The H5N1 avian influenza virus, commonly known as bird flu, has caused significant alarm globally, killing tens of millions of birds and over 40,000 sea lions and seals. While it’s a pandemic for animals, the Centers for Disease Control and Prevention (CDC) assures that the risk to humans remains low. Despite this, infectious disease experts are becoming increasingly worried about the potential for the virus to adapt and spread among humans.

Human Cases Emerging

In March, Australia reported its first human case of H5N1 when a 2-year-old child fell ill after returning from Kolkata, India. The child exhibited symptoms including loss of appetite, fever, coughing, vomiting, and irritability, leading to a hospital stay of two and a half weeks, which included admission to the intensive care unit. The World Health Organization (WHO) announced this case, highlighting the growing concern as human infections appear in various parts of the world.

“There’s a lot going on,” says Dr. Monica Gandhi, a professor of medicine and associate chief of the Division of HIV, Infectious Diseases, and Global Medicine at the University of California, San Francisco. “I’m becoming more worried.”

Epidemiologists like Christopher Dye, a professor and senior research fellow at the University of Oxford, share this concern. “There’s such a vast amount of virus at the moment. And clearly, it is changing and doing new and unexpected things,” Dye told Business Insider. Dye recently co-authored a paper in the medical journal BMJ, arguing that the risk of a major human outbreak is “large, plausible, and imminent.” He emphasizes that influenza has always been a concern, but the current situation with H5N1 has elevated it to an unprecedented level of worry.

Rodent Infections and Domestic Risks

The US Department of Agriculture reported that 47 house mice in New Mexico tested positive for H5N1. These mice, along with some domestic cats, likely contracted the virus from drinking raw milk from infected cows. Public health experts strongly advise against consuming unpasteurized, or “raw,” milk due to the risk of contamination. The presence of the virus in common rodents is particularly troubling as it brings the virus closer to human homes, raising the likelihood of transmission.

“Mice are kind of everywhere,” says Dr. Gandhi. “They’re around other animals, they’re around humans a lot. And it’s a little worrisome.”

Rick Bright, former director of the Biomedical Advanced Research and Development Authority, stressed the urgency of the situation, telling The Telegraph, “This is out of control.” Each new population of infected animals and every new exposure to humans presents an opportunity for the virus to mutate and adapt. The CDC’s analysis of a virus sample from the second US farmworker infected with H5N1 showed a mutation in the virus’s replication machinery. This mutation is associated with the virus’s adaptation to mammalian hosts, indicating a shift towards becoming more infectious to humans.

Mutations and Human Infection

The latest US case involved a farmworker in Michigan who exhibited respiratory symptoms, including a cough and sore throat. This is more concerning than previous cases where the infected individuals only had pink eye. Finding H5N1 in the respiratory system is alarming because respiratory infections can spread more easily through coughing and sneezing. The CDC has not found evidence that the virus spread from the coughing farmworker to anyone else, but the presence of the virus in the lungs increases the potential for mutations that could facilitate human-to-human transmission.

Many experts fear that the USDA and CDC are not monitoring cattle and farmworkers closely enough to detect concerning mutations early. There is a risk that other human cases may be going undetected. “I think there’s enough of a threat here to be very alert so that we have a surveillance system in place that, as soon as this happens, we can find it,” says Dye.

Vaccines in Development

The good news is that scientists have been tracking the H5N1 virus and its entire viral family tree for decades, allowing them to develop key elements of a vaccine in advance. The US is beginning to manufacture millions of vaccines using “candidate vaccine viruses” developed by the CDC. These vaccines, while not perfect matches to H5N1, could provide some immunity in the event of a human outbreak.

Additionally, the proven mRNA vaccine technology, which was first approved for use with COVID-19 vaccines, offers a more flexible and faster approach to vaccine development. Researchers at the University of Pennsylvania have developed an experimental mRNA vaccine for H5N1, which has shown success in tests with mice and ferrets. If H5N1 becomes a significant threat to humans, a vaccine could be integrated into the annual flu shot.

Monitoring and Preparedness

Infectious disease experts emphasize the importance of vigilant monitoring and early detection of concerning mutations. “There’s enough of a threat here to be very alert,” says Dye. The USDA and CDC need to closely monitor cattle and farmworkers to catch any potential human cases early.

While the immediate risk to humans is currently low, the H5N1 avian influenza virus remains a looming threat. With ongoing developments and the potential for mutations, it is crucial to stay informed and prepared for any future outbreaks. Scientists are working diligently on vaccine development to ensure readiness in case the virus becomes a significant human threat. The situation underscores the importance of continued surveillance, research, and preparedness in managing potential pandemics.

The Information is Collected from Yahoo and USA Today.