A CAUSAL RELATIONSHIP BETWEEN BORDETELLA-PERTUSSIS AND BORDETELLA-PARAPERTUSSIS INFECTIONS

Bordetella parapertussis is isolated during the late stages of pertuss is outbreaks and occasionally from patients infected with pertussis. T he relationship between Bordetella pertussis and B. parapertussis was investigated in mice with monoinfections and mixed infections. Four gr oups of 10 2-week-old suckling mice were studied: mice born to mice va ccinated against pertussis during pregnancy and unvaccinated controls consequently did and did not receive antipertussis toxin (PT) antibody transcolostrally. The mice were infected transnasally with B. paraper tussis strain 422 and 2 identical groups were infected transnasally wi th B. parapertussis strain 422 and B. pertussis strain 18-323. Bacteri al colonization of the lungs and trachea was studied at 1, 2, and 3 we eks after challenge. No persistent colonization by B. parapertussis of the lungs or trachea of monoinfected suckling mice were observed. Per sistent colonization by B. parapertussis was observed when suckling mi ce that received anti-PT antibody transcolostrally mere infected with both species. These findings are consistent with the clinical characte ristics of B. parapertussis. The results of this study demonstrate tha t B. pertussis infection facilitates B. parapertussis infection.