Spatial distribution of households with a member IgG positive against scrub typhus in Vientiane city in 2006. MK-8617 elutes. We validated the accuracy of ELISA of these elutes against ELISA using serum samples. The overall prevalence of scrub and murine typhus IgG antibodies was 20.3% and 20.6%, respectively. Scrub typhus seropositivity was significantly higher among adults living in the periphery (28.4%) than in the central zone (13.1%) of Vientiane. In contrast, seroprevalence of murine typhus IgG antibodies was significantly higher in the central zone (30.8%) as compared to the periphery (14.4%). In multivariate analysis, adults with a longer residence in Vientiane were at significant greater risk of past infection with murine typhus and at lower risk for scrub typhus. Those with no education, living on low incomes, living on plots of land with poor sanitary conditions, living in large households, and farmers were at higher risk of scrub typhus and those living in neighborhoods with high building density and close to markets were at greater risk for murine typhus and at lower risk of scrub typhus past infection. == Conclusions == This study underscores the intense circulation of both scrub and murine typhus in Vientiane city Rabbit Polyclonal to ARPP21 and underlines difference in spatial distribution and risk factors involved in the transmission of these diseases. == Author Summary == Scrub typhus and murine typhus are neglected but important treatable causes of fever, morbidity and mortality in South-East Asia. Epidemiological data suggests that scrub typhus would be more common in rural areas and murine typhus in urban areas but there are very few comparative data from places where both diseases occur, as is the case in Vientiane, the capital of the Lao PDR. We therefore determined the frequency of IgG antibody seropositivity against scrub typhus and murine typhus, as indices of prior exposure to these pathogens, in a randomly selected population of 2,002 adults living in different neighbourhoods in Vientiane. The overall prevalence of IgG against these two pathogens was 20%. However, within the city, the spatial distribution of IgG against these two diseases was radically different – past exposure to murine typhus being more frequent in MK-8617 urbanized areas while past exposure to scrub typhus more frequent in outlying areas. This study underscores the importance of ecological characteristics in improving the understanding of both scrub typhus and murine typhus transmission and epidemiology. == Introduction == Scrub typhus and murine typhus are important but under-recognized treatable causes of fever, morbidity and mortality in South-East Asia[1],[2],[3],[4]. There has been a recent resurgence of interest in these diseases, which both cause undifferentiated fever, headache and myalgia progressing, in a minority, to jaundice, pneumonitis and meningo-encephalitis[5],[6],[7],[8],[9]. Scrub typhus, caused byOrientia tsutsugamushi, occurs in Asia and northern Australia and is transmitted by the bites of infected trombiculid mites[10]. Murine typhus, caused byRickettsia typhi, occurs globally and is transmitted through the infected flea bite site or by scratching infected faeces into the skin[11],[12]. Scrub typhus and murine typhus were first differentiated, in Malaysia, in 1936[13]. Chiggers and rodents are thought to be most important reservoirs of scrub typhus and murine typhus infection, respectively. Studies suggest that scrub typhus is more common in rural areas and murine typhus in urban areas[11],[13],[14],[15],[16],[17],[18],[19]but there is very little recent information on the epidemiology of scrub and murine typhus in places where both diseases occur. The Lao People’s Democratic Republic (Laos) is situated mostly east of the Mekong River and borders Thailand, Cambodia, Burma, China and Vietnam. The majority of the population (88%) of 5.6 million people lives in rural areas (2005 census from National Statistics Centre). Vientiane, the capital of Lao PDR is the most populated urban area in the country, with less than 300,000 inhabitants. The diagnosis of non-malarial fevers in Laos remains difficult due to limited laboratory diagnostic facilities. In 2000, the main differential diagnoses for adults admitted with fever to hospital were slide-positive malaria or slide-negative malaria syndrome and, in both situations patients were treated with antimalarials, with additional antibiotics for those with malaria syndrome. Since then it has become apparent that both scrub and murine typhus are common causes of fever in Laos[20],[21],[22]. In Mahosot Hospital, Vientiane, among MK-8617 427 adults admitted with unexplained fever, 14.8% and 9.6% had serological evidence for scrub typhus and murine typhus, respectively[20]. As these diseases are usually relatively straightforward and inexpensive to treat with short courses of doxycyline, their recognition in Laos raises the prospect that a significant proportion of non-malarial fevers can be diagnosed.