Numerous Hong Kong people mysteriously contracted hepatitis virus from mice

Scientists have discovered that rats are a source of transmission of hepatitis E to some people, but are still investigating how transmission occurs.

One day in 2018, experts in infectious diseases at the University of Hong Kong (HKU) discovered a strange patient. The 56-year-old man recently had a liver transplant, and is showing abnormal liver function without a clear cause.

Tests show that the patient's immune system responds to hepatitis E , but the doctor is unable to find the person's strain of the virus (HEV) in his blood, according to CNN.

Choi Wan Apartment in Hong Kong, where the first patient infected with mouse HEV virus was discovered in 2018. (Photo: AFP)

Detecting shock

Hepatitis E is a liver disease that can cause fever, jaundice and aneurysm. The virus is only circulating in 4 animals and at that time, only 1 species has the ability to infect humans.

With the HEV tests in humans negative, doctors redesigned the diagnostic procedure, and for the first time in history, the virus was found to cause hepatitis E in mice in humans.

"Suddenly, we have a virus that can jump from mouse to person," said Dr. Siddharth Sridhar, a microbiologist at HKU who discovered the incident.

This is a case unusual and not a precedent, I told the team to question whether the work can occur only once because the patient was in the "wrong place, wrong time" or is not.

But such cases continue to appear.

Since the first study in 2018, 10 more Hong Kong people were positive for HEV in mice. The most recent case was discovered two weeks ago: a 61-year-old man with abnormal liver function and tested positive for the hepatitis E virus in mice on April 30. Dr Sridhar thinks there could be hundreds of other undiscovered patients.

According to the World Health Organization (WTO), hepatitis E strains in humans are often transmitted through contamination of faeces of infected people with water. But the mouse virus has raised a new question, because no one knows how these patients are infected.

In the two years since the discovery, researchers have yet to determine the exact route of transmission from mice to humans. They make assumptions such as patients drinking contaminated water, or coming into contact with contaminated objects - but nothing is certain.

The 61-year-old patient was extremely confused by officials and health professionals, because there were no rats or rat droppings in his home. No one else in his family has symptoms and he has no recent travel history.

"Based on available epidemiological information, the source and route of transmission of the disease cannot be determined," the Hong Kong Health Protection Center (CHP) said in a statement on April 30. The patient is still being treated in a hospital, and the CHP investigation is still ongoing.

Queen Mary Hospital, Hong Kong's leading medical facility, is treating the latest patient infected with mouse HEV virus. (Photo: South China Morning Post).

Research teams and city officials have gained a better understanding of this new health threat since 2018. They have made some progress, improved diagnostic procedures, and improved health awareness. health of the community as well as warning doctors about the existence of hepatitis E virus in mice in humans.

Scientists are also randomly testing mice across the city to detect outbreaks before the virus can infect humans. They now have data on how many mice in the city carry the hepatitis E virus, and which areas have the most mice.

But there are still many unknowns, including the incubation period of the human mouse HEV virus - how long it will take for patients to develop symptoms after infection. Next, they are also looking for a suitable treatment, because the drug for human hepatitis E does not have stable results for rat HEV virus.

And of course, the biggest mystery that scientists have a headache about is determining how to infect humans. If this cannot be determined, preventing infection will be difficult - even making the collected data useless.

For example, theoretically, people living in areas with many rats are at higher risk, but some infected patients come from very few neighborhoods.

"What we know is that mice in Hong Kong carry the virus, and we examine patients and find viruses. But specifically how the virus jumps from mouse to person - whether the mouse will poison the food of we, or any other animal involved, we don't know. That's the missing link , " said Dr. Sridhar.

Threat in the future

One solution is thought to be to eliminate all rats in Hong Kong, but killing rats is a long, complicated, and impossible war. Currently, all officials can do is call people to take precautions such as washing their hands before eating, storing food properly or putting it in the fridge, and keeping their shelters clean. Avoid rats nesting.

This is not even a Hong Kong problem, and it's possible the infection has been around for a long time, according to experts. It is possible that the mouse HEV virus is infecting New York or Paris people without our knowledge, because no one is testing.

"My feeling is that this has been going on for a long time. 2017, 2018 is certainly not the first time it has happened in the world," said Sridhar.

In Hong Kong, 11 confirmed cases could be just the tip of the iceberg, Sridhar said. Doctors found mouse HEV virus in these patients because they went to the hospital when they had symptoms, or accidentally discovered it before they performed a transplant.

An apartment complex in Hong Kong disinfected and called on people to keep clean to prevent mice from living. (Photo: South China Morning Post).

But there may be hundreds of cases in the community that are not among these, and so have not been diagnosed, according to Sridhar. Many people with hepatitis E only experience mild symptoms and in some cases do not even know they have the infection.

However, the virus can have serious health consequences, especially for patients with weak immunity. It can cause chronic hepatitis that can cause long-term liver damage.

Out of 11 cases in Hong Kong, only one other case of rat HEV infection has been confirmed worldwide - a Canadian patient who has been to Africa. He came to the hospital after suffering from urticaria, nausea, severe jaundice and inflamed liver, test results showing he was positive for mouse HEV virus.

The only reason this patient was discovered was because doctors used a wide test that could detect many strains of the hepatitis E virus.

This is a cause for concern, because most countries do not test mouse HEV viruses, so they may not be detected in the community.

A separate test is needed to detect mouse HEV in humans, as in the case of the University of Hong Kong. This test is not difficult to perform, but it is not widely used because recently no one thinks that mouse HEV virus is a threat to humans.