Psittacosis: Understanding Parrot Fever and Its Impact on Human Health

 

By George Garber, RN

IC Preventionist

 

Psittacosis—also known as parrot fever and ornithosis—is an infectious disease in humans caused by a bacterium called Chlamydia psittaci, contracted from infected parrots such as macaws, cockatiels, and budgerigars (also known as common parakeets, shell parakeets, or budgies). Pigeons, doves, and poultry like turkeys and ducks can also become infected. Chickens rarely have this infection. The bacteria are found in an infected bird’s droppings and respiratory fluids. When these fluids dry, they can release bacteria into the air as dust. The disease spreads between birds through contaminated dust or direct contact. Less commonly, a bird can infect a human by biting or touching its beak to the person’s mouth.

 

Signs and Symptoms

In humans, psittacosis typically presents as a flu-like illness with an incubation period of 5–19 days. The severity of the disease varies, ranging from asymptomatic cases to systemic illness with severe pneumonia.

 

Spleen enlargement is common toward the end of the first week, and psittacosis may then progress into a serious lung infection. As the disease advances, it primarily manifests as atypical pneumonia, characterized by a persistent dry cough, shortness of breath, and fatigue.

 

Other complications include:

• Myocarditis (inflammation of the heart)
• Pericarditis (inflammation of the membrane covering the heart)
• Encephalitis
• Hepatitis (liver damage)
• Arthritis
• Sepsis

 

Severe cases can lead to extensive lung involvement, as seen in X-rays showing patchy infiltrates or diffuse whiteout of lung fields. Severe pneumonia may require intensive care support, though fatal cases remain rare, occurring in less than 1% of infections.

 

Transmission Route

Humans contract psittacosis through inhalation of airborne particles from dried bird excreta, feathers, or respiratory secretions. Less commonly, direct contact with infected birds or contaminated materials may also lead to infection. The bacteria can survive in the environment for extended periods, increasing the risk of indirect transmission.

 

Birds, especially parrots, cockatiels, and pigeons, can carry Chlamydia psittaci without showing symptoms, but stressed or immunocompromised birds may develop respiratory distress, lethargy, and weight loss. Infected birds may intermittently shed the bacteria, even if they appear healthy.

 

Diagnosis

Diagnosing psittacosis can be challenging due to its non-specific symptoms, requiring a combination of clinical evaluation, laboratory tests, and exposure history. Blood analysis typically shows a normal white blood cell count, though marked leukocytosis can occasionally occur. Liver enzymes are abnormal in about half of the patients, with mild elevations in aspartate transaminase. Inflammatory markers, such as erythrocyte sedimentation rate and C-reactive protein, can be significantly elevated.

 

Treatment

Psittacosis is effectively treated with antibiotics, primarily tetracyclines:

• Doxycycline (first-line treatment, typically prescribed for 10–14 days).
• Macrolides (e.g., azithromycin) may be used for patients who cannot tolerate tetracyclines.

 

Early treatment reduces the risk of severe complications and hospitalization. If left untreated, the disease can become severe, leading to respiratory failure or multi-organ involvement.

 

Prevention and Control

To minimize the risk of psittacosis, several preventive measures should be taken:

• Maintain proper hand hygiene when handling birds or cleaning cages to reduce contamination. Wash your hands carefully after being around your pet, even if you haven’t touched them.
• Avoid contact with saliva, droppings, urine, mucus, blood, and other body fluids of your pet, especially if you know they are infected.
• Wear protective gear when handling pet habitats like coops and cages, as well as pet food and water dishes.
• Clean your pets’ cages frequently to prevent the accumulation of dried feces that can become airborne.

 

Additionally, avoiding exposure to sick or wild birds, particularly in high-risk areas, further reduces the chances of infection.

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