Since can cross-react with SFG rickettsiae , and can cross-react both with other SFG rickettsiae and , those sera that are both TG- and SFG-positive may be due to either rickettsia. suspected. If public health interventions are to be implemented to reduce the risk of rickettsioses as a significant public health problem, improvements in TCS 21311 rickettsial diagnostics and surveillance will be necessary. . Humans are incidental hosts, where the pathogen causes a non-specific febrile illness often with fever, headache, arthralgia and rash . Murine typhus is one of the most widely distributed arthropod-borne infections throughout the world, yet it is frequently unrecognized or misdiagnosed due to its non-specific and usually mild clinical presentation . Despite the fact that murine typhus can cause severe illness and death [4, 5], clinical signs and symptoms in untreated (undiagnosed) patients usually last for 7C14 days followed by spontaneous resolution of the illness [6, 7]. Hence, its incidence is likely to be under-reported. Of the rickettsiae TCS 21311 only and is primarily transmitted by the oriental rat flea, is maintained by the classic ratCrat flea cycle, where rats are the main reservoir hosts that can be infected by the inoculation of infected flea faeces into the bite wound , or the regurgitation of rickettsiae by the infected flea during blood feeding . Studies within the United States have reported antibodies against in opossums and domestic cats and dogs  and a shift in the life-cycle of from the classic ratCrat flea cycle to opossumCcat flea cycle [2, 12]. In comparison, the disease ecology of is less clear . However, DNA is most highly reported in cat fleas, worldwide . Up to the end of 2014, 72 locally acquired murine typhus cases had been recorded in New Zealand (; Institute of Environmental Science and Research, written personal communication). For infections have recently been reported . It is important to note that because rickettsiosis shares SNF5L1 a similar clinical profile to murine typhus (and potentially similar vectors and reservoirs), infection can be mistaken for a suspected case of . The first reported New Zealand-acquired murine typhus TCS 21311 case occurred in greater Auckland in 1989 , where it has continued to occur at low-incidence levels. Since then cases have also been reported up to 130?km away to the south in the Waikato region (Fig. 1) [6, 17]. A marked increase in cases reported in this region from 2006 to 2008 raised concerns with health authorities that the disease may be continuing to both increase in prevalence and spread further south, i.e. is an emerging disease. In response, we conducted the first seroprevalence study in New Zealand for and in the Waikato region, covering beyond the southernmost known distribution. Open in a separate window Fig. 1. Northern part of North Island, New Zealand, highlighting the Waikato District Health Board study region and the location of the 12 and six infections (including one dual infection). METHODS Clinical suspicion of rickettsial infections is most widely confirmed by serological tests with the indirect immunofluorescence assay (IFA) being the gold standard [18, 19]. However, members of the genus are notorious for cross-reactivity in serological tests . For example, antibodies against in human sera have been reported to cross-react with in IFA . For this reason, coupled with the fact that both and rickettsioses share similar clinical manifestations, we established, in New Zealand, a specific laboratory methodology using Western blot (WB) and cross-adsorption assays to distinguish between and infections . These assays, in combination with IFA, have been shown to be reliable in serological differentiation among several rickettsioses [20, 21]. From 2009 to 2010, serum samples were obtained from 989 blood donors visiting the New Zealand Blood Service in Hamilton City (Fig. 1). Of these, 950 were from the Waikato District Health Board region with 435 residing to the north and 515 to the south of the city limits. All donors visiting the collection centre, except those residing within Hamilton city, were invited to participate and were enrolled sequentially during the study period. Participants were provided with a project information sheet, gave written, informed consent, and completed a standardized questionnaire. The questionnaire covered risk factors such as overseas travel, animal contact, TCS 21311 and place of residence/employment. No participants withdrew from the study. The Northern Y Regional Ethics Committee of New Zealand approved this study (no. NTY/08/09/085). Although samples from Waikato were the focus of our study, all sera were tested.