Have tsetse flies disappeared from Brazzaville town?

Background: From 1980 to 1985, the zoological park of Brazzaville was the only tsetse resting site located in downtown which supplied others temporary sites. The last trapping survey carried out in this area in 1987 showed that there were no more tsetse flies. Knowing that areas free of tsetse used to be reinvaded many years later, we have carried out an entomological survey in the area with the aim to verify what has happened more than twenty years later; given that suitable environmental conditions for Glossina are still available. Methods: Sixteen pyramidal traps were set out at the edge of the forest, along paths and around animal’s cages and were examined twice a day, at 10 a.m. and 4 p.m. during four days. Results: No tsetse fly was captured. Using the formula previously described; the probability of capturing a tsetse fly is 0.002. Conclusion: The zoological park seems close to be free of tsetse flies. Long-lasting surveys within the town and around are required before stating a complete disappearance of tsetse in the town

Assessment of the Efficiency of Insecticide Paint and Impregnated Nets on Tsetse Populations: Preliminary Study in Forest Relics of Abidjan, Côte d’Ivoire

Glossina palpalis palpalis is the main vector of human and animal trypanosomiasis in Côte d’Ivoire. This species, being the only tsetse species in the city of Abidjan, is hosted by the National park of Banco located in the middle of Abidjan, the zoological park and in a relic forest within the University of Nangui-Abrogoua, both in Abidjan. A programme for the elimination of these suburban tsetse populations has been initiated, in the context of which various tsetse control tools have been evaluated. In the zoological park, insecticidal paint (Inesfly®) was applied around the animal cages, and then supplemented with insecticide-impregnated netting around the larger animal cages. Tsetse population densities were monitored with Vavoua-style traps both inside the zoological park and in the site of University Nangui Abrogoua used as control site. Tsetse densities in the traps fell by over 90% following application of the insecticidal paint, and declined to zero after adding the insecticide impregnated nets in both study sites. The study confirms the close contact between tsetse populations from the zoological park and the University Nangui Abrogoua area, and shows that the sequential use of insecticide paint and impregnated nets can be effective for tsetse control

Contribution à l’évaluation de la diversité des vecteurs biologiques de la Trypanosomose Humaine Africaine et de leur activité journalière dans le Parc National de l’Ivindo (Nord est Gabon)

Objectifs : Afin d’évaluer les risques épidémiologiques liés à la présence des glossines dans le Parc National de l’Ivindo (Gabon), des enquêtes entomologiques ont été effectuées pour connaître l’abondance des glossines et suivre leur activité journalière.Méthodologie et résultats : Les captures ont été réalisées en petite saison sèche avec des pièges, Vavoua et Nzi, placés en forêt primaire, en forêt secondaire et au village Loaloa. Par ailleurs, trois pièges vavoua ont été visités chaque deux heures, de 8 heures à 18heures, durant quatres jours consécutifs. Quatres espèces et sous-espèces de glossines ont été identifiées : G. tabaniformis (46,04%), G. palpalis palpalis(32,37%).G fusca congolensis(12,95%) et G. tachinoides(8,63%). Par ailleurs, les cycles d’activité de ces quatre espèces sont variables : G. palpalis palpalisa une d’activité journalière bimodale, alors que G. tachinoides a un cycle unimodal. G. fusca congolensis a un pic d’activité entre 12heures et 14heureset G. tabaniformisa présenté des faibles pics d’activité.Conclusion et application : Les connaissances sur les insectes hématophages constituent un élément important dans la lutte anti vectorielle, car ces insectes constituent un risque pour la santé humaine et animale. Mieux connaitre la répartition des vecteurs, les risques de diffusion des pathogènes et leur évolution représente un enjeu majeur pour la mise en place d’une stratégie de contrôle de vecteurs. Aussi, les résultats de cette étude, bien que préliminaires invitent à présent à élaborer et de prendre en compte les stratégies de lutte et de contrôle des vecteurs de parasitoses. Ainsi, une étude plus approfondie mérite d’être effectuée afin de connaître la dynamique spatio-temporelle de ces insectes et de leur activité journalière.Mots clés : Glossines, piège Nzi, piège Vavoua, parc, Gabo

Transmission of human African trypanosomiasis in the Komo-Mondah focus, Gabon

Background: Knowledge about transmission of sleeping sickness in a given focus is of a great importance since it governs the efficacy and the cost-effectiveness of control strategy. The Komo-Mondah focus is the most endemic sleeping sickness focus of Gabon. This focus has hardly been investigated and available publications are more than thirty years old. In order to update transmission features of sleeping sickness in that focus, we have conducted epidemiological and entomological surveys in March-April 2008. Methods: Epidemiological investigation relied on a casecontrol study using a quantitative and qualitative methodology (a structured questionnaire). Cases were affected people (parasitological positive) diagnosed by the national control program from 2004 to 2007, controls were those found disease-free after clinical examination and biological tests in the same period. They were asked to respond to a standard questionnaire concerning their activities after having signed a written consent. An unvaried analysis was first performed and then a multivariate analysis using the conditional logistic regression for matching method. Traps were then set out for four days in areas where people were working. Tsetse flies captured were identified and dissected; their density and human-fly contact points were determined. Results: A risk of infection was associated with fishing activities (Odds-ratio: 5.69; CI95%: 3.38-9.57). Three species of Glossina were captured: Glossina palpalis palpalis, Glossina fuscipes fuscipes and G. Caliginea. Human-fly contact points were mainly landing stages. Conclusion: A combined strategy of case-detection and vector control targeted at landing stages should be efficient against the disease.Key words: Epidemiology, entomology, transmission, trypanosomiasis, Glossina, Gabo