Two farmworkers in California tested positive for H5 bird flu, the US Centers for Disease Control and Prevention confirmed on Thursday.
The confirmation came hours after the California Department of Public Health announced the first two presumptive positive cases in humans in the state. Both workers’ specimens were submitted to CDC for confirmatory testing.
Health officials said the two cases appeared to be unrelated. The people worked on different dairy farms in California’s Central Valley and both farms had cattle known to be positive for H5N1 avian influenza.
Both people had mild symptoms. The main symptom in both cases was red eyes, or conjunctivitis, a sign that a person has been infected through their eyes. This can happen if a person rubs their eyes with virus on their hands or if infected milk splashes on a person’s face. Neither worker had respiratory symptoms or was hospitalized.
Health officials say the risk to the general public remains low. Farm workers are at higher risk, however, and the CDC has recommended that farmworkers wear personal protective equipment including a face shield or goggles, a face mask and gloves to reduce the risk of infection.
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“Ongoing health checks of individuals who interact with potentially infected animals helped us quickly detect and respond to this possible human case. Fortunately, as we’ve seen in other states with human infections, the individual has experienced mild symptoms,” Dr. Tomás Aragón, CDPH director and state public health officer, said in a news release after the first case was announced. “We want to emphasize that the risk to the general public is low, and people who interact with potentially infected animals should take prevention measures. CDPH continues to support local health departments and farms with prevention recommendations, health checks and guidance on proper notification, testing and treatment.”
With these additions, there have been 16 cases of avian flu in humans in the United States since March; most of them have been connected to ongoing outbreaks in poultry and dairy cattle. Previous cases were identified in workers in Texas, Colorado and Michigan. Missouri has also identified a case in a patient who was not known to be exposed to animals.
Infectious disease experts are watching this virus closely because each time it infects a new human host, it has an opportunity to change in ways that may allow it to better adapt to people. If that occurs, there are fears it could spark a wider outbreak. Most pandemics have been caused by different strains of the flu.