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Experimental cryptosporidiosis in a primate model
R A Miller1, M A Bronsdon, W R Morton
1Regional Primate Research Center, University of Washington, Seattle 98195.
Abstract:
Cryptosporidium causes a disease in infant macaques that is clinically, histologically, and microbiologically indistinguishable from that seen in young children. A reproducible experimental model of cryptosporidiosis has been developed in pigtailed macaques (Macaca nemestrina) and used to studied the infectious dose of oocysts and the effect of inoculum size on severity of disease. Inoculation with either 2 x 10(5) or 10 oocysts via nasogastric tube resulted in clinical enteritis and the fecal passage of large numbers of cryptosporidial oocysts in all four primates studied. The size of the inoculum had no apparent effect on the severity or duration of disease. Rechallenge 2 weeks after resolution of the primary infection demonstrated partial acquired immunity. The small inoculum size coupled with the passage of large numbers of oocysts contributes to the highly contagious nature of cryptosporidiosis among captive primates and may be relevant to the epidemiology and control of cryptosporidiosis in humans.
Insights
A new macaque model for cryptosporidiosis accurately mimics human infant disease. This study found that inoculum size did not affect disease severity, but partial immunity was observed after reinfection.
Area of Science:
- Veterinary Medicine
- Infectious Diseases
- Primate Models
Background:
- Cryptosporidium infection in infant macaques closely resembles human pediatric cryptosporidiosis.
- A reproducible experimental model is crucial for studying this parasitic disease.
Purpose of the Study:
- To establish and utilize a macaque model to investigate the infectious dose and inoculum size effects on cryptosporidiosis.
- To assess the development of acquired immunity following infection.
Main Methods:
- Pigtailed macaques (Macaca nemestrina) were inoculated with varying doses of Cryptosporidium oocysts via nasogastric tube.
- Clinical signs, oocyst shedding, and response to rechallenge were monitored.
- Histological and microbiological assessments were performed.
Main Results:
- All inoculated macaques developed clinical enteritis and shed large numbers of oocysts, regardless of inoculum size (2 x 10(5) or 10 oocysts).
- Inoculum size did not influence disease severity or duration.
- Partial acquired immunity was evident upon rechallenge two weeks post-infection.
Conclusions:
- The macaque model effectively replicates human cryptosporidiosis, offering a valuable tool for research.
- Low infectious doses and high oocyst shedding contribute to cryptosporidiosis's contagiousness in primates.
- Findings have implications for understanding and controlling human cryptosporidiosis epidemiology.