Dr. Siddharth Sridhar, clinical assistant professor at the University of Hong Kong said, "Previous laboratory experiments have found that rat hepatitis E virus can not be transmitted to monkeys, and human hepatitis A virus can not be transmitted to rats", explaining that when it comes to disease susceptibility, monkeys are the closest to humans.
The man exhibited unusual and recurrent liver dysfunction following the transplant, the BBC reports, with subsequent tests revealing the presence of a "highly divergent" version of the hepatitis E known to afflict humans.
In a statement, they added: 'This study conclusively proves for the first time in the world that rat HEV can infect humans to cause clinical infection'.
The clinical assistant professor at the University of Hong Kong continued: 'Rat hepatitis E virus now joins the list of infections as an important pathogen that may be transmitted from rats to humans'.
The man lived in a housing estate where there were signs of rat infestation outside his home.
The human strain of hepatitis E is typically spread through contaminated water or food, according to the Centers for Disease Control and Prevention.
There had been no previous evidence that this strain of the virus could be transmitted to humans.
Hepatitis results in inflammation of the liver caused by various viruses. But because the rat strain is present in rats all around the world, it may be time to modify the diagnostic tests used for hepatitis to include such strains, to see whether this can solve "cases of unexplained hepatitis", he said.
The man is said to be recovering.
The infected person will face a variety of symptoms like fever, nausea, discoloration of the eyes, dark urine, pale stools, and an enlarged liver.
There is no treatment for hepatitis but it usually clears up by itself. It was not previously known the disease could be passed from rats to humans.
The human form of hepatitis E is generally transmitted through contaminated water and is guesstimated to infest 20 million people worldwide, consequential of 3.3 million people showing symptoms each year as per the World Health Organization.
Hepatitis E is a major health threat in developing countries in Africa and Asia and in the past has been contracted from eating undercooked pork and deer meat.
A sustained period of hot and humid weather has caused rodent problems in Hong Kong to escalate, multiple sources reported.