Abstract
Tsetse flies (Glossina spp.) are responsible for the transmission of trypanosomes, agents of animal and Human African Trypanosomiasis (HAT). These diseases are associated with considerable animal and human economical loss, morbidity and mortality. The correct identification of trypanosomes species infecting tsetse flies is crucial for adequate control measures. Identification presently requires technically difficult, cumbersome and expensive on-site fly dissection. To obviate this difficulty we explored the possibility of correctly identifying trypanosomes in tsetse collected, under field conditions, only for number determination. Tsetse flies, that remained exposed for weeks in field traps in the Vista Alegre HAT focus in Angola, were obtained. The flies were not dissected on site and were stored at room temperature for months. DNA extraction using the whole tsetse bodies and PCR analysis were performed in 73 randomly chosen flies. Despite the extensive degradation of the tsetse, DNA extraction was conducted successfully in 62 out of the 73 flies. PCR analysis detected the presence of T. brucei s.l DNA in 3.2 % of the tsetse. This approach could be cost-effective and suitable for vector related HAT control activities in the context of countries where entomological trained personnel is missing and financial resources are limited.
Highlights
In tropical regions of Africa, Glossina (Diptera, Glossinidae) or tsetse flies can carry and transmit several species of trypanosomes (Trypanosoma vivax, Trypanosoma congolense, Trypanosoma simiae, Trypanosoma brucei s.l.), which can infect a large number of vertebrates, including man (Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense) [1,2]
Sixty-five flies used in our experiment were identified as Glossina palpalis palpalis; the remaining eight flies could only be identified as belonging to the palpalis group, due to their extensive deterioration
It should be noted that 10 out of the 62 flies presented a very weak polymerase chain reaction (PCR) signal for tubulin, probably reflecting the extensive deterioration of the tsetse flies when they arrived at our lab
Summary
In tropical regions of Africa, Glossina (Diptera, Glossinidae) or tsetse flies can carry and transmit several species of trypanosomes (Trypanosoma vivax, Trypanosoma congolense, Trypanosoma simiae, Trypanosoma brucei s.l.), which can infect a large number of vertebrates, including man (Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense) [1,2]. The presently used standard method for trypanosome detection in tsetse flies is based on the direct microscopic observation of the parasite after organ dissection of freshly collected flies. This method, often performed under field conditions, is laborious and dependent on skilled personnel and does not allow trypanosome identification below the subgenus level [6]. Tsetse flies (Glossina spp.) are responsible for the transmission of trypanosomes, agents of animal and Human African Trypanosomiasis (HAT). Identification presently requires technically difficult, cumbersome, and expensive on-site fly dissection To obviate this difficulty we explored the possibility of correctly identifying trypanosomes in tsetse collected, under field conditions, only for number determination. Conclusions: This approach could be cost-effective and suitable for vector-related HAT control activities in the context of countries where entomological trained personnel is missing and financial resources are limited
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