Rédaction Africa Links 24 with Helen Branswell
Published on 2024-04-05 08:30:33
News that H5N1 avian influenza has been detected in dairy cows has surprised the flu science community. While cows had shown susceptibility to human flu viruses in the past and could be infected with H5 in a lab setting, the absence of cow involvement in H5’s history led scientists to believe that the species was not within the virus’s scope.
Adding to the concern is the recent case of a dairy farm worker in Texas who was infected with H5N1, with the only symptom being conjunctivitis. This new development prompted STAT to consult Dutch virologist Ron Fouchier, a prominent expert on H5N1, for his insights on these recent twists in the H5 saga. Fouchier, based at the Erasmus Medical Center in Rotterdam, was at the center of a controversy regarding H5N1 research in 2012, involving gain-of-function studies on virus mutations.
Fouchier expressed unease at the current situation, noting that while current strains of H5N1 appear to infect people less frequently and cause mild illness, the broad distribution of H5 viruses and the diverse range of mammals they can infect present a unique challenge. The unpredictability of flu viruses, as well as the unprecedented number of mammal species affected by H5, make it difficult to anticipate the virus’s future trajectory.
In his assessment, Fouchier highlighted the decrease in zoonotic events involving H5N1 after 2015, coinciding with a surge in outbreaks among wild birds across different continents. This shift suggests a reduced zoonotic risk as the virus adapts more to wild bird hosts and less to poultry and humans. However, the increased presence of the virus in the environment poses new risks, especially in scenarios where animal-to-human transmission can occur, such as in dairy farming.
The contamination of milk cows with H5N1 raises concerns about human exposure during the milking process, where aerosols containing the virus could pose a risk of transmission to farmers. Fouchier emphasized the need for stringent hygiene practices to prevent the spread of the virus on dairy farms. Reflecting on past outbreaks of avian influenza, such as H7N7 in the Netherlands, where human infections were linked to poultry contact, Fouchier stressed the importance of vigilance and proactive measures to contain potential outbreaks.
Regarding ongoing research, Fouchier highlighted the investigation of reassortment patterns in H5N1 strains to understand changes in zoonotic risk. By comparing the replicative capacity of early versus current virus variants in different bird species and human cells, researchers aim to decipher the evolving nature of the virus and its potential impact on human health.
In conclusion, Fouchier underscored the need for thorough epidemiological investigations to determine the source of H5N1 transmission to dairy cows and implement preventive measures. The evolving nature of H5N1 and its expanding host range underscore the challenges of predicting future disease patterns and the importance of continued surveillance and research to mitigate potential threats.
