Conjunctivitis as a Potential Indicator of H5N1
Reminder to providers to assess for H5N1 exposure risks when presented with patients with conjunctivitis or acute respiratory infection
This message is being sent to local health officers, Tribal health directors, and the health alert network.
Key points
- Highly pathogenic avian influenza (HPAI) A (H5N1) has caused outbreaks in U.S. dairy cattle and poultry; several recent human cases have been detected in U.S. dairy and poultry workers.
- Many human cases infected after exposure to dairy cattle have experienced conjunctivitis, either as the only symptom or alongside acute respiratory infection (ARI) symptoms.
- People with conjunctivitis and/or ARI symptoms who have exposure to birds or dairy cattle should be tested for influenza A at the Wisconsin State Laboratory of Hygiene (WSLH) by PCR.
- Clinicians should assess occupational and recreational exposures to animals for patients presenting with conjunctivitis or ARI.
Background
Highly pathogenic avian influenza (HPAI) A (H5N1) is currently circulating among animals in the U.S., with more than two dozen reported human cases to date in 2024. All but one of these cases have been occupationally linked to animal exposures, either on dairy farms or poultry farms. Conjunctivitis has been one of the most common and notable features of these cases, although respiratory and other flu-like symptoms have also been noted.
To date, there have been no known HPAI A(H5N1) dairy cattle outbreaks in Wisconsin; however, the potential for undetected animal infections and animal-to-human transmission cannot be fully ruled out. Studies of retail dairy products have also shown traces of deactivated HPAI A (H5N1) in pasteurized dairy products from states without known dairy cattle outbreaks. While there is no food safety concern with such pasteurized products, the results raise the possibility of infected but undetected dairy herds in some states thought not to be affected by HPAI A (H5N1). For this reason, it is critical that clinicians are vigilant when assessing individuals with exposure risk factors and clinically consistent symptoms, such as conjunctivitis, for HPAI A(H5N1).
Assess occupational or recreational exposure risks for patients with conjunctivitis or respiratory symptoms
Patient occupation should be collected from patients presenting with conjunctivitis and/or ARI. Occupational exposures are particularly important for this outbreak, but asking your patients about work is a general best practice that can be used to help identify any number of occupational exposures or diseases.
Additionally, patients with conjunctivitis or cold and flu symptoms should be asked whether they have had recent contact with dairy cows, raw milk, poultry, or any sick or dead wild birds or animals through occupational or recreational exposures. While dairy and poultry farm workers are thought to have the greatest risk, occupational risk factors have also been identified for veterinary workers, animal health responders, public health responders, dairy laboratory workers, and workers in certain meat and dairy processing roles. Though the risk to the general public is low, potential recreational exposures such as farm visits should also be considered even if the individual did not have direct contact with dairy cows or poultry. Please contact your local or Tribal health department or the Bureau of Communicable Diseases at 608-267-9003 for assistance determining which situations may warrant testing for influenza A (H5N1).
What to do if you suspect a patient has H5N1
Patients with symptoms and occupational or recreational exposures should be tested for influenza A at the WSLH with the prior approval of the Wisconsin Department of Health Services (DHS), Division of Public Health at no charge.
To obtain approval for testing, please contact the Bureau of Communicable Diseases at 608-267-9003.
In-house testing, especially rapid influenza diagnostic testing, is discouraged, as specimens testing positive for influenza A from individuals with these exposures will need to be sent to the WSLH for additional characterization.
Prevention information for individuals with occupational risk factors
Clinicians are encouraged to provide education to occupationally at-risk patients on strategies to prevent HPAI A (H5N1). Prevention resources are available in both English and Spanish on the CDC (Centers for Disease Control and Prevention) and DHS websites.
Additionally, dairy and poultry workers are a priority population to receive the seasonal flu vaccination this season. While the seasonal flu vaccination does not protect against HPAI A (H5N1), it can reduce the possibility of seasonal flu and HPAI co-infections in occupationally at-risk individuals. Routine seasonal flu vaccination of animal workers is a long-standing recommendation to reduce the potential for viral reassortment resulting from human and animal influenza co-infections.
Contacts
For questions regarding HPAI A (H5N1) testing recommendations, please contact the Bureau of Communicable Disease at dhsdphbcd@dhs.wisconsin.gov.
For questions about occupational exposures to HPAI A (H5N1), please contact DHS Occupational Health at DHSOccHealth@dhs.wi.gov.
Additional Resources
For health care providers:
For patients and members of the public:
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