After struggling to contain COVID-19 for months, Hong Kong has once again been struck by a strange disease.Recently, about ten residents of Hong Kong have tested positive for hepatitis E. This virus, which is found in rats, is also known as rat HEV.A disease that surfaced in 2018This disease was first detected in 2018. At the time, a 56-year-old man who had just had a liver transplant was showing abnormal liver function tests with no obvious cause. Doctors ran a number of tests on him and the results revealed that it was hepatitis E, but the patient didn't actually have a human strain of the virus in his blood.In their efforts to learn more about this unusual illness, researchers managed to link this case to rats. In other words, it was the first case of human infection with rat hepatitis.New cases in Hong KongThis liver disease, which causes fever, jaundice, and organ enlargement, was deemed 'a one-off incident' by doctors, who concluded that the patient had just been in the wrong place at the wrong time.On April 30th of this year, a 61-year-old patient was diagnosed with HEV in Hong Kong. Since then, there've been more new cases, and doctors believe that many people could unknowingly be carrying the virus.How do you get hepatitis E?Hepatitis E is normally transmitted through fecal contamination of drinkable water or contaminated products. The first patient's home was inspected, but no traces of rat droppings were found there. So for the time being, doctors are unable to establish how it's being passed on between humans and rats.As far as treatment goes, drugs commonly used to treat hepatitis have shown very mixed results. While for some people the infection can be mild, for others, it can have serious consequences.Will New York and Paris be hit next?In an interview with CNN, Dr. Siddharth Sridhar, a microbiologist and researcher at HKU, gave suggestions to prevent the onset of this disease:For now, all authorities can do is urge people to take preventative measures, like washing their hands before eating, storing food properly or in the fridge, and keeping the household clean and disinfected with minimal nesting places for rodents.Then added:This could be happening everywhere. This likely isn't just a Hong Kong problem, or even a recent one, experts say. Rat HEV could be infecting people in New York or Paris, and we just don't know it – because nobody is testing for it. Within Hong Kong, the 11 confirmed cases are likely just the tip of the iceberg.