Variations of Glossina sp. and trypanosome species frequency within different habitats in a sleeping sickness focus, Gabon

Introduction: Knowledge of the infectious status of the Glossina is an indicator of risk of resurgence of Human African Trypanosomiasis (HAT). Environmental conditions have an impact on the density and diversity of both vector and Trypanosoma. The aim of the study was to determine the diversity and the infection rate of Glossina as well as the diversity of trypanosome species within habitats of an old HAT focus, in Gabon. Methodology: Glossina were captured in September 2012 in three ecological sites. Vavoua traps were installed for twelve days. All captured flies were identified. Glossina were selected for trypanosome identification by Polymerase Chain Reaction. Results: 1178 Glossina were captured: 55.8% in degraded forest, 28.9% in flood area and 15.4% in secondary forest. Glossina fusca congolensis (37%) and G.palpalis palpalis (36.4%) were the most abundant vector species. G. fusca congolensis was predominant in secondary forest and in flood area, while in degraded forest, it was G.palpalis palpalis. Trypanosoma infection rate was 30.7%, 42% in secondary forest, 32% in degraded forest and 18% in flood area. Trypanosoma congolense savannah was the main species detected (18.7%) followed by T.brucei brucei (10.7%) and T. brucei gambiense (4%). T. congolense savannah type was predominant in the secondary forest and in degraded forest (66.7% versus 55.5%). Conclusion: Glossina density and trypanosome infection rate varied according to the habitat within HAT focus. The density of tsetse was the highest in degraded forest while the infection rate was highest in secondary forest. Continuous disease surveillance and control measures are needed.

Synanthropic triatomines (Hemiptera, Reduviidae) in the state of Pernambuco, Brazil: geographical distribution and natural Trypanosoma infection rates between 2006 and 2007

INTRODUCTION: The present study shows a descriptive analysis of triatomine occurrence and its natural Trypanosoma infection rates in the state of Pernambuco, Brazil, between 2006 and 2007. METHODS: Entomological data for the species, such as specimens captured in both intra and peridomiciles and natural infection index, were obtained via domiciliary capture in 147 municipalities from 11 Regional Managements of Health. The database was obtained from a sample of insects (100% infected and 20% non-infected) sent to the Central Laboratory of Pernambuco. RESULTS: A total of 18,029 triatomines were analyzed from 138 municipalities of the state. Triatoma pseudomaculata (35%), Triatoma brasiliensis (34%), and Panstrongylus lutzi (25%) were the most captured species. These species also showed a widespread geographical distribution in the state. Panstrongylus megistus, Triatoma petrocchiae, Triatoma melanocephala, Triatoma sordida, Rhodnius nasutus, Rhodnius neglectus, and Triatoma infestans showed more limited geographical distribution and lower relative abundance. The parasitological research showed that 8.8% of the triatomines were naturally infected with flagellates morphologically similar to Trypanosoma cruzi and 91.3% of them were captured inside houses in 113 municipalities. P. lutzi showed the highest rates of natural infection. CONCLUSIONS: After the control of T. infestans, synanthropic species, such as T. brasiliensis, T. pseudomaculata, and P. lutzi, maintain the risk of T. cruzi transmission to humans in the state of Pernambuco. These species are widely distributed, and infected specimens have been found inside houses. Thus, an enhanced surveillance and vector control of Chagas disease is recommended in Pernambuco.