A new immunological technique - patients infected with malaria are treated with prophylactic chloroquinine - can confer immunity against re-infection of at least 2.5 years, longer than normal (naturally acquired immunity) *. The findings are reported in the article Online First and the upcoming Lancet, written by Professor Robert W Sauerwein, Radboud University Medical Centre Nijmegen, the Netherlands, and colleagues.

In a previous study by the same group showed that immunity against infection with Plasmodium falciparum can be induced (experiment on volunteers who have never been immunized malaria) through the bite of infected mosquitoes and prevent disease with prophylactic chloroquine. But it was not known how long the immunity lasted perhaps the last, 2.5 years later, these authors have completed advanced studies.



** Four of the six volunteers who bersangkuta immunity was found to be free from infection after the first attempt made to reinfect them after 2.5 years, pending development of malaria in the remaining two volunteers immunized. More detailed analysis showed that the immune system T-cells in individuals immunized 'remember' previous infection and able to quickly clean up the re-infection. The four volunteers are protected reported some mild side effects while trying to moderate the re-infection, in which the most frequently reported symptoms are headache (one to three episodes per volunteer). Both patients with delayed infection has side effects similar to those in the control group.

While encouraged by the results, the authors noted several limitations to learning. These include that the same strain used to re-infect that has been used to initially give immunity, whereas in the natural environment can no genetic variation. They also recorded the volunteers for this study were adults, while most people in the world are children when they first become infected.

The authors conclude: "Our simple immunization protocol is the blueprint for sustainable anti-malarial immunity induced, providing new techniques to explore the mechanisms of immunity and highlight new research priorities Precedence should be given to basic understanding of the mechanisms of protection and those in our study. Factors that hamper the protection of open natural populations. "

They say that further research on their methods should be part of the agenda for sustainable development of malaria vaccines.

In a related comment, Dr. Brian Greenwood and Dr Geoffrey Targett, London School of Hygiene & Tropical Medicine, UK, said: "If the immunity induced by malaria parasites highly strain-specific whole, this can cause big problems for those working on vaccines based on this model, however, if previous exposure to malaria is the explanation for this difference,. it will be very important to vaccinate early in life in endemic areas prior to any contamination of naturally acquired infection has occurred. Challenging volunteers with different types of single use to induce protection or immunization to do and study the challenges similar to those described by Roestenberg and colleagues at the people affected by malaria will help to resolve what the most likely explanation is true. "

Source
The Lancet