Bird flu outbreak in Maharashtra: How it infects humans and why experts are on alert

How does bird flu infect humans?

“Bird flu can infect humans through close contact with infected poultry, contaminated surfaces or during culling operations. People handling infected birds are at higher risk, which is why surveillance and early treatment are critical,” says Dr Vinay Sonewane.

Human infection generally occurs through direct contact with infected birds, their saliva, droppings, feathers, or contaminated environment such as poultry farms and live bird markets. The virus may enter the body through the eyes, nose or mouth, or through inhalation of contaminated droplets and dust particles.

Unlike seasonal influenza, bird flu viruses do not spread easily between humans. This limited human-to-human transmission has so far prevented large outbreaks among people.

Those at highest risk include poultry workers, veterinarians, transporters, and workers involved in culling infected birds.

What happens when humans are infected?

As Dr Sonewane says, “Once inside the body, the virus mainly attacks the respiratory system. Initial symptoms may resemble common flu, including fever, cough, sore throat, muscle pain, fatigue and breathing difficulty.”

However, doctors warn that the infection can worsen rapidly. Severe bird flu cases may lead to pneumonia, where the lungs become inflamed and filled with fluid, severely affecting oxygen supply. Some patients may develop acute respiratory distress syndrome (ARDS), a life-threatening condition requiring ventilator support and intensive care.

Experts also warn of an excessive immune reaction known as a “cytokine storm”, where the body’s immune system begins damaging healthy tissues and organs while trying to fight the infection.
In rare cases, bird flu may affect multiple organs, leading to kidney failure, liver dysfunction, or neurological complications.

What about treatment?

Treatment involves antiviral drugs such as oseltamivir (Tamiflu®), zanamivir (Relenza®), or peramivir (Rapivab®) to reduce severity and mortality. The effectiveness is highest when treatment begins within 48 hours of symptom onset.

Why are scientists concerned despite limited human cases?

The biggest concern among scientists is the virus’s ability to mutate. At present, strains such as H5N1 do not spread efficiently between humans. But influenza viruses are known to evolve rapidly. If the virus acquires mutations that enable sustained human-to-human transmission, experts warn it could potentially trigger a pandemic. This risk is particularly significant in areas with dense poultry farming and frequent human-animal interaction.

Farmers have repeatedly sought permission to vaccinate chicks against avian influenza but it is not currently allowed in India, even though it is used in some other countries. Arief Balesaria (63), owner of the farm and president of the Navapur Poultry Association, says the “vaccination is permitted for the low-pathogenic H9N2 avian influenza, which costs around Rs 3.50 per dose and requires two doses, first at 14 days and the second about six weeks later. If an effective vaccine for H5N1 were available, lakhs of birds would not have to be culled.”

However, as per a 2025 Government of India statement, vaccines are currently permitted only for low-pathogenic strains like H9N2 avian influenza, while vaccination against highly pathogenic avian influenza remains under consideration. Officials have noted that existing vaccines do not provide complete immunity and may complicate disease detection and surveillance, and further scientific evaluation is under way before any policy decision is taken.

What precautions should people take?

Health experts advise people to avoid direct contact with sick or dead birds and maintain hygiene while handling poultry products.

Poultry meat and eggs should be cooked thoroughly, as proper cooking destroys the virus.

Dr Sonewane urged people to follow precautions similar to those adopted during the Covid-19 pandemic. “People should wear masks, use sanitisers, avoid crowded places if they develop flu-like symptoms, and avoid contact with infected poultry,” he says. Workers involved in poultry farming and culling operations are advised to use protective equipment such as gloves, masks and PPE kits to minimise exposure.