Following a request for assistance from a Cypriot cargo ship sailing off the coast of French Guiana, samples were collected and medical examinations were conducted on a deceased individual who had died from a fever complicated by a coma, as well as on the crew. The medical intervention on board was carried out in accordance with established procedures and using personal protective equipment appropriate to the risk. Analyses conducted by the P4 laboratory at the Pasteur Institute in Lyon and the P3 laboratory at the Pasteur Institute in Cayenne ruled out a diagnosis of FHV and identified Plasmodium falciparum as the cause of death. This experience provides a better understanding of the challenges of responding to a suspected FHV case and confirms the importance of developing a protocol for managing suspected cases on a ship or among people returning from trips to the deep Amazon rainforest. (R.A.)