US reports first severe bird flu case: How worried should humans be?

The United States has reported its first severe case of bird flu, marking a significant development in the ongoing outbreak of avian influenza. A 65-year-old resident of Louisiana is currently hospitalised in critical condition after exposure to an infected backyard flock.

This case has been linked to the H5N1 strain of bird flu and is the first severe human case reported in the country, according to the Centers for Disease Control and Prevention (CDC).

“CDC confirms first severe case of H5N1 Bird Flu in the US. While an investigation into the source of the infection is ongoing, it has been determined that the patient had exposure to sick and dead birds in backyard flocks,” stated the agency.

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Despite this alarming development, the CDC has reiterated that the overall risk to public health remains low.

How bird flu spreads to humans

Avian influenza primarily affects birds, but human infections, though rare, occur through direct contact with infected animals or contaminated surfaces, says the World Health Organisation (WHO).

The virus is shed through the saliva, mucus, and feces of birds, becoming airborne in environments like barns where litter and feathers are disturbed. Farm workers and those handling backyard flocks are at higher risk.

“The best way to protect yourself from bird flu is to avoid sources of exposure,” advises the CDC. This includes wearing personal protective equipment (PPE) such as goggles, gloves, and N95 masks when handling potentially infected animals.

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Bird flu’s adaptation to infect a broader range of mammals, including dairy cattle, has become a growing concern. Scientists have identified mutations that could enable the virus to bind more effectively to human respiratory systems.

A recent study published in Science warned that even a single genetic change could significantly enhance its ability to infect humans, although predicting when or if this might happen remains challenging.

Symptoms & diagnosis of bird flu in humans

Human cases of bird flu range from mild to severe, with symptoms that can vary widely. Common symptoms include:

• Eye redness (conjunctivitis)

• Fever

• Sore throat

• Shortness of breath

• Fatigue

• Muscle aches

In severe cases, symptoms progress to pneumonia, requiring hospitalisation. Notably, conjunctivitis has been a prominent symptom among farm workers, possibly due to the similarity between human eye tissues and bird respiratory systems in terms of viral receptor compatibility.

Detection of bird flu in humans requires laboratory testing, as symptoms alone are insufficient for diagnosis. Swabs from the upper respiratory tract or, in critical cases, lower respiratory specimens are tested to confirm infection.

Early diagnosis improves accuracy, although it may be difficult to detect the virus in recovered patients.

What preventive measures can you take

To mitigate the risk of infection, the CDC advises avoiding contact with sick or dead birds and contaminated surfaces. For those who must interact with potentially infected animals, the agency recommends comprehensive PPE, including gloves, goggles, coveralls, and N95 masks.

Raw milk poses additional risks, as the virus can survive in refrigerated milk for up to five days. Pasteurisation effectively eliminates the virus, but raw milk consumption remains a concern due to its association with other pathogens like E. coli and salmonella.

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Studies indicate that infected cats and calves have contracted bird flu after consuming contaminated milk, highlighting the risks of raw dairy products. Cats have been infected after drinking raw cow’s milk, reported CNN.

In kitchen practices, experts recommend cooking poultry and eggs to safe temperatures and avoiding cross-contamination. The US Food and Drug Administration (FDA) assures that safeguards prevent infected eggs from reaching consumers, but cooking remains a critical safety step.

Rising infections among livestock

Since March 2024, bird flu infections have surged among dairy cattle and poultry. This marks the first time the virus has been detected in dairy herds in the United States. To date, 61 human cases have been confirmed nationwide, with 37 linked to dairy cattle, including 33 cases in California.

California’s response to the outbreak has been swift. Governor Gavin Newsom declared a state of emergency, highlighting the importance of resource allocation and rapid action.

“This proclamation is a targeted action to ensure government agencies have the resources and flexibility they need to respond quickly to this outbreak,” Newsom stated. California, boasting the nation’s largest testing and monitoring system for avian influenza, has implemented aggressive containment measures.

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The outbreak has also prompted new federal regulations. The US Department of Agriculture (USDA) now mandates the testing of raw, unpasteurised milk for bird flu and requires dairy farms to report disease-related data.

The USDA’s Animal and Plant Health Inspection Service confirmed that pasteurisation is highly effective in eliminating the virus from milk and dairy products.

“While the risk to the public remains low, we will continue to take all necessary steps to prevent the spread of this virus,” Newsom assured.

A global pandemic in the making?

The spread of bird flu has significant implications for both public health and agriculture. Globally, the virus has led to the culling of millions of poultry to contain outbreaks. Since the US outbreak began in 2022, over 123 million birds have died or been culled due to the virus.

International and domestic agencies are intensifying surveillance efforts. The CDC’s monitoring program includes tracking mutations in avian flu strains to anticipate changes in transmissibility and virulence. The agency’s collaboration with state health departments ensures rapid identification and containment of new cases.

“The spread of bird flu viruses from one infected person to a close contact is very rare,” the CDC says, adding that ongoing vigilance is essential to prevent the virus from gaining the ability to spread more easily between humans.

With inputs from agencies