Mythbusters: Birds as a public health threat

Nancy Troyano

In our new Mythbusters series, Rentokil’s lead entomologist, Dr. Nancy Troyano, works to debunk pest-related old wives’ tales, internet myths, and commonly repeated incorrect information. 

This month, Nancy is tackling the topic of birds – specifically, whether or not birds are merely a nuisance pest. 


Birds are only a nuisance pest. Their presence poses zero risk to humans. 


We all know that birds can be an annoyance at times, like aggressive seagulls on the beach or unsightly smeared droppings left behind on balconies. 

But did you know that many bird species pose threats to public health and safety when in close proximity to humans and structures? Birds can spread upwards of 60 disease-causing pathogens to humans through their fecal droppings, feathers, feet, and nests. 

Birds are essential to the ecosystem, but those deemed as pests pigeons, house (English) sparrows, European starlings, seagulls, and Canadian geese, for example can be harmful to human health and businesses. Even other species, including those we keep as pets, such as parrots, parakeets, and cockatiels, can spread diseases to humans. 


Pigeons and bird poop on a park bench

Health and safety

The most commonly reported microbe passed through birds is Salmonella. How does Salmonella get transferred to humans from a bird, you may wonder? The short answer is this: bird poop. When humans ingest food and water contaminated with fecal matter, salmonellosis follows. The same outcome can occur through direct contact with an infected bird. Bacteria such as E. coli, Cryptococcus, and Listeria can be contracted in a similar fashion, all of which lead to foodborne illness and in some cases even death. 

In addition to bacterial microbes in droppings, birds such as pigeons and starlings can also carry a harmful fungus, Histoplasma capsulatum, which is also naturally present in soil. Disturbing contaminated feces or the soil disperses these spores into the air. Once inhaled, these spores can inflict debilitating pulmonary illnesses such as histoplasmosis, which can happen during cleanup, remodeling, and working outdoors without a respirator mask. 

A bird’s nest can harbor feces, bacteria, fungi, and ectoparasites such as lice, mites, fleas, and ticks. These ectoparasites typically feed on birds, but if a bird abandons the nest, the ectoparasites—particularly bird mitescan migrate into nearby structures and feed on people. This is problematic because bird mites are tiny, making them difficult to control. 

Birds are also carriers of West Nile virus, a disease spread to humans by mosquitoes. Mosquitoes that feed on humans and infected birds alike can transfer and spread the virus to humans. Although birds can’t directly pass this virus to humans, they can carry it to new geographies as they migrate and fly to new areas of the country. Once they reach those new geographies, mosquitoes therewho may not be carrying West Nile virus alreadycan feed on these birds, and then begin spreading this dangerous disease to humans. 

sparrow building a nest in the gutter

Safety and damage concerns

In addition to diseases, bird activity on or around structures can cause a number of costly problems for any business. 

Any bird species can block gutters and rain spouts with nesting materials, which often leads to leaks or water damage. They can also create fire hazards by stuffing nesting materials near lighting, electrical equipment, or even in chimneys. 

Bird feces are also highly corrosive. Their droppings can damage structures, equipment, or anything below a bird resting site, such as vehicles. 

Bird management should never be taken lightly, for a variety of reasons. Federal, state, and even local laws protect many bird species. Therefore, interference without the proper permits can be a criminal offense. Bird management efforts not handled properly can cause public relations concerns for businesses. 

Think you may have a bird problem? Use Rentokil’s checklist to assess your property. 

For more information on developing an integrated bird management program to address health, safety, and structural concerns, contact Rentokil at 800.488.9495. 

Nancy Troyano
Nancy Troyano

Nancy received her PhD in Entomology from Virginia Tech, with research primarily focused on virus transmission by mosquitoes. Nancy is also a Board Certified Entomologist, skilled in medical, veterinary and urban entomology. In 2009, Nancy began working for Rentokil North America, a billion dollar organization, where she currently serves as the Director of Operations Education and Training. Nancy is responsible for leading and supporting education and training for all lines of business and at all levels of the operation, which includes over 4500 pest technicians. She develops comprehensive academic programs and pest management courses that are utilized globally, and oversees a team that manages all of the learning and development needs of the organization. Additionally, Nancy provides ongoing technical support to field operations and acts as a subject matter expert for vector management programs.

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