Suspected cases of tuberculosis outbreaks at mass facilities more than tripled in South Korea over the past three years, a report showed Thursday. 

According to a report from the Korea Centers for Disease Control and Prevention, the government conducted 3,502 epidemiological investigations in 2016 for possible TB outbreaks at schools, hospitals and other mass facilities where at least one person was confirmed to have contracted the infectious disease. The number of surveys more than tripled from 1,142 in 2013.

This year, from January to June, health authorities carried out 1,791 such surveys. 

By type of facilities investigated, 288 were schools, 590 were medical institutions, 54 were military or police units, 302 were correctional or social welfare facilities, 491 were companies and 66 were other organizations. 

Forty-one people were confirmed with TB from the examinations, while 4,408 others were found to have acquired inactive TB -- a condition in which the TB bacteria is in the body but inactive with no symptoms -- via exposure to 58,758 TB patients from group facilities.

TB is a bacteria-related disease that mainly attacks the lungs and is one of the world’s most infectious killers, along with HIV and malaria.

South Korea had the highest TB prevalence rate among 34 member countries of the Organization for Economic Cooperation and Development in 2015, with 63 patients per 100,000 people. Portugal ranked second with 25 patients, followed by Poland with 21.

According to doctors, only about 10 percent of latent TB patients are known to develop TB at some time in their lives, usually between age 15 and 40.
In March, the government implemented free wide-scale TB testing as part of efforts to cut the high incidence rate.

Some 600,000 high school freshmen, teachers and other school employees were tested in the following month, according to the Health Ministry.
Meanwhile, on Wednesday health authorities said 118 newborns were infected with inactive TB at an obstetrics clinic in Seoul from a nurse with TB who started working at the clinic in November last year. 

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