The threat of contagious bovine pleuropneumonia and challenges for its control
in the SADC region

F. L. Musisi^[2], B. Dungu^[3], R. Thwala^[4], M. E. Mogajane^[5], and B. J. Mtei^[6]

Introduction

Contagious bovine pleuropneumonia (CBPP) is currently considered one of the main deterrents to the growth of the livestock industry on the African continent. It is the only bacterial disease in the OIE list A diseases. CBPP is caused by Mycoplasma mycoides subspecies mycoides Small Colony (Mmm SC). The endemic form is characterized by hyperthermia, nasal discharge, cough, and rapid and difficult breathing. However, in many African countries where the disease has reached an endemic form, it is difficult to detect affected animals due to reduced clinical manifestations, mostly as a result of antibiotic treatment. In these conditions, a large proportion of animals become chronically infected; the so-called “lungers”, and have encapsulated lesions in the lungs.

In the 1960s and 1970s, sustained research on CBPP in Kenya, Chad and other African countries, coupled with a massive international campaign - code-named Joint Project 16 - resulted in the disappearance of clinical disease from most parts of Africa (FAO, 2002). However, because of economic decline and poorly financed veterinary services, the disease made a spectacular comeback in the late 1980s and early 1990s (Kusiluka, 2003; Provost, 1996). Today, more countries are affected by CBPP than there were 20 years ago either as an endemic or re-emerging disease or in epidemic form. Yearly losses directly or indirectly attributable to CBPP are estimated to be around US 2 billion (Masiga et al., 1999).

The Directors of Veterinary Services/Chief Veterinary Officers of the SADC Region have drawn up a 16-year regional strategy for transboundary animal diseases, during their workshop in Pretoria on 22 and 23 July 2003. In doing so, they have categorized TADs for SADC as follows:

• Strategic - FMD, CBPP;

• Tactical - ASF, RVF, NCD, LSD;

• Emerging/Exotic to SADC - rinderpest, PPR, BSE and AI.

Therefore for the SADC region, CBPP is regarded by Member Countries as a disease of strategic importance for which the CVOs will be seeking internal and donor funding for its progressive control leading to a SADC without CBPP over the next 16 years. This paper summarises the outcome of the workshop of the SADC Directors of Veterinary Services/Chief Veterinary Officers.

The threat to the SADC region

Currently CBPP-affected countries within SADC are Angola, Zambia, Tanzania, Democratic Republic of Congo (DRC), and northern Namibia. Countries with affected neighbours are Malawi, Botswana, Mozambique, Zimbabwe and Namibia. Thus these countries are at risk of CBPP incursion or invasion. In Angola, CBPP is endemic and there has been no control strategy for years due to civil strife; thus there is constant incursion into Zambia and Namibia with threats to northern Botswana.

The threat to the cattle industry in SADC is probably best illustrated by SADC’s meat export position in comparison to the rest of the African continent. Cattle farming constitute an important component of the agriculture production in the SADC region, occupying a large proportion of the population. Even though its 53 million head of cattle represent only 22% of the cattle population on the continent, the SADC region alone exports more meat than the rest of the continent. In 2001, the SADC exported 84% of meat and meat products from Africa, for a value of US$ 199 million versus US$ 236 million for the entire continent (Figure 1). Most of this export is attributed to Botswana, Namibia, and Zimbabwe, where many rural and urban livelihoods are dependent on this trade. For some of the countries in the region, such as Botswana, meat and meat products export represents the main agricultural product export, accounting for approximately 70% of the total agricultural product exports. The potential for export of meat and meat products from the other countries, namely Tanzania, Zambia and Angola ravaged by CBPP cannot be fully realized.

The lessons from the re-introduction of CBPP into Tanzania and Zambia are that once the disease is allowed to establish itself, it becomes difficult to eradicate, and that where it has been eliminated, it is at a great cost as exemplified by Botswana, which lost more than 300,000 cattle through the stamping out exercise before regaining freedom status. The current CBPP spread will affect trade interests in the region as will be illustrated in countries that experienced in the past or are experiencing the disease now.

The threat is at three levels, household, national and regional and is well illustrated in examples given below from the SADC countries of Botswana, Namibia, Tanzania, and Zambia.

The disruptive effects of CBPP

CBPP is one of the animal disease emergencies whose effects as FAO outlined include, (a) compromising food security through loss of protein/draught power, (b) major production losses, (c) increased production costs due to costs of disease control, (d) disruption of livestock/product trade, (e) inhibition of sustained investment in livestock production, and, (f) pain and suffering to animals (Paskin, 2003; Geering et al., 1999).

According to FAO (1990) animal disease constraints are thought to cause losses of up the 30% of annual livestock output in developing countries and where attempts have been made to measure the actual economic impact of livestock disease outbreaks, the results have been frightening. For instance, in 1995 re-introduction of CBPP in Botswana led to the slaughter of 320 000 cattle at a cost of US$100 million, with further indirect losses estimated at over US$400 million (Geering et al., 1999).

Vulnerability of smallholder households

The CBPP impact at national level indicated above for Botswana seems impressive but it is also necessary to examine the effects on poor resource households with small herds of cattle. This is especially important since according to the Minister of Agriculture, Botswana, nearly 80% of the livestock in Botswana is in the hands of smallholder management (J. K. Swartz, 2003). The effects of CBPP on households in Namibia highlighted below would equally apply to Botswana.

The impact at household level can be very crippling. According to Paskin (1995) this was clearly illustrated in interviews of pastoral households in Namibia who strongly feared CBPP despite the fact that the last epidemic had occurred decades before. The fear of the disease was such that vaccination campaigns instigated by the Veterinary Services enjoyed enthusiastic support, even during a period when CBPP was relatively quiescent. Thus the suffering caused by the well-known CBPP epidemic of 1860 was still well remembered by the Herero people of Namibia and 1860 has been given a special name - Otjipunga - the ‘year of the lung’ (Schneider, 1994). These families had no source of livelihood other than their stock thus their main source of protein was milk so such an outbreak would have alarming effects at household level.

In a study involving an agro-pastoral society in Namibia, Paskin et al., (1996) reported that the average herd size was 35 but the majority of households surveyed had relatively small herds, ranging from 10-20 animals and CBPP was rampant in the area and most owners reported it as a problem. In such a situation, a mortality rate of only 50% could reduce a herd of 10 animals to only five, with frightening implications in terms of draught power and family milk supply. A high level of dependence on livestock, combined with relatively small herd thus makes smallholder farmers very vulnerable to the effects of epidemic diseases such as CBPP (Paskin, 2003).

Threat in Tanzania

Njau (2003) reported that CBPP and FMD were number one and two priority diseases for Tanzania after rinderpest. CBPP affects Tanzania’s participation in international trade of animals and animal products, and is a constraint to improved livestock productivity.

CBPP was re-introduced into the Northeast and Northwestern parts of the country in 1990 and 1991 from Kenya and Uganda, respectively, after being absent for some 25 years and moved with trade stock to Morogoro in central Tanzania. Since its re-introduction, CBPP has been reported to spread to 54 out of 120 administrative districts of Tanzania (Kusiluka and Sudi, 2003). The geographical spread of CBPP is shown in Fig. 2 by the yellow shaded areas. The losses and population at risk for the period 1998 to 2002 are indicated in Table1. The Tanzania-Mozambique international border may not pose serious threat regarding CBPP spread because it has low livestock numbers that are mostly sedentary but the Tanzania-Malawi and Tanzania-Zambia borders (Mbeya, Iringa, Rukwa) are potentially problematic since pastoralists from the north have moved into these areas recently. It is estimated that 350,000 cattle, valued at Tanzanian shillings 40 billion (i.e. about $40 million), have been lost so far. Kitalyi and Njau (2003) estimated that CBPP is responsible for a compounded annual loss of approximately USD 3 million nationally.

Njau (2003) attributed the persistence of CBPP in Tanzania to the following:

• The disease does not lend itself to simple control measures like vaccination because vaccines currently in use do not confer long lasting immunity;

• Re-invasion occurred when Tanzania was in economic turmoil, which impacted the veterinary department for several years thus allowing the disease to flourish to levels that national resources alone cannot contain;

• The lack of comprehensive studies on the socio-economic impact of CBPP thus making it difficult to convince decision-makers to avail money for its control.

As indicated above, CBPP affects the country’s international trade in livestock and livestock products. Tanzania aspires and plans to establish a disease free zone (DFZ) in order to increase livestock and livestock product export by 6% per annum starting from 2008. An excellent candidate for DFZ is the area south of the central railway line currently with low livestock numbers but good carrying capacity because of reliable rainfall and low prevalence of transboundary animal diseases, and is far from the traditional entry points for ruminant livestock diseases and historically it is the last to be affected. However, with the threat of CBPP spreading even further south beyond the current distribution shown in Fig 1, it is impossible to establish this DFZ thus further constraining Tanzania’s livestock development and its contribution to improvement of the national economy. Thus lost trade opportunities -Tanzania with the largest cattle population in the region cannot benefit from related trade opportunities.

Threat in Zambia

In Zambia, CBPP was re-introduced in 1996 after 23 years in the Western Province of the country from Angola and as late as 2003 outbreaks have been reported (EMPRES-Livestock, 2003). It has since spread to Northwestern Province as shown in Fig.3 and is threatening the Copperbelt Province. It is also feared that the current CBPP situation in Zambia is a great threat to both the cattle population in Zambia and neighboring countries to the south. Like in Tanzania, CBPP is rated the most threatening transboundary animal disease in Zambia. It is blamed mainly on illegal cattle movements. Cases of incursions from Tanzania into Zambia have not been documented but the threat is real as clearly indicated in Fig. 2.

Threat in Angola

CBPP has been considered endemic in Angola since its presumed introduction in the 19^th century from South Africa (FAO, 1996). Despite continuous vaccination campaigns, the disease has been established in the Southern provinces, which accounts for 95% of the country’s estimated 3.5 million cattle (FAO, 2002). Due to the civil strife that disrupted normal governance including provision of veterinary services and adequate disease surveillance over nearly 3 decades, population movements have contributed to the spread of the disease north- and westward, as well as constituting a continuous threat to neighbouring countries. The limited vaccination campaigns and other control measures that have been sustained and supported by the Angolan government and the FAO are indicated in Table 2. Sadly, it appears that these measures have not prevented the spread of the disease, which still require a proper assessment.

The neighbouring countries of Namibia and Zambia have suffered from the CBPP incursions resulting from cattle movements with the refugees. However, it is now hoped that with the return of peace, better and realistic assessment of the CBPP situation can be made and national and regional strategies for its control implemented.

Regional level - SADC

In a recent workshop of Chief Veterinary Officers (CVOs) in SADC in July 2003, participants in the workshop identified two areas of concern, namely:

1. Southern Angola/Western Zambia/Northern Namibia;
2. Southern Tanzania/North-eastern Zambia/Northern Malawi.

Thus these are the current epidemiological clusters requiring immediate attention in terms of arresting the spread of the disease in the SADC region.

The challenges to CBPP control in SADC

Over many decades, CBPP control has basically relied upon cattle movement control and vaccination campaigns. Unfortunately, with increasing budgetary constraints and changes in administrative structures, e.g. creation and devolution of power to local government authorities (LGAs) that are demanded by international financial and other donor institutions to be implemented in the affected countries, these two key control measures have become difficult to implement effectively. For instance, the decentralized local administration might not consider CBPP or animal disease control a priority while the neighboring LGA does. Moreover, in some LGAs those in-charge of the decisions on livestock production have either very little or no comprehensive knowledge on animal disease issues. Furthermore, in some countries there is undefined responsibility for disease control between the LGAs and the central veterinary services authority.

The challenges that SADC countries face individually and collectively are implementation of effective cattle movement control, vaccination programs, active and passive surveillance, and plans for emergency preparedness.

Illegal cattle movements

The factors that make effective control of illegal movements of cattle difficult are many. These include socio-cultural ties between cross-border communities, political instability, trade associated with strong and weaker currencies, and lack of credible national animal identification systems. Many cross-border communities have similar ceremonies like dowry, funeral rites, initiation into adulthood, etc. in which donation of cattle is routine and which find restriction of passing on of the gifts offensive. Similarly, political instability linked to civil strife has lead to internal displacements and the imposition of refugee status of people and their livestock, this has been the case in Angola with Namibia and Zambia, and the case in Tanzania in regard to neighbouring countries of Uganda, Rwanda and Burundi. Trade associated with strong and rapidly depreciating currencies of neighboring countries continues to be a major factor; it drives communities from the disadvantaged side to seize the opportunity to acquire the powerful currency and improve the purchasing power while equally the advantaged side views the goods from the other side as cheap. This could be playing out in the Angola-Namibia situation just as it has done in the case of FMD between Botswana and Zimbabwe. Under these situations, the interested parties will do their utmost to avoid using normal cattle routes. Lack of well established national animal identification systems coupled with weak enforcement of legislation further undermine implementation of effective control of illegal movement of animals; the weak legislation was cited by Njau (2003) as contributing to the ineffective CBPP control in Tanzania. Where effective animal movement control exists, there are not always clear or updated indications on the requirements. The decision on issuance of permits is not always based on verifiable facts. In other instances, there are no clear indications on the required competence of the issuing authority.

Ineffective vaccination programmes

The factors contributing to vaccination programmes being ineffective include failure to adhere to the recommended vaccination regimes, several vaccine administrations in a relatively short period of time, disparities in budgetary support for countries in the region, reluctance of cattle owners to participate fully in the programmes, lack of common strategy and regional control programme, and lack of credible national animal identification systems. Njau (2003) attributed the persistence of CBPP in Tanzania, in part, to the disease not lending itself to simple control measures like vaccination because vaccines currently in use do not confer long lasting immunity. Inability to confer long lasting immunity dictates several administrations of vaccine in a relatively short period imposing undue pressure on logistics required for realisation of a successful vaccination programme. Reluctance of cattle owners to participate fully in vaccination programmes may, at times, result from occurrence of untoward vaccine reactions, cost recovery schemes, and others (Dungu, 2003). Disparities in budgets for disease control in the neighbouring countries coupled with lack of common strategy and regional control programmes further erode the effectiveness of the vaccination programmes; a good example of this is failure of neighbouring countries to harmonise and effect vaccination at the same time along common borders. This equally applies to neighbouring LGAs.

Credible surveillance systems

Many of the countries do not have credible active surveillance systems mainly due to limited availability and/or inappropriate use of available expertise. Njau (2003) reported that, amongst others, inadequate disease information, vaccination coverage and uncontrolled cattle movements pose a serious risk of spreading to neighbouring countries. In many affected countries, indication of the CBPP problem is given by abattoir inspection figures, which are thus derived from passive surveillance. Moreover, while valuable data can be obtained from examining lungs at slaughter, according to Bamhare and Kohrs (1999), in CBPP high-risk regions, animals are subjected to quarantine before slaughter thus eliminating visibly infected animals. Similarly, cattle owners tend to withhold cattle for fear of outright condemnation thus encouraging owners to dispose of such animals at “bush” abattoirs where there is no veterinary supervision. Both of these actions result in a lower estimation of the magnitude of CBPP in given populations. Active surveillance is thus required to make a better assessment of the disease status; this further demands accurate identification of individual herds, sources of infection, traceability of origin and all the contact herds.

Contingency plans

Unfortunately, for various reasons but mainly expertise and budgetary constraints, many countries in the region do not have “Emergency preparedness/Contingency plans” (EPPs) for dealing with CBPP outbreaks. This situation persists despite the recommendation on EPPs at the FAO Expert Consultation on EMPRES - Livestock Diseases Programme (FAO, 1996).

Studies to clarify role of carriers and “lungers”

It is also noted that there is an urgent need in SADC region for proper studies on the role of carriers in the epidemiology of CBPP. In a study in Tanzania small ruminants were implicated in the epidemiology of CBPP but since that report has ever been further investigations to confirm or show otherwise (Dungu, 2003; Kusiluka, 2000). These issues and the role of “lungers” remain a challenge and need to be clarified.

The way forward

In a recent CVOs’ workshop, geographical areas of concern were identified into epidemiological clusters that transcend national boundaries. Two phases to tackle the CBPP problem in SADC region were proposed, namely an emergency phase and a recovery phase. Thus the emergency phase would tackle the two geographical areas described earlier, namely Southern Angola/Western Zambia/Northern Namibia and Southern Tanzania/North-eastern Zambia/Northern Malawi.

The emergency strategy devised by the CVO workshop included the following key elements:

• Emergency vaccination of all cattle (i.e. 3 rounds at 0, 3 and 9 months) in the 12 Districts of Southern Tanzania bordering Zambia and Malawi, with possibly buffer vaccination of the contiguous northern areas of Zambia along the Zambia-Tanzania border;

• Emergency vaccination of cattle in Western and North-western Zambia to prevent further spread towards the Copperbelt and central Zambia;

• Heightened surveillance and movement control (Zambia/Malawi/Tanzania/Mozambique);

• Public awareness campaigns (Zambia/Malawi/Tanzania/Mozambique);

• Role of farmers - commitment to controls through heightened awareness (need for awareness tools); animal identification important for tracing and record of vaccination; community-participatory disease searches;

• Role of Veterinary Services - provide access to laboratory diagnostics, responsible for extension, must have a secure and direct chain of command, and a proper contingency plan with elaboration of responsibilities;

• Veterinarians must elaborate strategies that are practical and realistic to convince politicians;

• There is a requirement for economic impact assessments to illustrate importance of CBPP and other TADs.

Other observations of importance:

• Disease reporting to regional unit epidemiology currently poor, needs to be improved;

• SADC lacks a permanent structure for handling emergencies - this must be addressed;

• Industry role - with CBPP, transporters and traders are strongly affected - private sector should be lobbying government, and could assist with public awareness;

• Government must create the climate in which the private sector will feel it safe to invest;

• Vaccination must be free of charge;

• Proper economic assessment important.

The identified milestones of importance were:

1. Baseline study to assess size of population and incidence/distribution of disease;
2. Monthly feedback on vaccination coverage;
3. Assessment of vaccine impact (repeat study);
4. Assessment of status of neighbours at risk.

The workshop also devised a 15-year program for the control of CBPP in the region along the framework indicated in Annex 1 (at the end of this article).

The workshop defined the goal for control of the major transboundary animal diseases (CBPP and FMD) in SADC as “Sustainable food security, poverty reduction and equitable access to markets”. The purpose is “to progressively enhance livestock as a tradable commodity through assured animal health”. The goal and purpose are based on the concept of “progressive control of FMD and CBPP and enhanced preparedness for diseases exotic to the SADC region”. Further, the workshop conceptualised strategic control based on epidemiological clusters that transcend national boundaries and thus requires close liaison and cooperation between the member countries. The epidemiological clusters were defined as follows:

CBPP Cluster 1: Primary endemic disease - Angola, Northern Tanzania.

CBPP Cluster 2: Sporadic/Secondary endemic - Namibia North, Zambia, Tanzania South, DRC East.

CBPP Cluster 3: Presumed free but at immediate risk - Namibia South, Botswana North, Zimbabwe Northwest, Malawi Mozambique North, DRC Rest.

CBPP Cluster 4: Free at low risk - South Africa, Botswana South, Zimbabwe Rest, Lesotho, Swaziland, Mozambique South, Mauritius, Seychelles.

CBPP Cluster 5: Maintaining CBPP freedom - Zimbabwe, Malawi, Mozambique, South Africa, Botswana, Lesotho, Swaziland, Mauritius, Seychelles.

The designation of clusters and the intended actions are summarized in Annex 1.

References

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Annex 1. A framework designed by the SADC Directors of Veterinary Services for the progressive control of CBPP in southern Africa

(An outline of key elements for a 16-year strategy for the progressive control of transboundary animal diseases in southern Africa)

Figure 1 (Source: Dungu, 2003)

Figure 2. (Source: Njau, 2003)

Table 1. CBPP Cases, 1998 - 2002 (Source: Njau, 2003)

Table 2. Summary of CBPP vaccination campaigns conducted in affected provinces of Angola between 1994 and 2001 (FAO, 2002)

Figure 3. The area affected and the cattle distribution in Zambia (Source:FAOSTAT 2002, in EMPRES, 2002)