Geographic boundaries of endemic malaria getting progressively smaller


Geographic boundaries of endemic malaria getting progressively smaller

For the last 150 years the geographic boundaries of endemic malaria have been steadily getting smaller, what experts call "The Shrinking Malaria Map". In the medical journal The Lancet's "Series on Malaria Elimination", Professor Richard Feachem, The Minister of Health for Ethiopia and team say that the Shrinking Map continues and there is every reason to hopeful for the short- and long-term future.

Professor Feachem, Director of the Global Health Group (GHG) and Chair of the MEG (Malaria Elimination Group), said:

The UCSF Global Health Group and the Malaria Elimination Group are proud to join with The Lancet to launch this synthesis of the best information and research available on malaria elimination today. We hope that this Series raises awareness of the great progress that has been made in elimination, illuminates the many challenges that remain, and mobilizes the malaria community and malaria-endemic countries to continue shrinking the malaria map.

The authors explain that elimination has occurred when endemic transmission has been stopped and the risk of a return of the disease is minimal. To ensure that elimination prevails there needs to be serious, ongoing commitment. Otherwise the best that can be achieved is a state of "controlled low-endemic malaria", in which the malaria public health burden is no longer a major problem, but where transmission still happens, even if it does not come in from abroad.

Up to 1945, about 178 nations had endemic malaria. Since then 79 countries have eradicated the disease, including:

  • UK, 1952
  • USA, 1952
  • Australia, 1970
  • Morocco, 2005
  • Turkmenistan, 2010
Malaria is still endemic in 99 nations. 32 of them are expected to become controlled low-endemic countries with the aim of eventual elimination, while 67 are controlling the disease.

The Malaria Map has been steadily shrinking over the last 150 years. Every single malaria eliminating country, 32 of them with a total population of over 2 billion people, are on the outer margins of the map. They consist of nations with all types of economies and climates, including Turkey, South Africa, Malaysia, Mexico, Iraq, China and Argentina.

There are 66 nations that are still controlling malaria. They are all either in the tropics or very near to it, and include the majority of countries in sub-Saharan Africa, some parts of South America and a large chunk of Southeast Asia. Sub-Saharan Africa refers to countries situated in the region of Africa south of the Sahara.

The authors write:

Countries deciding to switch from controlled low-endemic malaria to elimination need to do so based on comprehensive understanding of technical, operational, financial, and socioeconomic feasibility. Countries should avoid moving towards elimination based on national aspirations not backed by evidence.

The researchers explain that the drive to eliminate malaria focuses on two parasite species:

  • Plasmodium falciparum (P. falciparum)
  • Plasmodium vivax (P. vivax)
The two species are not identical and have unique features.

Scientists have made much more headway in fighting P falciparum, for which there are more medications, compared to P. vivax. 25 malaria-elimination nations are just or principally concentrating on dealing with P. vivax, as was the case with nearly all countries that managed to eradicate the disease.

In order to effectively combat P. vivax, there is an urgent need for:

  • Better diagnostic tests
  • A robust point-of-care method for testing for glucose-6-phosphate dehydrogenase deficiency, which affects between 5% and 20% of people in areas where P. vivax is endemic. Such people have a significantly higher risk of hemolysis when given primaquine. Hemolysis is the destruction of red blood cells.
  • New drugs are required to treat the hypnozoite stage of P. vivax malaria, when the parasite lays dormant in the liver, sometimes for many years.
Not only does the eradication of malaria bring more investment, tourism and a sense of national pride and achievement, but there are also benefits that go beyond that country's borders, the authors write - it has regional and global public benefits.

The drive to eliminate malaria has raised some concerns, including:

  • Will mosquitoes become more resistant?
  • Will the parasites become more resistant?
  • What is the economic impact of trying to eliminate malaria in countries still in the control phase?
  • If the efforts don't succeed, will malaria come back with a vengeance?
No country can achieve malaria elimination on its own, even if it is completely surrounded by sea, the authors stress. The mosquito and parasite to not respect borders. The authors conclude:

Eliminating countries must receive appropriate support and recognition for their efforts, and the historical trend since the middle of the 20th century in shrinking the malaria map must continue.

"Shrinking the malaria map: progress and prospects"

Prof Richard GA Feachem DSc, Allison A Phillips BA, Jimee Hwang MD, Chris Cotter MPH, Benjamin Wielgosz MA, Prof Brian M Greenwood MD, Oliver Sabot BA, Prof Mario Henry Rodriguez PhD, Rabindra R Abeyasinghe MD, Tedros Adhanom Ghebreyesus PhD, Prof Robert W Snow

The Lancet, Early Online Publication, 29 October 2010

doi:10.1016/S0140-6736(10)61270-6

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