The principal vector is Culex tritaeniorhynchus (inset). Photos: Google Maps, FEHD

A 38-year-old man who was reported to have been bitten by mosquitoes in a Tsuen Wan park was diagnosed with Japanese encephalitis on June 30, which was recorded as the second local case in Hong Kong this year.

The man developed a fever and headache on June 18, seven days after he visited Nina Fossil Garden in Tsuen Wan, Oriental Daily reported.

The man, who lives in Tin Shui (I) Estate, was admitted to Tuen Mun Hospital on June 28 and has been in stable condition. The clinical diagnosis was encephalitis.

His cerebrospinal fluid and blood samples tested positive for immunoglobulin M (IgM) antibodies against Japanese encephalitis upon laboratory testing, the Center for Health Protection (CHP) of the Department of Health said in a statement.

The patient had no travel history during the incubation period, and his home contacts have shown no symptoms but have been put under medical surveillance.

The Food and Environmental Hygiene Department is to conduct anti-mosquito measures in Tin Shui (I) Estate and nearby areas for the prevention of spread of the infection.

On June 9, the CHP announced the first local case of Japanese encephalitis this year. The 69-year-old patient with underlying illnesses who lives in Ying Ming Court of Tseung Kwan O was said to be in critical condition in the intensive care unit of Tseung Kwan O Hospital. He had traveled very briefly on the mainland and in Macau during the incubation. Symptoms of headache, dizziness and nausea were first noted on May 29, followed by fever on May 31.

There were two imported cases of Japanese encephalitis recorded in 2016, and one local and one unclassified case in 2015.