Why You Need To Know About Zoonotic Avian Infections

Neil Forbes, BVetMed DECZM FRCVS with eagle
Read in 14 minutes

The most important route of Salmonella spp. transmission is eating incompletely cooked food and drinks; however humans may also be infected from poultry and free-living birds.

Allergic alveolitis is a serious, under-recognized condition, that may affect bird owners after exposure to feather antigen.

Most human West Nile virus infections are asymptomatic although mild influenza-like signs may be seen in about 20%. A small proportion (less than 1%) develop more severe neurologic disease which is sometimes fatal.

Avian influenza may cause severe disease affecting the respiratory, digestive and/or nervous system and high mortality.

As avian veterinarians, we are all on the front line for identifying avian influenza.

Train staff to recognize clinical signs and answer questions.

Immunocompromised individuals commonly contract Mycobacterium avium infection from contaminated soil. Infection from birds is extremely rare.




Also known as parrot fever and ornithosis, psittacosis is caused by Chlamydophila psittaci, an obligate intracellular bacteria of birds. Infected birds shed bacteria through feces and oculonasal discharge.

Most human cases result from exposure to infected psittacines.

Apart from exposure to infected pet birds, individuals at risk include pigeon fanciers, employees in poultry slaughtering and processing plants, veterinarians and technicians, zoo, laboratory and avian quarantine employees, farmers, gamekeepers, and wildlife rehabilitators.

Humans can be infected during transient exposure to infected birds and contact may be so brief the patient may forget. Person-to-person transmission has been suggested but not proven.


An average 250 human cases of Chlamydophila psittaci are reported annually in the United States.

Clinical signs typically follows a 5 to 14 day incubation period.

Disease ranges from subclinical to systemic illness with severe pneumonia.

Most people demonstrate sudden onset fever, headache, malaise, and myalgia with a non-productive cough that can be accompanied by breathing difficulty and chest tightness.

Splenomegaly and a non-specific rash are also sometimes observed.

Chlamydophila can also cause endocarditis, myocarditis, hepatitis, arthritis, keratoconjunctivitis, and encephalitis. Respiratory failure, thrombocytopenia, hepatitis, and fetal death have been reported in pregnant women.

Disease is fatal in less than 1% of properly treated humans, however fatality can reach 15 to 20% where antimicrobials are not provided.

Humans exposed to birds with avian chlamydiosis should seek medical attention if they develop flu-like symptoms or respiratory problems.

Physicians should consider psittacosis in all ill patients exposed to birds, and early, specific treatment for psittacosis should be initiated.

Most states require physicians to report psittacosis cases to public health authorities.

Timely diagnosis and reporting can help identify the source of infection and control the spread of disease.

Animal and public health authorities may issue quarantine for all birds on premises where C. psittaci infection has been identified.

With the approval of state or local authorities, bird owners may: (1) treat birds in a separate quarantine area, (2) sell birds that have completed at least 7 days of treatment, provided the new owner agrees in writing to continue quarantine and treatment and is informed of the disease hazards, or (3) euthanize infected birds. After completion of treatment or removal of birds, quarantine can be lifted after infected premises are thoroughly cleaned and disinfected.

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