South Korean health authorities said Monday that they had found killer bush ticks in public parks along the Han River, raising alarm over the possible infection of deadly mite-borne diseases. 

A report released by Seoul Metropolitan Government’s Health and Environment Research Institute showed that 7,021 ixodid ticks were collected from 19 out of 35 parks and promenades around the Han River from 2014 to 2016. 

Ixodid ticks, a type of lethal mites, can cause thrombocytopenia syndrome (SFTS), which has a 30 percent fatality rate. A total of 41 patients have contracted SFTS from mites in South Korea this year. 

SFTS virus infections were first reported in the country in 2013, leading to 17 deaths out of 36 patients that year. The number increased from 55 infected patients and 16 deaths in 2014, to 79 infected cases and 21 deaths in 2015, and 19 deaths in 2016. 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. They may remain active until November, as relatively warm climates continue during the daytime. Earlier this summer, the sweltering heat had led to these mites becoming more active. About 1 1/2 times more mites were found outdoors, they added. 

The report, however, said an analysis on virus genetics showed that there was no SFTS virus detected from the collected mites. It added that falling outdoor temperatures will naturally diminish the risk of bites from mites. 

Seoul City’s quarantine authorities said they plan to monitor lethal mites at the Han River parks and execute timely quarantine measures such as weeding to prevent SFTS virus infections. 

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