Pigeons are a common sight in cities around the world. While many view them as dirty nuisances, pigeons can actually carry and transmit diseases to humans under certain circumstances. There are a few main diseases that pigeons may pass on to people through close contact with their droppings, feathers, or nests.
Psittacosis
One of the most concerning diseases humans can contract from pigeons is psittacosis, also known as parrot fever or ornithosis. Psittacosis is caused by Chlamydia psittaci, a type of bacteria that can infect birds. Pigeons are natural reservoirs for C. psittaci and can transmit the bacteria to humans through their droppings or respiratory secretions.
If a person inhales dust contaminated with infected pigeon droppings, they are at risk of developing psittacosis. Flu-like symptoms usually appear 5-14 days after exposure and may include fever, chills, headache, muscle aches, cough, and shortness of breath. Psittacosis can progress to severe pneumonia and can even cause liver damage, endocarditis, and neurological complications in untreated cases.
Psittacosis Diagnosis and Treatment
Psittacosis is diagnosed by blood tests and respiratory cultures. Tetracycline antibiotics like doxycycline are used to treat the infection. Without antibiotics, severe psittacosis cases can be fatal. Even treated cases require hospitalization for 1-2 weeks.
To avoid psittacosis, it is important to avoid areas with large accumulations of pigeon droppings, especially in enclosed spaces where dry feces can be inhaled. Wearing an N95 mask and gloves during any cleanup of bird droppings can also help prevent infection.
Cryptococcosis
Cryptococcosis is another disease that can be transmitted from pigeons to humans. It is caused by the fungus Cryptococcus, found in soil and pigeon droppings. People can develop cryptococcosis lung infections by inhaling the spores.
Symptoms like cough, fever, chest pain, and shortness of breath usually take 2-4 weeks after exposure to develop. The infection can spread to the skin, bones, and brain if left untreated. While relatively rare, cryptococcosis can be life-threatening in people with weakened immune systems.
Cryptococcosis is diagnosed by growing the fungus from sputum or fluid samples. Treatment involves long-term antifungal medications like fluconazole. Avoiding areas contaminated with pigeon droppings can prevent cryptococcosis infection.
Histoplasmosis
Histoplasmosis is caused by the fungus Histoplasma capsulatum and is commonly found in pigeon droppings. When the droppings and contaminated soils are disturbed, the fungal spores can be inhaled. After an incubation period of 1-3 weeks, flu-like symptoms usually develop.
Most cases of histoplasmosis are mild, but the fungus can cause serious lung infections resembling tuberculosis in some people. It can also spread to other organs. Chronic lung problems like cough, chest pain, and shortness of breath may persist after the acute illness.
Histoplasmosis Testing and Treatment
Histoplasmosis is diagnosed through blood tests, chest x-ray, and lung fluid cultures. Mild cases usually resolve without treatment, while antifungal medications are used for severe disease. Any activity stirring up accumulations of pigeon droppings should involve protective masks and containment strategies.
Candidiasis
Pigeons may also harbor Candida fungi in their droppings. Candida normally lives in the human gut without issue, but inhaling Candida from pigeon droppings can lead to candidiasis infections.
In immunocompromised people, Candida in the respiratory tract can lead to pneumonia. Candida can also infect wounds and the bloodstream after exposure to infected droppings. Oral thrush and yeast infections are other common manifestations.
Fungal cultures help diagnose candidiasis. Antifungal drugs like fluconazole are first-line treatments. Reducing contact with accumulations of pigeon droppings through masks, gloves, and containment helps prevent infection.
Salmonella
Salmonella bacteria live in the guts of pigeons and are shed in large quantities in their feces. Pigeon droppings can contaminate soil, water, and surfaces. Humans ingesting anything contaminated with traces of pigeon feces can develop Salmonella food poisoning.
Symptoms like diarrhea, vomiting, fever, and abdominal cramps usually start 12-36 hours after ingesting Salmonella. While most people recover after a few days, Salmonella can cause severe diarrhea requiring hospitalization, especially in those with weakened immune systems.
Culturing the bacteria from stool samples diagnoses Salmonella. Antibiotics are only used for severe cases. Thoroughly cooking food, washing hands after contact with birds, and avoiding ingestion of anything potentially contaminated by pigeon droppings helps prevent Salmonella.
E. coli
Pigeon droppings may contain E. coli bacteria, including strains that can cause serious human illness. Not all E. coli are harmful, but pigeons can harbor pathogenic strains like E. coli O157:H7.
If E. coli contaminates food or water sources, humans can develop potentially life-threatening illnesses like:
- Hemorrhagic colitis – bloody diarrhea
- Hemolytic uremic syndrome (HUS) – kidney failure
- Thrombotic thrombocytopenic purpura (TTP) – blood clotting disorders
These disorders are most common in children, the elderly, and those with weakened immune systems. Diagnosis involves detecting Shiga toxin-producing E. coli in stool cultures. Treatment involves hydration, blood transfusions, dialysis, and other organ support.
Prevention includes thoroughly cooking meats, avoiding cross-contamination in kitchens, and washing hands after any contact with pigeon droppings.
Newcastle Disease
While rare, humans can develop mild conjunctivitis from certain strains of Newcastle disease virus found in pigeons. Newcastle disease is highly contagious between birds. Pigeons shed the virus in respiratory discharges and feces.
Humans working closely with infected birds have developed red, watery eyes 1-2 days after exposure. Symptoms usually resolve after 1-2 weeks without treatment. However, Newcastle disease virus can also rarely progress to serious viral pneumonia, especially in those with weakened immune systems.
There are no specific tests or treatments. Prevention involves wearing eye protection, masks, and gloves when handling sick birds to avoid infection.
Chlamydiosis
Chlamydiosis in pigeons is caused by Chlamydophila psittaci, a type of intracellular bacteria. Humans inhaling dried powders from infected bird droppings or fluids can develop psittacosis pneumonia or milder respiratory infections.
Symptoms like fever, chest tightness, and cough take 1-4 weeks after exposure to develop. Chlamydiosis can be diagnosed by growing the bacteria from respiratory samples. Antibiotics like doxycycline work well. Wearing respiratory protection when cleaning areas contaminated by pigeon droppings helps prevent infection.
Pigeon Tick-Borne Diseases
Ticks that feed on pigeon blood can transmit several diseases to humans as well:
Lyme Disease
Lyme disease is caused by Borrelia burgdorferi bacteria carried by ticks. Pigeons do not actually harbor Lyme disease, but they can transport infected ticks around in their feathers. Humans bitten by infected ticks may develop Lyme carditis, neuroborreliosis, arthritis, and rash. Antibiotics like doxycycline help treat Lyme disease.
Babesiosis
Babesia parasites cause babesiosis in humans bitten by infected ticks. Pigeons may disperse babesia-carrying ticks through their feathers. Symptoms like fever, chills, muscle pain, and anemia usually begin 1-6 weeks after the bite. Babesiosis is diagnosed through blood smears and PCR testing. Combination therapy with atovaquone and azithromycin works best.
Anaplasmosis
Anaplasma phagocytophilum is the bacterium causing human granulocytic anaplasmosis transmitted by ticks feeding on birds like pigeons. Symptoms include high fever, headaches, chills, nausea, and muscle pain within 1-2 weeks after a bite. Doxycycline rapidly treats anaplasmosis. Preventing tick bites remains key to avoiding these diseases.
West Nile Virus
While pigeons do not actually carry or transmit West Nile virus, they are highly susceptible to West Nile infection through mosquito bites. Monitoring deaths and illnesses in local pigeon populations can help signal West Nile virus activity in an area.
Humans can then take extra precautions like mosquito avoidance and vaccination to prevent West Nile disease, which causes symptoms like fever, rash, muscle weakness, and neuroinvasive disease. There are no specific treatments beyond supportive care.
Pigeon Mites
Pigeons may also be infested by pigeon mites or “bird mites”, especially in overcrowded flocks. These mites can occasionally bite humans when pigeon nests are disturbed, causing intense itching and skin irritation.
Though uncomfortable, the bites pose no serious health risks. Scabies treatments like topical permethrin and ivermectin can help resolve symptoms, along with reducing contact with bird nests and droppings. Properly cleaning or removing abandoned pigeon nests is key.
Toxoplasmosis
Toxoplasma gondii is a parasite shed in cat feces that causes toxoplasmosis. Pigeons do not carry toxoplasmosis directly. However, if they ingest food or surfaces contaminated by cat feces containing T. gondii, the parasite can replicate in pigeons and be shed in their droppings.
Humans ingesting contaminated materials from pigeon droppings can then develop toxoplasmosis. This causes flu-like illness in most healthy people but can severely impact those with weakened immune systems and pregnant women. Medications like pyrimethamine, sulfadiazine, and leucovorin help treat severe cases.
Pigeon Droppings Lung Damage
Even without infectious risks, inhaling dried bird droppings over time can irritate lungs. Pigeon droppings contain many allergens and toxins like ammonia which damage lung tissue.
People who work in enclosed spaces contaminated by heavy accumulation of toxic droppings are at risk of chronic lung inflammation and respiratory damage over months to years of exposure. Using proper protective equipment is critical in these environments.
Preventing Pigeon-Transmitted Diseases
While pigeons can carry concerning infectious diseases, the overall risk of transmission to humans is quite low with basic precautions:
- Avoid areas with large accumulations of pigeon droppings like roofs, ledges, statues, and bridges. If entry is required, wear an N95 respirator mask, gloves, coveralls, and goggles.
- After any contact with birds or droppings, immediately wash hands with soap and water. Disinfect any contaminated surfaces.
- Have qualified hazardous materials professionals test for and safely remove large quantities of droppings.
- Use nets, spikes, repellents, and other humane methods to discourage roosting and nesting on buildings.
- Cook all foods thoroughly, especially poultry and eggs.
- Prevent cross-contamination in kitchens by washing hands, utensils, and surfaces after preparing raw meats.
- Avoid touching eyes, nose, or mouth without washing hands first.
- Take precautions against tick bites like using repellents, performing checks, and controlling vegetation.
- Consider vaccination for diseases like West Nile virus if recommended for your location.
By using common sense hygiene and safety around pigeons, most healthy people are unlikely to acquire any serious diseases. However, any unusual or severe illness after contact with pigeons should prompt immediate medical evaluation. Healthcare providers should also obtain a detailed history of any pigeon exposure in symptomatic patients to guide accurate diagnoses and treatment.
Groups at Higher Risk
While pigeon-associated diseases are rare overall, certain categories of people are at somewhat higher risk:
Immunocompromised Individuals
Those with weakened immune systems like people undergoing chemotherapy, transplant recipients on immunosuppressants, or people with untreated HIV/AIDS are more prone to severe illnesses from psittacosis, cryptococcosis, candidiasis, Salmonella, E. coli, West Nile, and toxoplasmosis acquired from pigeons. Extra precautions are warranted.
Healthcare Workers
Doctors, veterinarians, poultry farm workers, and laboratory personnel in contact with infected birds have higher occupational exposures. Masks, gloves, protective clothing, and containment of droppings are important in these settings.
Pest Control and Construction Workers
Those performing cleanups, removals, or maintenance on structures heavily contaminated by pigeon droppings like building roofs, towers, and statues have high exposure risks. Masks rated N95 or higher, gloves, coveralls, and eye protection should be used.
Infants and Young Children
Due to developing immune systems and tendencies like putting hands in mouths, small children are at increased risk of diseases like Salmonella, E. coli, and toxoplasmosis from incidental ingestion of material contaminated by pigeon droppings. Supervision around pigeons can help prevent this.
Pregnant Women
Illnesses like psittacosis, toxoplasmosis, Salmonella, and E. coli can cause pregnancy complications like miscarriage, stillbirth, and birth defects if acquired during pregnancy. Contact with pigeons and droppings should be minimized during pregnancy.
Elderly Individuals
Advanced age typically weakens immunity, increasing risks from pigeon-associated diseases like West Nile, psittacosis, and Salmonella. The elderly should avoid direct contact with pigeons, droppings, and nests whenever possible.
Conclusion
Pigeons are capable of transmitting a diverse array of bacterial, viral, fungal and parasitic diseases to humans under the right conditions, primarily through their droppings. However, most illnesses remain rare, mild, and self-limited in the general population. Simple precautions can greatly reduce infection risks. Certain higher risk groups like the immunocompromised warrant more vigilance. But as a whole, the public health hazards posed by urban pigeons are minimal compared to many other common disease sources encountered in daily life. With proper education and prudent preventative measures, pigeons can be enjoyed and coexisted with safely in shared environments.
