1 out of 3 Koreans diagnosed with latent tuberculosis

By Kim Hyun-bin

It is believed that one out of every three Koreans are deemed to have latent tuberculosis (LTB), while 76.8 people out of every 100,000 are diagnosed with active TB, which is the highest rate among the OECD member states.

Each year in the country, 30,000 people on average are newly diagnosed with the disease and some 2,000 people die from it.

The U.S. Centers for Disease Control (CDC) notes, "The bacteria that cause TB are spread through the air from person to person when a patient with the disease coughs, speaks or sings. People nearby may breathe in these bacteria and become infected. People with TB usually have symptoms and may spread the TB bacteria to others."

Experts say checkup is important to diagnose and manage LTB, which is neither infectious nor symptomatic but could turn active.

Active TB can be contagious while LTB is not, and it is therefore not possible to contract TB from someone with LTB. However, the main risk is that approximately 10 percent of these people will go on to develop active tuberculosis. LTB patients who are young or have a weak immune system need to take extra caution as it can change into active TB.

TB infections began to increase drastically in 1985, partly because of the emergence of HIV. HIV weakens a person's immune system so it can't fight the TB germs. Even the United States, which provides stronger control programs, remains concerned for the spread of TB.

TB is a potentially serious infectious disease that mainly affects lungs. Many strains of TB have resistance to drugs that are used to treat the disease. People with active TB must take several types of medication for many months to eradicate the infection and prevent development of antibiotic resistance.

However, most TB infections are still in the latent form. The LTB virus infiltrates the body but is restrained by the immune system and is not contagious and tests negative for TB.

"Patients diagnosed with active TB should always wear a mask to prevent the spread of the bacteria," said Lee Jae-gap, professor of infectious diseases at the Hallym University Medical Center. "When having contact with a TB patient without a mask, there is a 30 percent chance of infection."

TB bacteria slowly spread through the body, consume nutrients and destroy organs. However, the initial symptoms are coughing, which many mistake for a cold and don't get proper treatment.

When the coughing continues for over two weeks, there is a high possibility of TB infection. Common symptoms are coughing that lasts three or more weeks, coughing up blood, chest pains, pain with breathing or coughing, unintentional weight loss, fatigue, fever, night sweats, chills and loss of appetite.

Once the TB become active, it will take longer to treat than when it is in the incubation stage. Experts say early discovery of the disease could prevent 90 percent of TB infections.

LTB checkup for people with weak immune system

People who have had contact with a TB patient or have weak immune systems should get checkups for LTB. According to the CDC, the high-risk group includes HIV patients, those who have had recent contact with TB patients, people with fibrotic changes on chest radiograph, and organ transplant recipients.

There are two types of tests to detect LTB ― tuberculin skin tests (TST) and interferon gamma release assay (IGRA). TSTs are administered to detect the presence of Mycobacterium tuberculosis, the bacterium that causes TB. TB proteins are injected into the arm to see whether the skin reacts by developing a firm red bump. The IGRA takes blood samples of the patient and finds the amount of interferon which is secreted by reacting TB antigens.

Experts say to fully cure TB, specific medications must be taken taken regularly in the right doses for a certain period of time. If not followed properly, there is a high possibility the treatment could fail.

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