Tuberculosis Is Still Spreading

Health officials appear to be making some progress in saving the lives of those with tuberculosis (TB), which remains one of the worst global public health threats. A new study by the World Health Organization (WHO) published in today's Journal of the American Medical Association shows the number of deaths holding steady across the decade while the number of cases has risen sharply. But the fact that 23% of all TB patients die "is something we should all be ashamed of," says Charles Nolan, chairman of the Advisory Council for the Elimination of Tuberculosis and director of the tuberculosis control program at the Seattle-King County Department of Health.

Caused by the bacterium Mycobacterium tuberculosis, TB is a respiratory disease spread mostly by coughing. Once the leading cause of death in the United States, it is curable with antibiotics and has been drastically curtailed in most Western countries during the last half century. Still, the disease remains a leading killer in impoverished nations, where TB drugs are scarce or too expensive and doctors aren't trained in the most effective diagnostic methods.

In 1997, there were 8 million new TB cases worldwide, up from 6.3 million in 1990. The death toll dropped slightly, from 2.0 million to 1.9 million, perhaps as a result of increased drug availability in some countries. But the researchers question the value of any comparison, citing the incomplete nature of the earlier figures.

The 1990 figures were based on regional estimates by WHO scientists. Aware that the worldwide distribution of TB had been dramatically altered during the 1990s by the collapse of the former Soviet Union and the spread of AIDS (which increases the risk of contracting TB) in Africa and Asia, members of WHO's Global Surveillance and Monitoring Project set out to produce country-by-country data on three TB measures: the number of new cases in a given year, the number of existing cases, and deaths. They tackled the Herculean task by teaming with 86 TB experts from more than 40 countries, poring over hundreds of TB surveys and analyzing mountains of WHO's own data, compiled from annual reports by health officials in 212 countries.

The results (see table below) show that Africa has by far the highest infection rate but that Southeast Asia suffers from the most new cases. Lead author and WHO epidemiologist Chris Dye says he hopes the new numbers will serve as a benchmark that health officials can use to monitor the spread of TB and assess their efforts to control it.

NUMBER OF NEW TB CASES BY WHO REGION, IN 1997
Per 100,000 Total (thousands)
Americas 52 411
Europe 51 440
Eastern Mediterranean 129 615
Africa 259 1586
Southeast Asia 202 2948
Western Pacific 120 1962
Total 136 7962

SOURCE: JAMA, WHO

Posted in Health, Biology