Unexplained H5N1 Infection in Missouri Sparks Concerns of Potential Human Transmission

Social Media · September 10

A person in Missouri has been infected with H5N1 bird flu, despite having no known contact with sick animals. This case has sparked concern among experts, who are racing to determine how the virus was transmitted to the patient. One theory is that the individual may have consumed raw milk infected with H5N1, which has been circulating among U.S. cattle. Another possibility is that the person unknowingly came into contact with an infected animal.

This case is particularly alarming because it marks the first time a patient in the ongoing H5N1 outbreak in the U.S. has become sick without known exposure to infected animals. Previously, all 13 reported human cases in the U.S. this year were among farm workers who had direct contact with sick cattle or birds. The patient in Missouri was hospitalized on August 22 and has since recovered, according to the Centers for Disease Control and Prevention (CDC).

The case was detected through the state’s seasonal flu surveillance system, raising concerns that there could be other cases that have gone undetected. The H5N1 virus, a deadly pathogen that has killed hundreds of millions of birds worldwide, has also been found in mammals such as foxes and otters in Britain. Some experts fear that such "spillover events" could ignite the next global pandemic.

The avian flu began spreading in U.S. dairy cattle last December, and over 200 herds across 14 states have since been infected, although none have been reported in Missouri. However, Missouri has seen cases of H5N1 in wild birds and poultry, suggesting a possible route of infection.

The primary concern among experts is that this unexplained H5 infection could signal the beginning of human-to-human transmission, which the World Health Organization (WHO) has warned would be of “enormous concern” due to its potential to trigger a global pandemic. "This is how pandemics start," said Kruitka Kuppali, a spokesperson for the Infectious Disease Society of America and a former WHO medical officer. "We need to scale up preparedness and response efforts."

The 2009 swine flu pandemic was first detected in a similar manner when two children in California, who had no known contact with pigs or each other, were diagnosed with an H1N1 flu infection that had been circulating in swine. Another theory being considered is that the patient may have consumed raw milk infected with H5N1, a pathogen that has already killed several barnyard cats in the U.S. this year.

Approximately three percent of the U.S. population, or around 10 million people, consume raw dairy, which some consider a "superfood," according to the National Institutes of Health. Thomas Peacock, an influenza virologist at the Pirbright Institute, questioned whether the patient might have consumed raw milk, stating, "The obvious question I would ask is: Have you ruled out that they’re not someone who’s got a big tub of raw milk in their fridge? Because that just seems like such an obvious route for a cryptic infection." However, Lisa Cox, a spokesperson for the Missouri Health Department, noted that the patient had not reported consuming raw milk. Dr. Peacock added that people aren’t always completely reliable in epidemiological investigations, so the possibility cannot be entirely ruled out.

Dr. Kuppali emphasized the importance of conducting a thorough epidemiological investigation to determine any potential exposures the patient may have had in the community, at home, or at work. The CDC has confirmed that Missouri health officials are conducting an on-the-ground investigation to identify the source of the infection, although it is unclear when the findings will be made public.

Scientists are eager to sequence the virus and upload it to GISAID, an international database that tracks dangerous new flu strains. This could provide clues as to whether the patient was infected with the variant circulating in cattle or if the virus has undergone adaptations that make it more capable of spreading between humans. So far, contact tracing has not revealed any additional cases, and the CDC continues to consider the risk to the general public as low.

Credit: Daily Telegraph 2024-09-11

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