What is psittacosis?

Psittacosis is a rare infectious disease, also called parrot fever or ornithosis, caused by the bacteria Chlamydia psittaci.¹ While commonly associated with birds, particularly parrots, cockatiels, and parakeets, psittacosis can also affect humans through the inhalation of contaminated airborne particles or direct contact with infected birds or their droppings. Psittacosis can manifest as a mild flu-like illness, progress to severe pneumonia, or, in some cases, lead to multi-organ failure. It is a risk to individuals who work with birds or have close contact with pet birds. It accounts for about 1.03% of all community acquired pneumonia (CAP).² Prompt diagnosis and treatment are crucial for managing patients with psittacosis and preventing complications. Public health measures, including education on bird handling practices and preventive measures, are essential for reducing the risk of psittacosis transmission to humans.

Who is at risk of developing psittacosis?

Several groups of people are at an increased risk of developing psittacosis due to their occupations, hobbies, or proximity to birds. These include:³

• Bird owners, breeders, and handlers, due to frequent contact with infected birds or their droppings
• Veterinarians and animal shelter workers, who are exposed to birds during routine care and treatment
• Pet store employees, who may handle birds and clean cages without proper protective measures
• Poultry farm workers, are at risk of exposure to infected birds or their faeces
• Aviary staff and volunteers, who interact closely with birds in confined spaces
• Travelers to endemic areas, where psittacosis outbreaks may occur
• Immunocompromised individuals may be more susceptible to severe complications if infected

What are the symptoms associated with psittacosis?

The incubation period, or the time from exposure to the onset of symptoms, typically ranges from 5 to 14 days, although it can vary depending on the individual's immune response, the extent of exposure, or the strain of the bacterium. During the incubation period, individuals may not experience any symptoms but can still be infectious to others. The clinical presentation of psittacosis can vary widely, ranging from mild flu-like symptoms to severe pneumonia requiring hospitalisation. Common signs and symptoms of psittacosis may include:

• Fever and chills
• Headache
• Muscle aches and joint pain
• Dry or productive cough
• Difficulty breathing or shortness of breath
• Chest pain
• Fatigue and weakness
• Nausea, vomiting, or diarrhoea
• Rash (less common)

How is psittacosis diagnosed?

Diagnosing psittacosis requires a comprehensive approach due to its nonspecific clinical presentation and potential for severe complications. The diagnostic methods used in identifying psittacosis are:

Clinical evaluation

The diagnosis of psittacosis often begins with a thorough clinical assessment, which includes a detailed medical history and physical examination. Healthcare professionals inquire about potential bird exposure, such as owning pet birds, working in bird-related occupations, or recent travel to endemic areas. Symptoms such as fever, cough, difficulty breathing, muscle aches, and headaches may prompt further investigation for psittacosis, especially in individuals with a history of bird contact.

Laboratory testing

Several laboratory tests may aid in the diagnosis of psittacosis:

• Serological tests. Serological testing involves detecting antibodies against Chlamydia psittaci in the patient's blood serum. Complement fixation reactions, enzyme-linked immunosorbent assay (ELISA), immunofluorescence tests, and immuno-peroxidase tests are commonly used serological techniques. Acute and convalescent serum samples (blood samples collected from different phases of the illness) may be required for definitive diagnosis due to the need to detect a rise in antibody titres over time
• Polymerase chain reaction (PCR). PCR is a molecular diagnostic technique that amplifies specific DNA sequences of Chlamydia psittaci in clinical specimens, such as respiratory secretions, blood, or tissue samples. PCR offers high sensitivity and specificity and is particularly useful for detecting the presence of the bacterium in the lower respiratory tract
• Metagenomic sequencing. Next-generation sequencing (NGS) techniques, such as metagenomic sequencing, allow for the detection of a wide range of pathogens, including Chlamydia psittaci, in clinical samples. Metagenomic data analysis provides rapid and accurate identification of the causative agent, enabling early diagnosis and appropriate treatment initiation⁴

Imaging studies 

Chest radiographs may reveal characteristic findings suggestive of psittacosis pneumonia, such as lobar or lobular infiltrates. Radiographic abnormalities, along with clinical symptoms, can aid in the diagnosis and management of psittacosis-associated respiratory disease.

Differential diagnosis

Distinguishing psittacosis from other respiratory infections, such as influenza, or atypical pneumonia caused by other pathogens, is essential due to overlapping clinical features. Diagnostic testing, including serological assays, PCR, and imaging studies, helps differentiate psittacosis from similar conditions and guide appropriate treatment decisions.

What is the management and treatment of psittacosis?

The treatment of psittacosis typically involves antibiotic therapy to eradicate the infection and alleviate symptoms. Today the mortality rate with prompt treatment is only 1%.⁵The treatment approach for patients with psittacosis involves:

Antibiotic therapy

• First-line antibiotic. Doxycycline is considered the first-line antibiotic for the treatment of psittacosis in both adults and children.⁶ It is a broad-spectrum antibiotic that effectively targets Chlamydia psittaci
• Alternative antibiotics. In cases where doxycycline is contraindicated or not tolerated, macrolide antibiotics such as azithromycin or erythromycin may be used as alternative treatment options

Supportive care

• Rest. Adequate rest is essential for patients with psittacosis to allow their bodies to recover from the infection. Patients are advised to limit physical activity and get plenty of sleep
• Fluids. Encouraging patients to drink plenty of fluids helps prevent dehydration and promotes recovery. Water, electrolyte solutions, and clear soups are recommended
• Fever Management. Over-the-counter medications such as acetaminophen (paracetamol) or ibuprofen may be used to reduce fever and alleviate discomfort associated with fever and muscle aches

Hospitalisation (in severe cases)

• Intensive care. Severe cases of psittacosis, particularly those complicated by pneumonia, respiratory failure, or septic shock, may require hospitalisation for close monitoring and intensive care. Patients may receive intravenous fluids, oxygen therapy, and other supportive measures as needed
• Intravenous antibiotics. In cases where oral antibiotics are not feasible or when the patient's condition deteriorates, intravenous antibiotics such as doxycycline or erythromycin may be administered in a hospital setting

Follow-up

• Post-treatment evaluation.After completing antibiotic therapy, patients should undergo follow-up evaluation to ensure the resolution of the infection and monitor for any lingering symptoms or complications. Repeat testing, such as serological assays or PCR, may be performed to confirm the eradication of the bacterium

How can psittacosis be prevented?

Preventing psittacosis involves implementing a combination of measures to reduce the risk of exposure to Chlamydia psittaci.

Hygiene practices

• Hand hygiene. Practice good hand hygiene, which is essential, especially after handling birds or their cages, feathers, or droppings. Wash hands thoroughly with soap and water for at least 20 seconds, particularly before eating, drinking, or touching the face
• Cage cleaning. Pet owners should maintain regular cage cleaning to minimise the accumulation of droppings and feather dust
• Avoid bird droppings. Minimise exposure to bird droppings, particularly in areas where birds roost or congregate. Avoid direct contact with bird faeces and contaminated surfaces, and promptly clean up any droppings using appropriate disinfectants

Personal protective equipment (PPE)

• Gloves and masks. Use disposable gloves and masks when handling birds, particularly if they appear sick or have respiratory symptoms. Gloves and masks help prevent direct contact with contaminated surfaces and airborne particles
• Eye protection. Consider wearing protective eyewear, such as goggles or glasses, when handling birds or cleaning cages to prevent accidental exposure to droplets or debris

Aviary and workplace safety

• Biosecurity measures: Implement biosecurity measures in aviaries, pet stores, and bird-related workplaces to prevent the introduction and spread of infectious diseases. This includes restricting access to designated bird areas, quarantining new birds, and regularly monitoring bird health
• Ventilation: Ensure adequate ventilation in bird enclosures and workplaces to minimise the accumulation of airborne particles and promote air circulation. Proper ventilation helps reduce the risk of respiratory exposure to Chlamydia psittaci

Bird handling practices

• Minimise close contact. Minimise close contact with birds, particularly wild or unfamiliar birds, to reduce the risk of exposure to infectious agents. Avoid cuddling or allowing birds to perch on your face or clothing
• Safe handling techniques. Practice safe bird handling techniques, such as gentle restraint and avoiding sudden movements, to minimise stress and reduce the likelihood of bites or scratches. Use caution when handling birds known to be carriers of Chlamydia psittaci

Travel precautions

• Endemic areas. If travelling to regions where psittacosis is endemic or outbreaks have occurred, take precautions to minimise exposure to birds and bird-related activities. Avoid visiting aviaries, petting zoos, or bird markets where close contact with birds is common

Education and awareness

• Public education. Raise awareness among bird owners, veterinarians, pet store workers, and other individuals at risk of psittacosis about preventive measures and the importance of early recognition of symptoms. Provide educational materials on safe bird handling practices and biosecurity measures
• Professional training. Provide training and continuing education for professionals working with birds, such as veterinarians, animal shelter staff, and poultry farm workers, on infection control, hygiene practices, and disease prevention strategies

Summary

Psittacosis is a rare but potentially serious infectious disease that can affect humans exposed to infected birds or their environments. Timely diagnosis, prompt treatment with appropriate antibiotics, and the implementation of preventive measures are essential for managing psittacosis and reducing its impact on human health. By adopting responsible bird husbandry practices and raising awareness about psittacosis prevention, we can safeguard both human and avian populations from this fascinating yet potentially harmful zoonotic infection.