Continent braces for deadly new TB strain

Africa is facing the prospect of a sharp increase in new and fatal strains of tuberculosis (TB) as drug-resistant forms of the disease find those living with HIV easy victims, according to medical experts.

Specialists in communicable diseases will gather in Johannesburg this week for a conference on the topic amid fears that a sharp rise in treating TB will add to the burden on already overstretched public health budgets.

Karin Weyer, a TB expert at the Medical Research Council, says an outbreak of an extreme drug-resistant (XDR) form of the disease in the eastern KwaZulu-Natal province of South Africa earlier this year set alarm bells ringing about its devastating consequences.

Fifty-two of the 53 patients who contracted XDR-TB in the Tugela Ferry area of KwaZulu-Natal, one of the provinces with the highest rates of HIV in the country, died from the outbreak, Weyer says.

“They were all HIV-positive. This is the frightening thing, XDR-TB has the potential to spread very rapidly in HIV-positive individuals and there is a very quick, very high mortality among patients. In this particular outbreak, they died in a median of 16 days,” Weyer says.

At any given moment, about 330 000 South Africans have TB and about 6 000 have the multiple drug-resistant (MDR) variant.

South Africa has the highest number of people living with HIV in the world after India, with 5,5-million of the country’s 47-million-strong population affected by the disease.

Organisers of the two-day conference from Thursday—which will be attended by representatives of the Medical Research Council, World Health Organisation and United States Centres for Disease Control and Prevention—say the rise of XDR cases is emerging as a “major threat to successful HIV treatment and care in sub-Saharan Africa”.

“Though data is limited, population-based surveillance has demonstrated increasing levels of MDR-TB in Botswana, Mozambique and South Africa,” they said in a statement.

Nomfundo Eland, of South Africa’s main anti-Aids lobby group, the Treatment Action Campaign, says many TB patients contract the disease as they do not follow their full course of drug treatment.
“When they fail to do so, they often develop MDR-TB,” she says.

The source of the Tugela Ferry outbreak “was probably an MDR-TB patient who didn’t complete his treatment and, as a result, then developed XDR TB and spread this to HIV-positive patients,” the Medical Research Council’s Weyer adds.

MDR-TB is generally resistant to isoniazid and rifampicin, the two main antibiotics traditionally used to fight TB. “XDR-TB means they are resistant also to other drugs, including those available to treat MDR-TB,” Weyer says. “This makes it a very serious thing because we have no drugs to treat it with.”

While the prevalence of MDR-TB is still relatively low at 2,9% of TB patients, it is increasing and costs significantly more to treat. Normal strains of TB can be treated at a cost of R400 per person, but MDR variants can cost up to R100 000.

“The threat to the broader community is fortunately much lower, and I’m saying that because when someone is HIV-negative and that person gets infected with TB or MDR-TB or XDR-TB, there is only about a 10% lifetime risk of that infection turning into active disease, so it is a small risk,” says Weyer.

“But when the immune system gets under pressure, like what happens with HIV-positive individuals, then that 10% lifetime risk is compounded to a 10% annual risk.”—Sapa-AFP

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