Kattula Deepthi, Jeyavelu Nithya, Prabhakaran Ashok D, Premkumar Prasanna S, Velusamy Vasanthakumar, Venugopal Srinivasan, Geetha Jayanthi C, Lazarus Robin P, Das Princey, Nithyanandhan Karthick, Gunasekaran Chandrabose, Muliyil Jayaprakash, Sarkar Rajiv, Wanke Christine, Ajjampur Sitara Swarna Rao, Babji Sudhir, Naumova Elena N, Ward Honorine D, Kang Gagandeep
Departments of Gastrointestinal Sciences and.
Biostatistics, Christian Medical College, Vellore, Tamil Nadu, India; and.
Clin Infect Dis. 2017 Feb 1;64(3):347-354. doi: 10.1093/cid/ciw730. Epub 2016 Nov 9.
Cryptosporidium is a leading cause of moderate to severe childhood diarrhea in resource-poor settings. Understanding the natural history of cryptosporidiosis and the correlates of protection are essential to develop effective and sustainable approaches to disease control and prevention.
Children (N = 497) were recruited at birth in semiurban slums in Vellore, India, and followed for 3 years with twice-weekly home visits. Stool samples were collected every 2 weeks and during diarrheal episodes were tested for Cryptosporidium species by polymerase chain reaction (PCR). Serum samples obtained every 6 months were evaluated for seroconversion, defined as a 4-fold increase in immunoglobulin G directed against Cryptosporidium gp15 and/or Cp23 antigens between consecutive sera.
Of 410 children completing follow-up, 397 (97%) acquired cryptosporidiosis by 3 years of age. PCR identified 1053 episodes of cryptosporidiosis, with an overall incidence of 0.86 infections per child-year by stool and serology. The median age for the first infection was 9 (interquartile range, 4-17) months, indicating early exposure. Although infections were mainly asymptomatic (693 [66%]), Cryptosporidium was identified in 9.4% of diarrheal episodes. The proportion of reinfected children was high (81%) and there was clustering of asymptomatic and symptomatic infections (P < .0001 for both). Protection against infection increased with the order of infection but was only 69% after 4 infections. Cryptosporidium hominis (73.3%) was the predominant Cryptosporidium species, and there was no species-specific protection.
There is a high burden of endemic cryptosporidiosis in southern India. Clustering of infection is suggestive of host susceptibility. Multiple reinfections conferred some protection against subsequent infection.
隐孢子虫是资源匮乏地区儿童中至重度腹泻的主要病因。了解隐孢子虫病的自然史和保护性关联因素对于制定有效且可持续的疾病控制和预防方法至关重要。
在印度韦洛尔的半城市贫民窟招募了497名儿童，自出生起进行为期3年的随访，每周进行两次家访。每2周采集粪便样本，腹泻发作时通过聚合酶链反应（PCR）检测隐孢子虫种类。每6个月采集血清样本，评估血清转化情况，血清转化定义为连续两份血清中针对隐孢子虫gp15和/或Cp23抗原的免疫球蛋白G增加4倍。
在完成随访的410名儿童中，397名（97%）在3岁前感染了隐孢子虫病。PCR检测到1053次隐孢子虫病发作，通过粪便和血清学检测，每名儿童每年的总体感染率为0.86次。首次感染的中位年龄为9（四分位间距，4 - 17）个月，表明感染较早。虽然感染主要无症状（693例[66%]），但在9.4%的腹泻发作中检测到隐孢子虫。再感染儿童的比例很高（81%），无症状和有症状感染存在聚集现象（两者P <.0001）。抗感染能力随感染次数增加而增强，但4次感染后也仅为69%。人隐孢子虫（73.3%）是主要的隐孢子虫种类，不存在种特异性保护。
印度南部地方性隐孢子虫病负担较重。感染聚集提示宿主易感性。多次再感染对后续感染有一定保护作用。
