Companion animals, vaccines, and risk to patients with cystic fibrosis

It is well-established that live-attenuated vaccines should be avoided in immunocompromised people, due to the risk of acquiring an infection even from weakened pathogens. Under the same principle, live-attenuated bacterial veterinary vaccines can pose a risk for certain immunocompromised individuals, specifically those with phagocytic function defects. For people with cystic fibrosis (CF), pet ownership of companion animals is popular, putting them at risk from acquiring an infection from their pet.¹

One pathogen of concern for both CF patients and their animal, is Bordetella bronchiseptica. It can cause respiratory disease in animals (kennel cough) and vulnerable humans.¹ Infection in humans is rare, with a small number of cases reported in literature.

The risk of acquiring B. bronchiseptica is highest for CF owners during the actual administration of vaccine if the clinician administers the vaccine incorrectly, or during the post-vaccination shedding period.¹ For example, one case involved a 14-year-old boy whose face was inadvertently showered with live nasally administered B. bronchiseptica vaccine during the vaccination procedure. No cultures were performed, but 5 days after the exposure the boy developed a cough that persisted for 3 to 4 months and was accompanied by posttussive vomiting.²

Another case report describes a pediatric patient acquiring B. bronchiseptica from her kitten that was acutely ill with the disease. B. bronchiseptica was isolated from her sputum sample, but she remained asymptomatic. The patient had been vaccinated for Bordetella pertussis, or whooping cough, which may have provided some cross protection.³ After the kitten was removed from the home, there was no further isolation of B. bronchiseptica from her sputum.

It is helpful to review a Summary of Product Characteristics for the B. bronchiseptica vaccines, which provides guidance on avoiding accidental inoculation. For the live-attenuated canine vaccine, it warns immunocompromised dog owners to avoid contact with their pet from a range of 35 days to 11 weeks. For the live-attenuated feline vaccine, the viral shedding period can last up to 1 year in the cat, therefore the recommendation is for CF owners with cats to avoid using this vaccine altogether.¹ Patients with CF should make their veterinarians aware of their status, so a safe and effective vaccine and strategy can be selected to protect both humans and pets from Bordetella bronchiseptica.

Ghatpande is a 2022 PharmD candidate at the University of Connecticut

References

1. Moore JE, Rendall JC, Millar BC. A doggy tale: Risk of zoonotic infection with Bordetella bronchiseptica for cystic fibrosis (CF) patients from live licenced bacterial veterinary vaccines for cats and dogs. J Clin Pharm Ther. 2022 Feb;47(2):139-145. doi: 10.1111/jcpt.13492
2. Berkelman RL. Human illness associated with use of veterinary vaccines. Clin Infect Dis. 2003 Aug 1;37(3):407-14. doi: 10.1086/375595.
3. Register KB, Sukumar N, Palavecino EL, Rubin BK, Deora R. Bordetella bronchiseptica in a paediatric cystic fibrosis patient: possible transmission from a household cat. Zoonoses Public Health. 2012 Jun;59(4):246-50. doi: 10.1111/j.1863-2378.2011.01446.x