A Colombian scientist claims to have discovered a vaccine which is effective against the most deadly form of malaria, one of the world's great killers.
Dr Manuel Patarroyo, of Bogota, has taken 17 years to develop the vaccine which is targeted at plasmodium falciparum, also known as cerebral malaria, which is responsible for only 30 per cent of malaria cases but 90 per cent of the more than one million deaths the disease claims a year.
To date, most research has concentrated on killing the malaria-causing parasite as it enters the human bloodstream after a mosquito bite. The parasite is contained in the mosquito's saliva, which contains an agent to prevent human blood clotting. Dr Patarroyo's chemical-based vaccine is designed to block the parasite in the later merozoite form, as it emerges from an initial incubation in the liver. The vaccine will have already stimulated antibodies, and the antibodies will prevent the parasites from infecting red blood cells, the final and often deadly phase of a malarial attack.
If the antibodies work they prevent the parasites assuming their male and female form in the later stages of the fever in which they stay in the human bloodstream waiting for another mosquito to bite. They need this second bite to transfer themselves back into the body of the insect to complete their breeding cycle.
By blocking the growth of the parasite in the human body the cycle which allows the malaria parasite to multiply is broken. There is no possibility of mutation.
Most attempts at achieving an effective anti-malaria vaccination have involved biological vaccines. The problem with them is that the malaria parasite recognises the danger and mutates to avoid being killed by the immune system.
In 10 years from 1985, 10 biological vaccines were tested by the US army and none was effective. Dr Patarroyo believes that his vaccine, by using an inert chemical process rather than a biological one, prevents the danger of mutation by the parasite.
This chemical malaria vaccine is not the first that Dr Patarroyo has developed. His first version produced a partial success in the late 1980s when 30 per cent to 50 per cent of those injected produced sufficient antibodies to protect themselves against malaria.
Dr Patarroyo has tested his new vaccine on 11,500 monkeys and the results are being reviewed. He says he is now ready to begin human trials.
He has 100 scientists working 12-hour shifts in state-of-the-art laboratories in Bogota and is supported by the Colombian government and Rockefeller Foundation. His work is audited by the World Health Organisation (WHO).
Dr Patarroyo said: "Since I was eight I have dreamed of making vaccines, particularly one for malaria. I am not interested in making money - in Colombia being rich makes you a target anyway.
"I am prepared to make the vaccine and sell it at cost. The drug companies will not like that and I will face opposition, but think what a difference it will make to the world."
The scientific community will inevitably be sceptical that a developing country such as Colombia could produce an effective vaccine, which was expected to take a further 15 years to develop.
However, Dr Patarroyo has his supporters. Mr Howard Engers, who is in charge of the WHO vaccination development programme, said: "I am very impressed by his work and when I last visited him 18 months ago his results with monkeys were already very impressive.
"He takes an original approach and his achievements in the 1980s provided a very large stimulus to the worldwide search for a vaccine."