Sheep pox is endemic in
the Maghreb countries, with comparable situations between Algeria, the Libyan
Arab Jamahiriya and Tunisia. In Morocco, the number of reported outbreaks
has decreased significantly during the last five years. This decrease is
related to the increase of the vaccination coverage of the ovine population.
In 1979-80, 30 to 40 percent of the ovine population was vaccinated against
sheep pox to reach, in 1984-85, 50 to 60 percent of the national ovine
population. This high mass vaccination coverage has resulted in the decrease
of the number of reported outbreaks. In 1998, no sheep pox outbreaks were
reported. Only two outbreaks were reported in 1997 and 13 outbreaks were
reported in 1996. In Algeria, the number of reported outbreaks was 36 in
1997, 33 in 1998 and only three outbreaks were notified during the six first
months of 1999.
The number of reported outbreaks may not reflect the reality of the disease situation in the Maghreb, since the disease seems underreported. For example, a questionnaire distributed in 1994 in the Oriental region of Morocco showed that livestock owners had observed clinical signs related with sheep pox and had not officially notified them to the veterinary authorities.
Each of the four Maghreb
countries is carrying out sheep pox vaccination programmes with different
levels of vaccination coverage.
Official figures for the Libyan Arab Jamahiriya are not available but an estimation of the vaccination coverage in this country may be calculated roughly using the number of imported doses of vaccines (2 to 3 million each year) and the estimated ovine population (4 to 5 million). In 1999, Tunisia changed its vaccination season to the spring. Because of the FMD epizootic in the Maghreb and the mobilization of all the resources to vaccinate the animals against this disease, only 614 993 head of ovine were vaccinated during the spring season, which represents only 29 percent of ovine animals normally vaccinated against the disease. This represents approximately 10 percent of the total ovine population.
In Algeria, the primary
results of the vaccination campaigns carried out in the wilayaat show a
vaccination coverage of 32 percent. In 1999, Morocco started a new sheep
pox vaccination strategy which consists of vaccinating animals in high-risk
areas. The vaccination coverage varies between 54 and 83 percent in provinces
where a vaccination programme is carried out.
In Morocco, Tunisia and the Libyan Arab Jamahiriya the sheep pox vaccine in use is the attenuated live vaccine. Algeria is using a sensitized vaccine, which will be changed to an attenuated live vaccine as soon as production starts in the veterinary laboratory of Draa Ben Khedda. Morocco and Algeria are vaccinating during the spring season while Tunisia and the Libyan Arab Jamahiriya until recently were vaccinating during the autumn season.
Sheep pox is a notifiable disease in the four Maghreb countries. The countries are generating data of a quantitative nature, mainly originating from passive surveillance of the disease. Because of its endemic nature and the decentralization of veterinary services in countries such as Tunisia, the efficiency of notification may be lower than it should be. In other cases, the number of reported outbreaks might be overestimated by misdiagnosing the disease and confusing it with such diseases as contagious pustular dermatitis. In Algeria, for each suspected sheep pox case samples should be submitted to the laboratory for confirmation. In Tunisia and Morocco, diagnosis is based on clinical signs of the disease.
Through the RADISCON project, a coordinated effort is being made to define the distribution of sheep pox in the Maghreb countries and to identify primary endemic areas where high vaccination coverage should be targeted.
FMD is sporadic in Tunisia,
Algeria and Morocco. The incriminated serotypes for the previous epizootic
in these countries are mainly O; serotypes A and C (Tunisia 1969) were also
reported.
The other FMD serotypes, namely SAT1, SAT2, SAT3 and Asia1, have never been reported in the Mediterranean Maghreb. Serotype A was first introduced into the region in Morocco in 1977, with the importation of frozen meat from South America. This serotype spread to Algeria the same year and to Tunisia in 1979. Serotype A was also introduced from Spain into Morocco in 1983, probably through subclinically affected sheep.
During the epizootic of
1989-1992 in the Mediterranean Maghreb, the incriminated serotype virus was
O1. This epidemic was characterized by being confined to sheep and goats.
The disease caused by serotype O (O/Tunisia/1989) spread from Tunisia to
Algeria and Morocco and caused high mortality rates in small ruminants.
Before 1999, the latest reported outbreaks in North Africa were chronologically as follows: Egypt, in March 1997; Libyan Arab Jamahiriya, in January 1994 (two outbreaks in Ejbadia region, in the western part of the country); and Tunisia, in August 1994.
FMD is a notifiable disease in all North African countries. An epidemic of FMD was first declared in February 1999 in Algeria. The disease appeared simultaneously in the wilaya of Souk Ahras (20 km from the Tunisian border) and in Algiers. Up to June 1999, the number of declared outbreaks in the country was 165.
Unlike the 1989-1992 epidemic, the virus involved in the 1999 epidemic did not exhibit specific tropism for small ruminants.
The disease mainly affected the bovine population. In Algeria, only two outbreaks were reported in ovine flocks, although a total of 40 outbreaks were recorded on premises which had mixed cattle and small ruminants. In Tunisia, the two reported outbreaks were observed in mixed bovine and ovine animals. In Morocco, the disease was not observed in small ruminants and only bovines were affected.
The disease was also reported
on 1 March 1999, in Grombalia (Nabeul Governorate) and on 11 March 1999 in
Ghardimaou (Jendouba Governorate) in Tunisia. The disease was first reported
in Oujda Governorate in northwestern Morocco on 25 February 1999. In Morocco,
a total of 11 outbreaks were reported, eight in Oujda in the eastern part
of the country, two in Khouribga and one in Beni Mellal.
The World Reference Laboratory at Pirbright demonstrated that the isolated serotype in Algeria was similar to the strain isolated in Côte d'Ivoire in 1999 (O/CIV/8/99) (less than 2 percent difference in D nucleotide sequence).
The Maghreb region is
epidemiologically considered as a single zone with two natural barriers.
The eastern barrier, the Libyan desert, impedes to a certain degree the
introduction of diseases from the Near East, and the southern natural barrier,
the Sahara, impedes the introduction of diseases from the Sahel countries.
The last epidemic of the disease in the Maghreb showed for the first time
in the recent history of FMD that the disease might have a western African
origin. If this is confirmed, other diseases which are exotic to the region
may enter and spread.
All the Maghreb countries have or have had FMD vaccination programmes. In Tunisia, vaccination has been carried out annually in bovine and small ruminants since 1989. The last vaccination campaign took place between September 1998 and January 1999. In Algeria, the latest vaccination campaign was carried out eight months before the start of the epidemic in February 1999 in the eastern part of the country, while vaccination stopped 18 months before that epidemic in the rest of the country. In Morocco, the last generalized vaccination (ovine and bovine) against FMD was carried out in November/December 1997. The Libyan Arab Jamahiriya has been vaccinating bovines twice a year since 1996. In 1997, the number of vaccinated bovines was 70 000 head, representing a vaccination coverage estimated at 50 percent (the bovine population is estimated to be 150 000 head).
During the epidemic of 1999, Algeria practised ring vaccination around the foci, before starting mass vaccination of all the bovine population and the vaccination of small ruminants along the eastern border of the country. On 22 June 1999, 1 216 960 bovines were vaccinated and 430 221 received a second injection of the vaccine; and 829 350 ovine and 48 561 caprine animals were vaccinated along the eastern border.
In Tunisia, the bovine and small ruminant population that had been vaccinated three months before the appearance of the disease were vaccinated again. In Morocco, the bovine vaccination campaign started along the border with Algeria (in the provinces of Oujda, Berkane, Figuig, Jerrada, Errachidia and Ouarzazate). Vaccination was extended to the buffer zone consisting of the provinces of Taza, Taounate, Fès, Al Hoceima, Boulemane and Nador. Following the appearance of three outbreaks in Khouribga and Beni Mellal, the vaccination was extended to include all of the bovine population. Vaccination was reinforced in the buffer zone and in the northern provinces.