The first-ever clinical trial involving controlled malaria infection, administered with parasites by injection, rather than mosquito bites could extend Africa’s ability to develop drugs and vaccines.
In the findings published in the American Journal of Tropical Medicine and Hygiene (AJTMH), researchers say the success of this trial, which was conducted in Tanzania, could save millions of lives in malaria-endemic African countries.
It also gives an opportunity for a malaria vaccine, once developed, to be administered in mass vaccination campaigns.
The study was made possible after Stephen Hoffman, the chief executive and scientific officer of the US company Sanaria Inc., developed technology to grow sporozoites in mosquitoes in the laboratory, and then package them in a purified, aseptic form acceptable for international human clinical trials.
The study established that in controlled laboratory conditions, which represent a real world setting, frozen, preserved whole sporozoites harvested from mosquito salivary glands, an infectious stage of the malarial parasite plasmodium falciparum can be used with a syringe to infect volunteers with malaria safely.
This innovation ensures that during malaria research for vaccines and drugs in Africa, no new live species of mosquitoes are introduced in the environment, thereby reducing the risk of public health concerns and keeping research costs low.
Why it is important
Before this innovation, the ability to test or “challenge” a vaccine’s effectiveness required deliberately infecting vaccinated volunteers with malaria, by exposing them to live infective mosquito bites in a specially constructed insectary.
Few such malaria insectaries exist, especially in Africa and due to the resources needed, these are limited to a handful in the United States and Europe, far from the countries where malaria toll is highest.
Salim Abdullah, the principal investigator of the study and chief executive director of Ifakara Health Institute (IHI) where the study was carried out in Tanzania, says they are excited by the good results, which opens up unprecedented opportunity for evaluation of new malaria drugs and vaccines in Africa.
Abdullah says the findings will accelerate malaria control and elimination in many African countries. The study is one of the first malaria products to be financially supported by the government of Tanzania, through the Tanzania Commission for Science and Technology.
Ugandan malaria expert, Dr Ambrose Talisuna described the findings as a promising development. “I think many countries in Africa need better tools than we have today to eliminate malaria,” says Talisuna, currently a a senior clinical research fellow at the University of Oxford-KEMRI-WellcomeTrust Research Programme.
Uganda is one of the countries with a high rate of malaria in Africa.
In the study conducted between February and August 2012, the researchers recruited 30 men, who had minimal exposure to malaria during the previous five years.
The scientists compared the infection rate to that of Dutch volunteers who participated in a similar study in the Netherlands in 2011. After about two weeks, all but two of the 23 Tanzanian volunteers injected with live sporozoites developed active infections, a rate similar to the Dutch volunteers.