Abramo C, Fontes C J, Krettli A U
Centro de Pesquisas Rene Rachou, Fundacao Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil.
Am J Trop Med Hyg. 1995 Aug;53(2):202-5. doi: 10.4269/ajtmh.1995.53.202.
Seroepidemiologic studies using the indirect immunofluorescent antibody test (IFAT) are valuable in malaria control programs in identifying local foci of malaria, in diagnosing malaria in asymptomatic, low-parasitemia blood donors in nonendemic countries, in detecting imported malaria and preventing its introduction into new areas, and in excluding recurrent fever from causes other than malaria. Because other diseases may occur in areas where malaria is prevalent, the aim of this work, using the IFAT, was to determine the frequency of cross-reactions between blood-stage antigens of Plasmodium falciparum and antibodies present in the serum of individuals with leishmaniasis, toxoplasmosis and Chagas' disease. Since malaria transmission does not occur in the study area (State of Minas Gerais, Brazil) where these other diseases are present, we studied sera from individuals living in this area who had never been in the areas endemic for malaria in the Amazon region. Positive reactivity of sera with blood malaria antigens evaluated by IFAT at dilutions > or = 1:40 was detected in 19 (38%) of 50 individuals with cutaneous leishmaniasis, five (62%) of eight individuals with visceral leishmaniasis, 14 (32%) of 44 individuals with Chagas' disease, four (11%) of 36 individuals with toxoplasmosis, and in none of the 14 uninfected controls. All 23 of the control malaria sera from the endemic area (State of Mato Grosso, Brazil) were positive at high dilutions. We found no correlation between titers of the IFAT with malaria and the specific antigens used for serodiagnosis of the other protozoan infections studied. At dilutions of 1:20 and 1:40, the sensitivity of the IFAT test was 100% and specificity was 52% and 72%, respectively. At a dilution of 1:80, the sensitivity was 86% and the specificity was 90%.(ABSTRACT TRUNCATED AT 250 WORDS)
使用间接免疫荧光抗体试验（IFAT）的血清流行病学研究在疟疾控制项目中具有重要价值，可用于识别疟疾的本地疫源地、诊断非流行国家无症状、低疟原虫血症献血者的疟疾、检测输入性疟疾并防止其传入新地区，以及排除疟疾以外其他原因引起的反复发热。由于在疟疾流行地区可能会出现其他疾病，本研究使用IFAT的目的是确定恶性疟原虫血液阶段抗原与利什曼病、弓形虫病和恰加斯病患者血清中抗体之间的交叉反应频率。由于在存在这些其他疾病的研究区域（巴西米纳斯吉拉斯州）未发生疟疾传播，我们研究了居住在该地区且从未去过亚马逊地区疟疾流行区的个体的血清。在50例皮肤利什曼病患者中，19例（38%）、8例内脏利什曼病患者中的5例（62%）、44例恰加斯病患者中的14例（32%）、36例弓形虫病患者中的4例（11%）的血清在稀释度≥1:40时通过IFAT检测与血液疟疾抗原有阳性反应，而14例未感染对照者均为阴性。来自流行区（巴西马托格罗索州）的所有23份对照疟疾血清在高稀释度时均为阳性。我们发现IFAT检测疟疾的滴度与用于其他原生动物感染血清诊断的特异性抗原之间没有相关性。在1:20和1:40的稀释度下，IFAT检测的敏感性为100%，特异性分别为52%和72%。在1:80的稀释度下，敏感性为86%，特异性为90%。（摘要截短于250字）
