California reports first suspected H5N1 bird flu patient amid fears virus is spreading between people for first time

A dairy worker in California tested ‘presumptive positive’ for the bird flu, possibly becoming the 15th person in the US to contract the disease. 

The unidentified patient works at a dairy facility that is currently experiencing an outbreak of the bird flu, H5N1, among its cattle. The person experienced mild symptoms, only reporting conjunctivitis, or red eyes. 

The local health department was notified and tested the worker for the virus, which returned a presumptive positive.

A sample is now being sent to the CDC for further testing.

The patient, the first in California, is being treated with antiviral medications and is isolating at home. 

Fears over the spread of bird flu are increasing as, for the first time, a patient in Missouri who had not come into contact with sick birds, cattle or other animals was diagnosed with the virus. 

The worst-case scenario is that the patient caught it from another person and that the virus has begun silently spreading between Americans. 

While this is unlikely, Dr Kruitka Kuppali, a spokesperson for the Infectious Disease Society of American and former World Health Organization officer, warned last month: ‘This is how pandemics start.’ 

The Missouri case was detected through the state’s seasonal flu surveillance system, which keeps track of influenza activity based on testing from symptomatic patients.

Another theory is that the Missouri patient drank raw milk that was contaminated with the virus.

Raw milk is becoming increasingly popular and studies have shown H5N1 particles can linger in it for up to five weeks if it is refrigerated, according to the National Institutes of Health (NIH).

Pasteurized milk is safe to eat because the process of pasteurization inactivates the bird flu virus.  

The CDC reported that since March 2024, the agency has monitoring more than 4,900 people who had been exposed to animals infected with H5N1 and more than 230 people have been tested.

Fourteen people have tested positive so far, but because bird flu does not always cause symptoms, there could be more sick people who never got tested.

In March, a a Texas dairy farmer tested positive for the virus and experienced similar symptoms to those reported in the Central Valley, California patient – conjunctivitis. 

This is the first picture of the Texas farm worker infected with bird flu. The infection began in the right eye, before spreading to the left

A case report detailing the man’s illness said the patient also suffered from a subconjunctival hemorrhage, or bleeding just beneath the conjunctiva, or clear surface covering the white part of the eye.

Scientists also noted a watery fluid being discharged from the right eye.

Other symptoms patients may experience include cough, sore throat, runny or stuffy nose, headaches and body aches or muscle soreness. 

The California Department of Public Health said the current risk of H5N1 to the public ‘remains low’ and that people with frequent contact with birds and livestock are at an increased risk.