Why the discovery of H5N1 bird flu in mice is so alarming

Although USDA have not released any information about how the mice contracted the virus, scientists suspect the creatures lived on a farm, and became infected after consuming unpasteurised milk from infected cattle. 

A study was released a month ago documenting the death of cats from Texas which are thought to have contracted the virus via the same route.

The US authorities are warning consumers not to drink unpasteurised milk or other dairy products.

Mice don’t stay in one place and can act as efficient vectors for disease.

Travelling in groups, they can climb through pipes, voids, and other tight spaces to move with ease from place to place, house to house. They thrive in groups of up to two dozen and practically live on top of each other – meaning viruses can rapidly spread between them. 

“House mice living near infected farms can spread H5N1 virus into residential areas, making containment of the outbreak significantly more challenging,” explained Dr Bright. “This is out of control.”

Need for ‘immediate action’

Rodents are infamous reservoirs of disease, and are responsible for a number of epidemics. The bubonic plague, or ‘Black Death’ – which killed off half of Europe in the 1300s – was transmitted via rats. 

Lassa Fever – which causes around 5,000 in West Africa every year – is carried by multimammate mice, which contaminate human food sources through urine and faeces.

“We know mice can transmit pathogens like hantavirus, leptospirosis, and LCMV,” explained Dr Krutika Kuppalli, a spokesperson for the Infectious Disease Society of America and former WHO medical officer.

“I suspect this could happen with H5N1, but we will need more studies to understand this,” she said. 

“We need urgent comprehensive testing to prevent a wider health crisis – the history of rodent-borne pandemics like the Black Death underscores the potential severity of the H5N1 virus’s spread into house mice, and the need for immediate action,” added Dr Bright.