Historia

Veterinarni Medicina, 52, 2007 (5): 207–212

Case Report

Infection with Anaplasma phagocytophilum in a young dog: a case report
O. Melter1,3, I. Stehlik2, H. Kinska1, I. Volfova1, V. Ticha1, D. Hulinska3
1 2

Labvet, Clinical Veterinary Laboratory, Prague, Czech Republic Veterinary Clinic, Prague, Czech Republic 3 National Institute of Public Health, Prague, Czech Republic
ABSTRACT: An11-months-old male Golden Retriever occasionally found to have Ixodes ricinus ticks attached to the skin developed the acute onset of fever, lameness and inappetence followed by rapidly progressive depression, ataxia and reluctance to move. Inclusions (morulae) were observed in granulocytes. The blood analysis revealed severe thrombocytopoenia, lymphopoenia, eosinopoenia, elevation of alkalinephosphatase and hypercholesterolaemia, mostly suggestive of an Anaplasma phagocytophilum infection. The amplification of a DNA sequence specific for Anaplasma phagocytophilum and detection of specific antibodies supported the diagnosis. Borrelia burgdorferi, another tick-borne pathogen, or specific antiborrelial IgG antibodies were not detected. The dog was treated with oral doxycycline for 14 days:clinical symptoms resolved within six days. Keywords: anaplasmosis; infection; dog

A. phagocytophilum is an obligate intracellular pathogen known to cause granulocytic infections in both animals and humans (Dumler et al., 2001; Cohn, 2003). The most common vector of A. phagocytophilum in Europe is the tick Ixodes ricinus. Pet animals are not a source of infection for humans but could serve as asentinel (Bjoersdorff, 2002). Canine granulocytic anaplasmosis has been documented sporadically worldwide, with prevalence varying widely among countries (Engvall et al.; 1996; Pusterla et al., 1998; Liddell et al., 2003; Bexfield et al., 2005; Shaw et al., 2005; Liebisch et al., 2006). The detection of morulae in granulocytes does not identify the agent to the species level and further testingis needed (Cohn, 2003; Sirigireddy and Ganta, 2005). Lester et al. (2005), Kirtz et al. (2000, 2005) and Pusterla et al. (1997) reported 5–37% of infected granulocytes in dogs with anaplasmosis. The culture detection of the agent is still not a routine method yet and serologic testing alone is not conclusive for diagnosis. The diagnosis of A. phagocytophilum infection is mostly achieved by anindirect immunofluorescence assay and by amplified DNA specific to the 16S rRNA

gene of the agent (Kirtz et al., 2005). Although two pet dogs with granulocytic morulae in their venous blood were reported in the Czech Republic (Huml et al., 1996), the causative species was identified only in game animals and humans by Hulinska et al. (2002, 2004). Clinical symptoms of the infection with A.phagocytophilum in dogs are not specific but usually include fever, lethargy, thrombocytopoenia, depression and anorexia (Engvall et al., 1996). In experimentally infected dogs only mild symptoms were described (Cohn, 2003). Dogs might be coinfected with other tick-borne species such as Ehrlichia spp. or Borrelia spp. and the disease manifests itself primarily as acute or subacute arthritis in contrast tothe infection in humans (Straubinger, personal communication). Antiborrelial antibodies can first be detected by ELISA in the serum of dogs between 4 and 6 weeks after infection, with their titre peaking in 90 to 120 days and remaining constant for at least 22 months after exposure (Straubinger, personal communication). Although PCR is sensitive and specific, negative results do not exclude theinfec207

Case Report
tion with B. burgdorferi (Cohn, 2003). Twenty-five percent of dogs healthy or suspected of borrelial or anaplasmal infection (n = 731) had significant titres for both infections. The coinfection with A. phagocytophilum and B. burgdorferi is more likely to induce illness in the dogs as compared to the infection with either organism alone (Beall et al., 2006). Infections...