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Rodents are not a source of endogenously-produced, fecally-transmitted Caryospora bigenetica oocysts
R J Douglas1, C A Sundermann, D S Lindsay
1Department of Zoology and Wildlife Science, Auburn University, Alabama 36849.
Abstract:
Fifteen Swiss-Webster mice (Mus musculus) and eight cotton rats (Sigmodon hispidus) were inoculated orally with Caryospora bigenetica oocysts. Feces from these animals were collected from 0 to 180 days postinoculation (DPI) and examined for endogenously-produced oocysts using Nomarski microscopy. Oocysts were recovered from mouse feces at 0, 1, 2, 3, 5, 7, 8, 10, and 14 DPI, and from cotton rat feces at 1, 2, and 9 DPI. The recovered oocysts were determined to be from the original inocula due to the presence of thick walls, polar granules, and Stieda and substieda bodies. All animals exhibited clinical signs at 8 DPI. Developmental stages of C. bigenetica were identified in various tissues of seven cotton rats found dead at 9, 10, 11, 12, and 13 DPI. Caryocysts were found in muzzle, tongue, footpad, scrotum, and rectum of mice and cotton rats at 30 DPI. Fecal samples collected from mice on 0, 8, 10, 12, 14, 16, and 18 DPI, and from cotton rats on 0, 9, 11, 13, 15, and 17 DPI were injected subcutaneously into 13 mice. Of the 13 mice, a Caryospora infection was observed only in the mouse inoculated with 0 DPI mouse feces. We propose that endogenously-produced C. bigenetica oocysts are not fecally-transmitted by Swiss-Webster mice or cotton rats.
Insights
Swiss-Webster mice and cotton rats infected with Caryospora bigenetica did not transmit the parasite through feces. This study investigated the fecal transmission of Caryospora bigenetica in rodents.
Area of Science:
- Parasitology
- Infectious Diseases
- Rodent Models
Background:
- Caryospora is a genus of coccidian parasites.
- Understanding parasite transmission is crucial for disease control.
Purpose of the Study:
- To determine if endogenously-produced Caryospora bigenetica oocysts are fecally transmitted by Swiss-Webster mice and cotton rats.
Main Methods:
- Swiss-Webster mice and cotton rats were orally inoculated with C. bigenetica oocysts.
- Fecal samples were collected and examined for oocysts using Nomarski microscopy.
- Infectivity of fecal samples was tested by subcutaneous injection into naive mice.
Main Results:
- Oocysts were recovered from mouse feces up to 14 days postinoculation (DPI) and cotton rat feces up to 9 DPI.
- Clinical signs were observed in all animals at 8 DPI.
- Only one mouse inoculated with 0 DPI mouse feces developed an infection, suggesting no fecal transmission.
Conclusions:
- Endogenously-produced C. bigenetica oocysts are not fecally transmitted by Swiss-Webster mice or cotton rats.
- Further research may be needed to elucidate alternative transmission routes.