A CDC report highlights that Avian Influenza A can affect the gastrointestinal tract of humans, causing symptoms like diarrhoea and vomiting.
The study, amid global H5N1 outbreaks, found no direct link to consuming raw milk but noted potential GI infections from seasonal and novel influenza viruses.
The CDC advised proper cooking to prevent illness.
Avian Influenza A affects gastrointestinal (GI) tract of mammals including humans, showed a new report from Centers for Disease Control and Prevention (CDC), United States.
The report published is in the context of widespread Highly Pathogenic Avian Influenza (HPAI) outbreaks witnessed in dairy and poultry farms across United States and other parts of the world.
Between January 1 and August 4, 2025, 26 human infections with avian influenza A (H5N1) viruses (H5 bird flu) have been detected globally, of which 23 were identified in seven countries outside of the US, including 11 infections that resulted in death, the CDC noted.
H5N1 infections have also been found among domestic and wild animals in captivity.
The study aimed to address a crucial question regarding the possible health risks to individuals from consuming food or drinks infected with avian influenza A (H5N1) viruses, including contaminated raw (unpasteurised) milk, according to CDC.
“While no human infections with A (H5N1) virus have been attributed to consumption of raw cow's milk or products made from raw cow milk, the research summarised in this report shows that some seasonal and novel influenza A viruses may have potential to cause infection of the GI tract,” CDC said.
The researchers conducted a review of medical literature to conclude that theoretically seasonal and novel influenza A viruses can cause infection through the gastrointestinal tract.
Besides cats, dogs and ferrets, the study observed that humans can also experience gastrointestinal symptoms during viral infections, as seen during the recent COVID-19 pandemic when patients reported diarrhea and vomiting among other symptoms.
Among humans, bird flu symptoms such as fever, headache, cough, sore throat, conjunctivitis and difficulty breathing are commonly known. The virus of subtypes A (H1) and A (H3) virus are also known to impact humans.
“A comprehensive meta-analysis described the prevalence of IAV-associated GI symptoms between 24.2 per cent and 30.9 per cent; by viral subtype, GI symptoms were less frequent during cases of A(H3N2) (24.2 per cent), and more frequent during cases of A(H1N1)pdm09 (30.9 per cent). Taken together, these data support that GI symptoms occur in a substantial proportion of seasonal influenza Avian viruses (IAV) cases,” the report read.
The scientists studied reports on how infections reflected health symptoms of animals such as dogs, cats and other animals after consuming A (H5N1) infected products such as raw milk or meat.
Among humans, it found faeces samples containing seasonal and novel influenza A causing gastrointestinal symptoms. “Additional studies found different influenza A virus subtypes are able to multiply within human GI tissues in laboratory settings, suggesting influenza A virus infection in the human GI tract may be possible,” the CDC observed.
In April earlier this year, a two-year-old girl from Andhra Pradesh state of southern India died after consuming raw chicken.
The CDC has warned that consuming uncooked or undercooked meat or poultry, drinking raw milk, including products made such as soft cheese, ice cream and yogurt, can be contaminated with germs that can cause serious illness, hospitalisation or death.
“Cooking poultry, eggs, and beef to the appropriate internal temperature kills bacteria and viruses, including avian influenza A viruses,” it said.