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Wednesday, 26 October 2016

Parrot Fever (Chlamydia psittaci)

This article should give the reader an indication of the covert nature of this organism, enabling it to exist without disease signs in many pet birds and aviaries. To fight an infectious disease, you must never underestimate the enemy and you must understand its many characteristics. The purpose of this article is to allow the reader to gain a better understanding of the Chlamydia psittaci organism and the effect it has on the pet bird industry.

Parrot Fever (Chlamydia psittaci)

Every year the Centers for Disease Control and Prevention (CDC) sponsor a Chlamydia psittaci compendium to review human and avian diagnostic tests and treatments. The CDC calls the human infection, human psittacosis, and the bird infection avian chlamydiosis. Since that is the official government designations, I will follow that format for this article and would encourage the aviculture community to do the same. Chlamydia organisms are nonmotile, obligate, intracellular, parasitic agents that have not yet been satisfactorily classified taxonomically.1,2 The most important fact that aviculturists and pet bird owners should remember regarding the description of the chlamydial organism is that it functions within the host's cell. The intracellular lifecycle makes it difficult to identify, especially if the bird is not showing signs of infection or if the infection involves a whole aviary.


How The Disease Occurs

A particular "strain" of the Chlamydia psittaci organism may live within a single bird or an aviary full of a single psittacine species. This organism can change its characteristics within the birds of an aviary over time, allowing the infected birds, say cockatiels, to become subclinical carriers, showing no signs of infection. If the aviculturist brings home a new psittacine species, such as an Amazon parrot, it may become infected and die within a short period of time once it is exposed to the organism in the cockatiel aviary. The cockatiels that were initially in the aviary may have adult death losses or chick deaths, especially in the second, third and fourth clutches, due to adult shedding from stress related to raising the young. This is a reason that aviculturists should always have birds necropsied if they are unsure of the cause of death. One necropsy now will prevent monetary loss in the future and help protect the aviculturist.

Once a bird is sold, the seller often provides a short time period for a health status examination by an avian veterinarian. This exam may be useful to determine any obvious clinical disease, sex or skeletal abnormalities, but it will be difficult to test and confirm that the bird is free of a Chlamydia psittaci infection. Since the chlamydial organism lives within the host cells and is shed through the feces and respiratory tract intermittently, diagnosis is difficult, if not impossible with the tests currently available.

If the bird is showing obvious clinical illness, it is much easier to diagnose avian chlamydiosis. A complete blood count may be the best way to determine a bird's health status regarding Chlamydia psittaci. For this reason, short-term post-purchase physical examinations cannot rule out the possibility of a new bird being infected with this intracellular bacteria. All bird owners must realize this fact and adjust their thought processes on post-purchase physical examinations. This is another reason that bird owners should quarantine all new birds and birds that have been to fairs and shows for at least six to eight weeks prior to allowing a bird to return to the main aviary .

The target tissue for the chlamydial organism is in the upper respiratory system. Bird breeders or pet bird owners who do not clean cages on a regular basis allow the organism, that is mainly shed in the feces, to aerosolize, thereby exposing themselves and susceptible birds. Maintaining a clean aviary will reduce exposure and illness to other birds and aviary personnel if there is a sick bird shedding the bacteria. Infectious organisms that can be transmitted from animals to humans are called zoonotic diseases. Pneumonia, high fever, sweating and general fatigue are the common associated with human psittacosis. It is recommended that all bird owners inform their physician of avian ownership, especially if they have the "flu-like" signs described above. This is a treatable illness, but if left untreated, may cause death in some cases. Human psittacosis is rare, and death associated with the infection in humans extremely rare. The aviculture community would like to keep it that way. So please do your part as responsible bird owners to keep all bird owners and especially new bird owners informed about this disease.

Clinical signs associated with the illness in pet birds include depression, anorexia, green diarrhea, difficulty breathing, choanal inflammation and nasal discharge. The chlamydial organism affects the liver and other major vital organs. Green diarrhea is associated with the hepatitis that occurs during an avian chlamydiosis infection. In large aviaries, especially cockatiel aviaries, neonatal death is common, especially before weaning, due to the shedding of the infectious organism by the immune stressed parents. As mentioned previously, young bird death occurs most frequently during the second, third and fourth clutches. If the aviculturist does not identify and treat the disease properly, it will become subclinical and affect future breeding success.

Once a bird or aviary has been diagnosed with Chlamydia psittaci, it is the responsibility of the owner to make sure that the bird(s) are properly treated. The chlamydial organism is an intracellular bacteria that makes it difficult to treat, and infected birds must be treated for a 45-day period. The drug of choice is tetracycline or a tetracycline derivative such as doxycycline. This drug may be administered in manufactured pellet form or in the water to treat a large aviary or difficult pet bird. For the single pet bird, oral medication or weekly injections may be given to treat avian chlamydiosis.

No other drug currently available has the beneficial therapeutic effect of doxycycline when treating this disease. One nutritional complication, calcium binding, may occur when treating with oral doxycycline. This is especially problematic when young growing birds are on long term doxycline drug therapy. Calcium supplement must be supplied between oral treatments or made available to birds within the aviary being treated in the water or pellets.

To realize breeding success and maintain pet bird health avian owners must understand the organism that causes avian chlamydiosis and human psittacosis. This is not only an important disease organism affecting avian species but humans, as well. Chlamydia psittaci is a difficult organism to identify, especially in the subclinical bird, so bird keepers must help their avian veterinarian and have all unknown deaths necropsied. Once identified, it is up to the owner to treat the birds properly. Currently, there are research investigations on better diagnostic tests and a vaccine for better identification and protection. Until the new tests become perfected and the vaccine is available, the bulk of the responsibility of controlling the organism lies with aviculturists, pet bird owners and avian veterinarians.