The Texas Department of State Health Services today reported a human case of avian influenza A(H5N1) virus in Texas. The case was identified in a person who had direct exposure to dairy cattle presumed to be infected with avian influenza.
The patient, who experienced conjunctivitis as their only symptom, was tested for flu late last week with confirmatory testing performed by the Centers for Disease Control and Prevention over the weekend. The patient is being treated with the antiviral drug oseltamivir.
Avian influenza A(H5N1) viruses have only rarely been transmitted from person to person. As such, the risk to the general public is believed to be low; however, people with close contact with affected animals suspected of having avian influenza A(H5N1) have a higher risk of infection.
Texas public health officials are providing guidance to affected dairies to minimize workers’ exposure and how people who work with affected cattle can monitor for flu-like symptoms and get tested. A health alert was issued to clinicians and public health departments to consider the possibility of avian influenza A(H5N1) virus infection in people with flu symptoms and relevant exposure history.
According to the health alert, signs and symptoms of avian influenza A(H5N1) infection may include:
- Fever (temperature of 100°F or greater) or feeling feverish or chills
- Cough
- Sore throat
- Runny or stuffy nose
- Headaches
- Fatigue
- Eye redness (conjunctivitis)
- Difficulty breathing/shortness of breath
- Diarrhea
- Nausea
- Vomiting
- Seizures
Although not commonly associated with seasonal influenza, conjunctivitis has been observed in avian influenza A virus infections. Because of this, healthcare providers including optometrists and ophthalmologists, should be aware of the potential of individuals presenting with conjunctivitis who have had exposure to affected animals.
The CDC confirmed in a press release that initial testing has not found changes to the virus that would make it more transmissible to humans.
This is the second person reported to have tested positive for influenza A(H5N1) viruses in the United States. A previous human case occurred in 2022 in Colorado. Human infections with avian influenza A viruses, including A(H5N1) viruses, are uncommon but have occurred sporadically worldwide. CDC has been monitoring for illness among people exposed to H5 virus-infected birds since outbreaks were first detected in U.S. wild birds and poultry in late 2021.
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“With the information available so far, the virus does not appear to be able to transmit from one person to another easily, but vigilance is needed to identify any evolution in the virus that can change that,” said Dr. Sylvie Briand, Director of Epidemic and Pandemic Preparedness and Prevention, WHO. “WHO is working closely with FAO and WOAH, and laboratory networks to monitor the evolution of these viruses, looking for signals of any change that could be more dangerous to humans. We encourage all countries to increase their ability to monitor these viruses and to detect any human cases. This is especially important as the virus is now affecting countries with limited prior experience in avian flu surveillance.” (World Health Organization)