Chances are, if you just have a parrot or two, and they never come in contact with other birds, your birds will never become infected with C. psittici and neither will you. Still, because it is a zoonotic disease and can be fatal in birds and people, psittacosis is something every bird owner should be knowledgeable about.
“If this disease stayed in birds, we wouldn’t worry as much about it as we do,” said Keven Flammer, DVM, Dip. ABVP-Avian. But because it can be transmitted to people, that carries both a legitimate human risk and also the chance that breeders and pet store owners can be sued if they sell a bird with psittacosis.”
On the other hand, if you take the zoonotic potential out of the picture, C. psittici is not as “bad” as a lot of other avian pathogens, according to Branson Ritchie, DVM, Dip. ABVP-Avian. “Chlamydiophila (psittacosis) is actually an easily treatable bacterial infection, unlike a lot of other bacterial infections,” he said. “You just have know what it is, and treat it with the right drug.” Psittacosis can certainly be fatal, he added, but that’s usually if the infected bird or person is immunocompromised or in poor health, or if the disease is left untreated. With early diagnosis and proper treatment, most patients fully recover from C. psittici infections.
What Is It?
In birds, C. psittaci infection is referred to as avian chlamydiophilosis. In the past, it was referred to as parrot fever and chlamydiosis and, while chlamydiophilosis is the technically correct term, many people continue to refer to it as chlamydiosis. It is found not only in pet birds, but also in wild birds, chickens and turkeys. Chlamydiosis is not a reportable disease in some states (depending on local laws). For this reason, it is impossible to know exactly how many birds get sick from psittacosis each year. However, based on the cases seen in their practices, avian veterinarians generally believe the incidence of the disease has gone down in the last 10 to 15 years.
Most avian veterinarians still see at least a few confirmed cases of chlamydiosis every year. California avian veterinarian Brian Speer, DVM, Dip. ABVP-Avian, usually sees two to three confirmed cases annually in his practice. Nationwide, there are usually about 10 to 15 outbreaks a year, where several birds in one location test positive for chlamydiosis.
A Problem For People?
C. psittaci is passed from bird-to-bird and bird-to-people via inhaled contaminated fecal dust or contaminated fecal matter that is ingested. Sometimes birds transmit the bacteria orally to other birds when they preen another bird’s feathers. A person can get the bacteria via a bird bite that punctures his or her skin or if the bird’s beak comes in contact with the person’s mouth. The bacteria can also be spread through discharges from a bird’s eyes and nose, which can become airborne or ingested.
Most commonly, the bacteria becomes airborne and is inhaled. “The infected bird sheds the organism in droppings.” Flammer explained. “When those droppings dry out, they become aerosolized into the air. When people and other birds breathe the air, they inhale the organisms.” Once outside the bird’s body, the organism can remain infective for several months.
There are no documented cases of human-to-human spread, although it is possible. This would require the infected person to cough very forcefully — filling the air with aerosolized droplets — and then another person breathing in those droplets.
“The species of Chlamydophila that causes psittacosis, C. psittaci, does not appear to readily transfer from birds to other pets,” Flammer said. He places it in the “possible, but unlikely” category.
Symptoms In Pet Birds
The time between exposure to C. psittaci and the onset of illness in pet birds ranges from three days to several weeks. The clinical symptoms can be variable, depending on the species infected, the virulence of the agent, the route of exposure and concurrent stresses. In general, birds with chlamydiosis exhibit a lack of appetite, weight loss, lethargy, diarrhea, nasal discharges, shivering and breathing difficulties. C. psittaci can attack some or all of a bird’s organ systems, but most commonly its liver, spleen, respiratory tract and digestive tract.
“The most common presenting sign that we see in the larger species of birds and sometimes in cockatiels is a bird that looks very depressed, it’s not grooming, it’s not preening, and has yellow or lime-green urates,” noted David Phalen, DVM, Dip. ABVP-Avian. Lime-green and yellow urates are a strong indicator that the bird has hepatitis, a condition that often accompanies chlamydiosis.
Of course, many of the above-mentioned symptoms mimic a lot of other avian diseases. The signs of avian tuberculosis and aspergillosis, for instance, are very similar to chlamydiosis. The only way to know for sure what’s going on with your bird is to take it to an avian veterinarian for a thorough examination including bloodwork.
There are multiple types of diagnostic tests available to veterinarians. One is a blood test called the Elementary Body Agglutination (EBA) test, which tests for the presence of antibodies to the organism. Another is the PCR (gene probe) test and that’s done on a swab of the oral cavity and the vent. Keep in mind that no one specific test is going to be accurate in every clinical situation.
Birds can also be asymptomatic carriers of the disease. “These birds appear healthy and do not show any symptoms, yet they can shed the organism and spread it to other birds and people,” Hicks said. Some birds carry the bacteria with no outward signs themselves, for as long as 10 years. The entire time, though, they may be transmitting the bacteria to others.
Symptoms In People
In people, psittacosis is primarily a respiratory disease. Chills, fever, sweats, headaches, fatigue, muscle and chest pain, fatigue, appetite loss, nausea, vomiting, diarrhea, shortness of breath and a dry cough are all common symptoms. Generally, signs appear within three to 15 days after exposure to the bacteria. The infection can vary in severity from a mild flu-like illness to severe pneumonia.
If you have any of the symptoms, tell your doctor that you have a bird or have been exposed to birds that may have been infected. “Many physicians will not consider psittacosis without being informed of exposure,” Phalen said. Psittacosis is [rarely diagnosed] in people, and most human physicians are not going to see it very often, if ever.
“Oftentimes a case of psittacosis will progress because the doctor misdiagnoses it as viral pneumonia and doesn’t treat it (since there aren’t antiviral drugs to treat viruses, and antibiotics which are available are not meant to cure viral infections), or the doctor might misdiagnose it as another bacterial infection and treat it with an antibiotic that is not good at killing Chlamydiophila,” Dahlhausen said.
Treatments For Psittacosis
The drug of choice for treating both people and birds is doxycycline. In people, the treatment is generally recommended for a minimum of two days. “Treatment is most likely to be successful if the infection is recognized early and if the patient completes the entire course of antibiotics,” she said.
Pet birds need to receive doxycycline for a minimum of 45 days, along with supportive care — heat, fluids, and tube feeding, etc. The antibiotic can be given by intravenous or intramuscular injections, orally, or mixed in proper ratios with food or water. Some forms of the drug may be a better choice than others for certain cases, depending on owner preferences, the seriousness of the bird’s condition, the number of birds being simultaneously treated, and the species of bird.
“For the bird that’s showing clinical signs of illness, you want to get drug into it fast and the best way to do that is either orally or by injection,” Flammer said. Oral doxycycline normally needs to be given once a day and is dropped directly into the bird’s mouth. Sometimes that’s not easy to do, especially for 45 days straight. For that reason, the injectable version of the drug is often chosen, in which case the bird would need to be taken to a veterinarian once every five to seven days for an injection.
Exactly how often the drug needs to be administered and at what dose depends on the species of pet bird. In cockatiels, for instance, 50 percent of the dosage of doxycycline is gone within four to six hours. “But when we give the same drug dose on a body weight basis to a Goffin’s cockatoo, it takes about 20 hours for the drug to be gone. That makes a huge difference in how often you’re going to give that drug,” Flammer said. For birds that are asymptomatic carriers, doxycycline medicated water usually works well.
“The water soluble doxycycline is ideal if you’re treating a large flock of cockatiels, lovebirds, passerines, or other small birds,” Dahlhausen said. “To try to treat each of these birds orally on a daily basis or even just doing an injectable once a week would be a difficult task, but the water treatment is fairly easy to administer.” Budgerigars in particular do not seem to do as well on the medicated water. Three years ago Flammer developed a treatment regimen for budgies using doxycycline-medicated seed, and he has had a lot of success with that.
There can be some side effects of long-term doxycycline use, so pet birds on treatment should have routine checkups with their avian veterinarian to monitor their condition. “There is the potential of toxicity from the drugs, as well as disruption of the normal digestive tract bacteria with an overgrowth of bacteria that can cause disease or with an overgrowth of yeast,” Phalen said. Oftentimes an anti-fungal drug or a broad spectrum antibiotic may be prescribed to tackle these secondary infections.
Finally, do not try to treat a pet bird with psittacosis on your own. Speer said, “Any disease process that’s been dabbled with pharmacologically is going to be much harder to diagnose later on when a veterinarian does see the bird.” An over-the-counter medication may kill just enough of the organism in the organism to make a PCR test go negative, for instance, and give the clinician the false impression that the bird does not have psittacosis.