Researchers at a conference in Los Angeles have said that as many as 85% of HIV-positive South Africans are also infected with an extensively drug-resistant form of tuberculosis (TB), Extensive Drug Resistant TB (XDR-TB).
The researchers suggest that XDR-TB is continuing to increase because of globally widespread flaws in the treatment of TB.
According to Karin Weyer of South Africa's Medical Research Council, cases of XDR-TB have been found in 40 hospitals in South Africa, as well as in every province in the country, adding up to a total of around 600 cases.
XDR-TB is resistant to the two most potent first-line treatments isoniazid (Nydrazid) and rifampin (Rifadin) and also to some of the available second-line drugs, and many patients have died.
Although XDR-TB does not seem to spread easily, it does pose a threat to people and health care workers who are HIV-positive and since September 2006, about 183 people, most of whom were HIV-positive, have died from XDR-TB in the country.
XDR-TB is expected to exacerbate the HIV/AIDS epidemic in South Africa, where about five million out of a population of 45 million people are HIV-positive and as many as 1,000 people die of AIDS-related complications daily.
According to the World Health Organization (WHO), the number of countries with XDR-TB cases has increased from 17 in March 2006 to 28 currently.
According to the Center for Disease Control (CDC) the most-affected countries include South Africa, South Korea and parts of Eastern Europe.
Weyer says XDR-TB creates a huge challenge in terms of infection control, especially in settings where high numbers of HIV-positive individuals are converging, such as hospitals.
Paul Nunn, the coordinator of WHO's TB drug-resistance unit, says the 85% mortality rate is "completely egregious" and it is important to increase awareness about XDR-TB worldwide without causing undue alarm.
Nunn estimates the cost to the international community to address the problem will be in the region of $650 million annually on efforts to control various strains of MDR-TB, of which XDR-TB is one.
The director of the CDC's National Center for HIV, STD and TB Prevention, Kevin Fenton, says the XDR-TB cases in South Africa are a "wake-up call" for bolstering TB surveillance and prevention efforts.
The data and conclusions presented by Dr. Weyer are preliminary as they are yet to be reviewed and published in a peer-reviewed publication.
Dr. Nunn says the continued rise of XDR-TB is "hugely problematic," especially for countries where HIV is also raging.
The impact of XDR-TB was starkly illustrated last year when researchers outlined an outbreak among HIV-positive people in South Africa, where 52 of 53 patients died within two weeks of diagnosis.
Dr. Weyer says possibly more alarming is that HIV-negative people stay on treatment but do not get well owing to the extensive drug resistance, making them reservoirs of disease.
Dr. Weyer presented the research at the 14th Conference on Retroviruses and Opportunistic Infections in Los Angeles early this week.