The World Health Organisation said today it had added 16 more malaria diagnostic tests to its approved list to help health workers quickly identify which patients have the disease and need immediate treatment, according to Reuters. The United Nations health body assessed 29 rapid tests from a range of different manufacturers and found that 16 of them met minimum performance criteria. Around 40 percent of the world's population is at risk of malaria, a potentially deadly disease transmitted via mosquito bites. It kills around 860,000 people a year worldwide, most of them children in Africa. There are also cases in Asia, Latin America, the Middle East and parts of Europe. "These rapid tests have been a major breakthrough in malaria control," Robert Newman, director of WHO's Global Malaria Programme, said in a statement. "They allow us to test people who cannot access diagnosis based on microscopy in remote, rural areas where the majority of malaria occurs." WHO malaria guidelines call for diagnosis using either microscopy or rapid tests before treatment in all suspected malaria cases, but in 2008, only 22 percent of suspected cases were tested in 18 of 35 African countries that reported data. The Geneva-based WHO said wider diagnosis would allow health workers to identify which patients with fever have malaria and need drugs, and which have other causes of illness and need other treatment. It would also improve overall childhood survival, a key U.N. development goal. "With 38 tests that now meet minimum performance criteria, malaria-endemic countries... have a wider choice of tests which have been assessed for quality and reliability," the WHO said. The best treatments for malaria are artemisinin combination therapy (ACT) drugs made by firms like France's Sanofi-Aventis , but they can also be expensive. Resistance to chloroquine and sulfadoxine-pyrimethamine, the cheapest malaria drugs, is becoming more common.