Studies malaria risk by mutated pathogens

Increased malaria risk from genetically modified pathogens

16/11/2013

Many people in tropical countries have natural protection against a specific form of malaria if they lack a certain amount of protein in their blood. However, this natural resistance could be circumvented with genetically modified pathogens, as American researchers discovered.

Natural protection against malaria
In tropical countries, many people have natural protection against a certain form of tropical disease., Malaria tertiana. They lack a specific protein on the red blood cells. They are called Duffy-negative and so far they were considered immune to a disease. But altered malaria pathogens could trick the natural resistance to the disease, as researchers from the US have found out with the help of genetic studies.

Mild form of malaria
These pathogens are parasites called Plasmodium vivax, which cause malaria tertiana. This form is a rather benign and mild variant of malaria and there are fewer complications or life-threatening conditions, as in other forms. But even here it comes to a high fever, which occurs in regular episodes and to nausea and vomiting. The pathogens can hide in the liver and later make the patients sick again. The experts presented their new findings at a Tropical Medicine Congress in Washington.

New phenomenon or just rediscovered
As stated in the congressional communication, over the past five years, researchers have observed that Africans and South Americans who are Duffy-negative nevertheless contract malaria tertiana. In sub-Saharan Africa, around 95 percent of the population is considered duffy-negative. With them, the parasites can not enter the red blood cells and do not multiply. But Peter Zimmermann of Case-Western Reserve University in Cleveland, Ohio, said: „We have uncovered previously unknown gene mechanisms in Plasmodium vivax parasites that could offer them other ways to invade red blood cells.“ That could be an explanation why these people also get malaria. It is still unclear whether this is a new phenomenon, or whether it is only now discovered.

220 million malaria diseases
The death rate in malaria tertiana is significantly lower than in the more dangerous malaria tropica. But the number of people threatened by contagion worldwide is estimated to be the same for both forms. In 2010, according to the World Health Organization (WHO), around 220 million people fell ill with one of the various types of malaria and about 660,000 patients died as a result. The tropical disease is transmitted through the bite of the Anopheles mosquito.

Results will be published soon
For their studies Zimmermann and colleagues examined, among other things, the genome of plasmodia from the African island of Madagascar. They found that over fifty percent of the parasites had a duplicate gene responsible for red blood cell penetration. And they came across a previously unknown gene in plasmodia from Southeast Asian Cambodia. This could allow the pathogens to invade the cell. The researchers want their results soon in the journal „PLOS Neglected Tropical Diseases“ publish.

Reduce illnesses by 75 percent by 2030

Tomorrow, Sunday, the Annual Meeting of the American Society for Tropical Medicine and Hygiene (ASTMH) will take place. It also presented WHO's goals for the development of malaria vaccines. According to the study, vaccines should be on the market by 2030, which should reduce illnesses worldwide by 75 percent. 27 products are currently being studied in clinical trials.

Pharmaceutical company develops malaria vaccine
The British pharmaceutical company GlaxoSmithKline (GSK) has evidently developed a vaccine called "RTS, S", which is specifically intended for African children. The vaccine was the most advanced compared to other developments, which is why the group said it wanted to boost its use of the new drug. According to this, the assessment of the vaccine by the European Medicines Agency should take place in the coming year so that, if the outcome is positive, the funds can be used in Africa as early as 2015. (Ad)

Image: Michael Bührke