The fight against malaria is slowing down amid a dramatic drop in efforts to reverse the epidemic, even as health officials insist they will try to meet their idealistic target of virtually eliminating deaths from the parasitic illness by the end of 2015.

Malaria causes symptoms including fever, chills, and vomiting and can kill if not treated early. It mainly strikes children under 5, mostly in Africa.

In 2010, about 145 million bed nets were given out across Africa to protect people against the mosquitoes that spread the killer disease. Last year, that fell to about 66 million. The number of homes in Africa sprayed with pesticides has also stalled, as have attempts to treat pregnant women, one of the high-risk groups.

si-malaria-child-220-cp-rtr

A man carrying his daughter, who was being treated for malaria by International Medical Corps doctors in South Sudan, in July. Fewer bed nets were given out across Africa last year to protect people against the mosquitoes that spread the disease. (Margaret Aguirre/International Medical Corps/Reuters)

While the malaria death rate has fallen by a quarter since 2000, officials say further improvements are in jeopardy.

"We must act with urgency and determination to keep this tremendous progress from slipping out of our grasp," Dr. Margaret Chan, WHO's director-general, wrote in a report released Monday. WHO blamed falling donations and said the $2.3 billion US invested in malaria programs in 2011 was less than half of what was needed.

The agency estimated there were about 219 million malaria cases and 660,000 deaths in 2010. But there were only solid data from countries representing just 15 per cent of cases worldwide; the remaining cases and deaths were largely based on estimates and modeling. There was no solid information on countries with the biggest outbreaks, including the Democratic Republic of Congo and Nigeria, which account for about 40 per cent of global malaria deaths.

WHO acknowledged there was "a large degree of uncertainty" about its figures.

Goal of near-zero malaria deaths questioned

"There are a lot of blind spots in surveillance," said Jorgen Stassijns, a malaria adviser at Doctors Without Borders who was not connected to the report. He thought efforts against malaria might be sluggish because of the financial crisis or donors prioritizing other health campaigns.

"In a lot of our work in the field, we don't see malaria going down," Stassijns said, citing clinics in Congo, Niger and Sierra Leone.

Some said the stalled progress wasn't unexpected.

"A disease is always more difficult to control at lower levels," said Richard Tren, director of the non-profit Africa Fighting Malaria. He said past initiatives to reduce malaria rebounded after a few years and advised officials to use their funds more wisely.

He said a $460 million program led by the Global Fund to Fight AIDS, Tuberculosis and Malaria should have been scrapped since there was no proof the initiative — which flooded private markets with malaria drugs — actually worked to reduce cases since there were no controls on who got the medicines. The program, the Affordable Medicines Facility for malaria, was renewed by the Global Fund last month.

Tren doubted that officials would meet the 2015 target of "near-zero" malaria deaths. "I'm not sure it's measureable or achievable," he said.