The city of Busan said yesterday that it will strengthen the watch on mosquitoes carrying the disease Japanese encephalitis which are also referred to as small red house mosquitoes in Korean.

While infection via Japanese encephalitis-carrying mosquitoes is known to cause none or mild fever like symptoms in more than 99% of the cases, some patients are known to have acute encephalitis symptoms, while as many as 20% to 30% of them are known to have died due to the infection.

Usually, these mosquitoes are first found in Busan in mid-April every year; however, for this year, it has been found in Jeju on the 6th of April for the first time.

Busan city has said it hasn’t found the disease-carrying mosquitoes yet in the port city but will carry out strengthened surveillance and control activities to prevent the spread of the infectious mosquitoes.

About 90% of the infected patients are 40-years-old or older, and that older people are more prone for serious symptoms.

The Korean Centers for Disease Control and Prevention has issued an advisory to all people in the nation to be on the watch for these mosquitoes.