This infection is one of the most common causes of death worldwide
Avian influenza refers to the disease caused by infection with avian (bird) influenza (flu) Type A viruses.
In December 2003, South Korea reported its first case of A/H5N1 bird flu. The outbreak caused serious economic losses in the poultry industry across the nation. Pictured are soldiers and national veterinary and quarantine service personnel on their way to bury hundreds of carcasses at a duck farm affected by the virus in Cheonan, southeast of Seoul.
These viruses naturally spread worldwide among wild aquatic birds like ducks and geese.
But they can also infect domestic poultry—chickens, for example—and other bird and animal species.
The bird flu virus A/H5N1 was first identified in 1959. Like other viruses, it has evolved over time, creating newer versions of itself.
Worryingly since 2020, the A/H5N1 virus has been spreading among more animal species—including dogs, cats, skunks, bears, and even seals and porpoises.
In April 2024, Texas announced the state's first case of bird flu in a human after a person became infected as a result of close contact with infected cows—the first known instance of a human catching bird flu from a mammal. Later in the year, there were three cases where humans contracted the virus but no interaction with a sick animal could be confirmed.
Sources: (Associated Press) (USA Today) (CDC) (National Center for Biotechnology Information) (WHO) (Health Policy Watch) (European Centre for Disease Prevention and Control) (Healthline)
See also: Diseases you can catch from animals that could be deadly
While the outbreaks of avian flu in the United States have raised concerns among the population, officials stress that the risk to public health remains low.
The bird flu virus currently drawing attention in the United States is Type A H5N1 (A/H5N1) a subtype of influenza A virus that primarily affects birds.
The first description of avian influenza, however, dates back to 1878 in northern Italy. Italian parasitologist Edoardo Perroncito (1847–1936) identified a contagious disease of poultry associated with high mortality. He termed it "fowl plague."
A/H5N1 was first isolated from a goose in China in 1996. In 1997, human infections with A/H5N1 viruses were reported during an outbreak in poultry in Hong Kong, according to the World Health Organization (WHO).
Since 2003, adds WHO, A/H5N1 has spread in bird populations from Asia to Europe and Africa, and to the Americas in 2021/22, and has become endemic in poultry populations in many countries. Pictured is a representation of the contamination of a hen by the A/H5N1 virus.
Bird flu viruses do not normally infect humans. However, sporadic human infections with bird flu viruses have occurred. In 2013 in Beijing, China, a number of people were infected with the A/H7N9 strain of bird flu, with several succumbing to the disease. Pictured is a seven-year-old girl with A/H7N9 receiving medical treatment in a hospital.
Indeed, contracting bird flu can be fatal. Since 2003, A/H5N1 strains have spread in an unprecedented manner in many Asian countries, and the outbreaks have resulted in numerous human deaths in Thailand, Vietnam, Cambodia, and Indonesia, according to data published by the National Center for Biotechnology Information.
The A/H5N1 virus arrived in Latin America in October 2022 through migratory birds and has spread throughout the continent. Avian influenza is affecting 53 species across Chile, including pelicans, seagulls, and Humboldt penguins, whose population has decreased by 10%. In 2023 alone, the National Fisheries and Aquaculture Service (SERNAPESCA) detected 8,140 deaths, almost double the total number of deaths in the last 14 years combined (4,392). Pictured is a group of pelicans and other seabirds on a beach in Lima, Peru.
In 2014, United States poultry and egg producers experienced an outbreak of another strain of the virus, type A/H5N2. This is currently the largest outbreak of bird flu in recorded history. Approximately 51 million birds were depopulated to control the spread of the disease. Dead migratory birds, including the endangered least tern (pictured), were examined for cause of death to determine if they were carriers. Today, according to the Associated Press, A/H5N2 has been detected in wild birds in every state, as well as commercial poultry operations and backyard flocks.
Back in the United States, the only symptom reported by the Texas farmworker during the current outbreak of A/H5N1 is pink eye, or conjunctivitis, according to the CDC.
But cases in humans can be far more severe. Symptoms can include fever, cough, sore throat, runny nose, body aches, headaches, fatigue, and shortness of breath or difficulty breathing. In extreme cases, it can prompt a bout of pneumonia.
Bird flu primarily spreads through contact with infected birds. Poultry farmers are especially vulnerable.
Most cases in humans have occurred after a person has unprotected exposure to sick or dead infected animals.
Handling an infected bird is believed to have been the source of the only other cases of bird flu recorded in a human in America. In 2022, a prison inmate caught the disease while taking part in a work program on a farm in Colorado.
Actually, human-to-human transmission of bird flu is extremely rare. It has never been shown to be easily transmissible between people.
Measures to prevent the spread of avian influenza include avoiding touching your mouth, nose, or eyes after contact with birds or surfaces that may be contaminated with saliva, mucous, or feces from wild or domestic birds.
If you keep backyard poultry, bear in mind that they can become infected by mixing with wild birds. Your birds' food, water, housing, or equipment can be contaminated by direct or indirect contact.
In 2006, a dead cat in Germany tested positive for the A/H5N1 type of bird flu—the first known case in Europe, according to the European Centre for Disease Prevention and Control. Pictured is a doctor inspecting a chicken in an isolation ward at the IZSVe Tri-Veneto Region Experimental Animal Health Care Institute in Padova, Italy, in the wake of the discovery.
Click through to learn more about the ongoing bird flu outbreak and its potential implications.
RFK Jr.’s bold bird flu plan: a game changer, or a risk?
The future of poultry farms is at stake
HEALTH Disease
Health and Human Services Secretary Robert F. Kennedy Jr. has suggested allowing the H5N1 bird flu virus to spread through poultry flocks to identify naturally immune birds, rather than culling or vaccinating. But many scientists warn this approach could be disastrous, increasing the risk of the virus mutating and potentially jumping to humans. The USDA is considering poultry vaccination, but Kennedy opposes it, fearing vaccinated birds could become "mutant factories" for the virus.
Click through to learn more about the ongoing bird flu outbreak and its potential implications.