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Toxoplasmosis in rams: possible significance of venereal transmission
Abstract:
Three rams were infected with tick-borne fever eight months after infection with toxoplasma. There was no clinical evidence of reactivation of the latent toxoplasma infection and semen samples from the rams were not infective to mice. Semen samples from 77 apparently normal rams were tested for toxoplasma infection by passage through mice; none of the samples produced patent infections in mice. Two rams with chronic toxoplasma infection were repeatedly mated with seronegative ewes. None of the ewes showed serological evidence of acquired infection and all lambed satisfactorily.
Insights
Tick-borne fever did not reactivate latent toxoplasma infections in rams. Toxoplasma gondii was not detected in ram semen, indicating no transmission risk to ewes or lambs.
Area of Science:
- Veterinary Parasitology
- Ovine Infectious Diseases
- Reproductive Immunology
Background:
- Toxoplasma gondii establishes latent infections in sheep.
- Tick-borne fever virus (TBFV) is an emerging concern in ovine health.
- The potential for TBFV to influence latent toxoplasmosis is unknown.
Purpose of the Study:
- To investigate if co-infection with tick-borne fever reactivates latent Toxoplasma gondii infection in rams.
- To assess the infectivity of semen from rams with latent toxoplasmosis.
- To determine the risk of Toxoplasma transmission from chronically infected rams to naive ewes.
Main Methods:
- Experimental infection of rams with TBFV following latent T. gondii infection.
- Semen collection and inoculation into mice to detect T. gondii.
- Serological testing of ewes mated with chronically infected rams.
- Monitoring of ewes and their offspring for signs of infection.
Main Results:
- No clinical signs of toxoplasmosis reactivation were observed in TBFV-infected rams.
- T. gondii was not detected in semen from infected rams via mouse inoculation.
- Testing of semen from 77 apparently healthy rams revealed no T. gondii.
- Ewes mated with chronically infected rams did not seroconvert, and lambing was normal.
Conclusions:
- Tick-borne fever infection does not appear to reactivate latent Toxoplasma gondii in rams.
- Semen from chronically infected rams poses no detectable risk for T. gondii transmission.
- Ovine toxoplasmosis control strategies remain effective despite potential co-infections.