Tuberculosis Part two

Taking several drugs does a better job of killing all of the bacteria and is more likely to prevent them from becoming resistant to the drugs. Careful adherence to the treatment schedule is necessary to prevent the development of resistance.

To ensure thorough treatment, it is often recommended that the patient takes his or her pills in the presence of someone who can supervise the therapy. This approach is called DOTS (directly observed treatment, short course). DOTS cures tuberculosis in 95 percent of cases. The Malawi National TB Control Programme has been implementing DOTS (the internationally recommended strategy for TB control) for two decades, achieving nationwide coverage.

The 2009 WHO guidelines recommend antiretroviral treatment for everyone with TB regardless of CD4 count, with antiretroviral therapy to be initiated soon after TB treatment. Antiretroviral therapy also reduces the incidence of TB at a population level among people living with HIV when a high level of access is achieved. A study in a South African township has shown that within three years of the introduction of ART, new TB cases fell by 60 percent among people with HIV.

In some settings, preventive treatment or ‘prophylaxis’ is also given to people with HIV who live or work in situations where exposure to tuberculosis is common. Examples include healthcare workers, caregivers and household contacts of people with active tuberculosis, miners and prisoners. Although prophylaxis can eliminate latent tuberculosis infection, it does not prevent a new infection.

When a strain of tuberculosis bacteria is resistant to two or more ‘first-line’ antibiotic drugs it is called multi-drug resistant TB or MDR-TB. When it is resistant to three or more ‘second-line’ antibiotics as well, it is classed as extreme drug resistant tuberculosis, or XDR-TB. Drug resistance usually arises when tuberculosis patients do not or cannot take their medicine as prescribed, and drug-resistant mutations of the bacteria are allowed to replicate. People can also catch MDR and XDR-TB from others.

Although HIV infection does not of itself increase the chance of drug resistance occurring, both MDR-TB and XDR-TB are very serious threats to HIV positive people, whose weakened immune systems render them unlikely to fight off tuberculosis naturally. Some 872 cases of MDR-TB were reported in 2007 in Malawi, but extensively drug-resistant (XDR) TB has not yet been reported.

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