Study of Hog Infection Leads to More Tests

Study of Hog Infection Leads to More Tests

Parasites compromise effectiveness of vaccination.

Using vaccination to induce a robust immune response has been an effective strategy for managing infectious diseases in humans and animals for more than a century. Now, Agricultural Research Service scientists and colleagues have found that a concurrent parasite infection significantly compromises the effectiveness of a commonly administered vaccine in swine. The study was conducted by researchers at the ARS Diet, Genomics and Immunology Laboratory in Beltsville, Maryland.

For the study, 36 pigs raised on a pathogen-free farm were divided into four groups and studied for nearly three months. The three groups included pigs that had been continuously exposed to a common worm infection; pigs that were exposed to the same worm infection, but vaccinated against Mycoplasma hyopneumoniae bacteria at week three; and a worm-free group that was similarly vaccinated against the bacteria at week three. The pigs were exposed to the bacteria via aerosol four weeks after the vaccine injections were administered.

After four weeks it was found that all worm-free, vaccinated pigs infected with M. hyopneumoniae tested 100% positive for vaccine-derived antibodies, meaning they presented an optimal serum response. But only 78% of the vaccinated pigs that had been worm infected developed serum antibodies. The other 22% were considered vaccine failures. The worm-infected pigs also had a higher percentage of lung pathology than their non-worm-infected counterparts after vaccination and subsequent bacteria exposure. More tests are forthcoming.

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