Novel Ehrlichia Genotype Detected in Dogs in South Africa

Abstract

DNA samples from dogs presenting with symptoms suggestive of canine ehrlichiosis, but with no morulae detected on blood smears, frequently failed to give a positive reaction with a North American Ehrlichia canis-specific PCR assay targeting the 16S rRNA gene. We suspected the presence of a pathogen genetically different from North American E. canis, and we performed experiments to test this hypothesis. DNA from one canine blood sample was subjected to PCR with primers designed to amplify Ehrlichia (Cowdria) ruminantium ruminantium 16S and map1 genes. Amplicon sequencing yielded 16S and map1 sequences which were more closely related to other E. ruminantium sequences than to those of any other Ehrlichia species. Fifty canine DNA samples were subjected to a PCR assay, previously found to be Cowdria-specific, which targets the pCS20 gene. Thirty-seven (74%) gave a positive signal, and 16 (32%) also gave visible amplicons after gel electrophoresis, suggesting that this E. ruminantium organism is common in the Pretoria-Johannesburg area. The organism has not been isolated in culture, so we cannot definitively state that it was responsible for the canine ehrlichiosis symptoms, although the occurrence of several similar cases suggests this to be so. Most importantly, we also do not yet know whether the organism is infective for, or causes heartwater in, ruminants.

Molecular diagnosis of Anaplasmataceae organisms in dogs with clinical and microscopical signs of ehrlichiosis

“…In cases of canine granulocytic ehrlichiosis (CGE) (caused by E. ewingii or A. phagocytophilum), morulae are not differentiated by optic microscopy (PREOZI and COHN, 2002). On the other hand, when dog blood samples with suggestive symptoms of ehrlichiosis, but with no morulae detected in blood smears, were submitted to molecular techniques, a negative result was obtained (ALLSOPP and ALLSOPP, 2001;DAGNONE et al, 2003). Low rickettsiemia can also lead to negative results by cytology and PCR (DU PLESSIS et al, 1990).…”

Prevalence and diversity of Babesia, Hepatozoon, Ehrlichia, and Bartonella in wild and domestic carnivores from Zambia, Africa

“…For example, an Ehrlichia ruminantium -like sp. has been detected by PCR in domestic dogs in South Africa (Allsopp and Allsopp 2001) and the serologic cross-reactivity of E. canis and E. ruminantium has been demonstrated (Kelly et al 1994). Previous studies have identified Bartonella henselae in lions, but both serologic and molecular-based prevalence rates are low (Molia et al 2004;Pretorius et al 2004).…”

Molecular Detection of a New Anaplasma Species Closely Related to Anaplasma phagocytophilum in Canine Blood from South Africa

“…Also, DNA of E. canis and DNA of a novel Ehrlichia sp. closely related to E. ruminantium have been found in the blood of dogs in South Africa (1). There is also little definitive data on infections in dogs in other parts of Africa.…”