Monitoring the susceptibility ofGlossina palpalis gambiensisandG. morsitans morsitansto experimental infection with savannah-typeTrypanosoma congolense, using the polymerase chain reaction

S. Ravel, P. Grébaut, C. Mariani, V. Jamonneau, D. Cuisance, R. H. Gooding, G. Cuny
2004 Annals of Tropical Medicine and Parasitology  
Teneral Glossina palpalis gambiensis and G. morsitans morsitans (Diptera: Glossinidae) were fed on mice infected with savannah-type Trypanosoma ( Nannomonas) congolense. The infection was monitored by checking the postfeeding diuresis uid (midgut infection) and saliva (mature infection) of individual ies for parasites, at diVerent times post-infection, using microscopical examination and a PCR-based assay. The results indicated that both tsetse species supported established midgut infections by
more » ... 10 days post-infection and that maturation occurred after 24 days in G. m. morsitans. Although, for both diuresis uid and saliva, the results of the microscopy showed good concordance with those of the PCR, the PCR identi ed more positive samples. Monitoring allowed determination of the status of the infection in individual ies, which was con rmed, 48 days post-infection, by the microscopical examination of the midguts and probosces dissected out of the ies and by the PCR-based ampli cation of any trypanosome DNA in these organs. Again, in terms of the detection of trypanosomes in the dissected organs, there was good concordance between the results of the PCR and those of the microscopy, although PCR revealed many more mature infections than did microscopical examination, particularly in the G. p. gambiensis investigated. There was a higher prevalence of immature infection in G. p. gambiensis than in G. m. morsitans (P <0.05) but the inter-speci c diVerences seen in the prevalences of any infection and of mature infection were not statistically signi cant. The intrinsic vectorial capacity for T. congolense of both tsetse species therefore appeared quite similar, although the true vectorial competence of G. p. gambiensis remains to be determined. Trypanosoma ( Nannomonas) congolense is one prevalent in cattle (Nyeko et al., 1990; Reifenberg et al., 1997b; Solano et al., 1999) of the most economically important trypanoand mainly transmitted, cyclically, by tsetse somes. The animal trypanosomiasis it causes ies. in sub-Saharan Africa seriously limits use Speci c associations between particular of large areas for livestock production. The species of trypanosomes and various tsetse savannah type of T. congolense is the most species and subspecies have been suspected for many years. For example, eld and laboratory observations indicate that tsetse
doi:10.1179/000349804225003028 pmid:15000728 fatcat:i2ovopw4kfa2vkhpsiw7yctgze