What is Psittacosis (Parrot Fever and Ornithosis)?
Psittacosis, also known as parrot fever or ornithosis, is a disease passed onto humans by birds. It is caused by a bacterium called Chlamydia psittaci that can only survive inside the cells of the host organism. The range of symptoms and the severity of the disease can vary from person to person.
The main carriers of this disease are birds, especially those from the parrot and chicken families. However, this doesn’t mean other bird species are safe. In fact, the disease has been found in nearly 467 different bird species across 30 different bird families. So, being around any bird could potentially pose a risk.
Humans usually get infected through direct contact with birds infected with the disease or by breathing in aerosolized bacteria from the bird’s feces, urine, or secretions from their respiratory system or eyes. While it’s possible for the disease to spread from one person to another, it’s a very rare occurrence.
What Causes Psittacosis (Parrot Fever and Ornithosis)?
C. psittaci is a type of bacteria that primarily lives in animals, especially birds and mammals. Medical professionals are able to identify different versions, or genotypes, of this bacteria through a process called real-time PCR, which allows them to study its characteristics and spread. Each different genotype is typically linked to a specific host animal, but all versions can infect humans and cause a disease called psittacosis.
So far, scientists have identified ten different versions of C. psittaci. However, information about this bacteria and the disease it causes is limited, making it difficult to fully understand. For instance, between the years 2006 to 2012, only 58 cases of psittacosis were reported to the Centers for Disease Control and Prevention (CDC) in the United States. Of these cases, only two were confirmed through a method known as culture. The rest of the cases were diagnosed using serologic testing, which measures the body’s immune response to the bacteria.
Coming into contact with birds is the main way humans can get psittacosis. You can also get this disease from indirect exposure through bird feces, urine, and other excretions. Birds that commonly carry this bacteria include cockatiels, parrots, parakeets, and budgies. Poultry birds like chickens, ducks, and turkeys have also been found to carry this bacteria, sometimes causing outbreaks among poultry farmers.
Risk Factors and Frequency for Psittacosis (Parrot Fever and Ornithosis)
Psittacosis is a disease that can affect anyone, regardless of their age or gender, but it typically occurs in people between the ages of 35 and 55. The disease was first linked to pet parrots and finches in 1879, with global outbreaks in 1929 and 1930. However, psittacosis is considered a rare infection transmitted from animals to humans. Because of this, awareness of the disease is low among the public and health professionals. This, combined with the need for specific testing, means that psittacosis is likely under-diagnosed and underestimated in reports of its prevalence.
The Centers for Disease Control and Prevention (CDC) in the USA lists psittacosis as a reportable condition in most states, with fewer than ten confirmed cases each year. This is probably due to under-diagnosis and under-reporting. People who are at the highest risk of getting the disease are those who have exposure to pet shops, veterinary hospitals, bird exhibitions, and people who work in the poultry industry. The incidence of psittacosis in the USA between 1999 and 2006 was reported as 0.01 per 100,000 population. In studies examining patients hospitalized with pneumonia, less than 5% were found to have psittacosis.
Psittacosis has been reported worldwide. A review of community-acquired pneumonia (CAP) around the world found that C. psittaci, the bacteria that causes psittacosis, was the cause in 1.03% of cases, varying from 0 to 6.7%. Similarly, a review of studies from multiple countries reported that 1% of all hospitalised CAPs were caused by C psittaci. However, the reported incidence is much lower year-on-year, suggesting the disease is under-diagnosed. Outbreaks of psittacosis tend to happen sporadically, and often in connection with pet shops, poultry farms, and veterinary facilities.
Improved diagnostic techniques and strategies are expected to lead to an apparent increase in the incidence of psittacosis. According to a 2022 study from China, molecular techniques were used to identify pathogens in severe community-acquired pneumonia cases. The study found that Chlamydia psittaci, the bacteria that causes psittacosis, was the cause in 6.8% of the patients (15 out of 222).
Signs and Symptoms of Psittacosis (Parrot Fever and Ornithosis)
Psittacosis, a disease commonly linked to exposure to birds, can actually be contracted in areas populated with wild birds, even without direct contact. It’s been seen in places like Australia, where some towns are heavily populated by a diverse range of bird species. To diagnose this condition, medical professionals focus on the patient’s work, travel history, and hobbies, keeping a keen eye out for likely sources of exposure.
People with psittacosis often have symptoms that are similar to the flu, such as a high fever, chills, headaches, and a cough. This illness can take anywhere from 5 to 14 days to show symptoms after exposure. Early symptoms usually come on suddenly and prominently feature headaches, but also may include fever, muscle aches, nausea, vomiting, diarrhea, and a cough. In some cases, patients may experience a mental fog, mild neck stiffness, sensitivity to light, enlarged liver and spleen, and a sore throat.
Psittacosis can spread to multiple organs in the body, resulting in a variety of symptoms:
- Nervous system symptoms may include inflammation of the brain and spinal cord, loss of balance and coordination, weakness in facial muscles, partial or complete loss of spinal cord function, weakened reflexes, seizures.
- Respiratory system symptoms may include pneumonia, severe difficulty in breathing, respiratory failure, and severe septic shock.
- Cardiac symptoms are rare but could include inflammation of the heart muscle and outer lining, heart infections, and inflammation of the aorta.
- Kidney and digestive system symptoms can include kidney inflammation, kidney failure, inflammation of the kidney’s filters, liver inflammation, and pancreas inflammation.
- Blood irregularities can include a blood clotting disorder, an enlarged spleen, and a syndrome in which the body’s tissues and organs are attacked by its own immune system.
- Joint symptoms may include reactive arthritis and inflammation of the blood vessels supplying the joints.
Psittacosis can also result in both maternal and fetal complications during pregnancy, and it may be associated with a type of eye cancer called ocular lymphoma. Psittacosis patients may also present with chest abnormalities during a physical exam, such as crackling sounds in the lungs or signs of lung consolidation. Interestingly, while inflammation of the lining between the lungs and chest wall and fluid buildup in this area was previously thought to be rare, recent studies indicate that over 50% of patients show these symptoms. Skin abnormalities are rare. Patients with psittacosis often experience fever without a rapid heart rate, a condition known as relative bradycardia, which is found in as many as 71% of cases.
Testing for Psittacosis (Parrot Fever and Ornithosis)
Psittacosis, a type of lung infection, often shows normal white blood cell levels in lab tests. However, blood tests specific to inflammation like the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are often elevated in people with this disease. Other commonly elevated tests include creatine level and certain liver function tests.
Typically, the majority of people with psittacosis have abnormal chest imaging results which might show inflamed areas in the lungs. However, it’s crucial to understand that a normal chest X-ray doesn’t rule out psittacosis. Moreover, when computed tomography (CT) of the chest is conducted, it usually reveals inflammation in one lung, often affecting a single lobe.
Special testing options for a suspected case of psittacosis can include serologic testing, which measures the presence of specific antibodies in the blood. The two main types are complement fixation (CF) testing and micro-immunofluorescent (MIF) antibody testing. The latter has shown to be more sensitive and specific for detecting psittacosis.
Additionally, methods using monoclonal antibodies and DNA-based tests like a polymerase chain reaction (PCR) are being developed and show promise as rapid diagnostic tools. Furthermore, a novel technique called metagenomic next-generation sequencing (mNGS) also shows significant potential in increasing the rate of pathogen identification.
It’s important to remember that while these tools show promise, they are not widely available yet due to limitations like higher costs and technical limitations. Culture testing is currently the most specific and accurate method for diagnosing psittacosis but requires special safety measures due to the risk of transmission to lab workers.
Lastly, the Centers for Disease Control and Prevention (CDC) provides guidelines for diagnosing psittacosis. These guidelines suggest that a diagnosis can be made by detecting the causative organism from respiratory secretions, a significant increase in antibody levels between serum samples collected two weeks apart, or a single antibody titer detected by MIF of 1:16 or higher.
Treatment Options for Psittacosis (Parrot Fever and Ornithosis)
If someone is suffering from a specific type of bacterial infection, the most effective treatment usually involves taking antibiotics called tetracyclines, specifically a kind called doxycycline. This is supported by scientific research and people have been observed to improve, with symptoms like fever reducing within 48 hours of starting the treatment.
However, there are times when doxycycline cannot be used. For instance, pregnant women can’t take it. In these cases, other antibiotics like azithromycin and erythromycin, which belong to a group called macrolides, are used instead. If these antibiotics don’t work, fluoroquinolones may be used. However, they’re not as effective as tetracyclines or macrolides, so they’re usually the third option.
In children with a less severe form of the infection, macrolides are often the first choice. But if the infection is severe, and the benefits of doxycycline outweigh the risks, doxycycline might be used instead despite it usually being avoided in children. This is a decision that must be made carefully by the doctor.
It’s not entirely clear whether corticosteroids, another type of medication, can help in severe cases of this infection. There have been instances where they have been used when traditional antibiotics were not effective, and they did seem to help improve the patient’s symptoms. However, sadly in one case, even though the corticosteroids improved symptoms, the patient still did not survive. Because of this, more research is needed to understand the best way to treat severe cases of this infection.
What else can Psittacosis (Parrot Fever and Ornithosis) be?
When considering different types of infections that affect the lungs, physicians take into account the following possibilities:
- Mycoplasma pneumonia
- Legionella pneumonia
- Q fever (Coxiella burnetii)
- Tularemia (Francisella tularensis)
- Influenza
- Typhoid fever
- Brucellosis
- Bacterial pneumonia
- Fungal pneumonia
- Viral pneumonia (COVID-19, H1N1, etc.)
What to expect with Psittacosis (Parrot Fever and Ornithosis)
The outcome for those with psittacosis — an infectious disease usually caught from birds — can vary depending on several factors. These include the seriousness of the disease, other existing health conditions the person may have, and when treatment starts. Before antibiotics were available, about 15-20% of people with this type of infection in their lungs didn’t survive. It’s unclear though, how much of this was due to psittacosis specifically.
With the discovery of antibiotics, however, death due to psittacosis has become extremely rare. In fact, when the right antibiotic treatment is given, cure rates can be as high as almost 95%.
Despite this, in some rare cases, the disease progresses very quickly and is severe. In these cases, the death rate is reported to be 1% or less. It’s also worth noting that while cases of psittacosis during pregnancy are rare, they can result in death of both the mother and the unborn child.
Possible Complications When Diagnosed with Psittacosis (Parrot Fever and Ornithosis)
People infected with psittacosis, a disease often spread by birds, can show many different symptoms due to the disease spreading throughout their bloodstream after they are first infected. For comprehensive information on different complications, refer to the “History and Physical” section earlier.
In summary, psittacosis infection can cause several complications. These include acute respiratory distress syndrome (a severe lung condition), respiratory failure, inflammation of the heart wall (endocarditis and myocarditis), bloodstream infection (sepsis), disseminated intravascular coagulation or DIC (a condition affecting the blood’s ability to clot and stop bleeding), meningitis or encephalitis (infections causing inflammation in the brain), liver inflammation (hepatitis), and inflammation in the pancreas (pancreatitis). There’s also a small chance that a patient may show signs of a severe, rapidly progressing condition characterized by multiple organs failing together.
Complications associated with psittacosis:
- Acute respiratory distress syndrome
- Respiratory failure
- Endocarditis (heart wall inflammation)
- Myocarditis (heart muscle inflammation)
- Sepsis
- Disseminated intravascular coagulation (DIC)
- Meningoencephalitis (brain inflammation)
- Hepatitis (liver inflammation)
- Pancreatitis
- Fulminant disease characterized by multi-organ failure (rarely)
Preventing Psittacosis (Parrot Fever and Ornithosis)
According to the Centers for Disease Control and Prevention (CDC), it’s not necessary to isolate people or give them preventive treatment for psittacosis, a disease caused by a type of bacteria. This is because the disease is rarely passed from one person to another. However, it’s important to note that most U.S. states require psittacosis cases to be reported. Swift diagnosis helps control the spread of this disease.
The public needs to be aware of how to properly buy, handle, and clean birds and birdcages to prevent catching and spreading this disease. Psittacosis is quite common in birds, and the actual rate of human infection might be higher than we currently know. If a bird is suspected of being the source of an infection, it should be brought to a veterinarian or health department staff immediately. Taking good care of pet birds and implementing protective measures for poultry industry workers can significantly lower the health risks associated with this disease.
In 2017, the National Association of State Public Health Veterinarians composed a set of guidelines on how to control psittacosis infections. These guidelines, which were based on the United States Preventive Services Task Force (USPSTF) system for ranking levels of evidence, are as follows:
- People at risk of psittacosis and healthcare professionals should be educated about the disease’s signs, symptoms, and diagnostic procedures. (This guideline is Level B, which means that the organization recommends the service.)
- The public should be educated about how to handle birds correctly, wear protective clothing, and, if necessary, use a one-use particle filtration mask. (This guideline is Level B.)
- Health departments and healthcare staff should work together to educate the public and bird industry about the importance of keeping detailed records of all bird-related transactions. This can help identify potential sources of infection. (This guideline is Level B.)
- Birds that have been possibly exposed to psittacosis should be quarantined, and sick birds with signs of the disease should be isolated. (This guideline is Level A, which means that the organization highly recommends the service.)
- Appropriate disinfection methods should be used on all surfaces that may have been exposed to the disease. (This guideline is Level A.)
