Avian influenza can infect the mammary glands of multiple livestock species, according to a new study from Iowa State University that researchers say points to the need for wider monitoring of the virus in agricultural animals.
The finding expands the known range of tissues that H5N1 can target and suggests that current surveillance efforts, which have focused heavily on dairy cattle, may be missing other potential reservoirs of infection on farms.
The study examined the mammary glands of several livestock species and found that the tissue could support the virus, raising concerns about transmission pathways that are not yet fully understood. Researchers involved in the work say the results underscore the importance of looking beyond a single species when tracking the spread of H5N1.
Since the current outbreak of highly pathogenic avian influenza began, the virus has been detected in a growing number of mammal species, including dairy herds in multiple U.S. states. The discovery that mammary tissue is susceptible across species adds a new dimension to the outbreak and could help explain how the virus moves between animals in agricultural settings.
Public health officials have been monitoring H5N1 closely because of its potential to adapt and pose a broader threat. While human infections linked to livestock have been rare and generally mild, each new finding about how the virus behaves in mammals informs risk assessments and preparedness efforts.
The Iowa State researchers argue that surveillance programs should be broadened to include a wider range of livestock and to sample tissues that may not currently be part of routine testing. Such an approach, they say, could provide earlier warnings if the virus begins to spread more efficiently among farm animals.
The study also highlights the need for coordination between veterinary and public health agencies, as well as producers, to ensure that any changes in the virus are detected quickly. Effective monitoring depends on access to farms and on the willingness of producers to report unusual illness in their herds.
For now, the findings do not change the overall risk to the general public, which remains low, but they do reinforce the message that H5N1 is a dynamic threat requiring sustained attention. Researchers say continued investment in surveillance and in understanding the basic biology of the virus in different species will be critical to preventing a wider outbreak.
The work adds to a growing body of evidence that H5N1 is capable of infecting tissues and species beyond those originally expected, a pattern that has kept scientists on alert since the virus began spreading widely in wild birds and poultry. As the outbreak evolves, the Iowa State team's conclusions are likely to inform discussions about how best to protect both animal and human health.
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