The Microscopic and Molecular Detections of Canine Ehrlichiosis

Abstract

The applications of molecular detection using nested PCR and the routine microscopic examination of ehrlichiosis were applied to 43 clinically affected dogs residing in Bangkok and Samutraprakarn. This study, performed in 2005-2006, has determined that 79.5% (31/39) of the buffy coat smears were having the ehrlichial morulae plus initial bodies found in monocytes and lymphocytes. The nested PCR was used to confirm the occurrence of ehrlichiosis after tested by morulae identification. Both tests demonstrated that neither Ehrlichia chaffeensis nor E. ewingii, the zoonotic agents of human, were found in this area. However, the prevalence of E. canis alone detected by nested PCR and microscopy was at the rate of 65.12% (28/43). Having a lower number of microscopic morulae (33.33% or 13/39) than that of the initial bodies (72.09% or 31/43), the identification of initial bodies was subsequently taken into account for another factor for disease detection. The detection of initial body in the circulating blood of dogs had brought the sensitivity of the test to equalize the power of molecular identification. However, the nested PCR is still a method of choice to specifically determine ehrlichial infection and it has shown the strong association between thrombocytopenia and the infection of E. canis.