THE INFECTIVITY OF CRYPTOSPORIDIUM-PARVUM IN HEALTHY-VOLUNTEERS
THE INFECTIVITY OF CRYPTOSPORIDIUM-PARVUM IN HEALTHY-VOLUNTEERS
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DOI：
10.1056/nejm199503303321304
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发表时间：
1995-03-30
影响因子：
158.5
通讯作者：
JAKUBOWSKI, W
中科院分区：
文献类型：
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作者：
DUPONT, HL;CHAPPELL, CL;JAKUBOWSKI, W
背景少量的隐孢子虫卵囊甚至可以污染处理过的饮用水，并且在正常和免疫功能低下的宿主中摄入卵囊可以引起腹泻病。由于引起人类感染所需的生物体数量是未知的，我们进行了一项研究，以确定健康成人的寄生虫的感染剂量。在提供知情同意书后，29名无既往C.通过不存在抗隐孢子虫特异性抗体确定的微小孢子虫感染，给予30 - 100万C的单剂量。从小牛身上获得的细小卵囊。然后对他们的卵囊排泄和临床疾病进行为期八周的监测。监测家庭接触者的二次传播。在接受预期剂量为300个或更多卵囊的16名受试者中，14名（88%）被感染。在30个卵囊的剂量后，五分之一的受试者（20%）被感染，而在1000个或更多卵囊的剂量下，七分之七被感染。通过线性回归计算的中位感染剂量为132个卵囊。在激发剂量后排出卵囊的18名受试者中，11名有肠道症状，7名（39%）有临床隐孢子虫病，包括腹泻和至少一种其他肠道症状。所有患者均痊愈，家庭接触者中无继发腹泻病例。在没有既往感染过C. parvum、低剂量C.细小卵囊足以引起感染。
Background. Small numbers of Cryptosporidium parvum oocysts can contaminate even treated drinking water, and ingestion of oocysts can cause diarrheal disease in normal as well as immunocompromised hosts. Since the number of organisms necessary to cause infection in humans is unknown, we performed a study to determine the infective dose of the parasite in healthy adults.Methods. After providing informed consent, 29 healthy volunteers without evidence of previous C. parvum infection, as determined by the absence of anti-cryptosporidium-specific antibodies, were given a single dose of 30 to 1 million C. parvum oocysts obtained from a calf. They were then monitored for oocyst excretion and clinical illness for eight weeks. Household contacts were monitored for secondary spread.Reuslts. Of the 16 subjects who received an intended dose of 300 or more oocysts, 14 (88 percent) became infected. After a dose of 30 oocysts, one of five subjects (20 percent) became infected, whereas at a dose of 1000 or more oocysts, seven of seven became infected. The median infective dose, calculated by linear regression, was 132 oocysts. Of the 18 subjects who excreted oocysts after the challenge dose, 11 had enteric symptoms and 7 (39 percent) had clinical cryptosporidiosis, consisting of diarrhea plus at least one other enteric symptom. All recovered, and there were no secondary cases of diarrhea among household contacts.Conclusions. In healthy adults with no serologic evidence of past infection with C. parvum, a low dose of C. parvum oocysts is sufficient to cause infection.