In the past two years, bird flu has wreaked havoc on millions of wild and domestic birds worldwide, claiming the lives of seals, sea lions, and even a polar bear. Additionally, it has devastated mink farms and affected various other animals, including cats, dogs, skunks, and foxes.
Surprisingly, humans have remained largely untouched by this aggressive virus, leaving scientists puzzled. \"It's a little bit of a head scratcher,\" remarked Richard Webby, a flu researcher at St. Jude Children's Research Hospital in Memphis, Tennessee. Experts suggest that the way infection occurs or differences in species' microscopic docking points—the sites where flu viruses attach to cells—might be responsible.
Despite the current minimal impact on humans, concerns linger about future changes. Dr. Tom Frieden, former director of the U.S. Centers for Disease Control and Prevention (CDC) and head of the non-profit Resolve to Save Lives, emphasized the uncertainty. \"There's a lot we don't understand,\" Frieden stated. \"I think we have to get over the 'hope for the best and bury our head in the sand' approach. Because it could be really bad.\"
Historically, bird flu viruses have been precursors to severe human pandemics, such as those in 1918 and 1957. While the current strain, H5N1, has not yet become a deadly contagion for humans, its ability to mutate remains a significant concern.
U.S. health officials are preparing vaccines and other preventive measures, though they remain cautious due to the virus's limited impact on people and lack of evidence for human-to-human transmission. Since its identification in birds in 1959, H5N1 has caused sporadic severe human cases, primarily through direct contact with infected birds.
Recent reports indicate that animal outbreaks have surfaced in numerous U.S. dairy farms and poultry flocks, with a few human infections recorded among farm workers. Globally, 15 human cases have been detected, including one fatality in southern China in 2022. Most infected individuals experienced mild or no symptoms.
The virus exhibits varying levels of severity across different animal species. In cats, for instance, H5N1 has been found in the brain, causing severe neurological damage and death. Conversely, cattle infections are less severe, primarily affecting lactating animals' udders.
Researchers are investigating the transmission routes, with evidence pointing towards direct contact rather than airborne spread. Differences in species' susceptibility, particularly the presence of specific receptors that flu viruses bind to, may explain the varied impacts.
The potential for the virus to mutate into a more lethal form or to spread more easily among humans remains a critical concern. Pigs, known as ideal mixing vessels for flu viruses, are under observation, though current strains cause only mild disease in them.
As scientists continue to monitor and study the virus, the unpredictable nature of influenza underscores the importance of vigilance and proactive measures to prevent a possible future pandemic.
Reference(s):
Scientists want to discover why bird flu hardly affects people
cgtn.com
