Investing in effective tuberculosis control such as sustained antibiotic therapy would pay off many times over in countries worst hit by the disease, says a new World Bank report.
It forecast that the economic cost of TB-related deaths in sub-Saharan Africa alone from 2006 to 2015 would be $519 billion if patients were not treated effectively.
But if treatment was provided under current World Health Organization guidelines, this would provide $218 billion of economic benefits over the same time in those countries, at costs of between $12.2 billion and $22.2 billion, depending on what kind of strategy was used, the report found.
Effective treatment globally would total $5 billion to $6 billion a year.
"There were already compelling reasons to fight TB, which causes massive human suffering," WHO Director-General Dr Margaret Chan said in a statement.
She said the economic benefits were a further incentive.
"This report should wake up countries to the urgent need for a stronger financial commitment to TB control," added Michel Kazatchkine, executive director of the Global Fund to Fight AIDS, Tuberculosis and Malaria.
"Effective TB control has a positive impact on the lives of the millions of people infected with TB, on whole communities and it reduces the burden of disease on national economies."
Tuberculosis infects about a third of the world's population. Most cases are latent, meaning people have no symptoms and are not infectious to others.
But the infection can become active when people's immune systems are suppressed - most notably by the Aids virus, but also by malnutrition, cancer or other diseases.
The most ordinary forms of TB take months to eradicate with antibiotic cocktails. And two new forms have emerged - multi-drug resistant, or MDR-TB, and extensively drug-resistant, or XDR-TB, strains that are much harder, if not impossible, to cure.
The WHO reports that 8.8 million people became newly infected with TB in 2005 and 1.6 million people died.
The study, done on behalf of the Stop TB Partnership and funded by the Bill and Melinda Gates Foundation, assumed that therapy works, and presumed that 50 million people would be treated between 2006 and 2015, compared to 20 million who were treated between 1996 and 2005.
Treatment would include second-line drugs for 800 000 MDR-TB patients and HIV testing and counselling for 27 million TB patients.
"This report set out to test whether the economic benefits of TB control are greater than the costs. It turns out that likely benefits are of impressive magnitude," said Dr Jorge Sampaio, the UN Secretary-General's Special Envoy to Stop TB, and a former president of Portugal.
For example, in Zambia, so many maize and cotton farmers died that crop yields fell 15 percent. When children become ill, they leave school and if they survive, grow up to earn less, and thus contribute less to the economy, than if they had grown up healthy.
According to the report, the 22 countries with the most cases of TB are Afghanistan, Bangladesh, Brazil, Cambodia, China, Democratic Republic of Congo, Ethiopia, India, Indonesia, Kenya, Mozambique, Myanmar, Nigeria, Pakistan, Philippines, Russia, South Africa, Thailand, Uganda, Tanzania, Vietnam and Zimbabwe. – (Reuters Health)