A third case of bird flu has been confirmed in a dairy farm worker in the USA, the second identified in the state of Michigan. In contrast to the previous two cases, the infected individual has reportedly been experiencing traditional flu-like symptoms, though officials say they are now recovering.
The Centers for Disease Control and Prevention (CDC) confirmed on May 30 that another human case of bird flu has been identified. As with the previous two US cases, the infected person was a farm worker in the dairy industry, and it’s thought likely they contracted the virus after exposure to an infected cow.
The CDC stressed there is no evidence the three reported cases are linked in any way. They say the risk to the general public “remains low” but that people should take care when coming into contact with animals, especially if they are dead or appear sick.
“People should also avoid unprotected exposures to animal poop, bedding (litter), unpasteurized (“raw”) milk, or materials that have been touched by, or close to, birds or other animals with suspected or confirmed A(H5N1) virus,” the agency adds.
The dairy farm H5N1 outbreak has now hit nine states, according to data from the US Department of Agriculture. There had been 22 separate reports of infected cattle in Michigan at the time of writing. The two human cases of infection in the state occurred on different farms.
The two other farm workers who contracted the virus experienced mild symptoms of an eye infection. This time, the individual presented with respiratory symptoms that are more usual with the flu, including a cough, as well as eye discomfort. After being treated with the antiviral Tamiflu, the patient is said to be “isolating at home, and their symptoms are resolving.” No other staff at the farm, and none of the patient’s family or friends, are showing symptoms.
“With the first case in Michigan, eye symptoms occurred after a direct splash of infected milk to the eye. With this case, respiratory symptoms occurred after direct exposure to an infected cow,” said Michigan Department of Health and Human Services chief medical executive, Dr Natasha Bagdasarian, in a statement. “Neither individual was wearing full personal protective equipment (PPE). This tells us that direct exposure to infected livestock poses a risk to humans, and that PPE is an important tool in preventing spread among individuals who work on dairy and poultry farms.”
“We have not seen signs of sustained human-to-human transmission, and the current health risk to the general public remains low.”
Right now, the CDC is reporting no unusual patterns in human flu cases. Viral isolates from the latest patient are currently undergoing genetic testing – so far, it’s been confirmed that the virus is an H5 subtype, but more tests are needed before we have the second piece of the puzzle, the N (neuraminidase, an influenza virus surface protein). Given the patient’s history and exposure to H5N1-infected cattle, it’s suspected the virus will turn out to be H5N1 as well.
As this highly pathogenic H5N1 strain continues to spread in many species – birds and mammals – across the US and further afield, there are understandable fears that it will make the jump to sustained spread in the human population. We’re not there yet, but close surveillance of the virus will continue to ensure that health authorities can take any necessary precautions in a timely manner – which could include mRNA vaccines, according to recent reports.
