A nurse has gone missing from his Southampton home after taking part in a clinical trial for malaria.
Matthew Lloyd, 35, who works at Southampton General Hospital, failed to attend treatment in Oxford in relation with the trial.
Police said he phoned in ill to work in the days before his appointment on Thursday and has not been seen since.
Mr Lloyd, from the Shirley area of the city, requires urgent medication, a police spokesman said.
He added: "Police are appealing for anyone who has seen him, or thinks they know where he is, to contact them or for Matthew himself to give them a call."
As well as having connections with Oxford for his clinical trials, Mr Lloyd is known to have connections with Cornwall and the Avon and Somerset area.