4 reasons why Africa, Gates and Obama want to end plague

The Gateses aim to eradicate malaria by 2040 by doubling funding over the next decade to support the roll out of new products to tackle rising drug resistance to the disease.

Their goal of permanently ending transmission of the disease between humans and mosquitoes is more ambitious than the Sustainable Development Goal of ending epidemic levels of malaria by 2030.

They are also supporting a push to create the world's first vaccine against a parasite.

Here are four of their arguments for pouring money into the issue:

* It promises almost a 20-fold return on investment: Eradication could save 11 million lives and unlock $2 trillion in economic benefits by 2040 from a healthy, more productive workforce and health systems that are less burdened by the disease, Gates and the United Nations say.

They estimate eradication would cost a fraction of this -- $90 billion to $120 billion, making it one of the "best buys" in global development.

* It's the only way to deal with drug-resistance: If malaria is not eliminated from drug resistant "hot spots" in Cambodia, Laos, Myanmar, Thailand and Vietnam, multi-drug resistant malaria is likely to spread worldwide, increasing the cost and reducing the efficacy of malaria control programmes everywhere.

Donors have set a goal of eliminating malaria in this Greater Mekong region by 2020.

Tanzania's health ministry's acting permanent secretary, Nkundwe Mwakyusa, said the emergence and spread of resistance to artemisinin, the most commonly used drug against malaria, in Asia was "a major concern".

In parts of Tanzania, mosquitoes can survive up to 20 times the normal dose of permethrin, the insecticide used in nets, according to Sophie Weston, a researcher with the London School of Hygiene and Tropical Medicine.

* More children in school, less in hospital: Trials of the Mosquirix vaccine showed that young children in countries like Kenya fall sick with malaria up to five times in one year.

Malaria is one of the main reasons why Africans miss school or work, entrenching poverty as time and money are spent in hospital, rather than learning or earning.

More than half of the deaths of children under five in Tanzanian health facilities are due to malaria, according to the United States' President's Malaria Initiative (PMI).

Malaria in pregnancy also causes about a quarter of all underweight births in Africa, according to campaign group Malaria No More.

This translates to about 100,000 neonatal deaths a year, and underweight children tend to suffer poor health.

"There's so much talk about zika and the terrifying effects during pregnancy but just in sheer scale, malaria outstrips it many times over," said Martin Edlund, chief executive of Malaria No More.

* It frees up money for "the next epidemic": Malaria is no longer the leading cause of death among children under five in Africa, having been overtaken by acute respiratory infections, according to PMI.

It still accounts for a third of outpatient visits on mainland Tanzania, 7.3 million cases a year, it says.

"The next step is ... to focus also on non-communicable diseases," said Mohamed Alwani, medical director of Ithani-Asheri Hospital in the Tanzanian town of Arusha, referring to heart disease, diabetes and cancer.