Why malaria is more dangerous in children

May 23rd, 2008 - 4:42 pm ICT by admin  

Washington, May 23 (IANS) Malaria is likely to cause children’s immune systems to target their own DNA, prompting a more severe manifestation of the disease than in adults. The discovery, made by a team of US and Nigerian scientists, explains why DNA based malaria vaccines don’t work.

The scientists took blood samples from 21 Nigerian children under the age of 6, infected with Plasmodium falciparum malaria.

They tested them for the presence of immune components such as cytokines - signalling chemicals released by the immune system - and antibodies.

They found that the samples contained modified white blood cells, called NETs, which capture the malaria parasite.

But they also found that NETs release copies of the body’s own DNA. Samples also contained increased levels of antibodies specific to the children’s DNA.

This has led the researchers to speculate that the DNA causes the immune system to attack its own cells - known as autoimmunity - which, in children, leads to a worse state of sickness.

Autoimmune-like response is said to have a different effect in adults, particularly those repeatedly exposed to malaria. Adults have a more developed immune system, and the response actually helps strengthen protection against the parasite.

“This research sheds new light on how the children are responding to falciparum malaria. It appears that they are making antibodies that are not protective,” Virginia Baker, of US-based Chipola College and co-author of the study, told SciDev.Net.

Since some vaccines for malaria use DNA as an agent to increase immunity, the findings may help explain why these vaccines have failed to work.

Michael Oluseyi Obadofin, from Jos University Teaching Hospital in Nigeria and a co-author on the study, said the study offers a scientific explanation for a long-observed phenomenon.

The study has been published in the latest issue of Malaria Journal.

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