Scientific discoveries
Green trees deliver green benefits
Food supply may fall 25% by 2050, says UN
Argentine ants give weeds a boost
Temperature spikes key to malaria spread
Galactic impact leaves Milky Way ringing
Biomaterial helps rebuild broken bones
Biofuel rocket engine passes test run
Resistance gene stops rust in wheat
Stress, abuse damages childhood genes
Most wars occur in rich wildlife areas: study
Mice shed light on obesity gene
Dark energy to erase Big Bang's signal
Mexican corn contamination confirmed
Peanut allergy rate doubles despite avoidance
CO2 satellite plummets into ocean
Sharks fall foul of fishing bias
Fossil fish reveal prehistoric lovemaking
HIV proves to be a fast learner
Motor neurone disease culprit identified
Planet hunter ready for take-off
Visual adaptation stops life in the fast lane
Roofs can boost rainwater lead levels
Daily dose of TV doubles asthma risk
Biochar needs 'years more research'
  Temperature spikes key to malaria spread
Climate change is influencing the spread of malaria in ways far more complicated than previously thought, according to US researchers.

The disease's ability to spread depends not just on how temperature changes from month to month and year to year, but also on how temperature fluctuates throughout the day, says entomologist Dr Matthew Thomas of Pennsylvania State University.

By looking at climate patterns in more detail, the new data suggest that scientists may need to reconsider their predictions of where malaria epidemics might strike next.

"We may be overestimating the risk in warmer environments, but underestimating the risk in colder environments," says Thomas, who presented his findings recently at the American Association for the Advancement of Science annual meeting in Chicago. "We can be wrong by 50 to 100% or more."

The implications are enormous, says Professor Chris Thomas, of Aberystwyth University in the UK, who does related work.

More than a million children die from malaria every year in Africa. "That's one child every 30 seconds," he says. "This is for a preventable and treatable disease."

And things could get worse. With global warming, malaria is spreading into new regions, though scientists don't yet know exactly where, when and how patterns of the disease are going to change.

One reason for the uncertainty, says Matthew Thomas, is that most predictive models consider only a rise in average temperatures over days, months or even years.

But climate projections also forecast a spike in extreme weather events as well as a rise in variability as the atmosphere heats up. Already, a typical day in a malaria-infested place like Tanzania might average 25C, but nights can drop to 15C with daytime highs of 32C.

Those peaks and dips, Thomas suspects, might affect malaria-transmitting anopheles mosquitoes in a number of ways.
Parasites respond to temperature

When a mosquito drinks the blood an infected person, the insect also swallows the malaria parasite, which then must incubate and multiply before migrating into the insect's saliva.

The process can take weeks. And because mosquitoes are small-bodied and cold-blooded, outside temperatures make a big difference in how long it takes before they can transmit the disease. If it happens too slowly, the insects die before they can infect anyone.

In general, the malaria parasite does better at warmer temperatures, which is why the disease occurs most often in tropical environments.

But with mathematical models, Thomas has found that, even when conditions are warm, highly fluctuating temperatures over the course of a day slow down the rate of parasite incubation and larval development in the mosquito.

That, in turn, slows the spread of disease - and suggests that hot areas might be less at risk for malaria outbreaks than scientists have long thought.

At relatively cool temperatures, on the other hand, fluctuating temperatures speed up biological processes, which might help explain why malaria has already begun spreading into the traditionally cool highlands of East Africa.

These areas, which lie on the fringes of malaria's current distribution, are of extreme concern, because they are poor, rural, and have never been exposed to malaria. People there have no built-up immunity to the disease, so epidemics can be swift and deadly.

The research also underscores how little scientists know about the basic biology of mosquitoes. Getting to know the enemy, Thomas says, is the only way to figure out where to distribute bed nets, sprays and other limited resources.

"We have the whole genome of anopheles, but that tells us nothing about how temperature influences these mosquitoes," says Princeton University ecologist Professor Andrew Dobson.

"We need better ways to predict where malaria is going to occur."
Chernobyl wildlife depleted, deformed
Prostate studies give conflicting results
Indigenous fire to save CO2 emissions
Maggots no wonder cure for wounds
Finch head colour affects mating outcome
Abnormal sperm found in inbred animals
New genes linked to heart failure
Cold gas sparks cosmic stream debate
Red meat under the spotlight
Science nabs two new greenhouse gases
Calls to protect workers from nano risks
Bushfire origins lie in Indian Ocean
Sceptics cold over new fusion claim
Family homecomings put travellers at risk
Scientists find pieces of a shooting star
Nanotube tech transforms CO2 into fuel
Decoding the secrets of platypus venom
Very hot tea may cause throat cancer
Sickness certificates more harm than good
Australians 'complacent' to earthquakes
Action video games sharpen vision
Shells give new take on human evolution
Native ant may stop toad in its tracks
Stressed female corals become male
Pen-clicking 'should be investigated'
Call to halt falling Oz food productivity
Tropics are a boon for baby girls
GM viruses build a better battery
Earth critters to take a trip to Phobos
Two black holes found circling each other
Horses first ridden 5500 years ago
Japanese astronaut to fly 'magic carpet'
Amazon drought reduces carbon sinks
Shells 'thinning due to fossil fuels'
Lunar cycle affects cyclone strength
Piezoelectrics harness hamster power
Vitamin C wards off gout: study
Aussie turtles 'ride the EAC' to Peru
Alien worlds examined in the lab
Sea level rise underestimated: scientists
Blood type link to pancreatic cancer risk
Peking man much older than first thought
Americium dampens plutonium's punch
Global skies becoming dimmer: study
Clever coating makes scratches disappear
Call for carbon tax gets lukewarm response
Great white sharks had humble beginnings
Discovery to help power up space station
Early oceans had oxygen-loving life
Bushfire risk to water quality lingers
South America needs elephants: ecologist
Omega-3 benefits hurting fish numbers