It's the world's number one killer among infectious diseases, but tuberculosis has been eclipsed by HIV/AIDS as a focus of global attention and donor funding.

When world leaders gather at the United Nations next month, they will be asked to change that by committing to end the tuberculosis pandemic by 2030 and come up with $13 billion annually to achieve that goal.

A row between the United States and South Africa threatens, however, to cast a pall over the first high-level meeting on tuberculosis, to be held on the sidelines of the General Assembly meeting in New York.

Billionaire philanthropist Bill Gates whose global fund has done game-changing work to boost public health in poor countries will be among the headliners of the TB summit on September 26.

"TB is not a disease of the past, but if the world works together to fight it, I have no doubt it can be," Gates said in post on Twitter. Two months of negotiations on a final declaration were scheduled to wrap up in July, but the talks have dragged on after South Africa opposed US proposals to delete language that recognizes the right of poorer countries to access cheaper medicines.

Medical charity MSF has applauded South Africa's stance and urged countries to resist what it has described as "an aggressive push" by the US pharmaceutical lobby to restrict access to low-cost drugs. Diplomats said negotiations were continuing on a possible compromise.

Last year, the World Health Organization sounded the alarm when it said tuberculosis had surpassed HIV/AIDS as the world's number one infectious killer and was the ninth cause of death worldwide. About 1.7 million people died from TB in 2016 out of 10.4 million worldwide who became ill from the severe lung infection, according to the WHO.

Will leaders turn up?

A 30-point final declaration under negotiation would commit governments to end the global tuberculosis epidemic by 2030 by stepping up investment and innovation to fight the disease.

Five countries are the hardest-hit by the TB pandemic: India, which accounts for a quarter of cases, Indonesia, China, the Philippines and Pakistan, but it remains unclear whether these nations are sending high-level officials to the summit.

"TB is not just a health issue. TB is an economic issue, a development issue, a security issue and we need leadership from heads of states," said Paula Fujiwara, the scientific director of the Paris-based International Union Against Tuberculosis and Lung Disease.

At the summit, leaders will pledge to provide diagnosis and treatment to 40 million people with TB from 2018 to 2022, including 3.5 million children. "Innovation in TB is just limping along," said Fujiwara. Only two new TB medicines have become available in the last 50 years and there are no effective diagnostic tests for children.

The rise in TB is partly fueled by growing worldwide rates of diabetes, which weaken the immune system and make people more susceptible to TB. To tackle that global health concern, the United Nations will host a high-level meeting on September 27 on noncommunicable diseases.