Etude préliminaire de l’infestation des glossines par les trypanosomes dans le baï de Momba (Nord-Est Gabon)

Une étude préliminaire entomo-parasitologique a été effectuée pendant la grande saison sèche à l’interieur et autour du baï de Momba (nord-est Gabon) pour examiner les espèces de Trypanosomes transmises par les glossines. Ces dernières ont été capturées à l’aide des pièges vavoua et nzi. Les infections par les trypanosomes chez ces glossines ont été recherchées à l’aide d’un microscope au niveau des glandes salivaires, proboscis et intestins moyens des glossines. Ainsi, une infection du proboscis seul correspond à T. vivax, celles des glandes salivaires à T. brucei et celle du proboscis et de l’intestin moyen à T. congolense. Au total six espèces de glossines ont été identifiées : Glossina palpalis palpalis, G. nashi, G. fusca congolensis, G. tachinoides, G. frezili et G. fuscipes fuscipes. Le taux global d’infestation des glossines disséquées et observées au microscope a été estimé à 30 %. L’infestation des glossines par les trypanosomes témoigne de l’existence d’un risque trypanosomien dans le baï de Momba et suggère ainsi l’établissement d’un cycle de transmission Animal-Glossine-Homme dans ce milieu.Mots clés: Glossina, T. vivax, T. congolense, baï de Momba, trypanosomes. Preliminary study of infection of tsetse by trypanosomes in the baï of Momba North East GabonA preliminary study are insect parasitology was carried out during the long dry season in and around the baï of Momba (north-east Gabon) to examine the species of trypanosomes transmitted by tsetse flies. The flies were captured using traps and Vavoua nzi. Infections by trypanosomes were investigated using a microscope in the salivary glands and the proboscis intestines means tsetse. In total six tsetse species were identified : Glossina palpalis palpalis, G. nashi, G. fusca congolensis, G. tachinoides, G. frezili and G. fuscipes fuscipes. The overall rate of infestation of flies dissected and observed under the microscope is estimated at 30 %. The infestation of Bai Momba by flies carrying trypanosomes demonstrates the existence of a trypanosome risk and thus suggests the establishment of a transmission cycle Human-Animal-Glossina in this environment.Keywords: tsetse flies, T. vivax, T. congolense, baï of Momba, trypanosome

Phenetic and genetic structure of tsetse fly populations (Glossina palpalis palpalis) in southern Ivory Coast

Background: Sleeping sickness, transmitted by G. p. palpalis, is known to be present in the Ivory Coast. G. p. palpalis has recently been reported to occur in several places within the town of Abidjan, including: (i) the Banco forest, (ii) the Abobo Adjame University campus and (iii) the zoological park. Could these three places be treated sequentially, as separate tsetse populations, or should they be taken as one area comprising a single, panmictic population? Methods: The amount of gene flow between these places provides strategic information for vector control. It was estimated by the use of both microsatellite DNA and morphometric markers. The idea was to assess the interest of the faster and much less expensive morphometric approach in providing relevant information about population structure. Thus, to detect possible lack of insect exchange between these neighbouring areas of Abidjan, we used both genetic (microsatellite DNA) and phenetic (geometric morphometrics) markers on the same specimens. Using these same markers, we also compared these samples with specimens from a more distant area of south Ivory Coast, the region of Aniassue (186 km north from Abidjan). Results: Neither genetic nor phenetic markers detected significant differentiation between the three Abidjan G. p. palpalis samples. Thus, the null hypothesis of a single panmictic population within the city of Abidjan could not be rejected, suggesting the control strategy should not consider them separately. The markers were also in agreement when comparing G. p. palpalis from Abidjan with those of Aniassue, showing significant divergence between the two sites. Conclusions: Both markers suggested that a successful control of tsetse in Abidjan would require the three Abidjan sites to be considered together, either by deploying control measures simultaneously in all three sites, or by a continuous progression of interventions following for instance the "rolling carpet" principle. To compare the geometry of wing venation of tsetse flies is a cheap and fast technique. Agreement with the microsatellite approach highlights its potential for rapid assessment of population structure

Diagnostic accuracy of swine echinococcosis cytopathological tests and challenges for a differential diagnosis: slaughterhouse data

Echinococcosis disease shows clinical signs similar to many diseases. Hence we report cases that need to be confirmed using appropriate tests. A confirmatory study has been conducted to assess the accuracy of two cytopathological tests, with the histopathology test as the reference standard. The first cytopathological test evaluates the Ziehl Neelsen staining with an epifluorescence microscope (cytopath 1). The second cytopathological test uses the same staining followed by a transmitted light microscope examination (cytopath 2). Of a total of 2524 inspected pigs, 101 suspected cases of echinococcosis were detected, of which 67 were found positive with the two cytopathological tests and the histopathological one. The specificity of cytopath 1 (100 % [95 % CI 100 – 100]) and cytopath 2 (100 % [95 % CI 100;100]) were similar, as well as their respective positive predictive values: 100 % [95 % CI 100 – 100] vs. 100 % [95 % CI 100 – 100]. The sensitivity of cytopath 1 is 79.66 % [95 % CI 69.39 – 89.93], while cytopath 2 equals 66.10 % [95 % CI 54.02 – 78.18]. The difference in sensitivity of both tests was not significant. Negative predictive values found for cytopath 1, and cytopath 2 were 40 [95 % CI 18.53 – 61.47] and 28.57 [95 % CI 11.84 – 45.3], leading to the Generalized Estimating Equations (GEE) Model estimate for an odds ratio of 1.4 [95 % CI 0.41 – 5.2], p = 0.06. Cytopath 1 and cytopath 2 are equivalent in terms of specificity (100 % [95 % CI 100 – 100] vs. 100 % [95 % CI 100;100]) and positive predictive value (100 % [95 % CI 100 – 100]. Cytopath 1 is more sensitive than cytopath 2 but not significant (79.66 % [ 95 % CI 69.39 – 89.93] vs. 66.10 % [95 % CI 54.02 – 78.18]). However, the negative predictive value of cytopath 1 is better than that of cytopath 2: 40 % [95 % CI 18.53 – 61.47] vs. 28.57 % [95 % CI 11.84 – 45.3]

Assessment of the diversity of bloodsucking Diptera in a swampy forest clearing of Gabon with Vavoua and Nzi traps

The study aimed to assess the diversity of bloodsucking insects in the swampy forest clearings (bai) of Gabon with both Vavoua and Nzi traps. Twenty traps (10 of each type) were set up within and around Momba bai for seven consecutive days in June 2012. In each of the two biotopes, five pairs of traps (one Vavoua and one Nzi spaced about 30 m apart) were set at 250–400 m intervals. A total of 662 tsetse, 42 tabanids and 20 stable flies were collected. Vavoua traps captured many tsetse and stable flies, whereas Nzi traps caught more tabanids. Because of the short duration of capture, we later on pursued the investigation on the relative importance of these insects and their seasonal dynamics