South Korean health authorities said Tuesday that the heat wave nationwide is leading to an increased number of virus infections caused by mites that can be lethal.

A total of 41 patients have contracted thrombocytopenia syndrome (SFTS), which has a 30 percent fatality rate, from mites this year. This is a 30 percent rise from last year.

The surge is caused by the sweltering heat, during which the mites, named Haemaphysalis longicornis, become more active.

The SFTS virus infection was first reported in the country in 2013, leading to 17 deaths among 36 patients. The number increased from 55 infected patients with 16 dead in 2014 to 79 infected cases with 21 dead in 2015. There is currently no vaccine or cure to treat the virus contracted from the mites.

According to experts, humid and hot weather makes it easy for the mites to reproduce. The recent heat wave has led to at least 1 1/2 times more mites found outdoors, they added.

Ten of the infected cases occurred in Daegu, where the daytime temperature soared to 36 degrees Celsius over the weekend.

“The government should speed up the process to develop plans to curb the increasing number of mites, along with research in vaccine and treatment to prevent the rise in the number of health damages each year,” said Lee Hoi-sun, a professor of bioenvironmental chemistry at Chonbuk National University.

Main symptoms of SFTS include high fever, nausea, diarrhea and stomach cramps.

Since the symptoms are similar to those of flu, it is important to visit a hospital as soon as possible if there is persistent high fever, experts said.

As mites mainly inhabit places along the riverside and near barns of livestock, experts encouraged people to stay away from such areas. For those who cannot avoid visiting such places, such as those who work on farms, they advised wearing long sleeves and taking a shower immediately afterward.

By Kim Da-sol(ddd@heraldcorp.com)