FACT SHEET PS-23 Avian Diseases Transmissible to Humans1
Jacqueline P. Jacob, Jack M. Gaskin, Henry R. Wilson, and F. Ben Mather2
Introduction Chlamydiosis
Bird-keepers (pet bird owners and poultry producers)
Chlamydia psittaci, an unusual bacteria-like
should be aware that some avian diseases can be
organism, occurs worldwide and affects more than 100
transmitted to humans. It is important to note, however,
avian species. It causes a disease called psittacosis or
that such diseases are uncommon enough that they should
parrot fever when it occurs in psittacine birds (curve-
not discourage bird-keeping. For most people avian
beaked, like parrots, parakeets, etc.)and the disease is
diseases do not pose a serious threat, but bird-keepers
called ornithosis when diagnosed in all other birds or in
should be aware of them and seek medical assistance if
In the U.S., chlamydiosis is a major problem with
Zoonoses refer to infectious animal diseases that are
turkeys, pigeons, and psittacines. In Europe, the main
communicable to humans. The infectious agents can be
avian species affected are ducks and geese. Some birds
protozoal, fungal, bacterial, chlamydial or viral.
(turkeys) are extremely susceptible to chlamydiosis, while
Individual susceptibility and the seriousness of these
various microbial infections varies with age, health status,immune status (immunodeficient or immunosuppressed),
Chlamydiosis is primarily transmitted by inhalation of
and whether early therapeutic intervention is sought. The
contaminated fecal dust and is spread by carrier birds,
ability of a microorganism to make a person sick varies
which act as the main reservoirs for the disease. The
with the virulence of the organism, the dose to which the
organism is excreted in both the feces and nasal secretions.
person is exposed, as well as route of infection.
Shedding is sporadic and is usually induced by stress. Acarrier state can persist for years. The organism survives
Chlamydiosis, salmonellosis, arizonosis, and
drying, which facilitates oral spread and allows
colibacillosis are the most common of these infections.
transmission on contaminated clothing and equipment.
Chlamydiosis, salmonellosis, eastern equine encephalitis
Chlamydiosis can be transmitted bird to bird, feces to bird,
and avian tuberculosis may be serious and even life-
and bird to human. Human to human transmission can
occur, mainly by exposure to patient’s saliva.
This document is FACT SHEET PS-23, one of a series of the Dairy and Poultry Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First printed August 1997. Please visit the FAIRS Website at http://hammock.ifas.ufl.edu.
Jacqueline P. Jacob, poultry extension coordinator with Dairy/Poultry Sciences, Jack M. Gaskin, associate professor with Veterinary Medicine-Pathobiology,Henry R. Wilson, professor with Dairy/Poultry Sciences, and F. Ben Mather, poultry extension specialist with Dairy/Poultry Sciences, Cooperative ExtensionService, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.
The Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educationalinformation and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin. For information on obtaining other extension publications, contact your county Cooperative Extension Service office. Florida CooperativeExtension Service / Institute of Food and Agricultural Sciences / University of Florida / Christine Taylor Waddill, Dean
Chlamydiosis is an occupational hazard for persons
The incubation period is 6-72 hours, although 12-36
working with psittacines (parrots, parakeets, etc.) and
hours is most common. Salmonella are transmitted by
pigeons, or for people working in turkey slaughter plants
ingestion of food contaminated by fecal matter (fecal-oral
route). Excretion of the bacteria commonly varies from afew days to weeks. In some instances (e.g., S. typhi,
The incubation period for chlamydiosis is 4-15 days,
typhoid fever) infected persons can shed bacteria for life.
although 10 days is most common. In affected birds,
S. enteriditis in avian fecal material is able to penetrate
diarrhea, coughing, and ocular and nasal discharges are
eggshells, and may be present in uncooked eggs.
common signs. There may be a high mortality rate if thedisease is unrecognized or untreated. With turkeys there is
In most cases, treatment of salmonellosis simply
a drop in egg production. In humans, chlamydiosis
involves treatment of the symptoms with fluids and
manifests itself as a feverish respiratory disease. There is
electrolytes. Antibiotics such as chloramphenicol,
usually a sudden onset with chills, muscle and joint pains,
nitrofurans, or ampicillin are only indicated when the
headache, cough, loss of appetite, and chest pains.
bacteria has localized in areas of the body peripheral to the
Complications may result from an enlarged spleen,
inflammation of the heart muscle, and a reduced heart rate.
In Florida,salmonellosis is a reportable zoonotic
Affected birds must be treated with chlortetracycline
disease for both health and livestock officials. The
or other similar broad-spectrum antibiotics for up to 45
Department of Agriculture and Consumer Services must
days to clear the infection. Pigeons and turkeys may
be notified of any birds found to be infected with
require long- term flock therapy to eliminate carriers. Salmonella species. If a person is suspected of havingsalmonellosis, the county public health office must be
Affected humans are treated with tetracycline for at
least 21 days. Because this antibiotic may becomeirreversibly bound to certain minerals, the calcium content
Colibacillosis
of food needs to be kept low during treatment.
Colibacillosis is caused by Escherichia coli infection.
In Florida, chlamydiosis is a reportable zoonotic
E. coli is a bacteria which normally inhabits the intestinal
disease for both health and livestock officials. The
tract of all animals. There are a number of different
Department of Agriculture and Consumer Services must
strains, many species-specific. Not all strains are
be notified of any birds found to be infected with
pathogenic. In poultry, E. coli infections may cause
Chlamydia psittaci. If a person is suspected of having
septicemia, chronic respiratory disease, synovitis
ornithosis, the county public health office must be notified
(inflammation of the joints which can lead to lameness),
pericarditis (inflammation of the sac around the heart), andsalpingitis (inflammation of the oviduct). Humans with
Salmonellosis
colibacillosis usually manifest diarrhea which may becomplicated by other syndromes depending on the E. coli
There are approximately 200 different serotypes of
serotype. These complications may include fever,
Salmonella species. Most animals are susceptible to
dysentery, shock, and purpura (multiple small purplish
salmonella infection. This bacterial disease occurs most
hemorrhages in the skin and mucous membranes).
frequently in stressed individuals. Many infections aresubclinical. Common clinical symptoms in all species
The incubation period is 12 hours to 5 days, although
include diarrhea, vomiting, and a low-grade fever.
12-72 hours is most common. Transmission is via the
Infections can progress to dehydration, weakness, and
fecal-oral route. Colibacillosis is often food- or water-
sometimes, especially in the very young or very old, death.
In severe cases there can be a high fever, septicemia(blood poisoning), headaches, and an enlarged painfulspleen. Focal infections may occur in any organ, includingheart, kidney, joints, meninges (membranes whichsurround and protect the brain and spinal cord), and theperiosteum (fibrous membrane of connective tissue whichclosely surrounds all bones except at the joints).
In most cases, symptomatic treatment (fluids,
Most epidemics occur between late August and the
antidiarrheals) is all that is required. In more severe
first frost. Cases may occur year-round in areas like
infections, antibiotics such as tetracycline and
Florida which have a prolonged mosquito season.
EEE usually affects persons under 15 or over 50 years
In Florida, colibacillosis is not a reportable zoonotic
of age. In adults there is a sudden onset of high fever,
headache, vomiting, and lethargy, progressing rapidly toneck stiffness, convulsions, spasticity, delirium, tremors,
Arizona Infections (Arizonosis)
stupor and coma. In children, EEE is typically manifestedby fever, headaches and vomiting for 1-2 days. After an
Arizona infections are caused by the bacteria
apparent recovery, encephalitis (inflammation of the brain)
Salmonella arizona. S. arizona occurs worldwide. It
is characterized by quick onset and great severity follows.
occurs most frequently in reptiles and birds, but all
Retardation or other permanent neurologic consequences
animals are probably susceptible. The young are at
EEE is not a reportable zoonotic disease in Florida.
In most poultry species S. arizona infection results in
reduced egg production and hatchability. Poults and
Avian Tuberculosis
chicks show weakness, anorexia, and shivering. Outbreaks in turkeys, chickens, and canaries can have up
Avian tuberculosis is caused by the bacteria
to 60% mortality. In humans, diarrhea is most common.
Mycobacterium avium which is closely related to the
Many infections are subclinical. Septicemia can occur in
human and bovine tuberculosis bacteria. In birds, M.avium causes a chronic debilitating disease with tubercularnodules. In humans, M. avium infections can cause local
The incubation period is 6-72 hours, although 12-36
wound infections with swelling of regional lymph nodes.
hours is most common. Transmission is by the fecal-oral
The infection is most severe in immunocompromised
route. There is some transmission through eggs. Infected
individuals. M.avium is spread by ingestion of food or
birds can become long-term intestinal carriers. Numerous
water contaminated by feces from shedder birds.
antibiotics reduce case fatality, but do not clear intestines
Tuberculous poultry flocks should be depopulated.
of the carrier state. S. arizona is somewhat less hardythan most salmonella but can survive for months in soil,
While most Mycobacterium infections are treatable
with antibiotics, M. avium infection is the exception. M. avium is highly resistant to antibiotics. Surgical excision
Arizona infection is not a reportable zoonotic disease
and lymph node removal are often necessary to eliminate
Eastern Equine Encephalitis
In Florida, avian tuberculosis is a reportable zoonotic
disease for both health and livestock officials. The
Eastern equine encephalitis (EEE) is caused by a
Department of Agriculture and Consumer Services must
RNA virus in the genus Alphavirus, family Togaviridae.
be notified of any birds found to be infected with
Outbreaks can occur in commercially raised pheasants,
Mycobacterium avium. If a person is suspected of having
chickens, bobwhite quail, ducks, turkeys, and emus.
tuberculosis, the county public health office must be
Abdominal distress and dysentery are the most obvious
Histoplasmosis
EEE is mosquito-borne. The virus circulates in a
mosquito-bird cycle in which passerine birds (i.e., song
Certain fungi prefer to grow in soils enriched with
birds such as swallows, starlings, jays, and finches) are the
avian manures. Histoplasma capsulatum is one of these.
most common reservoir. The mosquitoes become infected
The fungus is also associated with construction sites and
and feed on birds, horses, and humans, further spreading
caves. Birds are not susceptible to infection, but
the infection. In pheasants, initial infection is mosquito-
histoplasmosis can affect humans, dogs, cats, cattle, sheep,
borne, but additional dissemination occurs by pecking and
The incubation period is 7-14 days. Most cases in
and spitting of blood from the respiratory tract, followed
humans are asymptomatic. Disease may be manifested in
by headache, stiff neck and visual disturbances.
three forms: acute pulmonary (most common), chroniccavitary pulmonary, and disseminated. The acute
As with histoplasmosis, this disease is avian-
pulmonary form is influenza-like and lasts up to several
associated, but not a zoonotic disease because the
weeks. It is characterized by chills, chest pain,
nonproductive cough, fever, and malaise. The chronicform occurs in people over 40 and resembles tuberculosis.
In Florida, cryptococcosis is not a reportable disease.
It is characterized by a productive cough, pus-like sputum(material expelled from the respiratory passages), weight
Cryptosporidiosis
loss, and shortness of breath. The disseminated formoccurs in the very young or the elderly. Lesions include
Cryptosporidiosis is caused by protozoa of the genus
enlarged spleen and liver, and mucosal ulceration. The
Cryptosporidium. There are three known species, C.
disseminated form of histoplasmosis can be fatal if not
baileyi, C. meleagridis and an unnamed species in quail.
treated. Amphotericin B has been used to treat
Cryptosporidiosis normally causes respiratory problems in
chickens and turkeys. It can also cause gastroenteritis anddiarrhea. In humans, it causes abdominal pain, nausea,
Transmission occurs by inhalation of spores produced
and watery diarrhea lasting 3-4 days. In
by growth of the mold. Histoplasmosis is not a
immunocompromised people, it can cause severe,
communicable disease. The reservoir is the soil,
persistent diarrhea with associated malabsorption of
especially when enriched with droppings from birds or
bats. Wet the area and wear a face mask or respiratorwhen working in suspect surroundings. Spraying the soil
The incubation period is 3-7 days, and it is spread via
with a formaldehyde solution has been used to kill the
the fecal-oral route by ingestion of infective oocysts.
In Florida, cryptosporidiosis is a reportable disease.
Although this disease is avian-associated, it is not a
If a person is suspected of having cryptosporidiosis, the
zoonotic disease, because the reservoir is soil and not the
county public health office must be notified within 48
birds. This is, however, of little consequence to the
Allergic Alveolitis
In Florida, histoplasmosis is a reportable disease. If a
person is suspected of having histoplasmosis, the county
Allergic alveolitis, also known as pigeon breeder’s
public health office must be notified within 48 hours.
lung, budgerigar dander pneumoconiosis, and a variety ofother complex names, is one of the most significant avian
Cryptococcosis
zoonotic diseases. It may occur as an acute, subacute, orchronic problem. Clinical signs are caused by reduced
Another fungus that prefers to grow in soils enriched
lung capacity due to a hypersensitivity reaction to feathers,
with avian manures is Cryptococcus neoformans. The
dander, or fecal dust. Inflammation of the pulmonary air
incubation period is probably weeks. Infections are seen
exchange units (alveoli) is the inciting lesion.
in many mammals, but occur most frequently in humans,horses, dogs, and cats. Infections are rare in birds.
The acute form of the disease is usually precipitated
by an overwhelming exposure in a previously sensitized
Transmission of cryptococcosis is usually by
individual, such as that which might occur in cleaning out
inhalation of this yeast-like fungus, although it can
a pigeon loft. Symptoms occur within a short time, and
occasionally occur by ingestion. Humans can pick up
include cough, difficult respiration, fever, and chills. If
cryptococcosis from exposure to old pigeon nests or
exposure ceases at this point, the symptoms resolve and no
droppings. In humans, cryptococcosis is manifested as
treatment is necessary. Chronic, low-grade exposure is
meningitis or meningoencephalitis, and it is usually
more serious, and symptoms may be mistakenly attributed
preceded by pulmonary infection with cough, blood-tinged
to a stubborn cold or flu. Affected individuals have a
sputum, fever, and malaise. The course of the disease is
chronic nonproductive cough, exercise intolerance, and
usually chronic. There is usually fever, cough, chest pain,
weight loss. Permanent lung lesions may develop,
including pulmonary fibrosis that reduces gaseousexchange and lung capacity.
Chronic allergic alveolitis can develop in as little as 2
years, but usually takes 10-20 years. Patients diagnosedwith the chronic form of the disease may have no choiceexcept to eliminate all exposure to birds. Exposure toeven minute quantities of feathers, dander, or feces mayprecipitate a recurrence of severe respiratory distress. Theseverity of the disease can be reduced by wearing facemasks while cleaning cages, cleaning cages daily, bathingpet birds frequently, and installing air purificationsystems. Conclusions
Bird-keepers should be aware that they can contract
certain illnesses from their birds. The frequency of diseasetransmission from birds to humans is low, but the veryyoung, the elderly, and those with compromised immunesystems should be cautious.
Many of these diseases are transmitted by ingestion of
food contaminated by fecal matter. Prevention of most ofthese diseases, therefore, simply involves proper hygieneand sanitation. Wearing a face mask to avoid inhalingbird dust is also recommended.
If you have persistent flu-like symptoms when no one
else you know is affected, see a doctor and mention thatyou raise birds. Such symptoms may be indicative of adisease spread from birds to humans.
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