Epidemiology of Bartonella henselae infection in pet and stray cats in Croatia with risk factors analysis

Abstract

Background Cats are the primary reservoirs of the bacterium Bartonella henselae, the main cause of cat-scratch disease in humans. The main vector of the bacterium is the cat flea, Ctenocephalides felis. In southeastern Europe, data are lacking on the prevalence of B. henselae infection in cats, the strains of B. henselae involved and the risk factors associated with the infection. Methods Blood samples collected in ethylenediaminetetraacetic acid-containing tubes from 189 domestic cats (156 pet cats and 33 stray cats) from Zagreb, the capital city of Croatia, and 10 counties throughout Croatia were cultured for Bartonella spp. Following culture, bacterial isolates were genotyped at eight loci after using PCR to amplify 16S ribosomal RNA (rRNA) and the internal transcribed spacer region between the 16S and 23S rRNA sequences. Univariate and multivariate logistic regression were used to identify risk factors for B. henselae infection in cats. Results Bartonella spp. was detected in 31 cats (16.4%), and subsequent genotyping at the eight loci revealed B. henselae in all cases. Thirty complete multilocus sequence typing profiles were obtained, and the strains were identified as four sequence types that had been previously reported, namely ST5 (56.7%), ST6 (23.3%), ST1 (13.3%) and ST24 (3.3%), as well as a novel sequence type, ST33 (3.3%). The univariate analysis revealed a significantly higher risk of B. henselae infection in cats residing in coastal areas of Croatia (odds ratio [OR] 2.592, 95% confidence interval [CI] 1.150–5.838; P = 0.0191) and in cats with intestinal parasites (OR 3.207, 95% CI 1.088–9.457; P = 0.0279); a significantly lower risk was identified in cats aged > 1 year (OR 0.356, 95% CI 0.161–0.787; P = 0.0247) and in cats sampled between April and September (OR 0.325, 95% CI 0.147–0.715; P = 0.005). The multivariate analysis that controlled for age showed a positive association with the presence of intestinal parasites (OR 4.241, 95% CI 1.243–14.470; P = 0.0119) and coastal residence (OR 2.567, 95% CI 1.114–5.915; P = 0.0216) implying increased risk of infection, and a negative association with sampling between April and September (OR 0.379, 95% CI 0.169–0.848; P = 0.018) implying a decreased risk of infection. After controlling for the season, an increased risk of infection remained for the coastal region (OR 2.725, 95% CI 1.200–6.186; P = 0.012). Conclusions Bartonella henselae is prevalent throughout Croatia and is a public health threat. Environmental and host factors can significantly affect the risk of infection, and these should be explored in more detail. The presence of intestinal parasites highlights the need to eliminate the flea vector, Ctenocephalides felis, as the most effective approach to control infections in cats and humans. Graphical Abstract