Kanamura H Y, Dias L C, Glasser C M, da Silva R M, Patucci R M, Chiodelli S G, Addiss D G
Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Brazil.
Rev Inst Med Trop Sao Paulo. 1998 Jul-Aug;40(4):225-31. doi: 10.1590/s0036-46651998000400004.
For a period of 2 years, five follow-up measures of prevalence and incidence rates were estimated in a prospective study of S. mansoni infection in a group of schoolchildren who were living in a rural area of the Municipality of Itariri (São Paulo, Brazil), where schistosomiasis is transmitted by Biomphalaria tenagophila. Infection was determined by the examination of three Kato-Katz stool slides, and the parasitological findings were analyzed in comparison to serological data. In the five surveys, carried out at 6-month intervals (March-April and September-October), the prevalences were, respectively, 8.6, 6.8, 9.9, 5.8 and 17.2% by the Kato-Katz, and 56.5, 52.6, 60.8, 53.5 and 70.1% by the immunofluorescence test (IFT). Geometric mean egg counts were low: 57.8, 33.0, 35.6, 47.3 and 40.9 eggs per gram of feces, respectively. Of the total of 299 schoolchildren, who submitted five blood samples at 6-month intervals, one for each survey, 40% were IFT-positive throughout the study, and 22% were IFT-negative in all five surveys. Seroconversion from IFT negative to positive, indicating newly acquired S. mansoni infection, was observed more frequently in surveys carried out during March-April (after Summer holidays), than during September-October. Seasonal trends were not statistically significant for detection of S. mansoni eggs in stool. The results indicate that the use of IgM-IFT is superior to parasitological methods for detection of incidence of S. mansoni infection in areas with low worm burden.
在一项前瞻性研究中，对居住在伊塔里里市（巴西圣保罗）农村地区的一群学童进行了为期两年的曼氏血吸虫感染情况跟踪调查，该地区血吸虫病由嗜气管双脐螺传播。通过检查三张加藤-凯茨粪便涂片来确定感染情况，并将寄生虫学检查结果与血清学数据进行对比分析。在每隔6个月（3 - 4月和9 - 10月）进行的五次调查中，加藤-凯茨法检测出的患病率分别为8.6%、6.8%、9.9%、5.8%和17.2%，免疫荧光试验（IFT）检测出的患病率分别为56.5%、52.6%、60.8%、53.5%和70.1%。每克粪便中的虫卵几何平均计数较低，分别为57.8、33.0、35.6、47.3和40.9个虫卵。在总共299名学童中，他们每隔6个月提交一份血样用于每次调查，整个研究过程中40%的学童IFT检测呈阳性，22%的学童在所有五次调查中IFT检测均为阴性。从IFT阴性转为阳性的血清学转换表明新感染了曼氏血吸虫，在3 - 4月（暑假后）进行的调查中比在9 - 10月进行的调查中更频繁地观察到这种情况。粪便中曼氏血吸虫虫卵检测的季节性趋势无统计学意义。结果表明，在蠕虫负荷较低的地区，使用IgM - IFT检测曼氏血吸虫感染发病率优于寄生虫学方法。
