Tuberculosis: Vaccine, Intervention, Prevention & Control

TB Vaccine: BCG

Bacille Calmette-Guérin (BCG) is one of the vaccines in the Expanded Program of Immunization (EPI). In many countries where tuberculosis is common BCG vaccine is ideally administered at birth. BCG vaccine main action is to prevent the complications of tuberculosis, such as extrapulmonary/non-infectious tuberculosis in children. BCG vaccine is not recommended to prevent and control tuberculosis in adult populations because BCG vaccine does not have any considerable effect on Tuberculosis transmission or incidence.

TB Intervention

Directly Observed Treatment, Short Course (DOTS) is ranked by the World Bank as one of the "most cost-effective of all health interventions”. Over the past two decades DOTS is developed from best practice experiences, clinical trials, and programmatic operations of tuberculosis control. In 1995, WHO launched the DOTS strategy for combating Tuberculosis. Ever since 184 countries out of 212; including the tuberculosis high burden countries (22 countries) have adopted DOTS. Even in the poorest countries the DOTS has produced cure rates of up to 95% (cure rates are for tuberculosis in the absence of HIV or multi-drug resistance).  DOTS program halts transmission of tuberculosis to the susceptible populations. It ensures that the full course of treatment is followed and decreases the risk of multidrug-resistant tuberculosis (MDR Tuberculosis). DOTS program is cost-effective to save a life, in some parts of the world a full course of drugs to treat typical tuberculosis case cost as little as US$16.  A sputum smear positive cases are more likely to be treated successfully if, treated under a DOTS program.

Tuberculosis is cured when the patient's sputum test reverts to negative at least once during treatment and then remains negative in the last month of treatment. Persons with a positive skin test reaction are of the high-risk groups and are prescribed drug (isoniazid) daily, for nine months. Isoniazid acts by killing tuberculosis bacteria that are inactive in the body. It also prevents the development of active tuberculosis from latent infection. However, before starting one-drug treatment it is very crucial to rule out active Tuberculosis. The latent tuberculosis is treated with only one drug whereas active tuberculosis is treated with four drugs at first.

HIV/Tuberculosis Co-infection

The co-infection of HIV/Tuberculosis is a lethal combination because each accelerates the other’s progress. Globally, almost 10% of all new tuberculosis cases are HIV positive. However, this number varies widely on a country basis and can be as high as 80%. In developing countries many people infected with HIV develop tuberculosis as the first manifestation of AIDS. The tuberculosis infection progresses faster in HIV-positive individuals therefore, if left undiagnosed or untreated it is almost certain to be rapidly fatal.

An estimated annual death due to HIV/AIDS is 2 million, 1.7 million due to tuberculosis and 2.1 million due to malaria. The global tuberculosis incidence is estimated to be expanding, to a certain extent, because of the powerful interaction between HIV and Tuberculosis. It is a leading cause of death among HIV positive population, 1 in 3 people with HIV/AIDS die of tuberculosis. Worldwide tuberculosis accounts for about 30% of AIDS deaths. An HIV positive person infected with tuberculosis is 50 times more likely to become sick with tuberculosis than HIV negative person infected with tuberculosis. Relative to HIV status, the lifetime risk of developing tuberculosis is 5% to 10% if HIV negative and 50% if HIV positive.

Direct observation of treatment (DOT) for co-infection of HIV/Tuberculosis

Evidences show that 85.4% of HIV-infected tuberculosis patients survived who received short-course chemotherapy (SCC) with direct observation of treatment (DOT). Whereas, only 56.7% of HIV-infected tuberculosis patients survived who received SCC without DOT. Tuberculosis could be prevented in millions of people infected with HIV through the use of IPT. Once active tuberculosis disease is ruled out, IPT can be safely used. There is no evidence that IPT increases isoniazid drug resistance.

The best way to prevent and control Tuberculosis is to find and successfully treat all cases of sputum smear positive (active) pulmonary Tuberculosis. The focus on case finding among high risk groups e.g., the homeless, malnourished, elderly, injection drug users, prisoners, and HIV-positive populations, facilitates case detection and earlier onset of treatment. This approach minimizes the number of inadequately treated tuberculosis patients, and the risk of drug resistance.

The health care workers can protect themselves against Tuberculosis infection by using masks when collecting or handling sputum, and caring for patients with sputum smear positive tuberculosis disease. The use of ultraviolet light is recommended in laboratories where sputum is collected from tuberculosis patient. Better ventilation is encouraged in the household, clinic, or workplace.

The key challenges to Tuberculosis control and prevention are; lack of political will and commitment at all levels, weaker health systems for case detection,  inadequate referral and follow-up, lack of adequately trained workforce, inadequate tuberculosis drug supply for all cases, discontinuous tuberculosis drug supply, tuberculosis/HIV Co-infection, tuberculosis drug resistance, insufficient technology for tuberculosis diagnosis, outmoded vaccine (BCG). Tuberculosis prevention program requires the community to understand the importance of Tuberculosis control. This helps identify creative solutions in communities where daily access to the health system is not possible. While implementing Tuberculosis prevention program it is crucial to understand the community perspectives. The programs are to be designed to address both TB/HIV infection and multidrug resistance (MDR), issues of stigma and discrimination associated with both tuberculosis and HIV among hard-to-reach groups and increase outreach. Addressing these issues will have a significant impact on Tuberculosis disease. Community education campaign is very effective in sharing knowledge that Tuberculosis is a curable disease.