How the immune system prevents repeated malaria fever episodes in highly exposed children

April 17, 2014

Children in Mali (and many other regions where malaria is common) are infected with malaria parasites more than 100 times a year, but they get sick with malaria fever only a few times. To understand how the immune system manages to prevent malaria fever in most cases, Peter Crompton, from the US National Institute of Allergy and Infectious Diseases, and colleagues in the US and in Mali, analyzed immune cells from healthy children before the malaria season and from the same children after their first bout of malaria fever during the ensuing malaria season.

As reported in PLOS Pathogens, the researchers exposed both sets of immune cells to parasite-infected red blood cells and found that their responses were different: When confronted with parasites before the malaria season, the 's immune cells produced large amounts of molecules that promote inflammation (which results in fever and other malaria symptoms). After a malaria fever episode, the immune cells responded by producing more anti-inflammatory molecules (which dampen the strength of the inflammatory response) and showed evidence of an enhanced ability to recognize and destroy parasites.

The ability of the immune cells to mount this "compromise" response (somewhat effective in controlling the parasites but avoiding systemic inflammation and fever) seems to depend on the continued exposure to parasites through bites of infected mosquitoes: When the researchers took blood again from the same children after the subsequent dry season (when there are few or no new infections) and exposed the to parasite-infected , they showed that the anti-inflammatory response had returned to baseline, leaving children susceptible again to malaria-induced inflammation and fever.

Discussing their findings, the researchers say they "shed light on the longstanding and enigmatic clinical notion of 'premunition'—a partially effective exposure-dependent immune response that protects against illness and high numbers of parasites in the blood without completely eliminating the infection" and suggest that it "evolved as an appropriate immune response . . . such that young children are at least partially protected from potentially life-threatening inflammation and unchecked parasite replication before they acquire . . . antibodies that reliably protect against the onset of malaria symptoms".

Explore further: Malaria vaccine offers new mode of protection against disease

More information: Portugal S, Moebius J, Skinner J, Doumbo S, Doumtabe D, et al. (2014) Exposure-Dependent Control of Malaria-Induced Inflammation in Children. PLoS Pathog 10(4): e1004079. DOI: 10.1371/journal.ppat.1004079

Related Stories

Malaria vaccine offers new mode of protection against disease

November 29, 2013
(Medical Xpress)—A novel malaria vaccine developed at Oxford University has shown promising results in the first clinical trial to test whether it can protect people against the mosquito-borne disease.

Viruses common complication in malaria patients

September 24, 2013
Scientists at the University of Liverpool have shown that viral brain infections may be a more important killer in African children than was previously thought.

How the immune system fights off malaria

January 13, 2014
The parasites that cause malaria are exquisitely adapted to the various hosts they infect—so studying the disease in mice doesn't necessarily reveal information that could lead to drugs effective against human disease.

How malaria evades the body's immune response

July 12, 2012
(Medical Xpress) -- The parasites that cause human malaria and make it particularly lethal have a unique ability to evade destruction by the body’s immune system, diminishing its ability to develop immunity and fight ...

Chronic inflammation of blood vessels could help explain high childhood mortality in malaria regions

September 18, 2013
Recurrent episodes of malaria cause chronic inflammation in blood vessels that might predispose to future infections and may increase susceptibility to cardiovascular disease, a Wellcome Trust study in Malawian children finds.

Drug protects mice against malaria brain damage, raises levels of BDNF in humans

March 6, 2014
Cerebral malaria is a serious complication of infection with the malaria parasite, affecting approximately one in a thousand children in areas where malaria is common. Many of the patients die, and among those who survive, ...

Recommended for you

Anti-malaria drug shows promise as Zika virus treatment

November 17, 2017
A new collaborative study led by researchers at Sanford Burnham Prebys Medical Discovery Institute (SBP) and UC San Diego School of Medicine has found that a medication used to prevent and treat malaria may also be effective ...

Decrease in sunshine, increase in Rickets

November 17, 2017
A University of Toronto student and professor have teamed up to discover that Britain's increasing cloudiness during the summer could be an important reason for the mysterious increase in Rickets among British children over ...

Scientists identify biomarkers that indicate likelihood of survival in infected patients

November 17, 2017
Scientists have identified a set of biomarkers that indicate which patients infected with the Ebola virus are most at risk of dying from the disease.

Research team unlocks secrets of Ebola

November 16, 2017
In a comprehensive and complex molecular study of blood samples from Ebola patients in Sierra Leone, published today (Nov. 16, 2017) in Cell Host and Microbe, a scientific team led by the University of Wisconsin-Madison has ...

Study raises possibility of naturally acquired immunity against Zika virus

November 16, 2017
Birth defects in babies born infected with Zika virus remain a major health concern. Now, scientists suggest the possibility that some women in high-risk Zika regions may already be protected and not know it.

A structural clue to attacking malaria's 'Achilles heel'

November 16, 2017
Researchers from The Scripps Research Institute (TSRI) and PATH's Malaria Vaccine Initiative (MVI) have shed light on how the human immune system recognizes the malaria parasite though investigation of antibodies generated ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.