Absence of zoonotic Bartonella species in questing ticks: First detection of Bartonella clarridgeiae and Rickettsia felis in cat fleas in the Netherlands

The zoonotic Bartonella clarridgeiae and Rickettsia felis were detected for the first time in Dutch cat fleas. B. henselae was found in cat fleas and B. schoenbuchensis in ticks and keds feeding on deer. Two Bartonella species, previously identified in rodents, were found in wild mice and their fleas. However, none of these microorganisms were found in 1719 questing Ixodes ricinus ticks. Notably, the gltA gene amplified from DNA lysates of approximately 10% of the questing nymph and adult ticks was similar to that of an uncultured Bartonella-related species found in other hard tick species. The gltA gene of this Bartonella-related species was also detected in questing larvae for which a 16S rRNA gene PCR also tested positive for "Candidatus Midichloria mitochondrii". The gltA-gene of the Bartonella-related species found in I. ricinus may therefore be from this endosymbiont.We conclude that the risk of acquiring Cat Scratch Disease or a related bartonellosis from questing ticks in the Netherlands is negligible. On the other hand fleas and deer keds are probable vectors for associated Bartonella species between animals and might also transmit Bartonella spp. to humans.Bartonella species are facultative intracellular Gram-negative bacteria which can infect humans and a wide range of animal species. Cat-scratch disease (CSD) is probably the most common Bartonella infection in the northern hemisphere [1,2]. The hallmark of CSD is enlargement and tenderness of lymph nodes draining the site of inoculation of the microorganism [3]. Regional lymphadenopathy usually develops 2 to 3 weeks after exposure and normally resolves spontaneously after several months [4]. Thirty percent of the patients report low-grade fever and a skin or mucous membrane lesion may be observed at the site of inoculation for 25% to >90% of patients [3,5]. Extranodal clinical manifestations, such as encephalopathy, neuroretinitis, arthritis, and lytic bone lesions, occur in approximately 10% of patients