Single-strand conformation polymorphism (SSCP) of mitochondrial genes helps to estimate genetic differentiation, demographic parameters and phylogeny of Glossina palpalis palpalis populations from West and Central Africa.

A good understanding of tsetse fly population structure and migration is essential to optimize the control of sleeping sickness. This can be done by studying the genetics of tsetse fly populations. In this work, we estimated the genetic differentiation within and among geographically separated Glossina palpalis palpalis populations from Cameroon, the Democratic Republic of the Congo and Ivory Coast. We determined the demographic history of these populations and assessed phylogenetic relationships among individuals of this sub-species. A total of 418 tsetse flies were analysed: 258 were collected in four locations in Cameroon (Bipindi, Campo, Fontem and Bafia), 100 from Azaguié and Nagadoua in Ivory Coast and 60 from Malanga in the Democratic Republic of the Congo. We examined genetic variation at three mitochondrial loci: COI, COII-TLII, and 16S2. 34 haplotypes were found, of which 30 were rare, since each was present in <5% of the total number of individuals. No haplotype was shared among Cameroon, Ivory Coast and the Democratic Republic of the Congo populations. The fixation index FST of 0.88 showed a high genetic distance between Glossina palpalis palpalis populations from the three countries. That genetic distance was correlated to the geographic distance between populations. We also found that there is substantial gene flow between flies from locations separated by over 100 km in Cameroon and between flies from locations separated by over 200 km in Ivory Coast. Demographic parameters suggest that the tsetse flies from Fontem (Cameroon) had reduced in population size in the recent past. Phylogenetic analysis confirms that Glossina palpalis palpalis originating from the Democratic Republic of the Congo are genetically divergent from the two other countries as already published in previous studies.

Trypanosome infection rates in tsetse flies in the "silent" sleeping sickness focus of Bafia in the Centre Region in Cameroon.

BACKGROUND: The Bafia sleeping sickness focus of Cameroon is considered as "silent" with no case reported for about 20 years despite medical surveys performed during the last decades. In this focus, all epidemiological factors that can contribute to trypanosomes transmission are present. To update our knowledge on the current risks of Human and Animal African trypanosomiases, different trypanosome species were identified in midguts of tsetse flies captured in the Bafia focus. METHODS: Tsetse flies were trapped using pyramidal traps. Each tsetse fly was identified and live flies were dissected and their midguts collected. DNA was extracted from each midgut and thereafter, blood meals and different trypanosome species were identified with molecular tools. The biological data were transported onto maps in order to have their distribution. RESULTS: Of the 98 traps set up, 461 Glossina palpalis palpalis were captured; 322 (69.8 %) tsetse flies were dissected and 49 (15.2 %) teneral flies identified. The average apparent density of tsetse flies per day was 1.18. Of the 35 (10.9 %) blood meals collected, 82 % were taken on pigs and 17.6 % on humans. Eighty two (25.5 %) trypanosome infections were identified: 56 (17.4 %) T. congolense savannah, 17 (5.3 %) T. congolense forest, 5 (1.6 %) T. vivax and 4 (1.2 %) T. brucei s.l. No infection of T. simiae and T. b. gambiense was identified. Sixty seven (81.7 %) infections were single and 15 (18.3 %) mixed involving one triple infection (T. congolense forest, T. brucei and T. vivax) and 14 double infections: 11 T. congolense forest and T. congolense savannah, two T. congolense savannah and T. brucei, and one of T. brucei and T. vivax. The generated maps show the distribution of tsetse flies and trypanosome infections across the focus. CONCLUSION: This study has shown that animal trypanosomes remain an important problem in this region. Meanwhile, it is very likely that HAT does not seem anymore to be a public health problem in this focus. The generated maps enabled us to define high risk transmission areas for AAT, and where disease control must be focused in order to improve animal health as well as the quantity of animal proteins.

Spatial and temporal variations relevant to tsetse control in the Bipindi focus of southern Cameroon.

BACKGROUND: Human African Trypanosomiasis (HAT) remains a public health problem in many poor countries. Due to lack of financial resources in these countries, cost-effective strategies are needed for efficient control of this scourge, especially the tsetse vector. It was shown that perennial water sources maintain a favourable biotope for tsetse flies and thus the transmission dynamics of sleeping sickness. The present paper aimed at assessing the transmission dynamics of HAT in a forest environment where the hydrographic network is important. METHODS: Two entomological surveys were carried out in July 2009 and March 2010 in the Bipindi sleeping sickness focus of the South Region of Cameroon. Entomological and parasitological data were collected during both trapping periods (including the climate variations throughout a year) and compared to each other. The level of risk for transmission of the disease during each trapping period was also evaluated at the trap level and materialised on the map of the Bipindi focus. RESULTS: Glossina palpalis palpalis was the most prevalent tsetse fly species captured in this focus. The overall densities of tsetse flies as well as the risk for transmission of HAT in the Bipindi focus were significantly higher in July than in March. At the trap level, we observed that these parameters were almost constant, whatever the trapping period, when the biotope included perennial water sources. CONCLUSIONS: This study shows that the spatial distribution of traps, as well as the temporal climatic variations might influence entomological and parasitological parameters of HAT and that the presence of perennial water sources in biotopes would favour the development of tsetse flies and thus the transmission of sleeping sickness. These factors should, therefore, be taken into account in order to provide more efficient vector control.