Steps to prevent tuberculosis spread: Understanding the key measures

Avoiding Tuberculosis Spread: Strategies for Prevention

Tuberculosis (TB) is an airborne infection caused by the bacterium Mycobacterium tuberculosis (M. tuberculosis), and it is crucial to understand how it spreads and how to prevent its transmission.

Firstly, it is essential to note that M. tuberculosis usually transmits from the lungs and throat, not from other locations such as the spine or kidneys. Transmission occurs when a person with active symptoms, such as coughing, is present. A person with active TB disease can spread the bacteria through coughing, sneezing, singing, speaking, yelling, laughing, or playing a wind instrument.

However, a person cannot become infected with TB through contact, such as handshakes, shared dishes, toilet seats, or faucets. To prevent transmission, a person with active TB disease should maintain physical distancing from others.

People with latent TB cannot spread the bacteria to others. Nevertheless, anyone with exposure to TB bacteria can develop TB disease, but certain people are more likely to get sick sooner. These include children under 5 years old, older adults, people who have had a TB infection in the last 2 years, those who use injectable illegal drugs, people who have received incomplete TB treatment in the past, those with low body weight, people receiving immunosuppressant therapy, low-income or medically underserved populations, those who have had intestinal bypass or gastrectomy surgery, people who drink large quantities of alcohol, people with certain medical conditions such as HIV, diabetes, certain cancers, chronic renal failure, silicosis, and people who have had pulmonary TB in the past.

TB infection is a reportable disease by law, and suspected or confirmed cases should be reported to the designated department or official. Employers in high-risk settings, such as healthcare, can maintain a TB prevention program and support the timely identification of people who carry the TB bacteria.

TB testing can identify latent TB, allowing prompt treatment and potentially preventing progression to active disease. Household contacts of a person with active TB may require preventive treatment and screening.

In some cases, TB screening can be complicated by the BCG vaccine. BCG vaccination is rare in the U.S. but common in many countries with high TB prevalence. Some immigrants and travelers to the U.S. may have been vaccinated with BCG. Because of this potential for false-positive TB skin tests, interferon-gamma release assays (IGRAs, or TB blood tests) are preferred for testing in persons who have received the BCG vaccine. Unlike the skin test, these blood tests are not affected by prior BCG vaccination and have higher specificity for TB infection, making them the recommended diagnostic method in this group in the U.S.

To reduce the amount of bacteria in the air, a person with active TB disease can wear a mask, ventilate rooms, cover their mouth and nose when coughing or sneezing, and use HEPA filters. Upper-room ultraviolet germicidal irradiation (UVGI) lamps may also kill or inactivate airborne TB bacteria, reducing the risk of infection in people in the room, particularly in healthcare settings. However, UV light can damage the skin and eyes, so lamps should be installed out of sight in HVAC systems or high up in a room, and technicians who service the lights should wear protective equipment.

Lastly, it is important to note that UV air purifiers can emit ozone, which may cause breathing difficulties. The California Air Resources Board has a list of electronic air cleaners that test found to emit less than 0.05 parts per million of ozone.

In conclusion, understanding how TB spreads and taking preventative measures is crucial in controlling its transmission. While BCG vaccination can complicate TB screening, TB blood tests are favored in this population in the U.S. to avoid false-positive interpretations. Proper ventilation, mask-wearing, and the use of UVGI lamps can also help reduce the spread of TB in high-risk settings.