Prevalence and Potential Risk Factors for Bartonella Infection in Tunisian Stray Dogs

Bartonellae are blood-borne and vector-transmitted pathogens, some are zoonotic, which have been reported in several Mediterranean countries. Transmission from dogs to humans is suspected, but has not been clearly demonstrated. Our objectives were to determine the seroprevalence of Bartonella henselae, Bartonella vinsonii subsp. berkhoffii, Bartonella clarridgeiae, and Bartonella bovis (as a proxy for Candidatus Bartonella merieuxii) in stray dogs from Tunisia, identify the Bartonella species infecting the dogs and evaluate potential risk factors for canine infection. Blood samples were collected between January and November 2013 from 149 dogs in 10 Tunisian governorates covering several climatic zones. Dog-specific and geographic variables were analyzed as potential risk factors for Bartonella spp. seropositivity and PCR-positivity. DNA was extracted from the blood of all dogs and tested by PCR for Bartonella, targeting the ftsZ and rpoB genes. Partial sequencing was performed on PCR-positive dogs. Twenty-nine dogs (19.5%, 95% confidence interval: 14-27.4) were seropositive for one or more Bartonella species, including 17 (11.4%) for B. vinsonii subsp. berkhoffii, 14 (9.4%) for B. henselae, 13 (8.4%) for B. clarridgeiae, and 7 (4.7%) for B. bovis. Statistical analysis revealed a few potential risk factors, mainly dog's age and breed, latitude and average winter temperature. Twenty-two (14.8%) dogs, including 8 of the 29 seropositive dogs, were PCR-positive for Bartonella based on the ftsZ gene, with 18 (81.8%) of these 22 dogs also positive for the rpoB gene. Partial sequencing showed that all PCR-positive dogs were infected with Candidatus B. merieuxii. Dogs from arid regions and regions with cold average winter temperatures were less likely to be PCR-positive than dogs from other climatic zones. The widespread presence of Bartonella spp. infection in Tunisian dogs suggests a role for stray dogs as potential reservoirs of Bartonella species in Tunisia.