Malaria drug warning. Skulls on a warning sign at a US Army hospital during World War II (1939-1945). Also known as quinacrine and mepacrine, the drug atabrine acts against the protozoan that causes malaria. Malaria is caused by protozoan parasites that are transmitted by the bites of mosquitoes. It causes periodic fevers and can kill. It affects millions of people in tropical and subtropical regions of the world. Atabrine was first approved in the 1930s. It has a bitter taste and could turn the skin yellow, so warnings were needed to encourage uptake of the daily dosages. Photographed at the 363rd Station Hospital, Port Moresby, Papua New Guinea.