The purpose of this article is to review the most significant diseases that can potentially spread from a bird to a human. I want to stress the word potentially,î because for almost all the diseases that I will mention, there have not been confirmed reports of a human being infected by a pet bird. The term zoonotic disease refers to any disease that a human can acquire from an animal. While there are literally hundreds of such diseases, when talking about pet birds, only a few are of concern. Every few years, we are bombarded by media reports of outbreaks of zoonotic diseases. Do you remember England mad Cow Disease in early 1996? That disease is caused by a virus-like particle called a Prion. In late 1993, fifty-one people died and many more became sick in the southwest US from a virus (hantavirus) that spread from rodent feces to humans. Even Hollywood has jumped at the opportunity to prey on our fears with movies such as Outbreak and Virus.

Why do I choose to talk about zoonotic diseases? Very recently, I was asked to address this subject in regard to a Peach-faced Lovebird that I gave to my wife for her classroom. A physician told one of the parents in that classroom that birds can be very dangerous and that he was appalled that the school would permit such a risk. The obviously concerned parent threatened to remove the child from the class if the bird was not taken away. I was asked to intervene to help calm the waters. Even though I knew that this bird posed little real risk to the children, I decided to research the literature for published articles that could support my opinion. I found multiple articles written not only by veterinarians, but also by many medical researchers and epidemiologists from the Center for Disease Control (the bastion for the study of communicable diseases). Most of the published material relates to zoonotic diseases that are considered dangerous to people with a compromised immune system.

Bird Toys

Currently these people fall into four groups:
· Newborn infants & the elderly
· Patients on chemotherapy (including high doses of prednisone)
· People infected with HIV
· Organ transplant recipients on immunosuppresive drugs

Why does the literature focus on these groups? These people are at a much higher risk, given that they are less likely to be able to fight off a disease that may be spreading through their body. What was most interesting was that in all the articles that I read, not a single one suggested that pet birds posed a large risk for people within these groups or to the average pet owner. Even if the risk is low, it is essential to be very aware that a potential risk does exist. As such, I will talk about the major diseases that are considered a zoonotic risk. No attempt will be made to be all inclusive given that such in-depth information is beyond the scope of this forum... I will also leave out the hundreds of diseases that are found in wild birds in other countries. These pose almost no threat, unless the reader routinely imports wild caught birds. I have divided the diseases into groups (bacterial, parasitic, fungal, etc.)

1) Fungal Diseases: Within this group, there are two serious threats. The first is mycobacteriosis (the group of fungi that includes the agent that causes tuberculosis). There are over 50 mycobacterial species which can cause disease in humans and animals. M. tuberculosis is the agent that causes tuberculosis in humans. M. avium and M. genavense are the two species that most commonly cause disease in pet birds. Although mycobacterial disease is common in up to 80- of AIDS patients1, during the past 15 years, there has never been a confirmed case of transmission occurring from a pet bird. Even the suggestion that exotic pets act as potential environmental sources of these organisms, has never been proven. An article2 by doctors from various branches of the National Center for Infectious Diseases at the Center for Disease Control states:

"Pet Birds are an unlikely source of M. avium infections in human beings, because M. avium isolates  from birds differ in antibiotic susceptibility, serovars, and genetic sequencing from human isolates."

The second threat within the family of fungi is from Cryptococcus neoformans. C. neoformans is a yeast organism that can cause life threatening meningitis in the terminal stages of AIDS. It has been suggested that the source of this organism is from pet birds. However, the previously mentioned article states to the contrary:

"Cryptococcus neoformans does not cause disease in birds, because of their high body temperature.  Cryptococcus neoformans is commonly isolated from soil and droppings from wild birds, especially  Pigeons, but seldom from droppings from pet birds.....Pet birds are therefore an unlikely source of  Cryptococcus infection in humans."

2) Parasitic Diseases: Most external parasites (i.e. lice, mites) affecting birds are species specific. This means that although it is possible for them to be found physically on a human, they are unable to cause an infestation. Giardia and Cryptosporidium are two of the more commonly mentioned parasitic diseases that can cause severe intestinal disease in humans. These organisms can also cause gastrointestinal disease in birds. However, to date, there has never been a documented case of a bird causing infection in a human.3

3) Bacterial Diseases: Salmonellosis, colibacillosis (E. Coli), campylobacteriosis and to a lesser extent, chlamydiosis (psittacosis) are the more common bacterial and bacterial-like organisms that can cause disease in humans. Salmonellosis is caused by a multitude of species of bacteria within the genus. Although common in poultry and ratites (emus, ostriches, etc.) and increasingly more common in green iguanas, salmonella is a rare cause of disease in pet birds. In the veterinary community, there has been a lot of concern about the potential spread of psittacosis to humans. The cause for the concern is two-fold. The first is the inherent difficulty to both diagnose the disease in infected birds or establish a disease-free state in healthy birds. The second concern is that birds have become popular pets at nursing homes, schools and other human-animal bond sites. The fear however, has not materialized in an increase of diagnosed cases of zoonosis. Escherichia coli is a bacteria that has hundreds of strains. Some of these strains can cause both watery or hemorrhagic diarrhea and hemolytic uremic syndrome in humans. Although many cases of E. coli poisoning in humans has been attributed to improperly cooked meat, experimental models have failed to show that birds and other animals can directly transmit E. coli to humans4.

4) Viral Diseases: The three most common avian viruses that are considered zoonotic are: Eastern/Western/Venezuelan Equine Encephalitis Virus (EEE, WEE & VEE). These virus occur in wild birds and to my knowledge, have never been reported in pet birds.
As discussed above, there are many diseases that can potentially be spread from birds to humans. Even if cases of zoonosis have not been documented, this does not eliminate the possibility that they may be reported in the future. Every bird owner has the responsibility to themselves and to others within their household to take measures to reduce the risk. The first step is to only acquire healthy birds. Buying a captive bred bird is less of a risk than a wild caught (open-banded) bird. Many avian veterinarians report seeing a dramatic decrease in the number of birds affected by these diseases as the pet bird demographics continues to shift toward captive bred animals.

All newly acquired birds should be examined by a veterinarian prior to a quarantine period of at least 30 days. A thorough new-pet exam with appropriate screening tests is essential. Although it is very tempting to have a new bird meet the family as quickly as possible, forgoing a proper quarantine period can lead to disastrous consequences. Any bird that dies of unknown causes should be necropsied (autopsy in animals) by your veterinarian. A necropsy is especially important in a multi-bird household where the spread of disease is more likely. Every bird should routinely (minimum once per year) be examined by a veterinarian. Maintaining a healthy pet is imperative. Your veterinarian will not be able to guarantee that your bird is free of disease, he/she will however, be able to look for the common indicators on physical exam and laboratory tests that my indicate that your pet is not in good health.

At home, there are certain measures that will help keep your bird healthy. I cannot over emphasize the importance of reducing stress in your pets life. Stress can be defined (courtesy of Random House dictionary) as "any stimulus that interferes with the normal physiological equilibrium of an organism". These stimuli include: improper temperature, incorrect sleeping cycles, loud noise, other pets, poor ventilation, and many more. Stress is difficult to measure, but it has the overall effect of weakening the immune system. Malnutrition also weakens the immune system and is often the direct cause of many diseases in birds. Finally, every member of the family must be instructed on proper hygienic precautions to take with every pet. Some of these are listed below.

1. Always wash your hands after handling a pet.
2. Never let your bird in areas where human food is being prepared.
3. Clean and disinfect your birds cage, toys and food bowls on a frequent basis.
4. Do not clean/disinfect pet related items in the kitchen or bathroom sink. Use a utility sink if available. If not     available, then disinfect sink afterwards.