Prevalence of Coxiella burnetii in ticks after a large outbreak of Q fever.

Q fever has emerged as an important human and veterinary public health problem in the Netherlands with major outbreaks in three consecutive years. Goat farms are probably the prime source from which Coxiella burnetii have spread throughout the environment, infecting people living in the vicinity. Coxiella burnetii infection not only spilled over from animal husbandry to humans but could also have spread to neighbouring wildlife and pets forming novel reservoirs and consequently posing another and lingering threat to humans, companion animals and livestock. In these cases, transmission routes other than airborne spread of contaminated aerosols may become significant. Therefore, the role of ticks in the transmission of Coxiella burnetii in the current situation was investigated. A total of 1891 questing Ixodes ricinus ticks and 1086 ticks feeding on pets, wildlife and livestock were tested by a recently developed multiplex Q-PCR. All ticks were negative, except for a few ticks feeding on a herd of recently vaccinated sheep. Coxiella-positive ticks were not detected after resampling this particular herd three months later. Based on these data we conclude that the current risk of acquiring Q fever from questing ticks in the Netherlands is negligible. However, for future risk assessments, it might be relevant to sample more ticks in the vicinity of previously C. burnetii infected goat farms and to assess whether C. burnetii can be transmitted transovarially and transstadially in I. ricinus ticks.

First detection of spotted fever group rickettsiae in Ixodes ricinus and Dermacentor reticulatus ticks in the UK.

A preliminary study was conducted to determine the presence of spotted fever rickettsiae in two species of British tick (Ixodes ricinus and Dermacentor reticulatus). The 16S rRNA gene of Rickettsia spp. was detected in 39/401 (9·7%) of ticks tested, including 22/338 (6·5%) I. ricinus and 17/63 (27%) D. reticulatus. Some positive I. ricinus samples showed 100% homology with Rickettsia helvetica (10/22), and most positive D. reticulatus showed 100% homology with R. raoultii (13/17). Five other Rickettsia spp. were detected exhibiting 96-99% homology. Ticks positive for rickettsiae were collected from various hosts and from vegetation from eight counties across Great Britain. The distribution of R. helvetica in various engorged and unfed stages of I. ricinus suggests that R. helvetica is widespread. R. raoultii was found in questing adult D. reticulatus in Wales and England. This is the first evidence of potentially pathogenic spotted fever rickettsiae in British ticks.