MECHANICAL TRANSMISSION OF TRYPANOSOMA-EVANSI AND TRYPANOSOMA-CONGOLENSE BY STOMOXYS NIGER AND S-TAENIATUS IN A LABORATORY MOUSE MODEL

Mechanical transmission of Trypanosoma evansi (South American origin) and T. congolense of Kilifi DNA type (Kenyan origin) was studied in la boratory mice using the African stable flies Stomoxys niger niger and S. taeniatus. Altogether, 355 flies were interrupted after feeding on infected blood and then transferred immediately to an uninfected mouse to complete feeding. Microscopy and subinoculation of triturated flie s into uninfected mice demonstrated the survival of T. congolense in S tomoxys for up to 210 min and T. evansi for up to 480 min. Parasites s urvived for much longer periods in the digestive tract than inside or on the mouthparts. Trypanosoma congolense was transmitted only by S. n . niger, and only at low rates of 3, 8 and 10% using flies of differen t feeding histories: fed on blood the previous day, freshly caught, an d teneral. Trypanosoma evansi was transmitted by both Stomoxys species at higher rates: S. taeniatus range 13-18%; S. n, niger range 17-35%. The highest transmission rate occurred with the combination of tenera l S. it. niger and T. evansi.