Record Bird Flu Cases Spark Alarm As US Reports Severe Human Infection

A record number of bird flu cases have been reported in 2023, impacting humans, cattle, and birds in what experts describe as an "astounding" wave of infections.

This week, the United States confirmed its first severe human case of H5N1. Shortly after, California declared a state of emergency to address the virus.

The Centers for Disease Control and Prevention (CDC) maintains that the virus poses a "low" threat to the general public and states there is no evidence of person-to-person transmission.

However, infectious disease experts warn that the unprecedented scale of cases raises the risk of mutations, potentially enabling human-to-human spread. Dr. Marc Johnson, a virologist at the University of Missouri, cautioned on X: "This virus might not go pandemic, but it is really trying hard, and it sure is getting a lot of opportunities."

Since January 2022, over 12,000 wild and domestic bird flocks in the US have been infected. This year, the virus spread to cattle, affecting 866 herds across 16 states, with most cases reported in California and Colorado.

Human cases have risen sharply, with 61 infections across nine states reported this year — the highest tally in at least two decades. Before this outbreak, the last human case of bird flu in the US occurred in 1997.

Most patients had direct contact with infected birds or cattle and experienced mild symptoms, such as conjunctivitis. Yet, infections in individuals without such exposure have begun to emerge.

In September, a Missouri resident became the first to contract the virus without direct contact with infected animals, though the source of their infection remains unclear. Similar cases followed, including a teenager in California and a patient in Louisiana. Both suffered severe illness, with the Louisiana patient requiring respiratory support.

Though no evidence suggests human-to-human transmission, the virus has been detected in raw milk, prompting the USDA to mandate testing from companies handling unpasteurized milk.

Critics, including World Health Organization officials, have called the US response inadequate, describing it as a pandemic "unfolding in slow motion." Mandatory testing of cattle is limited to those transported across state lines, with most monitoring efforts remaining voluntary until recently.

Concerns also mount over infections in other animals. Since May 2022, 419 non-bird wild animals, including foxes, seals, and raccoons, have tested positive, likely after scavenging infected bird carcasses.

In pigs, sporadic cases have alarmed researchers, as these animals can host both human and avian flu strains, potentially acting as "mixing vessels" for new variants.

Wastewater surveillance has detected the virus in 60 of the 250 monitored sites across the US, with over 80% of samples in California and Iowa testing positive.

While the US holds a stockpile of 20 million bird flu vaccines and capacity for rapid production of 100 million more, the Biden administration has stated it has no plans to authorize their use. Supplies of antivirals like oseltamivir (Tamiflu) are available and have been used successfully in severe cases, such as the Louisiana patient.

Efforts to develop a bird flu vaccine for poultry continue, alongside tests confirming that human antivirals can be effective in treating sick cattle.

As experts monitor the situation, the unprecedented scale of infections remains a significant concern, with fears that further spread could lead to dangerous mutations.