Pigeon in ductwork bird droppingsWashington DC — The most serious health risks arise from disease organisms that can grow in the nutrient-rich accumulations of bird droppings, feathers and debris. Not only are bird droppings an unsightly mess that can be difficult to remove and cause slip-and-fall accidents, they also harbor numerous human pathogens.  How dangerous are bird droppings to human health?  The question seems simple but quantifying a human’s risk of acquiring disease from a bird or its droppings is difficult since exposure to the pathogens does not always result in disease and most bird-related zoonotic diseases are not reportable to health authorities.

Examples of transmissible bird diseases associated with pigeons, geese, starling and house sparrows:

  • Histoplasmosis is a respiratory disease that may be fatal. It results from a fungus growing in dried bird droppings. It is a dimorphic fungus that can be either in yeast form or in filamentous form.
  • Candidiasis is a yeast or fungus infection spread by pigeons. The disease affects the skin, the mouth, the respiratory system, the intestines and the urogenital tract, especially the vagina. It is a growing problem for women, causing itching, pain and discharge.
  • Cryptococcosis is caused by yeast found in the intestinal tract of pigeons and starlings. The illness often begins as a pulmonary disease and may later affect the central nervous system. Since attics, cupolas, ledges, schools, offices, warehouses, mills, barns, park buildings, signs, etc. are typical roosting and nesting sites, the fungus is apt to found in these areas.
  • St. Louis Encephalitis, an inflammation of the nervous system, usually causes drowsiness, headaches and fever. It may even result in paralysis, coma or death. St. Louis encephalitis occurs in all age groups, but is especially fatal to persons over age 60. The disease is spread by mosquitoes which have fed on infected house sparrow, pigeons and house finches carrying the Group B virus responsible for St. Louis encephalitis.
  • Salmonellosis often occurs as “food poisoning” and can be traced to pigeons, starlings, sparrows and other rodents.  The disease bacteria are found in bird droppings; dust from droppings can be sucked through ventilators and air conditioners, contaminating food and cooking surfaces in restaurants, homes and food processing plants.
  • E.coli  infection: It is one of the common infection caused by an enteric bacteria. This bacteria often traced in the fecal matters. When some bird or rodent visit such sites they carry these and spread to humans. Such as when birds peck on cow manure, the E. coli (O157:H7) go right through the birds and the bird droppings can land on or in a food or water supply.

Bird fecal matter and feathers can have devastating effects on the heating and cooling components and indoor air quality of a commercial facility.  Pigeon problems can affect employees, maintenance personnel and potentially customers.

bird droppings contaminationDr. Rajiv Sahay, Director at EDLab at Pure Air Control Services stated: “heavy smells from the bacteria, fungi, and other organic matter from the birds can be infiltrate  through the ventilation system causing significant harm to not only buildings but also to the many building occupants”.

HVAC technicians, roofers, etc. should pay attention to the areas where outdoor air enters the HVAC system. They also should investigate accumulations of organic material in or near HVAC air intakes, rooftop heating and cooling units are a perfect place for pigeons to nest.  To seek shelter from the elements, pigeons and birds typically enter air handler units through the fresh air intakes and build their nests within the unit.  A single pair of pigeons can generate up to 18 new pigeons per year.  Once a nest is established, pigeons are extremely territorial.

According to a Center for Disease Control and Prevention report on histoplasmosis, HVAC technicians, demolition workers, bridge inspectors, chimney cleaners, maintenance staff, microbiology laboratory workers, farmers, roofers, spelunkers and gardeners all have removed bird droppings in a way that resulted in human illnesses. A particularly large outbreak of the disease occurred in 2001 when 523 high school students became ill after soil in their school’s courtyard containing bird droppings was rototilled by a maintenance worker. The largest outbreaks of histoplasmosis in the United States occurred in the late 1970’s in Indiana, when over 120,000 people became ill, and 15 died, after a building containing bird droppings was demolished.

contaminated coil - bird droppingsCan histoplasmosis or cryptococcosis be transferred into a building?   Yes, HVAC system distributes the air throughout a facility.  The designed air exchange rate is 15/minutes per hour.  The bacteria, fungi and parasites that live and grow in pigeon droppings can carry and transmit any of 60 known diseases can be reticulated.  Exposure to pigeon feces and other organic matter such as feathers carcasses and nesting material from the HVAC system may pose a considerable health threat to people who come in contact with them or inhale the airborne particles from them.  Every precaution should be taken to ensure that building occupants and maintenance personnel are protected from pigeon feces.

As pigeons live at and in the fresh air makeup, air handler units they peck through filter material allowing unfiltered air and pigeon contaminants to freely enter the ventilation system.  Damage to an HVAC system is numerous:

  • Fresh Air IntakesThe nesting of pigeons begins at the fresh air intake along with fecal matter associated.  Pigeons like the fresh air vent as a result of constant air movement, covered area from inclement weather and nesting place for the families. The fresh air intake, if not broken through, will cause clogging of the screen restricting air flow and fresh air into the building.  Talk about fresh air?
  • Filter banks: Birds can peck though filter banks allowing for unfiltered air and pigeon contaminants to be drawn into HVAC components and supply air ducts.
  • Fan Assemblies: Bird feathers, fecal matter and debris builds within the fan blades decreasing airflow.
  • Evaporator Coils: Bird feathers, fecal matter and debris clogs the air conditioner coils and clogs the drain pan.
  • Coil Drain Pans: With the drain pan water and pigeon fecal matter creates a potential source of dangerous/toxic microorganisms and other chemicals.
  • AHU Insulation: Birds can peck at the insulation to create nesting material allowing for raw fiberglass fibers to enter the associated air conveyance system.

For more information on developing an effective environmental diagnosis and/or cleanup campaign for pigeon/bird fecal matter for your buildings call the Building Scientists at Pure Air Control Services or Environmental Diagnostics laboratory (EDlab) at 1-800-422-7873.