Anyone who keeps birds, whether as pets or as production animals, should be aware that certain avian diseases are zoonotic, that is, they can be transmitted to humans. People rarely catch avian diseases and should not be discouraged from keeping birds because avian diseases do not pose a serious threat to most people. Bird owners should be aware of zoonotic diseases, however, and should certainly seek medical assistance if they suspect they may have contracted a disease from a bird.
Diseases that infect both animals and humans are called zoonoses. The infectious agents can be bacterial, fungal, protozoal, or viral. The seriousness of the disease in humans varies with human hosts age, overall health, and immune status (immunodeficient or immunosuppressed people experience more severe disease). The severity of the disease in humans is also affected by the virulence of the organism, the infective dose, and the route of infection. The effect of these diseases on the commercial poultry industry in Florida is minimal, but because there are many small flock owners within the state, these owners should be aware of these zoonoses.
Chlamydiosis, salmonellosis, avian influenza, eastern equine encephalitis (EEE), and avian tuberculosis infections may be serious or life-threatening.
In addition to being direct disease carriers, nuisance birds are often linked to more than 50 different types of ectoparasites, which can enter buildings and sting people. Approximately two thirds of these pests may be harmful to domestic animals’ and people’s overall health and well-being. The rest are considered nuisance or incidental pests.
Avian Influenza (Bird Flu)
Avian Influenza (AI) receives a lot of attention in the media because of its virulence in birds. The main strain of concern in humans continues to be Highly Pathogenic Avian Influenza (HPAI) H5N1. More than 700 infections have been reported to the World Health Organization (WHO) since November 2003 (http://www.cdc.gov/flu/avianflu/h5n1-people.htm). These infections have occurred in Asia, Africa, the Pacific, Europe, and the Near East. The first reported case of human infection with HPAI H5N1 in the Americas was in 2014 and occurred in a traveler who had recently returned from China. There have been no reported cases that originated in the United States. In cases where evidence is present, humans who have contracted avian influenza have been in areas where there is constant close contact between birds and humans or in cases where the humans were exposed to infected bird secretions. It is important to note that poultry that originate from areas of the world where the virus is common are not allowed to enter the United States legally. All commercial poultry that enter Florida from other states are required to have an entry permit and come from influenza-free flocks.
It is thought that H5N1 incubation lasts between three and seven days in humans, after which viral pneumonia manifests itself quickly. Fever, sore throat, aches in the muscles, cough, chest pain, lethargy, vomiting, and diarrhea are some other common flu-like symptoms. The death rate among humans infected with this virus is over 20%4040; nonetheless, the disease is exceedingly uncommon in humans, and this strain is not found in the United States.
More than 100 bird species are impacted by the bacterial organism Chlamydophila psittaci, which is present throughout the world. When it affects psittacine birdsa term for birds that resemble parrotsthe illness is also known as parrot fever. It is referred to as ornithosis in other birds.
The main way that chlamydiosis is spread is through the inhalation of contaminated fecal dust, which is carried by carrier birds who serve as the disease’s main reservoir. Both nasal secretions and feces contain the organism. The carrier state can persist for years. C. Because psittaci can withstand drying, contaminated clothing and equipment can spread the infection. Additionally, it can spread from one bird to another, from feces to birds, and from birds to people. Additionally, human-to-human transmission is possible, mostly through contact with infected saliva. Infection in humans is extremely rare and is often misdiagnosed.
Treatment for C. Tetracycline or microlides are typically used to treat psittaci in both humans and birds, though the duration of treatment may vary. Tetracycline is not recommended for children or pregnant women. Chlamydiosis is a zoonotic disease that health and livestock officials in Florida are required to report. This implies that the Florida Department of Agriculture and Consumer Services must be notified if a case of the disease is confirmed.
Additional information about the disease can be found at: http://www.cdc.gov/pneumonia/atypical/psittacosis.html
More than 2500 distinct Salmonella serotypes have been identified to date. Animals such as birds, reptiles, mammals, and amphibians are known to harbor Salmonella bacteria, which are found in the environment and usually reside in the gastrointestinal tract. Salmonella bacteria are ubiquitous, but disease is uncommon because most strains do not pose a threat. Infections in humans are mostly caused by fewer than 15 serotypes. All species share common clinical symptoms such as vomiting, diarrhea, and a low-grade fever. Other symptoms include dehydration, weakness, septicemia, and headaches. Although most cases of salmonellosis have an incubation period of 12 to 36 hours, the incubation period can vary from 6 to 72 hours. Salmonella bacteria are usually spread by the fecal-oral route, which involves eating undercooked food tainted with excrement.
The majority of salmonellosis cases are mild, meaning that no medication or antibiotics are necessary. Infections typically go away in a few days with rest and lots of water. Antibiotics may be used in situations where a human has been infected with a pathogenic strain of Salmonella that is causing a clinical illness. Some strains of Salmonella have developed resistance to some antibiotics.
Additional information on Salmonella and serotypes of the organism can be found at http://www.cdc.gov/salmonella/ and http://www.cdc.gov/salmonella/reportspubs/salmonella-atlas/serotyping-importance.html
Colibacillosis is caused by an Escherichia coli infection. Like Salmonella, E. Animal skin and the digestive tract both contain coli, which is a common component of the bacterial flora. E. coli strains vary considerably in their ability to cause disease. Many strains are not pathogenic, but some can cause disease. Consuming food tainted with a virulent strain of bacteria can cause serious illness. In poultry, most E. coli infections are a result of complications and the E. coli are considered opportunistic agents. In poultry, E. Septicemia, salpingitis, pericarditis, synovitis, and infectious cellulitis are among the conditions that can be brought on by coli. Humans with E. coli infection usually present with diarrhea and a possible fever. Complications for less common types of E. coli infection include dysentery, shock, and purpura (purple rash).
The majority of cases will manifest within 12 to 72 hours, but the incubation period spans 12 hours to 5 days. Treatment of most cases of E. coli involves treating the diarrhea and dehydration that can occur. Hospitalization and the use of antibiotics or other medications may be necessary in more serious cases. Antibiotic resistance is a major problem when treating E. coli infections.
Additional information about colibacillosis in poultry can be found at: http://www.merckvetmanual.com/mvm/poultry/colibacillosis/overview_of_colibacillosis_in_poultry.html
Viruses that cause encephalitis, such as Eastern Equine Encephalitis, St. Florida’s wild bird populations are susceptible to West Nile or Louis Encephalitis. Passerine birds, or songbirds like swallows, starlings, jays, and finches, are the most common reservoirs for these viruses, which are spread by mosquitoes. Mosquitoes that have previously fed on the blood of an infected animal are the means by which they spread to humans and other animals. These viruses cannot spread from one person to another or through eating eggs or chicken meat.
An encephalitis-carrying mosquito may bite a lot of people each year, but not everyone who gets bitten will get sick. These viruses usually only cause clinical illness in susceptible individuals, which is usually limited to adults over 50 and children under the age of 15. The majority of encephalitis virus epidemics happen between late August and the first frost of the season, though cases can happen at any time of year in places where the mosquito season lasts all year. Encephalitis viruses can cause a high fever, headache, vomiting, lethargy, stiff neck joints, convulsions, tremors, and even a coma.
Adult chickens are used by the Florida Department of Health and numerous other mosquito-control districts throughout the state to keep an eye out for these viruses. The coops in which these “sentinel chickens” reside are strikingly similar to those utilized by proprietors of backyard flocks. The chickens that are bitten by a mosquito that carries the virus do not get sick, but they do develop antibodies against it. Health authorities can assess the importance of a virus in a region by periodically testing for the presence of antibodies. The Florida Department of Agriculture and Consumer Services is responsible for receiving reports of animal diseases resulting from any of the encephalitis viruses.
Additional information about encephalitis viruses can be found at: Eastern Equine Encephalitis: http://www.cdc.gov/EasternEquineEncephalitis/, St. Louis Encephalitis: http://www.cdc.gov/sle/, and West Nile Virus: http://www.cdc.gov/westnile/
Avian tuberculosis is caused by the bacterium Mycobacterium avium. The bacteria that cause tuberculosis in humans and cattle are closely related to this particular bacterium. In bird species, M. avium causes a chronic debilitating disease with tubercular nodes. In humans, infection with M. Usually, avium will result in localized wound infections that enlarge the lymph nodes nearby. This bacterium is very uncommon to infect, and those with compromised immune systems are most at risk.
Human infection results from consuming food or water tainted with disease-carrying birds’ excrement, also known as “shedders'” droppings. Antibiotics can be used to treat most Mycobacterium infections; however, Mycobacterium avium is an exception due to its high level of antibiotic resistance. To completely eradicate the infection, infected lymph nodes must frequently be surgically removed. There is currently no cure for this disease, thus flocks of poultry affected must be put to death. Fortunately, M. Today’s commercial poultry industry does not use avium, however in small flocks where birds are kept for several years, there are occasional instances of the disease.
Additional information about avian tuberculosis in humans can be found at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1830337/
Newcastle Disease: A paramyxovirus is the cause of this deadly respiratory illness in chickens. The disease is extremely contagious in poultry, and its highly pathogenic formknown as velogeniccan wipe out entire flocks of both wild and domesticated birds. Although it is common in many other countries, the velogenic form is not found in the US poultry industry. This paramyxovirus can infect humans as well, but the way the disease manifests in people differs greatly from that in poultry. After first exposure, the paramyxovirus in humans causes conjunctivitis, a mild, localized infection of the eye. The conjunctivitis usually goes away entirely on its own without any treatment in five to ten days. Common symptoms include a “bloodshot” appearance in the eyes and mild discomfort due to the localized swelling. Because this paramyxovirus causes such mild conjunctivitis, those who are infected might not even be aware that they have the illness. To ease any pain and inflammation, topical eye drops and ointments are available.
People are most at risk of contracting this disease when
- administering live-virus vaccines to birds,
- performing post-mortem examinations on actively infected birds, and
- concentrating and isolating the virus in a lab for research
Additional information about Newcastle Disease can be found at: http://www.inspection.gc.ca/animals/terrestrial-animals/diseases/reportable/nd/fact-sheet/eng/1330202454619/1330202602677
Cryptosporidiosis is caused by a protozoan of the genus Cryptosporidium. The disease may cause respiratory illness in poultry, such as chickens and turkeys, but it can also cause gastroenteritis and diarrhea. In humans, symptoms of cryptosporidiosis include nausea, diarrhea, and abdominal pain that usually lasts three to four days. Immunocompromised people may experience severe, ongoing diarrhea from the illness, which can lead to weight loss and nutrient malabsorption.
When protozoal oocysts are consumed, the disease is transmitted, usually through the fecal-oral route. There is a three to seven day incubation period. Since Cryptosporidium is unrelated to other protozoal species that cause coccidiosis, anticoccidial medications do not work against it.
Additional information about Cryptosporidium can be found at: https://www.merckvetmanual.com/poultry/cryptosporidiosis/cryptosporidiosis-in-poultry
It is important for people who own poultry or other birds to understand that certain bird diseases can spread to people. People who keep birds, especially those with compromised immune systems or those whose immune systems are compromised due to illness or aging, should exercise common sense when handling or managing birds even though the likelihood of contracting an avian disease is low. The following actions will lessen the likelihood of catching a disease from birds:
- Practice biosecurity for your flock. Additional information on biosecurity can be found at: http://healthybirds. aphis. usda. gov/ .
- Make sure to have your birds examined by a veterinarian if you think one of them is sick.
- Avoid coming into contact with bird fluids or excrement unless you are wearing the appropriate protective gear.
- After handling any bird, properly wash your hands with soap and water. Use hand sanitizer or alcohol-based wipes in the absence of soap and water. Children should not be allowed to pet or kiss poultry, including young chicks.
Also Available in: Español
Release Date:October 5, 2015
Reviewed At:January 4, 2022
- Critical Issue: Agricultural and Food Systems
One of the Department of Animal Sciences’ UF/IFAS Extension series’ documents is PS23. Original publication date August 1997. Revised August 2015. Visit the EDIS website at https://edis. ifas. ufl. edu for the currently supported version of this publication.
Michael A. Davis, director, UF/IFAS Extension Baker County; Gary D. Butcher, professor at the College of Veterinary Medicine and expert in avian diseases Extension; and F Ben Mather, UF/IFAS Extension, Gainesville, FL 32611; associate professor emeritus; poultry Extension specialist, Department of Animal Sciences
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