Virus mutates in patient's body: first case of human bird flu adapted to respiratory tract

The bird flu virus is believed to have mutated in the body of a man who caught it in the United States, adapting to the respiratory tract. This is a first, the U.S. Centers for Disease Control and Prevention revealed on December 26, 2024.

The first serious human case of bird flu in the United States is carrying a virus that mutated inside his body to adapt to the human respiratory tract, U.S. health officials announced Thursday.

The H5N1 virus

The U.S. Centers for Disease Control and Prevention (CDC) announced on December 18 that an elderly patient was hospitalized in Louisiana in “critical condition” after being infected with the H5N1 virus.

A A small portion of the virus found in this patient's throat shows genetic changes that could result in “increased virus binding” to certain “human upper respiratory tract cell receptors”, the CDC revealed Thursday.

They have “probably were generated during virus replication in the patient,” the CDC said, adding that no transmission of the mutated virus has been identified. 60~/strong>

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These changes have not been observed in infected birds, including those with which the patient may have been in contact in a poultry yard.

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Experts contacted by AFP said it was too early to determine whether these changes could allow the virus to spread more easily, or cause more serious cases in humans.

The mutation in question constitutes “a necessary step for a virus to become more contagious”, Angela Rasmussen, a virologist at the University of Saskatchewan in Canada, told AFP. “But I stress that it is not the only one” needed, she added.

Rasmussen said the mutation could allow the virus to enter cells more easily, but that Further testing will need to be done on animals to confirm this.

Genetic changes have been observed in the past in critically ill bird flu patients, but have not resulted in increased transmissibility of the virus to humans.

What if it were “less serious” ?

Thijs Kuiken of the Erasmus University Medical Center in the Netherlands believes that these changes could lead to less severe infections, with the virus becoming “more likely” to “infect the respiratory tract upper respiratory tract,” causing runny nose or sore throat, as well as affecting the lower respiratory tract, leading to pneumonia.

These observations do not mean that we are approaching a “pandemic”, insisted Angela Rasmussen.

In addition to this Louisiana patient, 65 mild cases of the disease have been detected in humans in the United States since the beginning of the year, and others may have gone unnoticed, according to the CDC.

Avian influenza A (H5N1) has emerged for the first time in 1996, but since 2020 the number of outbreaks in birds has exploded and an increasing number of mammal species have been affected.