Polymerase chain reaction (PCR) detection of mixed trypanosome infection and blood meal origin in field-captured tsetse flies from Zambia
The prevalence of animal African trypanosomes and source of blood meal in wild field captured tsetse fly was assessed by single polymerase chain reaction using paraflagellar rod protein A (PFRA), protein kinase (KIN) and serum resistance- associated (SRA) primers, respectively for Trypanozoon group species, universal trypanosome species and Trypanosoma brucei rhodesiense. DNA samples (250) were extracted from tsetse fly collected in South Luangwa National Park in Zambia. Nine host species namely, African buffalo, hippopotamus, giraffe, lion, warthog, African elephant, greater kudu, human and bush pig were revealed in 54% (135) of the samples through amplification and sequencing of cytochrome-b gene. Mixed and individual infection rates in tsetse were successfully determined using a single PCR with KIN primers. Infection rates were highest for Trypanosoma vivax 38 (15.2%) followed by T. brucei 18 (7.2%), Trypanosoma congolense Kenya 16 (6.4%), T. congolense savannah 8 (3.2%), and lastly T. theileri and T. congolense forest, each found in 4 (1.6%) of all tsetse fly. T. vivax occurred more frequently in concomitant infections, implying a higher tendency of co-existence. KIN primers were able to amplify multiple trypanosomes DNA from field captured tsetse fly through a single PCR, which makes it a more efficient and cost effective diagnostic method applicable in field situations.
Key words: Tsetse fly, host blood meal, cytochrome-b gene, African animal trypanosomes, nagana, polymerase chain reaction (PCR) technology.