Hong Kong health authorities are investigating the city's first confirmed case of rat hepatitis E in 2025, after a 42-year-old man tested positive for the rodent-borne virus - a reminder that nature continues to find creative new ways to ruin our day.
According to the South China Morning Post, a spokesman for the Centre for Health Protection (CHP) confirmed that the patient's blood sample came back positive on May 5. The man already had chronic liver disease, which made him particularly vulnerable to the infection.
Wait, rats have their own hepatitis?
Yes, unfortunately they do. Rat hepatitis E - caused by the Rocahepevirus ratti virus, if you want to impress people at parties - is a strain distinct from the more commonly known human strains of hepatitis E. The fact that it can jump from rats to humans is what makes public health officials particularly antsy about it.
Hong Kong has recorded a handful of such cases over the years, and researchers have been keeping a close eye on the phenomenon since the first documented human case of rat hepatitis E was confirmed in the city back in 2018. That original discovery was actually something of a global first, putting Hong Kong on a scientific map that nobody really wanted to be on.
So how do you actually catch this thing?
The CHP told the public that while the exact transmission route in this particular case is still under investigation, rat hepatitis E is generally believed to spread through contact with rats or environments contaminated by rat droppings and urine. In other words: the usual rodent-related nightmare fuel.
Authorities have urged the public to maintain good hygiene practices and implement effective rodent control measures - which is solid advice at any point in time, really, rat hepatitis or not.
What's the risk to the general public?
The CHP stated, based on current epidemiological data, that the risk to the broader public remains low. Human-to-human transmission has not been established for this strain. However, people with pre-existing liver conditions are considered higher risk if exposed, as this latest case illustrates.
Health officials are continuing their investigation into the source of the infection. In the meantime, the standard advice applies: wash your hands, keep food storage areas sealed, and perhaps reconsider any lifestyle choices that put you in close proximity to rats.
Hong Kong has been monitoring rat hepatitis E cases with unusual scientific interest since its unlikely role as ground zero for the first documented human infections. Scientists worldwide have been studying the phenomenon to better understand cross-species transmission - a field that, post-2020, has everyone's full and undivided attention.
