Why You Need To Know About Zoonotic Avian Infections

Neil Forbes, BVetMed DECZM FRCVS with eagle
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Zoonotic Avian Infections describes the process whereby an infectious disease is transmitted between species (sometimes by a vector) from animals other than humans


Zoonotic Avian Infections can include:


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.


Salmonellosis,  Humans may also be infected by exposure to Salmonella spp. shed from poultry or free-living birds, particularly birds roosting at garbage dumps


Campylobacteriosis, infection causes acute enteritis and severe abdominal cramps


Yersiniosis – bacterial infection of birds. Pigeons and doves are the most common avian reservoir.

Newcastle Disease

Humans working in close contact with birds such as poultry farmers, slaughterers, and veterinarians can become infected from stock or live vaccine.


Allergic alveolitis

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

Acute allergic alveolitis occurs 4 to 8 hours after large-scale exposure, resulting in coughing, dyspnea, and fever. Sub-acute disease occurs after years of moderate exposure and is characterised by a dry cough and progressive dyspnea.


West Nile virus

West Nile virus (WNV) has caused sporadic cases and outbreaks in humans and horses in Europe since the 1960s. First found in North America in 1999, WNV has spread across much of the the Americas since then.


West Nile virus is predominantly an infection of birds and mosquitoes. Virus circulates in the blood of birds, then when mosquitoes take a blood meal from an infected bird they take up the virus as well.

The mosquito then transmits the virus to the next bird from which it feeds.

Other infected species, such as horses or humans, are incidental victims.

West Nile virus is not transmitted from person-to-person, except accidentally after blood transfusion.


Avian influenza in birds

Avian influenza (AI) naturally circulates in wild waterfowl causing little or no symptoms, however AI may cause severe disease affecting the respiratory, digestive and/or nervous system in many other bird species.

Clinical signs may include depression, anorexia, ruffled feathers, diarrhea, ataxia, respiratory distress, and petechia.

Outbreaks associated with high bird mortality are called highly pathogenic avian influenza (HPAI).

Key words: Zoonoses, Chlamydophila, psittacosis, Salmonella, Campylobacter, yersiniosis, pseudotuberculosis, Newcastle disease, allergic alveolitis, West Nile, influenza, Cryptococcus, Mycobacterium.


Key Points


Individuals that work or live with birds may be at risk for zoonotic diseases.

Psittacosis in humans may range from asymptomatic infection to flu-like signs to severe disease including pneumonia.

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