The nurse injected with malaria as part of a clinical trial has still not been found, prompting his mother to make a desperate plea for him to get treatment.

Matthew Lloyd, 35, may die within hours if he does not seek medical attention after being infected with malaria in a hospital trial but failing to turn up to receive the antidote.

Last night Lloyd’s mother, Doreen Holland, 64, described her son as a “responsible, ambitious and focused man” who was “excited to be taking part in the trial.”

In tears, his mother read a statement saying: “Matthew, if you’re out there and you are unwell, then please seek medical attention and ring police.”

Doctors have warned that the nurse will die within 24 hours if he does not seek urgent medical attention for his malaria. Police are urging him to attend the nearest hospital or surgery and have launched a desperate appeal to find him.

Six of the other participants are already showing signs of malaria and are being treated.

Hampshire police spokesman Ian Sainsbury said: “He needs drugs because he has done the first part of the clinical trial and needs to complete that trial.

“The last that was heard from him was when he rang in sick to work. He requires urgent medication which he does not have with him.

“We 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.”