Prevalence of Rickettsia spp. in Ticks and Serological and Clinical Outcomes in Tick-Bitten Individuals in Sweden and on the Åland Islands.

Tick-transmitted diseases are an emerging health problem, and the hard tick Ixodes ricinus is the main vector for Borrelia spp., tick-borne encephalitis virus and most of the spotted fever Rickettsiae in Europe. The aim of the present study was to examine the incidence of rickettsial infection in the southernmost and south central parts of Sweden and the Åland Islands in Finland, the risk of infection in humans and its correlation with a bite of a Rickettsia-infected tick, the self-reported symptoms of rickettsial disease, and the prevalence of co-infection between Rickettsia spp. and Borrelia spp. Persons with a recent tick bite were enrolled through public media and asked to answer a questionnaire, provide a blood sample and bring detached ticks at enlistment and at follow-up three months later. Blood samples were previously analysed for Borrelia spp. antibodies and, for this report, analysed for antibodies to Rickettsia spp. by immunofluorescence and in 16 cases also using Western Blot. Ninety-six (44.0%) of the 218 participants were seropositive for IgG antibodies to Rickettsia spp. Forty (18.3%) of the seropositive participants had increased titres at the follow-up, indicating recent/current infection, while four (1.8%) had titres indicating probable recent/current infection (≥1:256). Of 472 ticks, 39 (8.3%) were Rickettsia sp. positive. Five (31.3%) of 16 participants bitten by a Rickettsia-infected tick seroconverted. Experience of the self-reported symptoms nausea (p = 0.006) and radiating pain (p = 0.041) was more common among those with recent, current or probable infection compared to those who did not seroconvert. Participants who showed seroreactivity or seroconversion to Rickettsia spp. had more symptoms than those who were seronegative. Seven (3.2%) participants showed seroconversion to Borrelia spp., and three (1.4%) of these showed seroconversion to both Rickettsia spp. and Borrelia spp., in accordance with previous studies in Sweden. Symptoms of rickettsial disease were in most of the cases vague and general that were difficult to differentiate from other tick-borne diseases.

Serological survey of Borrelia infection of dogs in Sapporo, Japan, where Borrelia garinii infection was previously detected.

A serological survey of Borrelia infection of dogs was performed in Sapporo, Japan, where Borrelia garinii infection in dogs was detected in 2011. A total of 314 serum samples were collected from dogs that visited three animal hospitals in Sapporo from 2012 to 2014. The two-step evaluation method, involving screening ELISA followed by Western blot analysis, was used to detect antibodies against Borrelia species. A total of 34 samples were positive by ELISA. Among those 34 samples, 32 were positive for Borrelia spp. by Western blot. These findings suggest that the 32 dogs (10.2%) generated antibodies against Borrelia burgdorferi sensu lato, such as B. garinii or B. afzelii. Antibody positivity was 7.6% and 13.3% for dogs living in urban and rural areas, respectively. Dogs with a history of tick infestation showed a positive rate of 16.7%, which was higher, although not significantly, than the 6.7% among dogs without a history.

[The functioning of foci of mixed tick-borne infections on Russian territory]. / Funktsionirovanie ochagov smeshannykh kleshevykh infektsii na territorii Rossii.

Based on the studies of behavioral variations in ixodes persulcatus ticks under the influence of their carried pathogens, the authors forward a hypothesis for that there is antagonism between Borrelia and tick-borne encephalitis virus in the vector. Experiments demonstrated that Borrelia-infected ticks had a lower viral sensitivity than did noninfected ticks. There was inhibited viral reproduction in the ticks with double infection. Evidence is presented for that the Borrelia-infected nymphal ticks display the specific behavioral and viral susceptible features that are physiologically peculiar to older Borrelia-free individuals. It is concluded that the prevalence of Borrelia in the populations of ticks in the foci of mixed infections is associated with their property to suppress viral reproduction in the Borrelia-infected ticks.