LONDON — 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 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 disease. Last year, that fell to about 66 million. The number of homes in Africa sprayed with pesticides has also stalled.