Study Reveals New Malaria Parasitic States
Although malaria parasites have undergone extensive laboratory study, relatively little is known about how they behave in humans to cause disease. Newly published data from a study of malaria-infected human blood reveal two biological states of the parasite Plasmodium falciparum not observed under laboratory conditions. This information may help scientists develop new strategies for treating malaria.
A team led by scientists at MIT and Harvard University and supported in part by the National Institute of Allergy and Infectious Diseases, a component of the National Institutes of Health, collected blood samples from 43 P. falciparum-infected malaria patients in Senegal who were suffering from a range of malaria symptoms. The scientists isolated the parasites' genomic information and determined which of the nearly 6,000 P. falciparum genes were switched on or off during infection, revealing distinct groups of parasites with characteristic sets of active and inactive genes.
By comparing this information about P. falciparum with gene activation patterns in a similar but better-understood organism--baker's yeast--the scientists described three biological classes of malaria parasites, each with a different metabolic state. One state is well known from laboratory studies, but the other two have never been observed before. One newly described state appears to reflect starving parasites, while the other suggests parasites under extreme environmental stress. Remarkably, say the scientists, the latter group correlated with specific patient symptoms, including high fevers and elevated levels of inflammatory markers in their blood.
These findings suggest that the state of the parasite may correlate with a malaria patient's symptoms, which can range from mild, flu-like illness to coma and even death. If further research confirms such direct relationships, this could open the door to the development of new malaria treatments that ameliorate disease symptoms by targeting the parasite's behavior.