Surveys on Seroprevalence of Canine Monocytic Ehrlichiosis among Dogs Living in the Ivory Coast and Gabon and Evaluation of a Quick Commercial Test Kit Dot-ELISA

摘要

Canine monocytic ehlichiosis (CME), an enzootic disease in Africa, has been studied in canine blood samples (serum). These dogs, without any clinical sign of disease, were living in Abidjan (Ivory Coast) and in several small villages located in northeasst Gabon (Ogooue Ivindo). The results obtained by indirect fluorescent antibody (IFA) test, used as a point of reference, and by a quick test dot-Elisa were compared. Blood samples taken from 390 asymptomatic dogs in 2003 (137 in Ivory Coast and 253 in Gabon) were screened by IFA (antigen from Symbiotics Europe, Lyon) with a positive threshold set at 1/80. Afterwards, CME was detected by the commercial test kit Dot-Elisa in solid phase Snap 3Dx (Idexx, Westbrook, Maine, USA), using recombinant proteins which belong to Ehrlichia canis, p30 and p30-1. Using the IFA test, CME seroprevalence in the Ivory Coast is found to be 67.8%. Among 93 Ivorian seropositive blood samples, 76 samples show an antibody titer > 1/2560. In Gabon, IFA showed that seroprevalence is only 3.1%. Among 8 seropositive Gabonese dogs, only one sample shows an antibody test titer > 1/2560. Results from the Snap 3Dx test used on 390 blood samples are 100 positive samples and 290 negative ones. Comparison between IFA and Snap test 3DX revealed that the Snap test shows 97.9% specificity, 93.1% sensitivity, a 94% positive predictive value, a 97.6%, negative predictive value, and 96.6% reliability. In conclusion, CME seroprevalence in Abidjan is very high. Dogs studied for CME were watchdogs, living in kennels, where infection transmitted by Rhipicephalus sanguineus seems to be higher in the Gabonese area called Ogooue Ivindo, where semi-stray dogs were subjected to the test. These dogs where carried ticks identified as Haemaphysalis leachi, but this kind of tick is not considered as bearing Ehrlichia canis. Finally, results of the Snap 3Dx show that it is a simple and reliablemeans for quickly detecting dogs suspected of asymptomatic canine ehrlichiosis.