Mosquito-borne illnesses such as the Zika virus and dengue fever could increase in Southeast Asia in the second half of the year, South Korean health authorities said Tuesday.

The Korea Centers for Disease Control and Prevention forecast that the viral diseases transmitted by mosquitoes could thrive in countries such as the Philippines and Vietnam starting in October when the rainy season begins.

South Korea has so far confirmed 10 Zika virus cases, with three of the infected returning from the Philippines and two from Vietnam

The KCDC also forecast the disease would not be active in South American countries later this year, such as Argentina and Paraguay, where no cases have been reported in the past two months as it is currently dry season.

The KCDC also advised pregnant women and their partners who are worried about potential exposure to consider avoiding travel to such areas.

Those who have traveled to affected regions in the past two months are advised to avoid any sexual contact or wear condoms if their partner is pregnant.

Zika cases have raised concerns of a widespread epidemic in South Korea just a year after an outbreak of Middle East Respiratory Syndrome.

The KCDC said a total of 174 have been diagnosed with the respiratory disease across the globe so far this year, with 59 confirmed deaths.

In South Korea, the number of people suspected to have been infected with the potentially deadly MERS was 135 as of Saturday, KCDC officials said. (Yonhap)