Abdul Ezedi is still on a run a week after the attack; the female victim is still sedated in hospital and is said to be too ill to speak.
Ezedi was last seen crossing Vauxhall Bridge at 11pm on the night of the incident.
Commander Savell added: “We have worked with the National Crime Agency to commission medical experts to provide an assessment of Ezedi’s injuries.
“Those experts are clear Ezedi suffered a significant injury in the attack and is in increasing danger of an infection if he does not seek urgent medical attention. That will be extremely serious, if not life-threatening.
“To the best of our knowledge he has not been to hospital or sought professional medical help. At our request, all hospitals remain on high-alert. As time goes on, Ezedi’s health will continue to deteriorate.
”Ezedi – hand yourself into police, not only so we can speak to you, but so you can get the urgent medical treatment you obviously need.”
Darius Nasimi, from the charity the Afghanistan & Central Asian Association in Feltham, said: “This is a tragic incident for this mother and her two children. Violence against women and girls can not be tolerated.
“I would urge the Afghan community to help the police and provide any information at all about where Ezedi is, who is providing him with accommodation, who is harbouring him and helping him evade capture. You can also speak to our charity and we will help liaise with the police and pass information on if you feel you don’t want to speak to them directly.
“I make a direct appeal to him: hand yourself in. This has been going on for long enough. You need medical attention.
“What has happened in this case should have no reflection on the people of Afghanistan in the UK. This does not represent them.
You can speak to the Met’s investigation team via our hotline on 020 7175 2784, or for an immediate sighting dial 999. A £20,000 reward remains on offer for information leading to Ezedi’s arrest.