Hong Kong health officials are investigating a local case of Japanese encephalitis (JE) and urge the public to avoid going to rural areas from dusk till dawn when the vector, which breeds in large water bodies such as rice paddies, is most active.

Hong Kong/CIA
Hong Kong/CIA

According to the attending physician and the patient’s family, the male patient, aged 59 with good past health, lives in Healthy Village, North Point. He has developed confusion and abnormal behavior since September 11. He attended Pamela Youde Nethersole Eastern Hospital on September 18 and was found to have fever, left sided weakness and confusion and was admitted for management. He is now in stable condition.

His cerebrospinal fluid tested positive for immunoglobulin M (IgM) antibodies against JE upon laboratory testing.

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Initial inquiries revealed that the patient had no travel history in the incubation period. His local movements before onset were mainly from his residence to Tsuen Wan to the Hong Kong Boundary Crossing Facilities (HKBCF) of Hong Kong-Zhuhai-Macao Bridge (HZMB) for work. His home contacts have remained asymptomatic and have been put under medical surveillance.

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 “As the patient is suffering from confusion and unable to provide further details of his exposure history, epidemiological investigations are ongoing,” a spokesman for the Centre for Health Protection (CHP) said.

This is the fifth JE case recorded in 2017 and all were locally acquired, four of which were mosquito-borne and one was blood-borne. Two (imported) and two (one local, one unclassified) cases were recorded in 2016 and 2015 respectively.

13 Diseases You Can Get From Mosquitoes

JE is a mosquito-borne disease and the JE virus is transmitted by the bite of infected mosquitoes. The principal vector is called Culex tritaeniorhynchus. JE mainly occurs in rural and agricultural areas of Asia and the Western Pacific. The infected mosquito transmits the JE virus to humans and animals during biting. The mosquitoes breed where there is abundant water such as rice paddies and become infected by feeding on pigs and wild birds infected with the JE virus. Symptoms usually start around four to 14 days after being infected.