Bird flu’s red-eye warning: H5N1 may present first as conjunctivitis

Clinical takeaway: In patients with conjunctivitis plus recent exposure to sick or dead poultry, dairy cows, livestock, raw milk, or contaminated farm environments, consider H5N1 infection, use appropriate PPE, collect both conjunctival and respiratory specimens, and start oseltamivir when clinically indicated without waiting for confirmatory testing.

The American Academy of Ophthalmology is warning clinicians that conjunctivitis may be a key presenting sign of the current US H5N1 bird flu outbreak. From 2024 through May 2026, 71 human cases of highly pathogenic avian influenza A(H5N1) were identified across multiple states, largely tied to exposure to infected dairy cows and poultry. Two deaths were reported, but there has been no known person-to-person spread, and CDC continues to assess the risk to the general US public as low.

For ophthalmologists, the message is straightforward: red eye plus the right exposure history should raise suspicion. Multiple human infections presented with conjunctivitis as the only clinical sign or symptom, and in some patients, conjunctival swabs had higher viral levels than upper respiratory samples.

Patients of concern include those with conjunctivitis and exposure within the previous 10 days to sick birds, dairy cows or other livestock, raw cow milk, or contaminated farm environments. Symptoms can range from eye redness or discharge, tearing, fever, chills, cough, sore throat, rhinorrhea, fatigue, myalgias, arthralgias, and headache to severe disease including pneumonia, respiratory failure, ARDS, sepsis, multi-organ failure, seizures, or encephalitis.

Testing should not rely on routine influenza A assays alone, because they cannot distinguish H5N1 from other influenza A subtypes and are not approved for conjunctival swabs. For patients with conjunctivitis, AAO highlights CDC guidance to collect one conjunctival swab and one nasopharyngeal swab in separate viral transport media, with subtyping performed through public health laboratories.

Drug therapy centers on oseltamivir. CDC-based recommendations call for twice-daily oral oseltamivir for 5 days for outpatient treatment or prophylaxis when clinically appropriate. Treatment should begin as soon as possible for suspected, probable, or confirmed cases—especially severe illness—and should not be delayed pending lab confirmation. If initial testing is negative but suspicion remains high, treatment should continue and repeat swabbing should be performed.

Prevention remains essential. Clinicians should use gloves, N95 masks or equivalent, and goggles or face shields for high-risk exposures; workers should avoid unprotected contact with sick animals, raw milk, fecal matter, litter, and contaminated farm surfaces. As the AAO statement underscores, “Be alert to H5N1 as a cause of conjunctivitis” when exposure history fits.

Source: American Academy of Ophthalmology. May 2026. Novel H5N1 bird flu outbreak — 2026