Avian H5N1 (Bird) Flu, the next pandemic?

By Zainah Kabami

Just as the world is emerging from the unprecedented COVID-19 pandemic, another fast-mutating virus is currently causing the largest bird flu outbreak reported in history.

Since October 2021, it has killed over 15 million domestic birds, led to the culling of an unprecedented 193 million more and made its way to every continent except Australia and Antarctica.

This rampant virus has long been known to only cause outbreaks among poultry but is now increasingly infecting more and more migratory birds, spreading to new species and regions, which scientists worry raises the likelihood of a pandemic.

The purpose of this article is not to instil fear, but to educate —the more people are aware of public health issues, the better our chance at containing the next potential pandemic.

H5N1 bird flu viruses first emerged on a goose farm in China in 1996 and the first human cases appeared in Hong Kong in 1997, where transmission from animals to humans led to 18 infections and 6 fatalities. Since then, 868 laboratory confirmed human cases and 457 deaths have been reported to the World Health Organization (WHO), primarily from 21 countries in Africa, Asia, the Pacific, Europe, North America, and the Middle East.

In Uganda, we reported what would be the first ever, and so far only known outbreak of bird flu in the country in January 2017. The outbreak ended with an estimated death toll of over 1,200 white-winged terns along the shores of Lake Victoria in Wakiso and Masaka districts. No human cases were reported in that outbreak but it had a devastating impact on the economy as Kenya and Rwanda banned poultry products from Uganda.

Researchers have highlighted key events (new strains, infecting new species, and spreading to new regions) that need to occur to mark the progression of H5N1 toward becoming a pandemic, and all these have already occurred more rapidly than expected.

For instance, the current strain of the virus was first reported in the United States in January 2022 and since then reported outbreaks have led to the loss of over 58 million birds across 47 states; seven human cases of this clade linked to poultry exposure have been reported in US, England, Spain, and Ecuador. So far, human-to-human transmission has not occurred but three of the seven cases experienced severe disease and one died.

With every human infection, the virus is given an opportunity to mutate and may hit the perfect combination of genetic modifications required to unlock respiratory transmission, the very key to this becoming a pandemic virus. More alarming, it has been identified in species for the first time, like large scavengers, vultures, otters, and foxes.

Although the WHO has assessed the current risk to humans as “low”, this does not rule out the possibility of a pandemic. Based on 20^th century flu pandemics and increased globalization, epidemiological models suggest that if not well managed within three months of emerging, a flu pandemic virus has the potential to reach every continent and within 6–9 months, it could reach every country.

Worldwide, at least 12 companies and 17 governments are developing potential influenza vaccines in 28 different clinical trials that, if successful, could turn a deadly pandemic infection into a non-deadly one. However, if the COVID-19 pandemic taught us anything, it’s that vaccines and therapeutics take time to develop and even then, Uganda like other developing countries, will probably be last in line for any vaccine that would have been made.

The author is a Field Epidemiology Fellow with the Uganda Public Health Fellowship Program, Ministry of Health, Hosted at the National Public Health Emergency Operations Center