Mechanical transmission ofTrypanosoma evansiandT. congolensebyStomoxys nigerandS. taeniatusin a laboratory mouse model

Abstract

Mechanical transmission of Trypanosoma evansi (South American origin) and T. congolense of Kilifi DNA type (Kenyan origin) was studied in laboratory 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 flies into uninfected mice demonstrated the survival of T. congolense in Stomoxys for up to 210 min and T. evansi for up to 480 min. Parasites survived 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 different feeding histories: fed on blood the previous day, freshly caught, and 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 teneral S. n. niger and T. evansi.

Multiplex PCR for detection of Trypanosoma evansi and Theileria equi in equids of Punjab, India

“…In northern India, T. evansi is transmitted mechanically by biting hematophagous flies (Tabanids) (Sumba et al, 1998) and T. equi is mainly transmitted by longistrate tick, Hyalomma anatolicum anatolicum, causing significant morbidity and mortality in equids . As the vectors of both the diseases are habitual to hot plain areas of south-western Punjab, the epidemiological status of these infections in north-eastern parts of the province still remains unexplored.…”

Olfaction in vector-host interactions

“…The exception to this is when mechanical transmission occurs, during which pathogens are rapidly moved from insect to insect on contaminated mouth parts. One example is Stomoxys nigra Macquart, which transmit Trypanosoma evansi Steel in this way , Sumba et al 1998. The more general pattern is biological transmission, where the parasite may multiply in the insect vector, change into another developmental stage or both change and multiply Hurd 2002, Lehane 2005).…”

Stomoxys calcitrans as possible vector of Trypanosoma evansi among camels in an affected area of the Canary Islands, Spain

“…It has been reported that motile and presumably viable T. evansi remained in the proboscis of Stomoxys spp. for approximately 5-7min after feeding 15 , which could explain why T. evansi has been maintained within the camel herds without apparent infection of other surrounding livestock.…”