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、犬类及马匹样本开展血清学调查，并鉴定蜱媒媒介，评估巴西戈亚斯州基里诺波利斯市斑点热（spotted fever, SF）的发生可能性。2007年，研究人员针对与疑似病例（一名3岁儿童，该儿童在蜱虫暴露后出现立克次体病相关症状）相关的28名人类血液样本，开展了针对立克次体属（Rickettsia spp.）的间接免疫荧光抗体试验（indirect immunofluorescence antibody test, IFAT）检测。此外，研究人员还采集了5只家犬和42匹马的血液样本，其中仅12匹马（占比28.6%）血清学检测呈阳性。本次研究未检出卡真革蜱（Amblyomma cajennense）。7名人类样本对立克次体属呈阳性反应，其中大部分为该疑似病例的父系亲属。2008年，在同一地区，研究人员对30名无斑点热临床症状的人类样本开展了间接免疫荧光抗体试验，其中50%的样本对立克次体属呈血清学阳性。此外，研究人员还采集了24只流浪犬的血液样本，其中1只犬的检测结果呈阳性。本次研究在基里诺波利斯市的人类与动物居民中检出立克次体属细菌接触的血清学证据，表明巴西戈亚斯州可能存在斑点热或其他立克次体病的流行。