Do Montreal’s pigeons pose a threat to public health?
To maintain public health, government agencies and researchers regularly monitor the health of livestock, pets and wildlife, as animals often serve as reservoirs for diseases that infect humans. Pigeons are urban fauna that make up part of the city wildlife and coexist with the human population. As a result, pigeons are in daily contact with humans and may also come into contact with poultry raised in urban backwards, an increasingly popular agricultural activity. Due to their proximity to us, monitoring and studying the health of pigeons is an important source of information for public health as well as for the Ministère de l’agriculture des pêcheries et de l’alimentation du Québec (MAPAQ). This is the reason that two members of the CRIPA, Dr. Julie Arseneault, an epidemiologist, and Dr. Josée Harel, an expert in molecular diagnostics, decided to team up with MAPAQ veterinarians, Julie-Hélène Fairbrother and Natalie Côté, to identify potential veterinary and human pathogens present in Montreal’s urban pigeon population.
The researchers selected Montreal for their study because of its high population density and numerous parks. Vanessa Gabriele-Rivet coordinated the team that temporarily and safely captured 187 pigeons in 10 parks in order to collect feces and respiratory secretion samples. These samples then underwent diagnostic tests to detect the presence of Salmonella, Campylobacter, Coxiella burnetii and the virus responsible for Newcastle disease. Donald Tremblay oversaw the completion of the diagnostic tests that were performed as part of a collaboration between the MAPAQ and the diagnostic service at the Faculté de médecine vétérinaire de l’Université de Montréal.
Salmonella and Campylobacter are bacteria responsible for the majority of foodborne infections in humans, and birds often serve as reservoirs for both bacteria. This is why the poultry industry is concerned with these bacteria. Coxiella burnetii is the causative agent of Q fever in humans, a disease present in Quebec, which is mainly associated with farms that specialise in small ruminants. In 1989 and 1993, some cases of Q fever were associated with infected cats. This bacterium is of concern because a simple inhalation is enough to inhale the few Coxiella burnetii bacteria required to cause human infection. The Newcastle disease virus poses a low risk to human health, but can cause devastating economic losses in the poultry industry.
The good news is that only 9.1% of the pigeons were found to carry an infectious agent and in all cases the birds tested positive for Campylobacter jejuni.
As a side note, Campylobacter is not usually harmful to the health of birds (e.g. pigeons or chickens). However, this pathogen is considered to be a threat to human health since it causes severe gastroenteritis. Thus, indirect or direct contact with pigeons may lead to the transmission of this bacterium to humans. So the next time you go for a picnic in a public park, be sure to wash your hands and to keep that sandwich far from the pigeons... You also need to beware of cats that hunt pigeons!
