La descente d'insectes diptères sur les bovins est associée à la transmission contaminante de la fièvre aphteuse lors d'épidémies à Ngaoundéré-Cameroun

Abstract

This study was designed to identify the landing preference sites of common hematophagous symbovine Dipterans and relate it to the Foot-&-Mouth Disease Virus (FMDV) shedding sites. Three sets of zebu Goudali (from the DFG-COBE project herd) of different colors (black, brown and white) of same ages were restrained to sticks. Observations were made in October/November 2016 (seven days consecutively) and January 2017 (seven days consecutively). Data from literature on FMDV infectious doses (TCID50/ml) shedding areas in clinical cases was used to map such sites on cattle and associate it to the landing predilection sites of hematophagous dipterous insects. The total number of observed landing insects on cattle was 26779 and the following fly groups were identified in order of magnitude: Stomoxys (17453), culicids (8925), Simulium (293), Chrysops (74) and Tabanus (34). Chrysops preferred landing around front legs. Culicids preferred landing around front legs. Tabanus preferred landing around the head. Stomoxys preferred landing around front legs. Simulium preferred to alight around the belly region. Legs represented the highest insect-vector frequency spots. The alighting predilection of each insect-group differed statistically (P<0.05). The brown color of animals was most attractive to most insect groups. From the association test, an important number of each insect group observed was associated to at least one of the FMD contamination spots on cattle, but Stomoxys and culicids had a higher propensity of being contaminated as compared to others based on their high landing numbers on the exposed animals.