Disease experts suspect that highly pathogenic avian influenza (HPAI, or bird flu) is circulating among wild birds in Texas as waterbirds and waterfowl visit their wintering grounds. Widespread detections have occurred across Texas with recent findings in Wharton, Galveston, El Paso, Potter and Harris counties. The virus can sicken and even kill certain bird species. The current strain (H5N1) is known to cause heavy losses to poultry.
With the bird flu spreading among wild bird populations in the Lone Star State, Texans may be wondering how to protect themselves and the animals they love.
Currently, the transmission risk of avian influenza from infected birds to people remains low. But, if you're wondering about how our state's birds are faring against the disease, Texas Parks and Wildlife Department veterinarians Dr. Sara Wyckoff and Dr. Hunter Reed have your answers.
When was the bird flu outbreak first detected in the U.S.?
This current strain of highly pathogenic avian influenza (HPAI) H5N1 was introduced into the United States in 2021. Before this, the last HPAI outbreak in the United States was in 2015 when the H5N2 strain was detected in poultry. H5N1 was first detected in Texas in 2022 in a great horned owl found in Wichita County.
Do we know how the outbreak spread to Texas?
While the direct route is unknown, it is believed to have entered Texas via waterfowl migration through the Central or Mississippi flyway.
How does bird flu spread?
HPAI in birds is spread through respiratory droplets/secretions, feces and infected carcasses. However, some birds can be asymptomatic, meaning they do not show any symptoms or signs of illness. The disease can also spread through other species. In 2024, dairy cattle became infected by HPAI, and they are able to also shed the virus in milk, which had not been detected in mammals previously. The disease can also persist in an environment (bedding, soil, etc.) for a long period of time, especially in colder temperatures.
Which wild bird species have already been affected?
Sadly, the list is too long with more than 100 species with HPAI detections and over 10,000 wild bird detections in the U.S. since January 2022. Waterfowl likely represent the largest chunk of these species detections.
What wild bird species are most at risk?
The main susceptible species are shorebirds, waterfowl, raptors and scavengers. Specific species of greatest risk include gulls, shore/wading birds, ducks, geese, hawks, eagles and vultures. For raptors and scavengers, consumption of infected carcasses seems to be the major source of infection. Waterfowl travel vast distances and are the traditional host species of bird flu viruses, while shorebirds are in close proximity with waterfowl species. Scientists have detected isolated incidents of the disease in landfowl like turkey and pheasant, but these species have not suffered nearly the same morbidity.
What other species are at risk?
Something that has made this current strain of HPAI (H5N1) so concerning is its capacity to infect many species of wild mammals including coyotes, skunks, raccoons and foxes. It has been detected in marine mammals such as dolphins, has caused the death of tens of thousands of sea lions in South America, and has even infected dairy cattle for the first time. This indicates that HPAI is continuing to adapt and mutate in ways that allow it to infect new species, which is why H5N1 is a big concern for human health. Currently, the risk of human transmission from wildlife is low, and there has been no human-to-human transmission of H5N1. But the more species this strain can infect, the more opportunities it has to adapt into something much more virulent or deadly.
Could HPAI lead to species endangerment or extinction?
HPAI could have an impact on threatened and endangered species. After an HPAI outbreak among California condors in 2023, there was significant mortality. Ultimately, many of the birds were vaccinated and no new outbreak in condors has been detected since. Bald eagle nesting numbers have also been down since the introduction of H5N1 to the U.S.
The potential threat to birds is of great concern to birders and other outdoors people across the state. How can the public help?
The most important step for the general public is to NOT handle any sick or dead wildlife or to consume any wild carcasses, and to contact their local biologist with concerns. This reduces the risk of human transmission and the spread of HPAI in the environment. The public should also limit all unnecessary contact with wild birds, including not feeding or causing waterfowl to congregate in parks. While passerines are considered low risk species for HPAI, we recommend that bird feeders and bird baths be taken down or cleaned and disinfected on a regular basis because these allow birds to congregate and spread disease easily to each other. Additionally, game bird hunters should consider precautions such as disposing carcasses properly; wearing gloves when processing; avoiding consumption or processing of any sick bird; cleaning and disinfecting tools between carcasses; and cooking meat to proper temperatures.
What role is TPWD playing in managing the outbreaks?
Local biologists receive reports — almost constantly, at this point — that are funneled through our agency's five wildlife health specialists. Those wildlife health specialists work with us, the veterinarians, to investigate and get more information about the case. Then the veterinarians give a recommendation regarding testing, differential diagnoses and other methods of response to suspected HPAI outbreaks.
How does HPAI compare relative to other diseases out there?
This is one of the most significant wildlife diseases we have on our radar right now. We deal with a lot of wildlife health events, from epizootic hemorrhagic disease in deer or trichomoniasis in doves. But those diseases have boom/bust cycles and don't tend to linger in a population for too long. With HPAI, we get these higher morbidity and mortality events — but typically resistance grows over time. The main concerns are the disease's effect on commercial poultry because of the direct impact on consumers and human health implications.
What other agencies/groups are involved and what's being done?
The Texas Parks and Wildlife Department, Texas Animal Health Commission, Department of State Health Services and Texas A&M Veterinary Medical Diagnostic Laboratory have formed a One Health Consortium along with our state's USDA representatives. HPAI is considered a One Health issue, which means it encompasses not only wildlife health but also human public health and agricultural/food health. HPAI is a zoonotic disease, meaning it can infect humans and cause mild to severe illness, including death. TPWD communicates with DSHS for any human exposure or concern for human exposure to HPAI. HPAI causes severe illness in domestic poultry but mild illness in cattle, including a decrease in milk production. Both of these manifestations affect food safety and health, so collaboration and sharing of information among agencies is extremely important.