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The lone star tick, Amblyomma americanum, feeds upon a variety of hosts and is a known vector of several human pathogens. In Ohio, populations of A. americanumhave been expanding their range and increasing in abundance and distribution, thereby elevating the public health concerns regarding bites from this species. We used a set of PCR assays to detect the presence of ehrlichial and rickettsial species in A. americanumticks submitted to the Ohio Department of Health Zoonotic Disease Program over an 11-year period (2000–2010). We did not detect the presence of known pathogens Rickettsia rickettsiior Ehrlichia chaffeensis, but we did identify the presence of two other bacterial species: ‘CandidatusRickettsia amblyommii’, and Ehrlichiasp. Panola Mountain. ‘CandidatusR. amblyommii’ was the most common species identified (30.2%), whereas the ehrlichiae was quite rare (0.6%). With growing evidence implicating both ‘CandidatusRickettsia amblyommii’ and Ehrlichiasp. Panola Mountain in mild to moderate human disease, our results support the importance of continued monitoring of A. americanumticks for the presence of potential pathogens.

A previous surveillance study of human pathogens within ticks collected in the country of Georgia showed a relatively high infection rate for Rickettsia raoultii, R. slovaca, and R. aeschlimannii. These 3 spotted fever group rickettsiae are human pathogens: R. raoultiiand R. slovacacause tick-borne lymphadenopathy (TIBOLA), and R. aeschlimanniicauses an infection characterized by fever and maculopapular rash. Three quantitative real-time polymerase chain reaction (qPCR) assays, Rraoul, Rslov, and Raesch were developed and optimized to detect R. raoultii, R. slovaca, and R. aeschlimannii, respectively, by targeting fragments of the outer membrane protein B gene (ompB) using species-specific molecular beacon or TaqMan probes. The 3 qPCR assays showed 100% specificity when tested against a rickettsiae DNA panel (n=20) and a bacteria DNA panel (n=12). The limit of detection was found to be at least 3 copies per reaction for all assays. Validation of the assays using previously investigated tick nucleic acid preparations, which included Rickettsia-free tick samples, tick samples that contain R. raoultii, R. slovaca, R. aeschlimannii, and other Rickettsiaspp., gave 100% sensitivity for all 3 qPCR assays. In addition, a total of 65 tick nucleic acid preparations (representing 259 individual ticks) collected from the country of Georgia and the Republic of Azerbaijan in 2009 was tested using the 3 qPCR assays. R. raoultii, R. slovaca, and R. aeschlimanniiwere not detected in any ticks (n=31) from the Republic of Azerbaijan, but in the ticks from the country of Georgia (n=228) the minimal infection rate for R. raoultiiand R. slovacain Dermacentor marginatuswas 10% and 4%, respectively, and for R. aeschlimanniiin Haemaphysalis sulcataand Hyalommaspp. it was 1.9% and 20%, respectively.

Since the year 2005, clinical patterns resembling tick-borne rickettsioses have been noticed in Mongolia. Epidemiological data regarding species of the aetiological agent, tick vector, prevalence, and distribution as well as incidence of human cases throughout Mongolia are still sparse to date. In order to identify Rickettsiaspecies occurring in Mongolia, we investigated Dermacentor nuttalli(n=179) and Ixodes persulcatus(n=374) collected in 4 selected provinces. Rickettsia raoultiiwas the predominant Rickettsia(82% prevalence) found in D. nuttalliand was also detected in I. persulcatus(0.8%). The Rickettsiaprevalence in D. nuttallifrom different provinces varied between 70% and 97%. In addition, R. sibiricawas identified in approximately 4% of D. nuttalli, but solely from Arkhanghai province. The results of this study extend the common knowledge about the geographic distribution of R. raoultiiand its high prevalence in D. nuttalli.Although the pathogenicity of this Rickettsiais still unclear, it should be considered in Mongolian patients suspected of having tick-borne rickettsiosis.

In recent years, the spectrum and epidemiology of human rickettsioses has become an emerging topic in Chile. This survey aimed to assess the seroprevalence of spotted fever group rickettsiae (SFGR), typhus group rickettsiae (TGR), and scrub typhus group orientiae (STGO) in northern, central, and southern Chile. We performed a cross-sectional study of healthy adults in rural and urban settings of five regions. Participants were chosen by double stratified random sampling in urban and by convenience in rural locations (n = 1302). Serum specimens were analyzed for group-specific IgG antibodies against SFGR, TGR, and STGO by enzyme-linked immunosorbent assays (ELISAs). Overall seroprevalences to SFGR, TGR, and STGO were 5.3 %, 1.2 %, and 0.4 %, respectively. Prevalences showed geographical differences. Statistical analyses revealed an association of older age with seropositivity to SFGR and to TGR and of rural setting and male gender with seropositivity to SFGR. The study indicates that SFGR, TGR, and STGO are endemic in Chile. The very low STGO seroprevalence might indicate an insufficient sensitivity of serological tests using Asian O. tsutsugamushistrains as ELISA antigens for the detection of antibodies against Chilean Orientiaspecies.