Does H5N1 pose a threat for humans?

Sub: Science and tech

Sec: Public Health

Context:

The highly pathogenic avian influenza (HPAI) H5N1 strain has been affecting cattle across several States in the U.S., and for the first time, three cases of human infection in dairy farm workers were also reported.

More on news:

The districts of Alappuzha, Kottayam and Pathanamthitta in Kerala, where water bodies, migratory birds, fowls and integrated farms form part of the ecosystem, have reported H5N1 outbreaks in 19 places since April.
The death of crows in large numbers in Alappuzha, and subsequent confirmation of the H5N1 virus in their carcasses have given rise to concerns that the virus could spread far and wide.
According to the WHO, between 2003 and April 1, 2024, close to 900 human infections of H5N1 have been reported from 23 countries, of which, more than half were fatal.
Even though the risk of human infections from H5N1 is still perceived to be low, this can change rapidly as the virus spreads to more animals, especially cows or domestic mice, which have closer contact with humans.
In districts like Alappuzha where waterfowls, chicken, dairy cows and humans share the same environment, the opportunities for human infections should be perceived as high.

What is the H5N1 virus?

Influenza A virus subtype H5N1 (A/H5N1) is a subtype of the influenza A virus, which causes influenza (flu), predominantly in birds.
It is enzootic (maintained in the population) in many bird populations, and also panzootic (affecting animals of many species over a wide area).
A/H5N1 virus can also infect mammals (including humans) that have been exposed to infected birds; in these cases, symptoms are frequently severe or fatal.
Ever since it emerged in 1996, H5N1 has resulted in the mass killing of billions of wild birds as well as fowls.
According to scientists, the virus lacks changes that would make it better adapted to transmit between people and therefore, the risk to human health remains low.
The potential for influenza viruses to rapidly evolve and the wide geographic spread of H5N1 signals that more human infections should be expected.

What is the level of risk to humans?

The virus seems to spread from birds/animals to humans who may be closely interacting with these, without adequate personal protection.

What are the symptoms of H5N1?

The common symptoms of H5N1 are similar to those of influenza-A illnesses, including respiratory difficulties, fever, cough, sore throat and pneumonia, all of which can potentially worsen, especially in those who are immunocompromised or have underlying conditions.
In the U.S, Conjunctivitis or pink eye was the only symptom that was reported in one of the farm workers who was infected.
As of now, in Kerala, as only the poultry has been found affected in all outbreaks, the strategy adopted for containment is the mass culling of birds within a certain radius of the reported infection.
The incident of the mass death of crows has now changed the equation, as it is possible that the infection may have been taken by the crows beyond the current surveillance zone.

What are the necessary precautions?

People should avoid unprotected exposure to infected birds or animals or their contaminated environments.
If at all one has been exposed to a possible H5N1-contaminated environment, they should monitor themselves for new respiratory illness symptoms, including conjunctivitis for 10 days and seek proper medical advice.
It would be better to ensure that people use only pasteurized milk and poultry meat and eggs should be well-cooked to prevent any possible food-borne transmission of H5N1.
Kerala has taken ‘One Health’ beyond the conceptual framework and the project is currently being implemented as part of the World Bank-aided ‘Rebuild Kerala’ project in four districts — Alappuzha, Pathanamthitta, Kottayam, and Idukki.

What is One Health Approach?

One Health is a concept that promotes collaboration across various sectors to address health, productivity, and conservation challenges, particularly relevant to India due to its diverse wildlife, large livestock populations, and dense human population.