According to the World Health Organization (WHO), the number of new TB cases globally was 9.4 million in 2008 (WHO, 2009a). The disease killed 1.8 million people in that year, or 4,500 per day. While the highest number of cases of MDR TB (estimated annual numbers of new cases) is in Asia, the greatest per capita rates are in Africa (WHO, 2010a). No accurate and up-to-date data concerning the prevalence of MDR and XDR TB are available for most African countries. However, WHO estimates that more than 75,000 new MDR TB cases will occur in Africa in 2010 (Figure 2-1). By WHO estimates, 440,000 global cases of MDR TB arose in 2008; about 5.4 percent of these cases were XDR TB. About 15 percent of all TB cases, or 1.4 million, are associated with HIV infection. The 450,000 deaths caused by HIV-associated TB represent 26 percent of TB deaths and 23 percent of HIV deaths.

After briefly examining the relationship between reported incidence rates and the diagnostic tools used, this chapter summarizes information presented at the workshop on the incidence and burden of drug-resistant TB in South Africa. It then summarizes presentations and discussions that looked more closely at the outbreak of MDR and XDR TB in KwaZulu-Natal Province and that addressed coinfection with HIV/AIDS in southern Africa.

RELATIONSHIP BETWEEN REPORTED INCIDENCE AND DIAGNOSTIC TOOLS1

There is evidence that differences in the reported incidence of drug-resistant TB could be attributable, at least in part, to the diagnostic tools used in particular areas. Sturm reported that since 2005, the Church of Scotland Hospital (CoSH) in Tugela Ferry has been the only health care facility in KwaZulu-Natal Province to use culture diagnostics for all possible TB cases. The Msinga subdistrict, in which CoSH is located, is also the region in the province with the highest reported number of cases of XDR TB. Yet the incidence of drug-resistant TB in the Msinga subdistrict would not be expected to differ from that in the province’s other subdistricts and districts. The main difference appears to be that in the Msinga subdistrict, culture and drug susceptibility testing is done on all first contacts. Elsewhere, many patients die before a specimen is taken or the results of drug susceptibility testing become available.

Research also has found an association between the number of new cases of TB diagnosed by culture and the reported percentage of drug-resistant TB. In 2007, data on the presence of the F15/LAM4/KZN strain of

1

This section is based on the presentation of Adriaan Willem Sturm, Nelson Mandela School of Medicine, University of KwaZulu-Natal.



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