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Experimental infections of mice and guinea pigs with Haemophilus parasuis
Abstract:
The pathogenicity of Haemophilus parasuis for mice and guinea pigs was examined. Mice were inoculated intraperitoneally with 2 X 10(7) to 2 X 10(9) organisms suspended in saline or in broth containing fresh yeast extract. Most of them survived after inoculation. Death occurred only in mice inoculated with 2 X 10(9) organisms suspended in broth. The recovery rate of H. parasuis from all the dead mice varied from 28.9% of the brains to 71.4% of the lungs. There were no lesions observed in any mouse, except one. Guinea pigs were inoculated intraperitoneally with 1 X 10(8) to 1.6 X 10(10) organisms suspended in saline. Many of them died after showing septicemia and serofibrinous serositis, which were associated with purulent leptomeningitis or meningoencephalitis in some of them. H. parasuis was recovered abundantly from many organs, including the brain, in the guinea pigs. It was also recovered from guinea pigs inoculated with 1.8 X 10(9) organisms by various routes. Serositis was observed in guinea pigs inoculated intramuscularly or intrapulmonarily. These results suggested that guinea pigs might be available for investigation of the pathogenicity of H. parasuis.
Insights
Haemophilus parasuis caused severe disease and death in guinea pigs, but was less pathogenic in mice. Guinea pigs show promise for studying H. parasuis pathogenicity.
Area of Science:
- Veterinary Microbiology
- Animal Pathology
Background:
- Haemophilus parasuis is an important swine pathogen.
- Understanding its pathogenicity in different hosts is crucial for disease control.
Purpose of the Study:
- To evaluate the pathogenicity of Haemophilus parasuis in mice and guinea pigs.
- To determine the suitability of these animal models for pathogenicity studies.
Main Methods:
- Mice and guinea pigs were inoculated with varying doses of H. parasuis via different routes.
- Clinical signs, mortality, gross lesions, and bacterial recovery from organs were assessed.
Main Results:
- Mice showed low mortality, with limited bacterial recovery, and minimal lesions.
- Guinea pigs exhibited high mortality, septicemia, serositis, and central nervous system involvement.
- H. parasuis was consistently recovered from multiple organs in fatal guinea pig cases.
Conclusions:
- Guinea pigs are a suitable model for investigating Haemophilus parasuis pathogenicity due to their susceptibility.
- Mice are less suitable for studying H. parasuis pathogenicity.
- Further research using guinea pigs can elucidate disease mechanisms and inform prevention strategies.