Patients lie on beds covered with mosquito nets in a ward reserved for people suffering from dengue fever in a hospital at the Barrio Obrero district in Asuncion April 14, 2011. Paraguay is suffering the worst dengue epidemic in its history, according to Health Minister Esperanza Martinez, with 22,000 suspected cases and 23 deaths since the start of 2011. The mosquito-borne disease is a threat to nearly half of the world's population. Of the estimated 220 million people infected each year, two million -- mostly children in Latin America and Asia -- develop a severe form called dengue hemorrhagic fever. REUTERS/Jorge Adorno (PARAGUAY - Tags: HEALTH)