Molecular detection of Ehrlichia canis and Anaplasma phagocytophilum in blood samples from dogs in Bulgaria

Abstract

The aim of the study was to develop a molecular diagnosis protocol of monocytic ehrlichiosis and granulocytic anaplasmosis in dogs by conventional polymerase chain reaction (PCR) and to compare the results from PCR and a rapid serological test. One hundred and six blood samples from dogs were tested by the rapid serological test SNAP 4Dx Plus (IDEXX Laboratories, Westbrook, ME) and by conventional PCR. Sixty-two of them (58.49%) were positive for antibodies to Ehrlichia canis/Ehrlichia ewingii and 14 (13.21%) for antibodies to Anaplasma phagocytophilum/Anaplasma platys. In 24 (22.64%) blood samples, antibodies against both pathogens were simultaneously detected. Six (5.66%) samples were seronegative. Fourty-six of the 106 tested samples (43.4%) were positive for a 345 bp segment of the ribosomal gene of family Anaplasmataceae. In 28 of them the presence of a 444 bp fragment of the ankA gene of A. phagocytophilum was detected, and in 26: a 409 bp fragment of the gene of E. canis. Nine samples were simultaneously positive for genetic sequences of E. canis and A. phagocytophilum. The target DNA fragments specific for the two studied pathogens were not detected in one of the Anaplasmataceae-positive samples. In the remaining 60 cases (56.6%), the presence of a 345 bp segment of the ribosomal gene was not detected. In the present study, the DNA of E. canis and of A. phagocytophilum was detected for the first time in Bulgarian dogs by the conventional PCR.