Just two months after Hong Kong reported the world’s first rat-to-human hepatitis E virus (HEV) transmission, comes another report of a city resident who contracted the liver virus, the South China Morning Post reports.

City officials say this second case occurred less than two miles away from the first, although the infections do not appear to be linked. The news is raising concerns that rodents in crowded cities could pose a new risk for humans and confirms that the virus, has crossed over to the human population.

According to the Chinese news outlet, a 70-year-old Hong Kong woman with underlying illnesses and a suppressed immune system contracted the animal-borne virus, which bears some similarity to human hepatitis E virus, last year. The woman was hospitalized for abdominal pain, loss of appetite and malaise, treated and discharged four days after recovering.

Later, the patient’s blood sample was analyzed in labs at Hong Kong University, where researchers first discovered it to be carrying the rat hepatitis E virus. The university reported its findings to Chinese health authorities earlier this month.

In response to the infections, Hong Kong has significantly ramped up its efforts to combat rodent populations across the city and has caught more than 14,000 live rats and poisoned over 26,000 over the past year.

Authorities consider both cases to be isolated incidents.