The record summer has brought outbreaks of salmonella poisoning and even Korea's first case of cholera in 15 years.

The Ministry of Food and Drug Safety on Tuesday said schools nationwide are reporting cases of salmonella food poisoning.

More than 500 students at five middle and high schools in northern Seoul came down with salmonella poisoning last week, as did more than 200 students at schools in North Gyeongsang Province, Daegu and Busan.

Seventeen cases of mass salmonella poisoning had been reported across the nation as of Tuesday, with 1,284 people infected. That was a 34-percent increase compared to last summer and up 52 percent compared to the 2011-2015 average.

Yoo Moo-young at the ministry said, "If food ingredients are exposed for just three hours in 36-degree temperatures, staphylococcus bacteria rise to dangerous levels."