Cryptosporidium meleagridis: infectivity in healthy adult volunteers

Area of Science:

• Infectious Diseases
• Parasitology
• Microbiology

Background:

• Human cryptosporidiosis is commonly caused by Cryptosporidium parvum and Cryptosporidium hominis.
• Unusual Cryptosporidium species, including Cryptosporidium meleagridis, are increasingly identified through advanced genotyping.
• Cryptosporidium meleagridis infections are found in a small percentage of individuals with diarrhea, with higher prevalence in developing countries.

Purpose of the Study:

• To investigate the infectivity and clinical manifestations of Cryptosporidium meleagridis in healthy adult volunteers.
• To determine the course and resolution of Cryptosporidium meleagridis infections in a controlled human challenge study.

Main Methods:

• Five healthy adult volunteers were orally challenged with 10^5 Cryptosporidium meleagridis oocysts.
• Participants were monitored for six weeks for clinical symptoms and the presence of fecal oocysts.
• Fecal DNA was analyzed using polymerase chain reaction (PCR) targeting the Cryptosporidium small subunit ribosomal RNA gene for species confirmation.

Main Results:

• Four out of five volunteers developed diarrhea following oocyst challenge.
• Three volunteers shed detectable levels of fecal oocysts.
• One infected volunteer remained asymptomatic, indicating varied host response.
• Infections were self-limited, with oocyst clearance observed within 12 days post-challenge.

Conclusions:

• Healthy adults are susceptible to infection with Cryptosporidium meleagridis.
• Ingestion of Cryptosporidium meleagridis oocysts can lead to symptomatic illness, including diarrhea.
• Cryptosporidium meleagridis represents a potential cause of human cryptosporidiosis, even in immunocompetent individuals.