Still a mystery, not a single bird flu patient in America knows where the infection came from

TEMPO.CO, Jakarta – Dozens of new cases of virus infections H5N1 it reportedly appeared in the United States at this time of year. From the available evidence, it is suspected to be a virus bird flu It spreads to humans from infected animals such as cattle and poultry, not between humans.

However, one recent case in Missouri still raises questions. Cases reported by the Centers for Disease Control and Prevention (CDC) in the US on September 6. It is not yet known what kind of animal it came from.

Did the patient get an infection from someone else? The CDC dismissed this by saying that there is no evidence so far that anyone has passed the bird flu virus to their close contacts. “The public health threat from H5N1 remains low,” the statement said.

The CDC is still standing by that decision even though two health workers became ill after interacting with bird flu patients. One tested negative for the same flu.

Nahid Bhadelia of the Center for Emerging Infectious Diseases at Boston University agrees with the assessment that the risk from H5N1 remains relatively low. However, he also cautioned that he is cautious because there is a case in Missouri that remains a mystery.

He pointed to advanced cases of H5N1 disease that have spread among birds in the country since 2022, and then jumped to different mammals including cattle. The patient’s case in Missouri is believed to have originated from an infected cow but has not been traced. “Missouri has so far found 600,000 cases among poultry. Infected cattle herds may have been taken unawares,” he said.

Lakdawala view, certified partnerr field of microbiology at Emory University who studied H5N1 admitted that the number of animals tested was not enough to determine the geographic distribution of this virus. As of July 12, the Department of Agriculture (USDA) had only inspected 17 of the approximately 60,000 dairy cows there. “There has never been universal testing on dairy farms,” ​​he said.

Bird flu cases in Missouri

The patient in Missouri was hospitalized last August and became the 14th positive case of bird flu in the US so far this year. Complicated by other infections, this patient suffered from chest pain, diarrhoea, vomiting and weakness. However, the patient did not become seriously ill during treatment and has now recovered.

He first tested positive for influenza A, the large group of viruses from which H5N1 originated. This includes seasonal flu viruses such as H1N1 but the patient has tested negative for all subtypes. Further tests then revealed an H5N1 infection.

In its September 13 update, the CDC reported that it had obtained a partial analysis of the genome of the bird flu virus that infected the patient; There is not enough genetic material available to sequence a whole generation.

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The results show that the virus is still very similar to those circulating among livestock. In other words, the virus has not mutated enough to adapt well to human lungs – mutations that could pave the way for human-to-human transmission.

However, it was also found to contain two different mutations that had not been found in previous cases of the H5N1 virus in humans. The implications of this difference are not yet clear.

Was it from cow’s milk?

The CDC said one possible source of the virus’ spread was the unpasteurized cow’s milk the patient consumed. In this regard, Lakdawala explained that an infected cow can carry tens to hundreds of millions of infectious virus particles in every milliliter of milk, “And this animal produces gallons of milk. “

It is not yet known whether someone can catch bird flu from drinking fresh cow’s milk that has not been pasteurized, but it is known that the same substance spreads different germs.

Another possibility is human-to-human transmission, although this has not yet been discovered. For this possibility, the patient’s family contacts from Missouri were known to have developed similar symptoms on the same day but were not tested for bird flu.

Based on these symptoms, Lakdawala suspects that the patient and his family were simultaneously exposed to the same source of infection rather than spreading the virus from one person to another.

Lakdawala urged the USDA to do more to understand how the bird flu virus spreads among cattle. According to him, must cooperate with veterinarians and go to farms to check all milk tankers.

LIFE-SCIENCE, NEW SCIENTIST

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