TRICHINELLA BRITOVI ETIOLOGICAL AGENT OF SYLVATIC TRICHINELLOSIS IN THE REPUBLIC OF GUINEA (WEST AFRICA) AND A RE-EVALUATION OF GEOGRAPHICAL DISTRIBUTIONS FOR ENCAPSULATED SPECIES IN AFRICA.

Authors: POZIO, E - ROME, ITALY; PAGANI, P - LYON, FRANCE; MARUCCI, G - ROME, ITALY; Zarlenga, Dante; Hoberg, Eric; DE MENEGHI, D - GRUGLIASCO, ITALY; LA ROSA, G - ROME, ITALY; ROSSI, L - GRUGLIASCO, ITALY

Submitted to: International Journal for Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2005
Publication Date: 5/16/2005
Citation: Pozio, E., Pagani, P., Marucci, G., Zarlenga, D.S., Hoberg, E.P., De Meneghi, D., La Rosa, G., Rossi, L. 2005. Trichinella britovi etiological agent of sylvatic trichinellosis in the Republic of Guinea (West Africa) and a re-evaluation of geographical distributions for encapsulated species in Africa. International Journal for Parasitology. 35:955-960.

Interpretive Summary: Sylvatic and domesticated mammals are often the sources of parasites and infectious agents that cause zoonotic diseases in humans when such animals are used as food resources. Trichinellosis, caused by various species in the genus Trichinella is one such parasitic nematode, and most human cases of disease have been associated with the species T. spiralis circulating in domestic swine. However, not all cases of human trichinellosis can be attributed to this synathropic association, and provides the rationale for continued survey and inventory of parasite biodiversity to define the potential for disease outbreaks among humans in different regions of the world. In West Africa, Trichinella infection was documented in humans and animals from Senegal in the 1960s and the biological characters of one isolate showed a lower infectivity to domestic pigs and rodents when compared to that of a T. spiralis isolate in pigs from Europe. Survey for Trichinella in Senegal revealed the presence of T. britovi a parasite typically found in Europe and Eurasia. Trichinella larvae from these three viverrids were identified as Trichinella britovi and no difference was detected in three examined sequences from these African isolates and the reference strain of T. britovi from Europe, indicating common ancestry, an historically continuous geographic distribution, and recent isolation for African and European populations. The detection of T. britovi in West Africa modifies our knowledge about the distribution of encapsulated species of Trichinella in Africa. Thus, T. nelsoni is now considered to have a distribution limited to the Eastern part of the Afrotropical region from Kenya to South Africa, suggesting explanation for the presence of Trichinella T8 in Namibia and South Africa, and further suggests that T. britovi could be the Trichinella species circulating among wild animals of Northern Africa. Clear definitions for host and geographic distributions are necessary to understand and predict the sources and the potential for human-trichinellosis based on food borne infections in different regions of the world.

Technical Abstract: In West Africa, Trichinella infection was documented in humans and animals from Senegal in the 1960s and the biological characters of one isolate showed a lower infectivity to domestic pigs and rodents when compared to that of a Trichinella spiralis pig isolate from Europe. To identify the Trichinella species widespread in West Africa, a survey was conducted in the Republic of Guinea. Of 160 animals examined, 158 were mammals belonging to the families Suidae (12), Canidae (5), Viverridae (126), Felidae (5), Galagonidae (2), Cercopithecidae (7) and Hominidae (1), one was a vulture and one was a monitor lizard. Three Viverridae, one true civet (Viverra civetta) and two African palm civets (Nandinia binotata) from the Fouta Djallon Massif, Pilimini Subprefecture, were found positive by artificial digestion of muscle samples. Trichinella larvae from these three viverrids were identified as Trichinella britovi and no difference was detected in three examined sequences from these African isolates and the reference strain of T. britovi from Europe, indicating common ancestry, an historically continuous geographic distribution, and recent isolation for African and European populations. The detection of T. britovi in West Africa modifies our knowledge about the distribution of encapsulated species of Trichinella in Africa. Thus, T. nelsoni is now considered to have a distribution limited to the Eastern part of the Afrotropical region from Kenya to South Africa, suggesting explanation for the presence of Trichinella T8 in Namibia and South Africa, and further suggests that T. britovi could be the Trichinella species circulating among wild animals of Northern Africa.