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Corina Lupu, DVM
A zoonosis is a communicable disease from animals to man under natural conditions.
Many people work or live with birds daily, exposing themselves to numerous microorganisms and the potential of zoonotic disease. These diseases can be avoided by knowing their causes, clinical signs and modes of transmission.
The environmental, nutritional and host requirements of micro-organisms can be specific or broad.
The internal body environment of the avian host differs from that of the mammalian or human host thus not all micro-organisms can cross over from one to the other.
The effects of the same micro-organism can vary from bird to human, from one avian species to another, as well from one individual to another within the same species.
In order for cross transmission of an organism to occur certain conditions must exist:
-exposure to large numbers of organisms ,
-repeated exposure to the organisms,
-immune deficiency of the receptor host, and/or
-specific susceptibility to the organism.
· respiratory route:
inhalation of feather dust, or dried fecal material
· oral route
direct contact with fecal material
· Health exams
· Knowledge of medical history at point of purchase
· Recognition/awareness of disease and
· Relocation to a single bird home
The genus Chlamydia comprises 3 species: C. trachomatis and C. pneumoniae which are specific to humans and C. psittaci which affects most Psittaciformes, many non-Psittaciformes, many mammals and humans.
The disease caused by C. psittaci has been known as Psittacosis in Parrots and Ornithosis in all other animals and man.
Chlamydia must use the hosts cell for viability and in its replication cycle.
Chlamydiosis is highly contagious and may have different virulence in different species.
Transmission occurs via contaminated feather dust and feces.
Carrier birds: all but especially cockatiels.
Clinical signs in birds are variable ranging from mild rhinitis to diarrhea, dehydration and death.
Clinical signs in humans are flu-like: chills, severe headache, dry hacking cough, elevated temperature, general debilitation; if not treated may deteriorate into pneumonia and neurological signs and possibly death.
Diagnosis in humans as in birds requires culture or detection of Chlamydia antigen or measure of serum anti-chlamydial antibodies.
M. avium and intracellulare (MAI)
M. avium is the most frequent mycobacterial infection in birds.
Transmission of MAI in birds is via the fecal-oral route leading primarily to granulomatous lesions of the alimentary tract followed by generalised infection.
Clinical signs of MAI in birds are chronic wasting and diarrhea.
MAI can persist in the environment for months.
Humans are considered relatively resistant and infection usually occurs with lowered immune capacity, multiple exposure or exposure to large numbers of bacteria.
Transmission in humans via aerosolization usually results in pulmonary infections which can be difficult to treat.
M. tuberculosis is the most frequent mycobacterial infection in man.
Transmission of M. tuberculosis is via aerosolisation of bacteria from a coughing patient with pulmonary tuberculosis; infection leads primarily to a non specific pneumonitis in the lower and middle lungs of humans, followed by the formation of tubercles. The urinary tract is also a frequent site of infection.
Birds are considered relatively resistant and those affected are frequently pets of infected humans. They also can act as sentinels for detection of human disease.
M. tuberculosis in birds causes localised granulomas of the skin and other structures of the head: nares, around or behind the eye.
· Clinical signs and location of lesions
· Acid fast staining will confirm the presence of mycobacterium but will not identify the species
· Cultures will identify the species
· Several regimens are possible
· Euthanasia often recommended
Most vertebrates can be infected with one of the 2000 species of Salmonella.
Transmission is mainly via the oral route.
Salmonella can cause damage to an organism by the production of endotoxins or direct invasion and destruction of cells.
Clinical signs in birds include non-specific signs of lethargy, anorexia, diarrhea and polydypsia.
Avian strains of Salmonella are not a risk for healthy adults but can infect small children, geriatric individuals and those with suppressed immune systems.
Symptoms in humans include variable degrees of diarrhea, abdominal cramps and vomiting. If the bacteria spreads from the digestive tract to the bloodstream, they may settle in other organs such as liver, kidney, heart or in the joints and cause inflammation.
Most Salmonella infections are mild and do not require treatment. In more severe cases, treatment will include antibiotics and hydration.
This group of viruses affects poultry, swine, horses, free-ranging birds and humans.
Wild birds are thought to act as a natural reservoir of the influenza virus and as a vehicle of dissemination of this virus throughout the world.
The virus can pass from companion bird to a human but it is more likely that the passage occurs from human to bird.
Any bird demonstrating mild upper respiratory symptoms during flu season can be suspected of having the influenza.
Disease is spread through aerosol or direct contact with feces.
Although mammalian giardia can be zoonotic, the avian specie of this parasite ( Gpsittaci) is found to be non infective in humans.
C. neoformans causes central nervous system disease in parrots.
Symptoms include diarrhea and blindness, as well as paralysis, dyspnea, weight loss and anemia.
Frequently isolated from the droppings of pigeons but mode of transmission unknown.
Difficult to diagnose ante-mortem.
In humans, inhalation of dust from dried droppings can lead to respiratory illness, and potentially fatal meningitis.
Treatment of the avian patient is not recommended because of the serious zoonotic potential of the disease.
Newcastles Disease Virus - Paramyxovirus serotype -1
Principle disease for which quarantines were established.
Signs in birds can include mild to severe respiratory and gastro-intestinal signs, followed by neurological signs and death.
NDV can cause conjunctivitis and general malaise in humans.
Birds can be infected but there has been no report of birds acting as reservoirs or carriers nor of any documented case of transmission of the virus from birds to humans.
This is not a zoonotic disease but a serious allergic reaction of a susceptible human to heavy exposure to feather dust and dander.
Symptoms in humans: progressive asthma-like symptoms, dry cough eventually with bloody discharge, wheezing; can lead to death.
Affected human must permanently avoid contact with birds.
Corina Lupu, DVM
Corina Lupu graduated in Veterinary Medicine from the University of Montreal in 1977 and has specialized in treating birds and exotics since 1979. She has been a member of the Association of Avian Veterinarians (AAV) since 1981 and has held the position of Treasurer and chaired several committees in that organization. Dr. Lupu teaches continuing education seminars in companion avian medicine and wet labs to practising veterinarians at the University of Montreal, is a regular speaker at meetings of AAV and other veterinary organizations and bird clubs, and has appeared on radio and television.