Incidence of malaria-causing Plasmodium vivex worldwide. Red indicates local
infection rates greater than 7 percent; Light blue: one percent. More about map here.
When most people think of malaria, they usually think of its most deadly variety, caused by the parasite Plasmodium falciparum, the form most prevalent in Africa. But it’s not the only one: a second type, Plasmodium vivax, is a growing and overlooked disease in Southeast Asia and elsewhere in the world. More resources may need to be devoted to halt it’s spread, say researchers who presented the first comprehensive map of the disease’s worldwide prevalence Tuesday at the ongoing annual meeting of the American Society for Tropical Medicine and Hygiene in Philadelphia. Currently 97 percent of malaria-eradication funds are focused on P. falciparum, Oxford University researcher Peter Gething tells Nature News.
Despite the millions of dollars devoted to research and outreach, malaria has largely evaded our best efforts at eradication. The various strains of the protozoan that causes it, Plasmodium falciparum, use a number of different molecular methods to gain access to the red blood cells they infect, with no single molecule in common, and a common molecule, of course, is a requirement for developing an effective vaccine. But scientists now report that using a new technique, they’ve found a molecule that seems to fit the bill.
Blood smear of the Plasmodium falciparum parasite
Preliminary results from the largest ever field trial of a malaria vaccine show the vaccine cut infant’s risk of getting the disease by half. In development for more than 25 years by GlaxoSmithKline and others, the vaccine cut the risk of catching severe malaria by 47 percent amongst infants ages 5 months to 17 months in the year after receiving it. 6,000 kids enrolled in the study, whose early results were published yesterday in the The New England Journal of Medicine and announced at a Seattle conference organized by the Bill and Melinda Gates Foundation, a major funder of the study and other efforts to combat malaria. The vaccine represents the first against a parasite-borne infection and has been notoriously difficult to develop since the protozoan that causes the illness (mainly Plasmodium falciparum) changes shape as it moves from the blood to the liver and back again.
While 47 percent isn’t very effective—most vaccines aren’t approved until they reach 90 percent or better—even this level of protection could save millions of lives, Glaxo’s chief executive Andrew Witty tells the New York Times. Malaria kills an estimated 780,000 per year, despite being preventable and treatable, mostly claiming the lives of African children.
[Via The Guardian]
Image: CDC / Wikimedia
What’s the News: Biochemists at the University of Arizona have found a promising new way to fight disease-carrying mosquitoes. In their research project, published in the journal PNAS, the scientists blocked mosquitoes’ ability to digest blood, making blood-sucking deadly to the winged pests. This technique could someday be used alongside other strategies to battle mosquitoes, like repellents and traps.
As the number of bacteria in mosquitoes’ guts (x axis) went up,
the malaria parasite levels dropped faster than a cartoon anvil.
What’s the News: We know the bacteria living in our guts are important to our health—but the bacteria in mosquitoes’ guts could be too. Researchers have discovered a species of mosquito gut bacteria that destroys the malaria parasite, keeping the disease from spreading to humans. This explains why some Anopheles mosquitoes (the only genus that transmits malaria) don’t spread it, and it spurs the imagination towards possible ways of tamping down the disease.
Selfish genes could help destroy mosquitoes’ ability to carry malaria.
What’s the News: Many scientists have played with the idea of creating a genetically modified mosquito that won’t transmit malaria, which kills about 850,000 people a year, and releasing it into the wild. But in the face of the millions of mosquitoes out there that do ferry malaria around, how would the trait spread fast enough to make a difference?
Now, scientists have developed a way to cause a “selfish” gene to spread to more than half of a mosquito population over just a few generations, suggesting a method to quickly and broadly disrupt genes required for carrying malaria.
Several million years ago, Plasmodium falciparum – the parasite that causes most cases of human malaria – jumped into humans from other apes. We’ve known as much for decades but for all this time, we’ve pinned the blame on the wrong species. A new study reveals that malaria is not, as previously thought, a disease that came from chimpanzees; instead it’s an unwanted gift from gorillas.
Until now, the idea of chimps as the source of human malaria seemed like a done deal.
Check out the rest of this post at DISCOVER blog Not Exactly Rocket Science.
Not Exactly Rocket Science: Genetically-modified mosquitoes fight malaria by outcompeting normal ones
Not Exactly Rocket Science: Beer makes humans more attractive to malarial mosquitoes
80beats: Scientist Smackdown: Did King Tut Die of Malaria or Sickle Cell?
DISCOVER: Battling Malaria, Ninja-Style
Image: Wikimedia Commons
What struck down ancient Egypt’s King Tutankhamen at the tender age of 19?
Just this winter, Egyptian researchers seemed to think they had a definitive answer. After years of genetic tests and CT scans, they concluded that royal incest had produced a sickly boy with a bone disorder, and argued that a malaria-bearing parasite finished him off. But now a team of German researchers is arguing that the observations actually point to death from the inherited blood disorder sickle cell disease (SCD).
People with SCD carry a mutation in the gene for haemoglobin which causes their red blood cells to become rigid and sickle-shaped. A single copy of the sickle-cell gene confers increased immunity to malaria, so it tends to be common in areas where the infection is endemic – such as ancient Egypt. People with two copies of the gene suffer severe anaemia and often die young. [New Scientist]
Former Roman Catholic priest and respected evolutionary biologist Francisco Ayala has won this year’s Templeton Prize. The $1.53 million award honors a living person “who has made an exceptional contribution to affirming life’s spiritual dimension, whether through insight, discovery, or practical works.” The John Templeton Foundation cited Ayala’s dogged work through the years advocating the peaceful co-existence of science and religion in its decision. The somewhat controversial prize is often given to scientists who find common ground between religion and science, but previous winners have also included more traditional spiritual leaders like Mother Teresa and televangelist Billy Graham.
Ayala is the former president of the American Association for the Advancement of Science and is respected for his research into the evolutionary history of the parasite scientists have associated with malaria, with an eye toward developing a cure for the disease. He also pioneered the use of an organism’s genetic material as molecular clocks that help track and time its origins [The Christian Science Monitor]. But he is known best, perhaps, for being an expert witness in the 1981 federal court trial that led to the overturning of an Arkansas law mandating the teaching creationism with evolution in science class. In 2001, he was awarded the National Medal of Science.
Once again, to the bane of myth-makers and fans of historical intrigue, the simplest explanation may be the best: Scientists analyzing the DNA of the world-famous mummy of Tutankhamen say that he wasn’t done in by murder nor any of the exotic diseases put forth as explanations for his death at the age of 19. Rather, they say in the Journal of the American Medical Association, it was likely complications of malaria that killed King Tut, who was already frail thanks to royal inbreeding.
The team led by Egypt’s top archaeologist, Zahi Hawass, spent years taking CT scans and conducting genetic tests on mummies from the royal tombs. They say they confirmed that Tut was the son of Akhenaten, which is what scholars have long believed, but it hints at something else: It also identifies some of his grandparents and great-grandparents for the first time and suggests that his mother was Akhenaten’s sister [The Times]. A brother-sister pair wasn’t unusual during this period in ancient Egypt, medical historian Howard Markel says. Pharaohs were thought of as deities, so it makes sense that the only prospective mates who’d pass muster would be other deities [AP].