The World Health Organisation (WHO) said recently that the global tuberculosis epidemic may be leveling off, but this optimism is undermined by the reality of incomplete detection of the disease, high levels of mortality and poor information about the extent of drug resistant forms of the disease.
This week the WHO released its 2007 Global Tuberculosis Control report to mark World TB Day on March 24.
The new document says there were an estimated 8,8-million new cases of TB in 2005, of which 7,4-million were in sub-Saharan Africa and Asia. In the same year, an estimated 1,6-million people died of TB — the equivalent of 4400 a day.
Of these deaths, 195000 were associated with HIV.
The report says: ‘All three major indicators — incidence, prevalence and mortality rates — are now falling globally — Prevalence and death rates increased in the African and European regions between 1990 and 2005, but most dramatically in the former.†Incidence is the rate of new cases, while prevalence is the existing level of the disease.
Africa accounts for 23% of newly diagnosed infections. Of the 15 countries with the highest per capita rates of new TB cases, 12 are in Africa, headed by Swaziland, where 75% of TB patients were estimated to be HIV-positive.
In 2005, South Africa ranked seventh globally for newly diagnosed TB infections, with India and China ranking first and second. South Africa appears to be detecting more cases of TB, which is a notifiable disease.
Directly Observed Therapy short course (Dots), which requires people to be supervised when they take their cocktail of antibiotics, forms the basis of current TB treatment.
Laboratory tests for South African patients under Dots in 2004 indicated that 54% were cured while another 15% completed treatment and were assumed to have been cured. This put the overall ‘success†rate in South Africa at 70%, compared to 84% worldwide.
Of the remaining 30% of South African patients, 7% died and 11% defaulted on the treatment.
In 10% of cases the outcome was unknown, either because the patients transferred to another institution, or because they were not monitored. The WHO report says that this rate is ‘unacceptably highâ€.
Unsuccessful treatment, either because the drugs failed, the patient didn’t take them properly, or the drugs weren’t available, leads to the development of drug resistance.
Drugs ran out in 16 countries in Africa, including Mozambique, Uganda and Zimbabwe.
Multi-drug resistant TB (MDR-TB) is resistant to the two most important first-line antibiotics. A sub-set of MDR is extensively drug resistant TB (XDR-TB), which is also resistant to at least two further drugs.
In 2005, South African laboratories confirmed 2000 multi-drug resistant TB cases, of which 197 were in newly diagnosed people who were likely to have been infected with MDR strains, rather than having developed it as a result of unsuccessful antibiotic treatment.
The WHO said that better surveillance for drug resistance is needed to detect levels of XDR- and MDR-TB, and also improved patient support, especially for patients undergoing the lengthy and unpleasant repeat treatment.
This has particular resonance with the announcement this week that allegedly infectious TB patients protesting their care had absconded from hospital and had been sent back to bed by a court order.
In 2007, the South African government will fund the national treatment plan fully, although it has yet to implement the National TB Crisis Management Plan.
South Africa has one of the highest budgets and costs for treating TB among the 22 more heavily affected countries.