The H5N1 virus has infected three people across North America with no known sources of contamination, leaving epidemiologists worried about the potential for a new pandemic. This is not the first time the virus has appeared in the US; 53 cases have been reported among farm workers on dairy and poultry farms. However, these recent atypical cases are raising concerns about a similar scenario to the early days of the H1N1 flu epidemic in 2009.
British epidemiologist Adam Kucharski notes that understanding transmission is key during epidemics. Without knowing the source of infections, it’s challenging to assess the threat and control the situation. A first case with no known source was identified in Missouri on September 6. An investigation concluded that two people from the same household had contracted the virus simultaneously, but the origin remains unknown.
A second worrying signal came from Canada, where a teenager fell seriously ill in British Columbia. Samples from his family and environment showed no H5N1 presence, and it’s unclear how he contracted the virus. The provincial authorities closed the investigation due to lack of new information, but the patient remained hospitalized on a respirator.
This case is alarming as the virus has acquired additional mutations, particularly in the hemagglutinin protein. Professor Scott Hensley reported that two key mutations have appeared, enabling the virus to better attach to human lung cells. This change is significant, as the virus normally binds more readily to bird cells.
Source: https://www.lemonde.fr/en/environment/article/2024/12/05/bird-flu-in-north-america-is-worrying-epidemiologists-three-people-have-been-infected-by-the-h5n1-virus-with-no-source-of-contamination-detected_6735208_114.html