The Taeniasis-cysticercosis Complex in West and Central Africa

Taenia solium is present in most of the countries of West and Central Africa with the exception of strict Muslim areas, where pigs are not raised and pork is not eaten for religious reasons. Although the first reports about human and porcine cysticercosis date from the fifties, extensive surveys have only been carried out in a few countries such as Benin, Cameroon, and Togo. However, a lot of case reports and data from small scale surveys are available. Porcine cysticercosis is generally more widespread in Central than in West Africa. In several regions of Central Africa, prevalence figures in pigs of 20 to 30% (based on tongue or meat inspection) are not uncommon. In many West African countries, however, the prevalence of porcine cysticercosis is usually lower than 20% and often below 10%. There are indications that human cysticercosis is also more important in Central than in West Africa. Few data are available on human taeniasis and often no distinction is made between T. solium and T. saginata. Two large scale studies (Togo and Cameroon), in which the tapeworms were identified at the species level, revealed a percentage of about 0.1% T. solium carriers. Recently, an effort has been made to evaluate the economic impact of the disease in Africa. A very conservative estimate of the annual losses due to porcine cysticercosis in 10 West and Central African countries indicated that it might amount to 25 million Euro. For human cysticercosis, the financial losses are undoubtedly exceeded by the social impact of the disease, more particularly the stigmatising of epileptics in many African communities. and Togo). Data on porcine cysticercosis are available from several countries (Table 1). However, there are many countries, for which no data at all are available on the taeniasis-cysticercosis complex. In GuineaBissau, Liberia, and Sierra-Leone, for instance, there is no recent information on T. solium due to political instability over many years in these countries. Based on the available information, we can distinguish countries with a low prevalence of T. solium cysticercosis (ie prevalence of porcine cysticercosis <5% and only few case reports of human cysticercosis) and countries which are endemic to hyperendemic (ie porcine cyticercosis >5% and human cysticercosis frequently observed). Table 1 summarizes the data on human and porcine cysticercosis in West Africa. Since the prevalence figures in pigs are based on tongue or meat inspection, both of which are rather insensitive techniques, it has to be assumed that these data underestimate the real situation. Data on taeniasis are available from only a few countries. In Guinea (Conakry), 3.8% of 800 schoolchildren were found infected with Taenia spp (Gyorkos et al, 1996). In Nigeria, the prevalence of taeniasis was 8.7% in a survey of hospital patients (Onah and Chiejina, 1995). No attempt was made to differentiate T. solium from T. saginata in both countries. Dumas et al (1990), however, identified T. solium in 0.1 % of 1,170 adult people in Togo. Correspondence: Stanny Geerts, Department of Animal Health, Institute of Tropical Medicine, Nationalestroat 155, B-2000 Antwerpen, Belgium. E-mail: [email protected]; [email protected] INTRODUCTION Although many countries in West and Central Africa have a predominantly Muslim population, there are still many regions were pigs are kept. According to FAO the pig population in Africa has more than doubled over last 3 decades (FAOSTAT, 2001). Large numbers of pigs are present ia in Nigeria, Cameroon, Togo, Congo and Angola. Until recently, very few data were available on Taenia solium cysticercosis in Africa (Geerts, 1993). However, during the last decade quite a lot of studies have been carried out in several Westand Central African countries, so that the picture of the geographical distribution of taeniasis-cysticercosis in the region becomes more complete. The data presented in this review are based on published and unpublished information collected through contacts with staff of the veterinary services of the region. TAENIA SOLIUM TAENIASIS AND CYSTICERCOSIS IN WEST AFRICA There are only a few countries where large-scale surveys have been done on human cysticercosis (Benin