Rare bird flu strain raises potential of spread: 5 things to know

A newly identified strain of bird flu, H5N9, discovered at a California duck farm, has prompted concerns about the possibility of a larger outbreak, The Washington Post reported Jan. 29.

Health experts are monitoring the situation, particularly the potential for genetic mutations that could make the virus more easily transmissible among humans. 

Here are five more things to know: 

  1. The new strain is linked to the ongoing spread of H5N1, the more well-known avian influenza strain, through a genetic reassortment. The virus was identified after nearly 120,000 ducks were culled at the Merced County farm and genetic sequencing confirmed the presence of H5N9 in January. Though H5N9 is not an immediate threat to humans, experts are keeping a close eye on it. 

  2. The discovery of the H5N9 strain is concerning because of the reassortment process, in which viruses exchange genetic material when different strains infect the same host. This can result in a new virus with altered properties, potentially making it more easily transmissible between humans. Angela Rasmussen, PhD, a virologist at the University of Saskatchewan in Canada, told the Post that with enough H5N1 circulating in animals and seasonal flu present in humans, reassortment could increase the risk of a future pandemic. 

  3. The H5N1 strain, which is spreading across U.S. poultry farms and has infected dairy cows for the first time, remains a major public health concern. While human cases have been limited and typically involve those working closely with infected animals, experts are worried about the possibility of reassortment between H5N1 and seasonal flu strains. 

  4. In response to the bird flu outbreaks, the CDC has issued new recommendations for clinicians. One is that hospitalized patients with suspected flu should be tested for avian influenza A, particularly if there has been exposure to animals such as poultry or dairy cows. If the flu subtype is not immediately identified, further testing for bird flu should be conducted within 24 hours. 

  5. The Agriculture Department's Animal and Plant Health Inspection Service is working to contain the outbreak; the affected farm has been quarantined and cleanup procedures are underway.

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