Okhuysen P C, Chappell C L, Sterling C R, Jakubowski W, DuPont H L
Division of Infectious Diseases, The University of Texas Medical School and Center for Infectious Diseases, Houston 77030, USA.
Infect Immun. 1998 Feb;66(2):441-3. doi: 10.1128/IAI.66.2.441-443.1998.
Healthy adults are susceptible to infection with small numbers of Cryptosporidium parvum oocysts, resulting in self-limited infection. We investigated if infection of humans with C. parvum is protective 1 year after primary exposure. At 1 year after a primary challenge with 30 to 10(6) oocysts, 19 healthy immunocompetent adults were rechallenged with 500 oocysts and monitored for the development of infection and/or illness. Oocyst excretion was quantitated by direct immunofluorescence with a C. parvum-specific monoclonal antibody, and anti-C. parvum antibodies in serum were detected by an enzyme-linked immunosorbent assay. Fewer subjects shed oocysts after the second exposure (3 of 19; 16%) than after the first exposure (12 of 19; 63%) (P < 0.005). Although the rates of diarrhea were comparable after each of the two exposures, the clinical severity as determined by the mean number of unformed stools passed was lower after reexposure (11.25 versus 8.62; P < 0.05). The number of anti-Cryptosporidium immunoglobulin G and A seroconversions increased after secondary exposure. However, the C. parvum serum antibody response did not correlate with the presence or absence of infection.
健康成年人易受少量微小隐孢子虫卵囊感染，导致自限性感染。我们调查了人类初次接触微小隐孢子虫1年后感染是否具有保护性。在初次用30至10⁶个卵囊攻击后1年，19名健康的免疫功能正常成年人再次用500个卵囊攻击，并监测感染和/或疾病的发展。通过用微小隐孢子虫特异性单克隆抗体进行直接免疫荧光定量卵囊排泄，并通过酶联免疫吸附测定法检测血清中的抗微小隐孢子虫抗体。第二次接触后排出卵囊的受试者（19人中的3人；16%）比第一次接触后（19人中的12人；63%）少（P<0.005）。虽然两次接触后腹泻发生率相当，但再次接触后根据不成形粪便平均排出数量确定的临床严重程度较低（11.25对8.62；P<0.05）。二次接触后抗隐孢子虫免疫球蛋白G和A血清转化的数量增加。然而，微小隐孢子虫血清抗体反应与感染的有无无关。
