Zoonotic Diseases You Need to Know!
A recent news story told of the sad passing of a young boy from rat-bite fever, which he contracted from his pet rat. While this is a disease in rats, the fact that his rat transmitted this disease to a human shows by definition that it was a zoonotic disease. A zoonotic disease is a disease that can be passed between animals to humans. Zoonotic diseases can be caused by viruses, bacteria, parasites and fungi. As pet bird owners, we all need to know about the zoonotic diseases of our birds so that we can guard against them — to keep both them and us healthy and happy!
The most important zoonotic disease with our parrots is psittacosis, also called parrot fever. While it gets its name from the word parrot or psittacine, it may be transmitted to humans from other types of birds, including turkeys, pigeons and wild birds. Birds in the parrot family, or psittacines, that are more commonly associated with transmitting the disease include macaws, budgerigars (parakeets) and cockatiels. Avian chlamydiosis, the form of the disease in birds, can occur in canaries and finches but is infrequently diagnosed. The disease is caused by a bacterium called Chlamydophila psittaci. It is like a cross between a virus and a bacterium, as this bacteria replicates inside of cells, rather than outside, so the standard tests of gram stains and culture do not work for finding it.
Because psittacosis can be spread by birds in the parrot family, it has been occasionally found in pet-store workers and those who have purchased an infected bird. It may also be found in farmers and slaughterhouse workers who process turkeys. Many of the large pet store chains are concerned about the transmission of this disease, so they test the incoming birds for it. The most common technique for testing is through polymerase chain reaction (PCR) testing. This type of testing amplifies any Chlamydophila genetic information in a sample if it is present, allowing it to be detected even at low levels. It is important to discuss the testing of your bird with your veterinarian, because the manner in which samples are collected, the type of samples collected and the lab that is used can all influence the results.
Psittacosis in People
Human infection with C. psittaci usually occurs when a person inhales the organism that has been aerosolized from dried feces or respiratory tract secretions of infected birds. Other means of exposure include mouth-to-beak contact and the handling of infected bird’s plumage and tissues. Even brief exposures to birds or bird waste can lead to symptomatic infection; therefore, certain patients with psittacosis might not recall or report having any contact with birds. The onset of illness typically follows an incubation period of five to 14 days, but it can be longer. The severity of the disease ranges from a mild, non-specific illness to a systemic illness with severe pneumonia. Some people have died from this disease, but if there is knowledge of exposure and the correct antibiotic is used, the person usually regains health.
In humans, the symptoms are fever, headache, chills and sometimes pneumonia. Some people may only experience mild flu-like illness, or show no illness at all. A nonproductive cough is usually present and can be accompanied by breathing difficulty and/or chest tightness. As the disease progresses, weakness and inability to clearly think sets in. If you experience these symptoms, let your doctor know that you have birds and you may suggest that he or she consult with an infectious disease expert. Often, your doctor may not understand the level of testing in our birds that has a high degree of accuracy, and they may simply suggest that you get rid of your birds. However, companion birds are currently thought to pose a low risk to immune-compromised persons. Appropriate testing of your birds and then not exposing them to birds that have not been tested helps cut down the potential incidence of you or your bird catching this potentially life-threatening disease!
Psittacosis in Birds
In our psittacine birds, the usual incubation period of C. psittaci ranges from three days to several weeks. However, active disease can appear with no identifiable exposure or risk factor. Signs of avian chlamydiosis are non-specific and include lethargy, anorexia and ruffled feathers. Other signs include serous or mucopurulent (mucous with pus) ocular or nasal discharge, conjunctivitis, diarrhea and excretion of green to yellow-green urates. Severely affected birds may become anorectic (lack of appetite) and produce sparse, dark green droppings, followed by emaciation, dehydration, and death. Whether the bird has acute or chronic signs of illness or dies, this depends on the species of bird, virulence of the strain, infectious dose, stress factors, age, and extent of treatment or prophylaxis.
Our companion birds may show a variety of signs depending on the species. Commonly, budgies (or parakeets) and cockatiels may show respiratory or GI signs, but not both, when they have this disease. The larger parrots — including macaws — tend to show GI and respiratory signs. While cockatoos are less susceptible, they can be affected as well; lovebirds may not show any signs but be found dead in their cage. It is important to have these birds tested after death so that family members that may have been exposed are notified and appropriately medicated. Psittacine birds that are tested while apparently healthy or not and are found positive or highly suspicious for the disease are usually medicated for 45 days and then retested to make sure that they are cleared of the infection. It is important to work closely with your avian veterinarian to reduce exposure and infection of this disease.
Other Zoonotic Diseases
There are a number of other potential zoonotic diseases that as a bird owner you should be aware of. Salmonella can be transmitted by birds, particularly pigeons and doves. Avian tuberculosis has been found in some of our parrot species, but it is often the human that transmits the disease to the parrot instead of the other way around! Avian influenza, particularly the H5N1 strain, has had a lot of press but so far, with good monitoring of the wildlife and the poultry in the USA, there have been no cases reported. Canada just recently reported a case of a traveler from China to Canada who was confirmed to have the disease. A more important problem that is not infectious is allergic alveolitis in people. Those people have a hypersensitivity reaction to the feather dander of their birds. Species of birds that are known to more commonly create this problem are African greys, cockatiels and cockatoos.
While these diseases can be a serious threat, understanding them, including how to test and eradicate them when possible, helps reduce possible exposure and infection. Let’s all learn how to play safe.