Trichinella infections in animals and humans in sub-Saharan Africa: A review

Abstract

The aim of this review is to provide information on Trichinella infection in humans, livestock and wildlife in sub-Saharan Africa mainly focusing on geographical distribution of species/genotypes, biology, host range, life cycles and to identify research gaps. Trichinella britovi, Trichinella nelsoni and Trichinella zimbabwensis and one genotype (Trichinella T8) are known to occur in sub-Saharan Africa. Distinct geographic ranges with overlapping of some taxa in some areas have been observed. Genetic variants of T. nelsoni has been reported to occur among parasites originating from Eastern and Southern Africa and sequence heterogeneity also occurs among T. zimbabwensis isolates originating from different regions of Zimbabwe and South Africa. Field observations so far indicate that sylvatic Trichinella infections in the region are common in carnivores (mammals and reptiles) and to a lesser extent in omnivores. Cannibalism, scavenging and predation appear to be the most important routes of transmission and maintenance of the sylvatic cycles of the Trichinella taxa. To date, human trichinellosis has been documented in only four sub-Saharan countries (8.7%, 4/46). Bushpigs and warthogs have been the source of human infection with T. britovi and T. nelsoni being the aetiological agents. An increase in bushmeat trade and the creation of Transfrontier Conservation Areas (TFCAs) may have increased the risk of human trichinellosis in the region. With the creation of TFCAs in the region, sampling of wildlife hosts from protected areas of most sub-Sahara African countries is required to fully map the distribution of Trichinella species/genotypes in this region. More structured field surveys are still needed to determine the sylvatic host distribution of the different Trichinella taxa. Biological data of the Trichinella taxa in both wild and domestic animals of sub-Saharan Africa is very limited and further research is required.