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Psittacosis; The Parrot Fever and Innovations in Diagnosis


Summary: Psittacosis, commonly known as parrot fever, is an infectious disease caused by the bacterium Chlamydia psittaci. This zoonotic disease primarily affects birds such as parrots, cockatiels, and poultry like turkeys and ducks. Even birds that appear healthy can carry the bacteria in their droppings and secretions, which can become airborne as dust particles and be inhaled by humans, leading to infection. People can also get infected through bites or direct contact between their mouth and a bird's beak. The symptoms of psittacosis can vary from mild flu-like symptoms to severe pneumonia, with a range of other symptoms including fever, headache, dry cough, muscle pain, chills, nausea, diarrhea, and in some cases, a rash. Complications can include myocarditis, pericarditis, encephalopathy, hepatitis, arthritis, sepsis, and acute respiratory distress syndrome (ARDS). Diagnosis involves isolating the bacterium from respiratory secretions or detecting a significant increase in antibody levels. Treatment typically involves antibiotics such as doxycycline, with supportive care as needed. Preventive measures include avoiding contact with bird secretions, wearing protective gear when handling birds, and practicing good hygiene. Early recognition and treatment are crucial to prevent severe complications and reduce the risk of transmission.


Keywords: Psittacosis; Parrot fever; Chlamydia psittaci; Bird-borne diseases; Zoonotic infections.



Picture Credit:  CDC


What is Psittacosis?

Psittacosis, commonly known as parrot fever, is caused by the bacterium Chlamydia psittaci. This infectious disease primarily affects birds such as parrots, cockatiels, and poultry like turkeys and ducks.


Psittacosis is a zoonotic disease, meaning it can be transmitted from animals to humans. People can become infected through inhaling dust or dried feces from infected birds, or through handling and being bitten by infected birds. Symptoms of psittacosis in humans can range from mild flu-like symptoms to severe pneumonia, and in some cases, it can be fatal. [1]


It's important for bird owners, veterinarians, and those working with birds to take precautions to prevent the spread of psittacosis. This includes practicing good hygiene, avoiding close contact with sick birds, and seeking prompt medical attention if symptoms develop.



Mode of transmission


Psittacosis, or parrot fever, can be transmitted through various means, with the most common being the inhalation of contaminated airborne particles. Do you know, what’s more interesting? Even seemingly healthy birds can carry the bacterium, Chlamydia psittaci, and shed it in their droppings and secretions. When these substances dry, they can become airborne as dust, carrying the bacteria with them.


In addition to inhalation, less common modes of transmission include direct contact with infected birds, such as through bites, or contact between a person's mouth and a bird's beak. Activities such as cleaning bird cages or handling birds, especially when they spread their wings, can also lead to exposure to infectious particles. While person-to-person transmission of psittacosis is rare, it is possible in some cases.


Individuals at higher risk of contracting psittacosis include bird owners, employees at aviaries and pet shops, poultry workers, and veterinarians, as they frequently come into contact with birds or work in environments where exposure to infected birds is more likely. Practicing good hygiene, such as washing hands thoroughly after handling birds or cleaning cages, and wearing appropriate personal protective equipment can help reduce the risk of infection among those at higher risk.


What are the symptoms of psittacosis?


Psittacosis, or parrot fever, can manifest with various symptoms, from mild to severe, including potentially life-threatening complications. The onset of symptoms typically occurs 5-14 days after exposure to the bacteria Chlamydia psittaci.


The most common presentation of psittacosis is similar to an upper respiratory tract infection, with symptoms such as fever, headache, dry cough, muscle pain, chills, nausea, diarrhea, and, less commonly, a rash.


In birds infected with C. psittaci, signs may include reduced appetite, red or swollen eyes, labored breathing, and diarrhea. Monitoring for a slow pulse, metabolic imbalances, and respiratory failure is crucial in managing the disease.


Complications of psittacosis can be severe and may include:


  • Myocarditis (inflammation of the heart)

  • Pericarditis (inflammation of the pericardium)

  • Encephalopathy (brain dysfunction)

  • Hepatitis (liver inflammation)

  • Arthritis (joint inflammation)

  • Sepsis (body-wide infection)

  • Acute respiratory distress syndrome (ARDS)



Picture Credit: Springer


In some cases, patients may develop a fulminant disease course characterized by multi-organ failure, necessitating intensive care and mechanical ventilation.


Prompt recognition and treatment of psittacosis are essential to prevent severe complications and reduce the risk of transmission to others. If you suspect you or someone you know may have psittacosis, seek medical attention immediately.



Diagnostic criteria for psittacosis:


The diagnosis of psittacosis, caused by the bacterium Chlamydia psittaci, involves several methods recommended by the Centers for Disease Control and Prevention (CDC).


Isolation of the causative organism from respiratory secretions is one diagnostic approach. Another method is to detect a significant increase in antibody levels between two serum samples collected two weeks apart, using tests such as the complement-fixation test (CFT) or micro-immunofluorescence (MIF) assay. As detected by MIF, a single IgM antibody titer of 1:16 or higher can also indicate an active infection. 


Chest imaging typically shows lobar infiltrates with interstitial inflammation. Psittacosis is characterized by a normal white blood cell count with toxic granulation or a left shift on laboratory testing, with or without leukocytosis.


Serological testing, including complement fixation (CF) testing and micro-immunofluorescent (MIF) antibody testing with paired sera, is commonly used to confirm suspected cases of psittacosis. MIF testing is considered more sensitive and specific.


A newer diagnostic test, metagenomic next-generation sequencing (mNGS), has shown higher sensitivity than PCR (polymerase chain reaction) as it can detect pathogens even with lower DNA loads, providing new insight into diagnosis. [5]


Culture remains the most accurate method of diagnosis, but isolating the pathogen requires biosafety level three facilities due to the potential infectiousness of C. psittaci.


In conclusion, a combination of clinical findings, serological tests, imaging studies, and advanced molecular techniques may be necessary for the accurate diagnosis of psittacosis. Prompt diagnosis and treatment are essential to prevent severe complications and reduce the risk of transmission.


 Picture Credit: Semantic Scholar


Treatment and management: 


Psittacosis, caused by the intracellular bacterium Chlamydia psittaci, is typically treated with antibiotics. The first-line drug of choice is tetracycline, with doxycycline being the preferred agent.


The recommended regimen for adults is doxycycline 100 mg orally or intravenously every 12 hours for 7-10 days. For pregnant women or individuals with contraindications to doxycycline, a macrolide antibiotic such as azithromycin may be prescribed. It's important to note that doxycycline is contraindicated in children with developing teeth due to the risk of tooth discoloration. Fluoroquinolones are another option for treatment. [1]


Early initiation of appropriate antibiotics can lead to rapid improvement in the patient's condition and reduce the risk of complications. However, if left untreated, psittacosis can progress to severe pneumonia and, in rare cases, death.


In addition to antibiotic therapy, supportive care, such as rest, adequate hydration, and fever management, may be necessary to help the patient recover.


Healthcare providers need to consider psittacosis in patients with compatible symptoms, especially those with a history of bird exposure, and to initiate appropriate treatment promptly to prevent severe complications.



Prevention strategies: 


Preventing psittacosis, or parrot fever, involves several key strategies to reduce the risk of exposure to the bacterium Chlamydia psittaci, which is commonly found in birds. [3]



  • Avoiding Contact with Bird Secretions: It is essential to avoid direct contact with bird droppings, saliva, urine, mucus, blood, and other fluid secretions. This includes avoiding touching your face after handling birds or cleaning their cages.


  • Wearing Protective Gear: When handling bird cages and coops or cleaning areas contaminated with bird droppings, wearing protective gear such as gloves, masks, and goggles can help prevent exposure to the bacteria.

  • Practicing Good Hygiene: Washing your hands thoroughly with soap and water after handling birds or cleaning their cages is crucial. This simple practice can help remove any bacteria that may be present on your hands.

  • Regular Cleaning and Disinfection: Keeping bird cages and equipment clean and regularly disinfecting them can help prevent the buildup and spread of bacteria.


  • Seeking Veterinary Care: If your bird shows signs of illness, seek veterinary care promptly. Sick birds should be isolated from other birds to prevent the spread of infection.


  • Educating Yourself: Understanding the risks associated with handling birds and the importance of preventive measures can help you take appropriate precautions to avoid infection.


By following these preventive strategies, individuals can reduce their risk of contracting psittacosis and enjoy the companionship of birds safely.


Author: Dr. Heer Patel, MBBS, GMERS Medical College, Ahmedabad, India. 


Editor: Dr. Sidhant Ochani, MBBS, Khairpur Medical College, Khairpur, Pakistan.


Reference


  1. New York State Department of Health. Psittacosis. https://www.health.ny.gov/diseases/communicable/psittacosis/fact_sheet.htm. Accessed 16/02/2024.

  2. Mount Sinai Health System. Psittacosis. https://www.mountsinai.org/health-library/diseases-conditions/psittacosis. Accessed 16/02/2024.

  3. WebMD. Skin Infections: What You Should Know. https://www.webmd.com/skin-problems-and-treatments/ss/slideshow-skin-infections. Accessed 16/02/2024.

  4. Centers for Disease Control and Prevention. Psittacosis (Chlamydia psittaci) Diagnosis, Treatment, and Complications. https://www.cdc.gov/pneumonia/atypical/psittacosis/about/diagnosis-treatment-complications.html. Accessed 16/02/2024.

  5. National Libraray of medicine . Psittacosis https://www.ncbi.nlm.nih.gov/books/NBK538305/. Accessed 16/02/2024

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