EPIDEMIOLOGICAL SURVEY OF SUPPOSED SPOTTED FEVER OUTBREAK

Abstract This study aimed to evaluate the suspition of spotted fever (SF) occurrence in Quirinopolis city (Goias State) through serological survey in human, dogs and horses samples, and identification of tick vectors. In 2007, indirect immunofluorescence antibody test (IFAT) was carried out for Rickettsia spp. in blood samples taken from 28 persons, related to the suspected case (a 3-year-old child who showed signs of rickettsial disease after exposure to ticks). Also, blood samples were collected from five dogs and 42 horses, from which only there horses (28.6%) were seropositive. The tick Amblyomma cajennense was not found. Seven humans were reactive to Rickettsia spp., most of them were paternal relatives of the suspected case. In 2008, in the same region, IFAT was performed on 30 human samples without clinical signs of SF and 50% of them were seropositive for Rickettsia spp. Additionally, blood samples were collected from 24 stray dogs, and one of the animals showed seropositivity. Serologic evidence of the contact between the bacteria of the genus Rickettsia with human and animal inhabitants from Quirinopolis city indicates that the SF or another rickettsial disease may be occurring in Goias State, Brazil.

摘要 本研究旨在通过对人类、犬类及马类样本开展血清学调查，并对蜱媒媒介进行鉴定，评估巴西戈亚斯州基里诺波利斯市出现斑点热（spotted fever, SF）的可能性。2007年，针对与1名疑似病例相关的28名个体采集血液样本，采用间接免疫荧光抗体试验（indirect immunofluorescence antibody test, IFAT）检测立克次体属（Rickettsia spp.）抗体；该疑似病例为1名3岁儿童，在接触蜱虫后出现立克次体病症状。同时采集5只犬与42匹马的血液样本，其中仅12匹马（28.6%）血清学检测呈阳性。未检出卡真革蜱（Amblyomma cajennense）。7名受检者的立克次体属抗体呈阳性反应，其中多数为该疑似病例的父系亲属。2008年，在同一地区，对30名无斑点热临床症状的个体采集血液样本并开展间接免疫荧光抗体试验，其中50%的样本立克次体属抗体呈阳性。此外，采集24只流浪犬的血液样本，其中1只犬血清学检测呈阳性。基里诺波利斯市人类与动物居民接触立克次体属细菌的血清学证据表明，巴西戈亚斯州可能存在斑点热或其他立克次体病的发生。