BERLIN – As the world is preparing for the Soccer World Cup in South Africa, the country has already won a world championship that no one covets - with regard to a deadly respiratory disease, tuberculosis (TB).

Researchers from the German Central Committee for the Fight Against Tuberculosis are warning against the dangers of multidrug-resistant TB (MDR-TB) in Sub-Saharan Africa.

They fear that, although the incidence of TB in western Europe is declining, the world as a whole faces a catastrophe that will also affect industrialised nations. The main reason, aside from TB/HIV co-infection, is the rise of resistant TB strains.

In early 2008, the World Health Organization (WHO) reported an unexpectedly large increase in the number of cases of drug-resistant tuberculosis. At present, an estimated 5% of the more than 9 million people who develop TB around the world every year are infected with an MDR-TB strain, i.e. a strain that is resistant to (at least) the two most powerful anti-TB drugs currently available, isoniazid and rifampicin. The current WHO report also contains data on extensively drug-resistant tuberculosis (XDR-TB), which was first described in 2006.

By definition, XDR-TB is MDR-TB that is additionally resistant to at least one of the fluoroquinolones and to one of the three injectable second-line anti-TB drugs, amikacin, kanamycin, and capreomycin.

One of the key messages conveyed in the article is that not only did almost 2 million deaths occur due to TB in 2007 but that many of the cases were coinfected with HIV, a particular problem in Africa.

HIV and TB go hand in hand

South Africa, with some 5.7 million people infected with HIV, already faces the world's largest HIV epidemic. To make matters worse, almost one in 100 people is infected with TB (2007).

“It is estimated that worldwide, in 2007, 1.37 million of the 9.27 million persons with new tuberculosis infections were co-infected with HIV (14.8%), and 456,000 persons died of tuberculosis in the presence of an HIV infection,” writes Professor Robert Loddenkemper in the journal Deutsches Aerzteblatt.

In some countries of Sub-Saharan Africa, the TB/HIV co-infection rate has risen dramatically, to 50–80%. HIV-positive people carrying a latent Mycobacterium tuberculosis infection are at markedly higher risk of developing TB. Next to malaria, tuberculosis and HIV are the deadliest infectious diseases worldwide, and TB is one of the main causes of death in HIV-infected people.

It is unclear whether HIV infection is a risk factor for drug-resistant or MDR-TB. Known factors that can promote the development of resistance include malabsorption, drug intolerance, drug interactions, and noncompliance among intravenous drug abusers.

There was a catastrophic development in South Africa in 2006, when XDR-TB was transmitted from infected patients to members of a village community with a high prevalence of HIV. The affected patients were hospitalised, whereupon a large number of patients and hospital employees died within a few weeks. The main causes for the persistent transmission of XDR-TB in South Africa are, aside from the high prevalence of HIV, delays in diagnosis and treatment and the inadequate availability of modern diagnostic procedures, second-line drugs and precautions against infection.

“The widespread presence of [XDR-TB] is a matter of great concern. Such infections are usually impossible either to diagnose or to treat in countries with limited resources, and they are therefore of major concern to public health,” write the researchers.

Reference:
Loddenkemper R et al. Dtsch Arztebl Int 2010; 107(1–2): 10–9