Psittacosis / Chlamydiosis

Psittacosis
A Bourke Parrot with conjunctivitis caused by Chlamydiosis

Psittacosis or Chlamydiosis. Psittacosis (also called chlamydiosis or chlamydophilosis) is a bird disease that can, on rare occasions, be transmitted to humans. In birds it typically causes respiratory and/or liver problems or gastrointestinal upsets and can cause death. In humans it can cause respiratory disease and flu-like symptoms and, on rare occasions, if untreated, it can be fatal.

It is caused by Chlamydia psittaci, a germ that is bigger than a virus but smaller than most bacteria

How do birds or people catch psittacosis?

Birds or people generally contract psittacosis by inhaling particles of infected material shed by chlamydia-infected birds. The parrot chlamydia may be excreted in droppings, discharge from the eyes or nostrils or exhaled air. To develop psittacosis infection a bird must initially be exposed to the chlamydia organism through contact with a chlamydia infected bird or its droppings or discharges. It is possible for the disease to be carried by birds in a dormant state and then be activated by some stressing factor such as moulting, extremes in weather conditions (e.g. a cold snap), transportation, changes in husbandry or concurrent illnesses. Some birds may carry the organism for years without showing any clinical signs. There has been a case of a solitary pet bird, seemingly well and isolated from other birds for over ten years, dying from psittacosis. Psittacosis is widespread in Australia’s wild bird population and is a cause of illness in wild birds.

What symptoms do affected birds show?

Clinical signs of chlamydiosis  are quite variable and can range from sudden death in apparently healthy birds, to simply showing a lack of energy. Often birds show signs of psittacosis like conjunctivitis, respiratory, liver or intestinal disease. These may include any of the following: lethargy, depression, ‘fluffed’ feathers, depression, loss of appetite, weight loss, diarrhoea, biliverdinuria (green droppings due to bile pigments), laboured respiration, eye discharge, seizures or neurological symptoms. Some birds may show feather colour change (green to yellow or grey to black). Others parrots with chlamydia may chew at their feathers or bodies, possibly due to discomfort associated with internal organ damage. Species of birds that may be affected with psittacosis include cockatoos, cockatiels, budgerigars, parrots, finches, chickens and ducks.

How is psittacosis/chlamydiosis diagnosed?

Psittacosis or Chlamydiosis
Autopsy on a Macaw showing an enlarged spleen that is typical with psittacosis

Because clinical signs of psittacosis are highly variable and can be the same as those caused by other diseases, avian chlamydia diagnosis needs to be confirmed by laboratory testing and/or post mortem examination. Common tests done in live birds check for the
• presence of the psittacosis organism. This is generally done by a PCR test that needs to be sent away to a laboratory and takes around two weeks.
• presence of antibodies in the blood to the avian chlamydia organism. This test is done at the clinic results can be ready in several hours.
It is important to understand that neither these tests, are 100% accurate. A bird may not shed the bird chlamydia organism constantly, in which case there could be a negative PCR test result but the bird could still be infected. The avian vets at Bird Vet Melbourne can advise you which tests may be most appropriate depending on individual circumstances.

How is psittacosis/chlamydiosis treated?

There is no treatment currently available that will 100% guarantee the elimination of the psittacosis organism. The main difficulty is that the organism can go into a dormant phase against which antibiotics are ineffective. The most effective current treatment is a course of doxycyline given orally or by weekly injections for 42 days. Drinking water medication is less effective as birds may not drink the medicated water, but it may be the only practical means of treatment in an aviary outbreak.
In the majority of cases 42 days of doxycyline administered at the appropriate dose rate will resolve the disease. On rare occasions, because of the problems in treating the organism when it is in a dormant phase, a bird may show recurrent symptoms months or years after the treatment has finished, even though treatment has been carried out correctly. Birds do not develop lasting immunity following infection from psittacosis so it is possible for the same bird to contract the disease more than once.

Psittacosis in people

In humans psitacosis is rare. If it occurs the onset is typically abrupt with fever, chills, headache, muscle aches, general malaise and respiratory tract infections. Cough is often, but not always, a feature. The illness usually lasts for 7-10 days and is generally mild or moderate but may be severe or fatal in older, immunocompromised or untreated patients. The incubation period is 4-15 days. Relapses can occur. It is important to consult your doctor if you or anyone coming into contact with your bird(s) develops signs.

How can you prevent psittacosis/chlamydiosis
Because even apparently healthy birds may shed the psittacosis organism, it is difficult to completely eliminate the risk of psittacosis if you keep birds. If you are considering treating a bird with psittacosis you should be aware of the possible human health risk and discuss any concerns with your doctor.
Control measures that will reduce the risk of spreading psittacosis include the following:

  • Have your birds tested for psittacosis by an avian veterinarian
  • Follow veterinary advice regarding isolation and treatment of individual sick birds
  • If psittacosis has been identified, do not introduce any new birds until treatment has been completed and then only introduce new birds of known origin.
  • Quarantine and treat new birds, as advised, for 4 weeks before introducing them to previously treated birds
  • Minimise stress and focus on good husbandry, good nutrition and regular cleaning
  • Bleach, F10 or quaternary ammonium compounds are effective disinfectants
  • Avoid creating dust or aerosols. Wearing a mask may reduce the risk of infection in humans