For months, avian influenza, previously believed to be a problem exclusive to wild birds and poultry, has been spreading through US dairy farms, infecting cattle and workers alike.
In California, the country’s leading milk producer, the insidious virus has struck hard, infecting 110 cattle herds and 11 dairy industry workers, according to the Centers for Disease Control and Prevention (CDC).
Given the size of California’s dairy industry (more than 1,100 dairies located primarily in the San Joaquin Valley), the number of infected cattle and workers is likely to increase.
But despite the expected rise, public health officials have stated that the risk to the public is low.
Could this change and become the next pandemic?
CDC scientists and the California Department of Public Health are investigating that possibility. What is known is that mutations occur in viruses and accumulate as they spread from person to person. Mutations give rise to variants that may have different attributes, including drug resistance or increased transmissibility.
Although there is no evidence that human avian influenza has spread from person to person, experts are closely monitoring any changes through a testing process known as genomic sequencing.
State epidemiologist Dr. Erica Pan has stated that by identifying the genetic material, or genotype, of an organism, scientists can detect whether mutations have occurred. “If we monitor it, we can tell whether it is responding to treatment or not,” she said.
People infected with human avian influenza are being administered medication to treat it and outcomes have been positive, says Pan. She has also noted that human avian influenza is not new, having been present worldwide for more than 20 years with sporadic human cases, and finds it reassuring that too many different variants have not been observed during this period.
County public health officials are also working to monitor the virus among dairy farm workers who have been infected. Carrie Montero, spokesperson for the Tulare County (California) Public Health Department, has stated that they conducted contact tracing of individuals living in the households of infected workers and that none had presented symptoms.
Nevertheless, in preparation for additional human avian influenza cases, CDC officials have provided State Public Health with 5,000 additional doses of seasonal influenza vaccine for agricultural workers.