. UNICEF working through NGOs using CBAHWs and thermostable vaccine are carrying out vaccinations. UNICEF working from Kenya vaccinated 1.3 million cattle between 1989–92, 1.5 million in 1993, 1.8 million in 1994 and 1.1 million in 1985. This is a commendable effort under very difficult circumstances. However, the disease still persists although at a low level. Only two clinical outbreaks were seen in 1995 and one in 1996 but there were most probably more.

A new project has just started, again coordinated by UNICEF, but from Khartoum, to operate in areas more accessible from the north instead of from Kenya. A new project to support the Government in implementing rinderpest control in northern Sudan is being drafted.

Until the disease can be eliminated the policy is to surround the whole of southern Sudan with a sanitary cordon to try and prevent the disease escaping. Because of trade and transhumance movements there is a particular danger of the disease spreading to the west. Because of this, the cordon between Sudan and its western neighbours of Chad and CAR has been strengthened.

Kenya

The disease was diagnosed in the north of Turkana District near the Sudanese border in July 1995 although it had probably been smouldering there for some time. The cattle there do mix with the cattle from Narus in Southern Sudan where the disease was diagnosed clinically in 1994. The outbreak has been controlled.

In mid 1994 there were some deaths in buffalo and kudu in Tsavo East National Park. This was followed by a large number of deaths in buffalo in Tsavo West in November-December, with the animals showing clinical signs of rinderpest. No clinical disease was seen in domestic animals. The areas round the park were revaccinated. It would appear that the disease killed between 50 and 60% of the buffalo and 80% of the Kudu in the ecosystem.

The virus isolated from a buffalo was put into experimental cattle and produced a mild febrile reaction and only one calf showed very mild mouth lesions. The virus has been sequenced and its closest relative is that isolated from a giraffe in northern Kenya in 1961. (RGK1)

Active investigations into the source of the outbreak continue. This involves sampling both wildlife and domestic stock.

In April 1996 samples taken from two calves in Mandera District in north east Kenya were reported to be positive on the AGID test. This was reported to OIE. However duplicate samples sent to Pirbright have all been negative and so have all other samples collected subsequently both from domestic and wild animals. Investigations into this enigma continues. The whole of Mandera District has been revaccinated. Continued active and passive surveillance is continuing.

Uganda

The last outbreak of the disease was in mid 1994 in Moroto district in Northeast Uganda. Vaccination campaigns are continuing with emphasis on the northern half of the country. A new PARC project is starting.

Somalia

Because of the civil strife proper surveillance and control measures cannot be carried out. However, a number of NGOs are operating veterinary programmes coordinated by the European Union and they have not reported any disease. But the possibility of the disease, especially the very mild form, being present in the area west of the Juba river, cannot be ruled out. An FAO consultant who visited the area in March and April 1996 stated. No clinical disease (rinderpest) was observed in Somalia and no specific traceable reports of active clinical disease were received from Somalia since the onset of the rains, although he considered that the disease had been there previously.

We are aware of the problem and will continue to investigate any suspicious reports. The NGOs operating in the areas have been alerted and asked to fully investigate any suspicious cases.

3. Cessation of Vaccinations.

There has been a great reluctance by many West African countries to cease vaccinations despite the fact that the last outbreak in Central and West Africa occurred in mid 1988. The Gambia ceased vaccinations and declared itself provisionally free from rinderpest in 1990 and a number of other countries like Sierra Leone, Liberia and Guinea Bissau have not had the disease or vaccinated for many years.

At the 10^th PARC Regional Coordination Meeting for Central and West Africa held in Dakar in June 1996, the decision was taken by most countries in West Africa to cease vaccinations and move down to OIE pathway to the declaration of freedom from rinderpest. Chad, CAR and Cameroon will continue to vaccinate while the threat of rinderpest from Sudan still exists. Egypt has ceased vaccination and declared itself provisionally free from the disease. Southern Tanzania, southern Uganda and central Kenya have ceased vaccination.

4. Conclusion

Progress is being made to finally eradicate the disease from Africa. The disease is only remaining in areas where there is insecurity which affects control operations. The Community Based Animal Health Workers are being used in these areas to successfully overcome some of these problems.

The strain of virus which is present in part of east Africa is very mild and is not causing a “plague” in cattle. Active searching for the disease is required to pin point where the virus is lurking and then take appropriate action.

We would like to thank the donors particularly the European Union for their financial support and also OAU Member States for the efforts they have made in controlling this scourge.

RINDERPEST ERADICATION IN SOUTH ASIA

K. Rajan ³

India is a federal country and the Constitution provides that the States are responsible for livestock development and animal disease control. The first step for control and eradication of rinderpest in India was taken in 1934 with the development of a suitable vaccine for the disease by the Indian Veterinary Research Institute, Izatnagar. A more focussed approach towards control and eradication of rinderpest was adopted in the early fifties as it was recognized that this disease was a major contributory factor in losses in the livestock economy. Measures for control and eradication of the diseases were taken up as a part of consecutive national development plans. Financial assistance was provided to the State Governments for this purpose.

Nevertheless, outbreaks of rinderpest continued resulting in morbidity and mortality among livestock. In the year 1987, in consultation with EEC, a national project for eradication of Rinderpest in a period of 6 years was formulated. EEC is supporting the project and extending financial assistance to it. The National Project on Rinderpest Eradication (NPRE) was launched on 1.4.1992 with the objective of eradicating the disease by 1998 using the OIE pathway, approved in the 59th General Session in 1991, as a guide line. Since the start of the NPRE, the number of outbreaks of the disease in different parts of the country have been as given below:-

Statewise data about rinderpest outbreaks amongst bovines are given in Appendices I to III. In the year 1996, up to June, we experienced no outbreak of rinderpest and two outbreaks of PPR.

Since launching of the project at the national level with full cooperation of all the States in the union of India in 1992, a systematic and scientific approach to RP eradication has been adopted, using up-dated technology made accessible by the provisions of EC assistance to the programme. For proper coordination, a project management unit was created at Centre and an institutionalized mechanism for regular and periodical interaction with States has been evolved.

³ Secretary, Ministry of Agriculture, Department of Animal Husbandry and Dairying, Krishi Bhavan, New Delhi 110001, India. Fax 91 11 3388006 e-mail [email protected]

The technical part of the programme has to be implemented by all States. Frequent dialogues and interactions are made through on-going system of regional/zonal coordination meetings with state officials and action plans are prepared suitable to their situation.

The project has been managed on the basis of a specific time schedule as both the Government of India and the EC (external donor) are insistent that RP has to be eradicated from India within six years. At the level of Project Management Unit, an effective mechanism for a regular monthly reporting system covering information about disease outbreaks and current vaccination programme was developed. On the basis of these inputs, the Project Management Unit developed a series of annual strategies incorporating mass vaccination of specific areas within States, the creation of safety belts and eventually the termination of all mass vaccination in zones where no outbreaks had occurred for 24 consecutive months. For immunization, efforts were made to produce quality vaccine corresponding to well recognised international standards. In addition, adequate measures are being taken to prevent the movement of infected animals across the geographical boundaries (inter-state and international).

The approach for total eradication of rinderpest is based on the OIE strategy. On the basis of occurrence of rinderpest in the past decade in various parts of the country, India has been geographically delineated into four zones, namely Zone “A” consisting of States in the North Eastern parts of the country, Zone “B” consisting of Northern States in the country, Zone “C” consisting of Southern States and Zone “D” consisting of Union Territories of Andaman & Nicobar Islands, Lakshadweep and Minicoy Islands (vide map).

As a result of various control programmes, in the island territory of the country, and in several States, rinderpest disease outbreaks did not occur after the mid and late 80 s'. As shown in the map an effective programme for intensive sero-monitoring and sero-surveillance work was taken up (details are shown in attached Annex IV & V). For clinical disease surveillance annual village searches, covering all villages, has been made an integral part of the project. During the year 1995– 96, searches were carried out in 140, 936 villages in the country.

India has declared States and Union territories in Zone “A”, B & D as being provisionally free from rinderpest with effect from June, 1994 to which the State of Maharashtra and Goa were added in January, 1996. In all the areas which have been declared as provisionally free from rinderpest, vaccination against rinderpest has been stopped. Only in the event of a confirmed outbreak of PPR among small ruminants, the rinderpest vaccine is permitted to be used because of the nonavailability of specific homologous PPR vaccine. The use of TCRV for prophylactic vaccination of small ruminants has been prohibited in order to avoid complication in sero-surveillance programme. However, this is causing grave difficulties to State authorities who badly need a homologous vaccine. An immune belt to a depth of 30 kms in the districts adjoining Pakistan, Nepal and with Zone “C” States is maintained as a sanitary cordon. Simultaneously, a similar sanitary cordon to a depth of 30 kms is maintained in the districts of Andhra Pradesh, Karnataka and adjoining Zone “B” making the immune area as 60 kms wide.

Even in the Zone “C” States, consisting of Karnataka, Kerala, Tamil Nadu, Andhra Pradesh and Union territory of Pondicherry, there have been no outbreak of rinderpest in Karnataka and Kerala in the last 15 to 18 months (vide table).

The occurrence of bovine rinderpest in the States of Andhra Pradesh and Tamil Nadu have also very significantly reduced. In Tamil Nadu no outbreak of bovine rinderpest was seen in the last 10 months.

In Zone “C” the Government of India and the State Governments have decided to intensify the vaccination work covering all susceptible population in border districts and undertake systematic regulation of movement of animals. In addition to exercising the legislative provisions included in various State Acts on prevention of spread of contagious animal diseases, a systematic disease surveillance has been carried out clinically and in the laboratory by doing village searches, serosurveillance and monitoring. At least in 1994 and 1995, we believe, that most outbreaks occurring in small ruminants in Zone “C” were due to PPR. Technology transfer for the differential diagnosis of RP from PPR using Immunocapture ELISA is taking place at present.

By March, 1997, it is expected to complete the intensive vaccination programme in the Zone “C” States. We anticipate that as a result of these measures there would be no case of rinderpest occurrence throughout the Indian territory by the middle of next year. Further by that time, the requirement of a two year period of the absence of clinical case of rinderpest in Southern States would be fulfilled for us to proceed for declaration of Southern Peninsular States as provisionally free so that the entire country could be shown as free from rinderpest in about three years time.

India has borders with Pakistan on the West, Nepal and Bhutan in the North, Bangladesh and Myanamar in the East. Many of these countries have not had outbreaks of rinderpest in the recent past. To the South, Sri Lanka last reported an outbreak of rinderpest in 1994. No outbreak of rinderpest has been reported after that. The vaccination programme has been stopped on Indian borders with Bangladesh. Discussions have been undertaken with the Royal Government of Nepal to suspend the vaccination programme across the Indo-Nepalese border. Nepal last reported an outbreak of rinderpest in 1991. Bhutan reported in 1994 that there has been no outbreak of rinderpest in the country since 1969. For some decades now Bangladesh has not reported any incidence of rinderpest.

Conclusion

There are seven countries in the SAARC region. In the long run the livestock economics will fail or prosper together. Most countries including India are now in a favourable situation in eradicating RP in the stipulated time frame provided there is no threat of recrudescence of outbreak from infected countries. We strongly advocate that the whole of the region achieves freedom from rinderpest in the shortest time remaining, taking into consideration the GREP objective of making the globe free of rinderpest virus.

* : false positive as determined by FAO Reference Laboratory

Notes:
Last reported bovine outbreak in Kerala occurred in October, 1994
Last reported bovine outbreak in Karnataka occurred In January, 1995
Last reported bovine outbreak in Andhra Pradesh occurred in February, 1995
Last reported bovine outbreak in Tamil Nadu occurred in September, 1995

CURRENT STATUS OF RINDERPEST IN PAKISTAN AND AFGHANISTAN

Rafaqat H. Raja ⁴

INTRODUCTION

Rinderpest is known to have occurred in cattle and buffaloes in Pakistan since the beginning of this century. Two epidemics were recorded in the 1950s when hundreds of thousands of animals died. Since then the disease has smouldered with occasional outbreaks causing substantial losses in all provinces. Rinderpest remains endemic in the Landhi Cattle Colony near Karachi and possibly in other cattle colonies. For some years it was considered that Rinderpest did not occur in Pakistan, possibly because of confusion in diagnosis between Rinderpest and other conditions such as mucosal disease, bovine viral diarrhoea and foot and mouth disease. Nevertheless it is particularly certain that much of what was reported as “Rinderpest like disease” was in fact classical Rinderpest. Clinical field diagnosis together with results from the Central Veterinary Laboratory, Sindh since 1991 indicate that Rinderpest has occurred sporadically through-out each year in many places in Sindh Province.

There is constant circulation of Rinderpest virus in Landhi Cattle Colony, fuelled by the continuous introduction of susceptible animals under its rather unusual management system in which animals constantly leave for mating and return at the beginning of the next lactation. There is little doubt that Landhi Cattle Colony is the source of much of the Rinderpest infection in Sindh and probably also in other parts of the country. The disease also occurs sporadically in other areas. It is probable that Rinderpest is enzootic at very low prevalence over much of the country.

Although severe mortalities were reported in epizootic of Rinderpest in earlier decades, large scale outbreaks have not been reported for sometime and areas where vaccination has been undertaken. This is probably due in part to lack of field disease investigations and reporting and partly to a change in the epizootiology of Rinderpest in Pakistan following the earlier vaccination of the stock. This may have resulted in partially immune population in which low levels of Rinderpest virus could cycle, causing more chronic, low-level infection compared to the intermittent but explosive episodes of the past. Recently a major epizootic has been reported from Northern Areas in Gilgit and Hunza Valleys where about 30,000 animals have died between April 1994 to May 1995.

In September an outbreak of Rinderpest in Khost Region was reported by FAO Afghan Project in Islamabad. FAO, Rome responded to the problem with an emergency vaccination campaign. Khost is immediately adjacent to Pakistan and infection was said to have been introduced through the importation of cattle from Sargodha District of Punjab Province of Pakistan. Although Rinderpest was confirmed near Lahore in 1994 it has not been suspected near Sargodha although a severe outbreak of a Rinderpest-like disease occurred at Shah Jeewna nearby Jhang in 1988.

CURRENT STATUS OF RINDERPEST IN PAKISTAN

The Northern Areas: According to the investigations of Mr. Paul Rossiter, Lead Consultant during November–December, 1995 and by Dr. Manzoor Hussain, National Consultant during May, 1996, only one small and apparently confined focus of disease at Khaplu has been confirmed. According to the Animal Husbandry Department, Northern Areas sporadic cases are being reported but occasionally on investigation the disease is H.S. It is believed that virus is circulating in the Northern Areas cattle population however, epizootics are not recorded because of vaccination and re-vaccination of about over 60% of cattle population by now.

⁴ Deputy Animal Husbandry Commissioner, Ministry of Food, Agriculture and Livestock (Livestock Wing), Islamabad, Pakistan.

Karachi: The dairy yards of Karachi, especially the Landhi Colony, are endemically infected with Rinderpest. Many have close links with farms in the interior of Sindh, Punjab and Balochistan. In the past outbreaks of Rinderpest directly attributed by the affected farmers to movement of animals from Karachi have occurred at Quetta (1986–87) and in Punjab (1988). It is difficult to assess the amount of direct movement of livestock from Karachi to Afghanistan but some almost certainly does occur with attendant risk. More usually, Karachi animals pass through parts of Balochistan especially Quetta before entry into Afghanistan.

Balochistan: A report from a trader in Bhalwal cattle market stated that his brother had seen Rinderpest in Quetta in October, 1995. This was later confirmed by the Director, Veterinary Services, Balochistan. The risk of transmission from Quetta to Afghanistan is high. Traders in Bhalwal also reported that Iranian cattle dealers buy cattle and buffaloes in Quetta to sell in Iran.

Punjab: According to the various reports Rinderpest has occurred almost annually in Punjab. Nevertheless, there is no convincing evidence that Rinderpest in Punjab is maintained independent of introduction from Karachi. There is a possibility that sporadic, localised epidemics of Rinderpest frequently occur in Punjab probably as the result of infection from Karachi. However, why they do not spread to become large clearly recognisable pandemics in the largely unvaccinated population of 20 million bovines is difficult to determine.

In conclusion, the dairy colonies of Karachi are endemically infected with Rinderpest and any trade with them, transboundary or otherwise, carries a very high risk of transmitting the virus to a new location. The Northern Areas are still definitely infected but the risk of transmission to neighbouring areas other perhaps than Chitral and Azad Jammu and Kashmir is not high. The possibility of transboundary spread of Rinderpest from the other provinces of Pakistan is probably greater than the risk from the Northern Areas. The control of animal movement is impossible.

CURRENT STATUS OF NATIONAL RINDERPEST PROJECT

The European Commission Project Formulation Mission has visited Pakistan during January-February, 1996 and assessed current situation. They have identified project components including mass vaccination, disease monitoring and surveillance and strengthening of vaccine production and distribution system. Their final Report is yet awaited. It is expected that the Report will be made available by the end of this month. After the Report is received project proposal will be submitted to the Planning and Finance Ministries for approval of the Government of Pakistan. It is expected that project will be launched by July, 1997.

CURRENT STATUS OF RINDERPEST IN AFGHANISTAN

According to the field investigations by Dr. Paul Rossiter during December, 1995 the Rinderpest was widely spread in Khost. Rinderpest has been reported and later confirmed in a number of widely apart villages in Khost such as Lakan (Shamal) and Ismail Khile. FAO, Afghan Project in Islamabad undertook mass vaccination with the collaboration of local vets and para-vets and since February, 1996 no disease outbreak has been reported. It is believed that virus may be circulating and it may spread to neighbouring part of Afghanistan and Pakistan if rapidly and carefully planned vaccination is not undertaken properly.

THE CURRENT RINDERPEST SITUATION IN THE NEAR EAST, MIDDLE AND CENTRAL ASIA

Gholam Ali Kiani⁵

EPIZOOTIOLOGICAL BACKGROUND

From time immemorial until now rinderpest regularly devastated cattle and buffalo in Asia and the Near East and especially in West and South Asia with so many economical losses.

During the 1990s several outbreaks have occurred in this region (I.R. Iran, Afghanistan, Iraq, Turkey, Pakistan, Saudi Arabia, Oman, UAE, Mongolia, Russia, …).

Some of these countries have been cleared of the disease but rinderpest is remaining in many other countries in the region and damaging animal health and production.

Rinderpest complicates the situation in the region due to a lack of education and other factors such as social, financial problems and war. The needs are:

1. vaccine

2. vaccination campaign

3. equipment and cold chain

4. monitoring, surveillance and diagnosis (clinical and laboratory)

5. control of movement and animal trade

6. reporting system

CONCLUSION

Eradication of rinderpest in the endemic area in this part of the world requires:

1. more financial resources for implementation of vaccination programmes

2. vaccine and equipment

3. clinical and serological surveillance

PROPOSED CONTROL POLICY

1. Detect endemic foci in the region by clinical and sero-surveillance

2. implement vaccination campaign

3. establish vaccine bank

4. establish diagnostic laboratory

5. monitoring and evaluation of rinderpest vaccination

6. establish border quarantine and movement control

⁵ Director of Animal Disease Control and Rinderpest National Coordinator, Veterinary Organisation, Ministry of Jihad-e-Sazandegi, Teheran, Islamic Republic of Iran.

^* since 1990 sporadic cases

EPIDEMIOLOGICAL AND CLINICAL FEATURES OF RINDERPEST IN THE 1990s

Paul Rossiter ⁶

Classically rinderpest has two main disease patterns. Epidemic rinderpest, at its worst the feared cattle plague, occurs when virus from an endemic or sporadically infected area is introduced to a population of cattle or other species that have little innate resilience to the clinical disease and which have low or non-existent herd immunity. Under these circumstances the virus spreads rapidly with high morbidity in animals of all ages and increasingly high case mortality rates that may exceed 90%. Serology shows that immediately after an outbreak virtually all of the animals in infected herds have high titres of antibody to the virus. Subsequent samplings then show that stock born after the end of the outbreak have no antibody. In contrast endemic rinderpest is generally believed to occur in populations of cattle in which the virus is maintained by transmission within the continual supply of young stock. Morbidity rates are comparatively low, perhaps less than 20%, and case mortality rates much lower still perhaps undetectable in animals without concurrent infections. Serological surveillance would reveal that a very high proportion of the older animals in such populations have antibody to the virus (in fact endemic rinderpest in unvaccinated cattle has never been studied, the introduction of suitable techniques in the 1960s coinciding with the development and widespread use of cell-culture vaccine. The best available results come from studies of the Serengeti-Mara wildlife species in the early 1960s). Using these basic patterns, which have been supported by computer simulations, it is possible to classify most outbreaks into one or other of these two main types though in the field some outbreaks may appear to be intermediate between these two extremes such as when the disease seems to cycle in a widespread area returning to affect herds every three to five or more years.

Epidemiological features in the 1990s

In the 1990s all the basic patterns of the disease have occurred in the infected areas of Asia, Africa and the Middle East. Classic cattle plague killed perhaps 40–50,000 hill cattle within a year (1994–1995) in the Northern Areas of Pakistan before finally being controlled by vaccination. The population of wild buffaloes in the Tsavo National Parks of Kenya declined by over 60% and the lesser kudus by 90% in 1994–1995 at which time severe clinical rinderpest was confirmed in them.

In parts of southern Sudan mortality rates of 40% or more affect younger stock every one or more years. Mortality rates in the Sanga cattle of the infected Afar region of Ethiopia and Eritrea similarly are often higher than would perhaps be expected in a classic endemic situation such as seen in the East African zebus of the Maasailands in the early 1960s.

Currently perhaps the mildest form of rinderpest in the world today is in the Horn of Africa. The confirmed rinderpest in wildlife in southeastern Kenya has not been seen in nearby cattle and experimental infections with virus from infected wildlife have shown that the unique genotype of virus responsible produces only a very mild disease in cattle. A similarly mild syndrome was detected in young cattle in Kenya near its borders with Somalia and Ethiopia. The disease was not a priority for the stockwners and elucidation of the true extent and epidemiology of this virus is at present a priority for PARC. So far investigation has not yet found a population of cattle or other species where the pattern of endemic rinderpest is evident.

⁶ FAO Chief Technical Adviser, Strengthening of Epidemiology Component for the Pan African Rinderpest Campaign Project (GCP/RAF/317/EC), P.O. Box 30786, Nairobi, Kenya.

However, many anomalies exist. Rinderpest is constantly present in the huge Landhi Dairy Colony of Karachi but it is difficult to say strictly whether it is endemic or a static epidemic in which susceptible adult animals are brought to the virus rather than the virus moving through a susceptible population. Also in Pakistan is the challenging situation whereby localised outbreaks occur sporadically within the main population most of which is not vaccinated. Why these outbreaks, not all of which are likely to have been eradicated by local vaccination campaigns, do not erupt into huge epidemics is at this stage uncertain and will require more detailed investigation supported by serology. Until very recently clinically severe rinderpest was prevalent in the hilltop cattle of Yemen and considered endemic though how the virus transmitted and maintained is far from understood.

Not surprisingly the outbreak of disease in Tsavo, apparently affecting only wildlife, resurrected the old question of a possible wildlife adapted strain that might be ineradicable unless of course the wildlife itself is removed (as is in fact happening). However, the disease pattern in the wildlife is classically epidemic and serology of adult wildlife in immediately contiguous areas show them to be antibody negative, an unlikely scenario if the virus was endemic in wildlife in the region. In South Asia the long held belief that rinderpest was maintained in sheep and goats is being reconsidered now that most isolates of the virus involved in these outbreaks have been confirmed as the closely related virus of peste des petits ruminants. Nevertheless, rinderpest is still being confirmed in small ruminants in southern India where the incidence of cattle rinderpest has declined almost to zero.

Questions still remain about the epidemiology of rinderpest. Do all outbreaks fit within classic predictable patterns or are there some situations in which husbandry practises and vagaries of host and virus might combine to produce new patterns of infection that might evade detection? The latter seems unlikely but eradication surveillance must be thorough enough to detect infection which may be persisting at low prevalence levels in quite localised populations or possibly circulating within trade routes.

Is it sufficient for rinderpest simply to be either epidemic or endemic? Can endemic rinderpest exist in a population in which most of the animals are susceptible? Is it possible to have a prolonged epidemic of clinically mild rinderpest?

Fortunately the tendency for some observations to fall outside predicted classical patterns is not restricted to ways in which the virus might evade eradication and appears equally to work in favour of eradication. During the recent epidemic in northern Pakistan a goat was found with mild rinderpest, later confirmed in the laboratory, and it was thought that this might have important epidemiological significance. But when sera from goats and sheep in the same village were examined for antibody a few months later a very low prevalence, less than 5%, was found. This was welcome news for control but if the virus could infect some goats why did it not then spread throughout the other goats which it had ample contact with? Rinderpest appears to have been eradicated from West Africa but analysis of the vaccination campaigns and serology during and before this period suggests that factors other than mass vaccination must also have been involved. Similarly the incidence of cattle rinderpest in India has been declining steadily over the past five years but there is no conclusive evidence that this is due to vaccination or herd immunity.

Clinical features

The range of clinical signs seen in the reported outbreaks in the 1990s have all been described in the text books: cattle plague in Pakistan; severe outbreaks in West Asia; mild disease in cattle in East Africa; typical severe disease in hypersusceptible East African wildlife; and mild disease in sheep and goats. What the 1990s outbreaks do show is that the complete range of clinical syndromes of rinderpest are still present in the world today. The outbreak in northern Pakistan is perhaps the best example of cattle plague in the world for twenty years. The recently discovered mild disease in northeastern Africa has demonstrated to some investigators that such forms of the disease do indeed exist though similar outbreaks in Africa were described in the 1940s and 1960s. The significance of eye and skin lesions in wildlife has been clearly demonstrated such that some earlier observations of similar signs can now be confidently attributed to rinderpest.

Summary

It would seem that all the classic epidemiological and clinical features of rinderpest are still present in the infected areas of the world. There is no evidence for new forms of rinderpest that might evade customary control and eradication measures and only people and politics stand in the way of global eradication.