First detection of small babesiae in two dogs in Hungary

BABESIOSIS is a well-recognised tickborne protozoal disease of veterinary importance in domesticated animals including dogs. It was originally thought that only two species of Babesia could infect dogs, namely Babesia canis and Babesia gibsoni. B canis belongs to the group known as the large babesiae because it is one of the largest Babesia species, measuring up to 5 μm in length and 2·5 to 3 μm wide. This species has three subspecies or genotypes, namely Babesia canis canis, Babesia canis vogeli and Babesia canis rossi (Uilenberg and others 1989). B gibsoni, which is smaller than B canis (3 to 4 μm x 1 to 2 μm), was thought to be the only small species of Babesia known to infect dogs, but recently new piroplasms, designated as Babesia microti-like and B gibsoni-like, were detected in dogs (Kjemtrup and others 2000, Zahler and others 2000, Kocan and others 2001). These findings have resulted in a major change in the concepts of epidemiology and diagnosis of babesiosis in dogs. Canine babesiosis caused by B canis has been reported in several European countries, particularly in the Mediterranean region, where Rhipicephalus sanguineus Latreille and Dermacentor reticulatus Fabricius are its vectors. The presence of small babesiae in dogs in Europe was uncertain until the end of the 1980s. Although some cases have been described recently, knowledge of the veterinary and zoonotic importance of these parasites is still very limited (Casapulla and others 1988, Zahler and others 2000, Camacho and others 2001, 2002, Suarez and others 2001). Babesiosis of dogs caused by B canis is endemic in Hungary, where it is transmitted by D reticulatus (Horvath and Papp 1996). However, to the authors’ knowledge, confirmed cases of B gibsoni or other small babesiae in dogs have not been reported in the country. This short communication describes two confirmed cases of canine babesiosis in Hungary caused by small babesiae. In February 2002, a six-month-old male Scottish terrier was taken to a local small animal clinic because of weakness, lethargy and anorexia. According to the owner, the animal had never left Budapest. The owner had walked the dog in two different parks in Budapest about a week previously. On clinical examination, the dog had pale mucous membranes and a rectal temperature of 39·5°C. The animal was treated with antibiotics. It was also examined the following day when no recovery was observed and abdominal pain was detected. The veterinarian suspected that the clinical signs might be due to ileus; therefore, the animal was referred to the Department and Clinic of Surgery and Ophthalmology, Faculty of Veterinary Science, Szent Istvan University. After ultrasonography, a laparotomy was performed. Severe internal haemorrhage in the abdominal cavity due to the rupture of the spleen was observed. The dog was splenectomised and a diagnosis was made by examination of splenic impression smears obtained from the ruptured spleen after the operation. The thin smears were stained with modified Wright’s stain (Diff-Quik) and examined. Erythrocytes were infected with many small parasites which appeared to be round to ring-shaped, oval or comma-like. The infected red cells contained two, four or eight organisms, but the parasites were not connected to each other (Fig 1). It was not known whether multiple infection had resulted from one parasite subsequently dividing. Morphometric studies were performed on the intracytoplasmic parasites. The mean (sd) diameter of the parasites measured at random was 1·81 (0·34) μm (n=35). One tick specimen was removed from the animal and identified as a partly engorged female D reticulatus. After surgery, the dog was treated with antibiotics and 5 mg/kg imidocarb diproprionate (Imizol; Schering-Plough Animal Health) subcutaneously, and then sent home. Two weeks later the dog had recovered; there were no clinical signs of the protozoal disease. Four months after surgery the dog was healthy. The second case involved a three-year-old male collie from Budapest, which was kept in the garden of a detached house and walked regularly in a neighbouring forest. In March 2002, the dog was found to be healthy during a clinical examination. A blood sample was taken for routine haematological and biochemical profiles. Haematological values (Table 1) showed slight erythropenia and leucopenia and mild thromShort Communications