The mother of a nurse who went missing after being infected with malaria has made an emotional appeal for him to get in touch as fears grow for his health.
Matthew Lloyd, 35, who works at Southampton General Hospital, needs life-saving treatment after taking part in an anti-malarial drugs trial.
He failed to turn up for a follow-up appointment in Oxford on 7 October.
His mother Doreen Holland, from Somerset, urged her son to seek medical attention if he became unwell.
"We all care about you and we just want to know you are ok and we want you back safe and sound," she said.
"We love you, son."
Police think Mr Lloyd could have travelled to London.
Officers have also tracked his movements to Birmingham and Milton Keynes.
As well as having connections with Oxford for the clinical trial, Mr Lloyd is known to have links with Cornwall and the Avon and Somerset area.
Det Insp Dave Jackson, of Hampshire police, said: "Our concerns for Matthew's health are increasing because he needs urgent medication, which he does not have with him.
"Even the smallest detail could prove crucial in finding Matthew so he can receive his life-saving medication in time."
His family have said his disappearance is out of character and it is not known why he has gone missing.