Infections Transmitted Through Bird Droppings
Bird droppings can transmit several serious infections to humans, with psittacosis (Chlamydia psittaci infection) being the most commonly reported and histoplasmosis, cryptococcosis, and allergic alveolitis also presenting significant health risks.
Psittacosis (Chlamydia psittaci infection)
Psittacosis is the primary infection concern from bird droppings, particularly from psittacine birds (parrots, macaws, cockatiels, parakeets).
Transmission
- Occurs when a person inhales C. psittaci organisms aerosolized from:
- Dried feces of infected birds
- Respiratory secretions
- Bird urine 1
- Even brief, passing exposure to infected birds or contaminated droppings can cause infection 1
- Other transmission routes include:
- Mouth-to-beak contact
- Bird bites
- Handling infected birds' plumage and tissues 1
Clinical Presentation
- Incubation period: 5-14 days
- Symptoms range from inapparent illness to severe pneumonia 1
- Typical symptoms include:
- Abrupt onset of fever, chills
- Headache, malaise, myalgia
- Nonproductive cough
- Breathing difficulty and chest tightness
- Pulse-temperature dissociation (fever without elevated pulse)
- Enlarged spleen and rash (sometimes) 1
- Radiographic findings: lobar or interstitial infiltrates
- Complications can include:
- Endocarditis
- Myocarditis
- Hepatitis
- Arthritis
- Keratoconjunctivitis
- Encephalitis 1
- Mortality: <1% with proper treatment (compared to 15-20% before antimicrobial agents) 1
At-Risk Populations
- Bird fanciers and pet bird owners (43% of cases)
- Pet shop employees (10% of cases)
- Pigeon fanciers
- Occupational exposure:
- Poultry processing plant workers
- Veterinarians and vet technicians
- Laboratory workers
- Avian quarantine station workers
- Farmers
- Zoo workers 1
Cryptococcosis
Cryptococcosis is another significant infection transmitted through bird droppings, particularly from pigeons.
Transmission
- Caused by encapsulated yeasts Cryptococcus neoformans and C. gattii
- Infection occurs primarily through inhalation of the fungus from:
- Pigeon and other bird droppings 2
- Environmental sources (fruit and bark of trees)
- High prevalence: C. neoformans found in 77.5% of pigeon dropping samples in some studies 3
Clinical Presentation
- Most infections have a benign course and resolve spontaneously
- Severe forms seen in immunocompromised patients, particularly those with AIDS 2
- May present as:
- Acute, subacute, or chronic lung disease
- Nonpurulent cerebrospinal fluid meningitis
- Severe infection with fever, anemia, lymphadenopathy, and hepatosplenomegaly
- Eye involvement with partial or total vision loss 2
Other Infections and Conditions
Histoplasmosis
- Caused by inhalation of Histoplasma capsulatum from bird droppings
- Results in pulmonary infection that can be severe 4
Allergic Alveolitis (Pigeon-breeder's lung)
- Not an infection but a hypersensitivity reaction to avian droppings or feathers
- Causes recurrent pulmonary symptoms
- Best treated by avoiding further exposure 4
Other Opportunistic Fungi
- Multiple fungal species have been isolated from pigeon droppings, including:
- Rhizopus species (found in 38.3% of samples)
- Various other opportunistic fungi 3
- Birds of prey can also act as carriers and spreaders of C. neoformans and other zoonotic yeasts 5
Prevention Measures
- Avoid direct contact with bird droppings, especially from pet birds and pigeons
- Wear protective equipment (masks, gloves) when cleaning areas contaminated with bird droppings
- Properly clean and disinfect areas contaminated with bird droppings
- Maintain good hand hygiene after any potential exposure
- Individuals with compromised immune systems should be particularly cautious around areas with bird droppings 1
Special Considerations
- Immunocompromised patients are at significantly higher risk for severe cryptococcosis and should avoid exposure to environments with bird droppings 2, 3
- Children and elderly individuals are also at increased risk for opportunistic infections from bird droppings 3
- Brief exposures can lead to infection, so even transient contact with contaminated environments poses risk 1