The CDC wants clinicians and health departments to consider potential infections with the highly pathogenic avian influenza (HPAI) A(H5N1) virus, commonly known as bird flu, in people with exposure to potentially infected animal sources.
The health advisory alert comes on the heels of Monday’s announcement by the CDC and the Texas State Department of Health that a farmworker on a commercial dairy farm was infected with the H5N1 virus after exposure to presumably infected cattle. That person’s only symptom was mild conjunctivitis. The case was the second one in the U.S., following a case in 2022 in Colorado.
The new case is notable because it is the first instance of presumed transmission from a cow to a human, occurring in the midst of a first-ever outbreak of the virus in dairy cattle. The CDC alert said no additional cases in humans have been reported and that no human-to-human transmission of the virus has been identified, with the patient’s household members receiving post-exposure prophylaxis with oseltamivir (Tamiflu).
“The current risk these viruses pose to the public remains low,” the CDC alert stated. However, people with job-related or recreational exposures to potentially infected animals are at higher risk of infection.
The advisory alert recommended that clinicians should consider the possibility of H5N1 infection in people showing signs or symptoms of acute respiratory illness and/or conjunctivitis and who have relevant exposure history, such as:
- Contact with potentially infected sick or dead birds, livestock, or other animals within the week before symptom onset
- Direct contact with water or surfaces contaminated with feces, unpasteurized milk or unpasteurized dairy products, or parts (carcasses, internal organs, etc.) of potentially infected animals
- Persons who have had prolonged exposure to potentially infected birds or other animals in a confined space
Symptoms compatible with bird flu can range from mild upper respiratory illness to severe systemic disease. If compatible signs and symptoms are present, the CDC recommends that clinicians should do the following:
- Isolate the patient, use personal protective equipment (PPE), and follow infection control recommendations
- Initiate empiric antiviral treatment as soon as possible with oral or enteric oseltamivir, twice daily for 5 days
- Treatment should not be delayed while waiting for laboratory results and should be initiated regardless of the time since onset of symptoms
- Notify state and local health department to arrange testing for the H5N1 virus
- Collect respiratory specimens from the patient to test for H5N1 virus at the state health department; if the affected person has conjunctivitis, with or without respiratory symptoms, both a conjunctival swab and a nasopharyngeal swab should be collected for testing
Patients should be encouraged to isolate away from household members and not go to work or school until test results indicate they are not infected with the virus.
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