New research published today (17 June) by scientists funded by the Biotechnology and Biological Sciences Research Council (BBSRC) shows that malaria is tens of thousands of years older than previously thought. An international team, led by researchers at Imperial College London, have found that the potentially deadly tropical disease evolved alongside anatomically modern humans and moved with our ancestors as they migrated out of Africa around 60-80,000 years ago. The research is published in the journal Current Biology.
The findings and the techniques in the study could be important in informing current control strategies aimed at reducing the prevalence of malaria. There are an estimated 230 million cases each year, causing between 1 and 3 million deaths, and around 1.4bn people are considered to be at risk of infection.
Dr Francois Balloux from the Medical Research Council (MRC) Centre for Outbreak Analysis and Modelling at Imperial College London was lead researcher on the project. He said: "Most recent work to understand how malaria has spread across the tropics has worked on the premise that the disease arose alongside the development of agriculture around 10,000 years ago. Our research shows that the malaria parasite has evolved and spread alongside humans and is at least as old as the event of the human expansion out of Africa 60-80,000 years ago."
The international team worked on the largest collection of malaria parasites ever assembled. By characterising them by DNA sequencing they were able to track the progress of malaria across the tropics and to calculate the age of the parasite. The scientists discovered clear correlation of decreasing genetic diversity with distance from sub-Saharan Africa. This accurately mirrored the same data for humans suggesting strong evidence of co-evolution and migration.
Dr Balloux said: "The genetic sequencing of the malaria parasite shows a geographic spread pattern with striking similarities to studies on humans. This points to a shared geographic origin, age and route of spread around the world. This understanding is important because despite the prevalence and deadly impact of malaria little research has previously been done to understand the genetic variation of the parasite. The genetic diversity of malaria parasites is central to their threat as it helps them to overcome the immune system and to develop drug resistance, making this research vital in informing new and more effective control strategies."
Contact
Dr Francois Balloux, MRC Centre for Outbreak Analysis and Modelling, Imperial College London
Tel: +41 21 601 25 69, email: fballoux@imperial.ac.uk
BBSRC External Relations
Matt Goode, Tel: 01793 413299, email: matt.goode@bbsrc.ac.uk
Nancy Mendoza, Tel: 01793 413355, email: nancy.mendoza@bbsrc.ac.uk
Notes to Editors
This research is published on 17 June 2010 in the journal Current Biology - Tanabe et al., Plasmodium falciparum Accompanied the Human Expansion out of Africa, Current Biology (2010), doi:10.1016/j.cub.2010.05.053
- 35 countries (30 in sub-Saharan Africa and 5 in Asia) account for 98% of global malaria deaths.
- 89% of the malaria deaths worldwide occur in Africa.
- Malaria is the 5th cause of death from infectious diseases worldwide (after respiratory infections, HIV/AIDS, diarrheal diseases, and tuberculosis).
- Malaria is the 2nd leading cause of death from infectious diseases in Africa, after HIV/AIDS.
- Among the malaria species that infect humans, Plasmodium vivax and P. ovale can develop dormant liver stages that can reactivate after symptomless intervals of up to 2 (P. vivax) to 4 years (P. ovale).
- After a single sporozoite (the parasite form inoculated by the female mosquito) of Plasmodium falciparum invades a liver cell, the parasite grows in 6 days and produces 30,000-40,000 daughter cells (merozoites), which are released into the blood when the liver cell ruptures. In the blood, after a single merozoite invades a red blood cell, the parasite grows in 48 hours and produces 8-24 daughter cells, which are released into the blood when the red blood cell ruptures.
All malaria information from the Centers for Disease Control and Prevention. http://www.cdc.gov/malaria.
About BBSRC
BBSRC is the UK funding agency for research in the life sciences. Sponsored by Government, BBSRC annually invests around £450 million in a wide range of research that makes a significant contribution to the quality of life in the UK and beyond and supports a number of important industrial stakeholders, including the agriculture, food, chemical, healthcare and pharmaceutical sectors.
BBSRC provides institute strategic research grants to the following:
The Babraham Institute, Institute for Animal Health, Institute of Biological, Environmental and Rural Studies (Aberystwyth University), Institute of Food Research, John Innes Centre, Rothamsted Research, The Genome Analysis Centre and The Roslin Institute (University of Edinburgh). The Institutes conduct long-term, mission-oriented research using specialist facilities. They have strong interactions with industry, Government departments and other end-users of their research.
For more information see: http://www.bbsrc.ac.uk
About the Medical Research Council
For almost 100 years the Medical Research Council has improved the health of people in the UK and around the world by supporting the highest quality science. The MRC invests in world-class scientists. It has produced 29 Nobel Prize winners and sustains a flourishing environment for internationally recognised research. The MRC focuses on making an impact and provides the financial muscle and scientific expertise behind medical breakthroughs, including the first antibiotic penicillin, the structure of DNA and the lethal link between smoking and cancer. Today MRC funded scientists tackle research into the major health challenges of the 21st century. http://www.mrc.ac.uk
Journal
Current Biology