Ehrlichia Canis Infections - Results of Sero-epidemiological Study in Dogs in Bulgaria
The serological monitoring of CME in Bulgaria was motivated by the following circumstances: 1). the unclear epidemiology of the disease and the lack of studies on ehrlichiosis in Bulgaria as a whole; 2). the observation of clinical symptoms similar to those of CME; 3). the presence of the vectors of disease in the country; 4). the detection of CME in adjacent countries.
Materials and methods
One hundred and two canine blood sera, originating from four regions in Southeastern Bulgaria: 24 from the region of Plovdiv, 24 from the region of Stara Zagora, 24 from the region of Varna and 30 from the region of Burgas have been collected. The specimens obtained from two kennels, one in Burgas (n=20) and one in Plovdiv (n=18) were the most numerous. The other sera were from ambulatory patients referred to veterinary clinics in the respective towns. The samples were taken during the winter months (January and February) from dogs aged between 1 and 12 years. Until analysis, blood sera were stored at - 20 oC. All specimens were assayed by the indirect immunofluorescence technique. Serological sera higher than 1:100 were accepted as positive (1).
From all 102 studied sera, 38 or 37.25% were positive for E. canis, thus evidencing a presence and circulation of CME. The lowest titre (1:100) was detected in 31.57% of dogs; those with a titre of 1:200 were 10.52%, with a titre of 1:400 34.21% and with a titre of 1:800- 23.68%. The regional prevalence of seroreagents was as follows: Plovdiv (94.11%), Varna (44.09%) and Stara Zagora (7.84%). In the region of Burgas, there was no positive sample for E. canis. The history records showed data for tick infestation in 32 of studied dogs. In 25 out of them or 78.12%, an Ehrlichia antibody production was proved. The high percentage obtained in our studies could be easily explained, because the brown dog tick (Rhipicephalus sanguineus) is widely spread in Bulgaria (2). The sex-related incidence of infected dogs is characterized by 60% seropositive males and 40% females. The age distribution of infected dogs showed equal percentages in dogs under 3 years and dogs aged 3-7 years: 35%: In adult dogs (over 7 years) the percentage was lower (30%).
The results indicate a high exposure of the dogs in Bulgaria to the rickettsia E. canis. A planed tick-control programme in endemic regions throughout Bulgaria is recommended.
1. Mylonakis M., Kutinas A., et al., 2003. Evaluation of cytology in diagnosis of acute canine monocytic ehrlihiosis (Ehrlichia canis): a comparison between five methods. Veterynary Microbiology. 91, 197-204.
2. Serbezov B. , 2002. Karlego-prenosimi smeseni infectsii pri choveka-problem li sa te za zdraveopazvaneto v Bulgaria? Infectologia, XXXIX, (3), 3-5.