Eighteen people have died from heat-related causes so far this year, officials said Thursday, as intense heat with apparent temperatures of over 35 C continues to grip the country.A total of 1,907 people had suffered heat-related illnesses from May 20 to Thursday, and 18 of them have died, according to the interior ministry.During the same period last year, the number of heat-related patients totaled 1,891, and 25 people died.From June 11 until Wednesday, nearly 420,000 livestock died due to extreme heat, including 393,000 poultry. Some 430,000 fish were also reported dead in fish farms.For the time being, most regions will continue to see apparent temperatures go up to about 35 C and experience tropical nights where the nighttime temperatures stay above 25 C.Strong rain of 30 to 50 millimeters is expected in parts of Gyeongsang provinces on Thursday, and some regions will see showers accompanied by thunder and lightning continue until Friday.Source : Yonhap News Agency