Health authorities in Hong Kong are investigating a growing number of rat hepatitis E cases in humans, confirming animal-to-human transmission—but the exact pathway remains unclear.
The issue surfaced in 2018 with a 56-year-old liver transplant patient showing unexplained liver dysfunction. Tests ruled out human hepatitis E strains and identified a rat-specific variant instead.
Initially viewed as isolated, this has led to 11 total cases in Hong Kong (plus one in Canada in 2019). The latest, on April 30, involved a 61-year-old patient. Experts suspect hundreds more undetected cases. A report to the World Health Organization (WHO) underscores the seriousness.
Hepatitis E virus (HEV) spreads via fecal-oral route, prevalent in areas with poor sanitation. Since the early 2000s, it's emerged in developed nations. Globally, it infects 20 million people annually, causing 44,000 deaths.
Typically mild, symptoms can include jaundice, headache, nausea, vomiting, muscle aches, fatigue, and dark urine.
Transmission occurs through contaminated water, infected produce or shellfish, or undercooked meats from pigs, wild boars, or rabbits. In France, undercooked pork liver is the primary source.
The rat HEV strain was previously unknown to infect humans. Key uncertainties persist: What's the transmission route? No rats or droppings were found in the latest patient's home, and no family members were affected.
Other gaps include incubation period and optimal treatments—standard hepatitis drugs yielded mixed results in these cases.
Hong Kong officials have launched public awareness drives and are testing rat populations for clusters to curb spread, echoing COVID-19 strategies.
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