VICTIM Gyobe Saiku, a woman with river blindness in Kambre, Nigeria
Vanessa Vick for The New York Times

 

 

 

The New York Times, July 13, 2011, by Donald G. McNeil Jr.  —  Scientists have proposed an intriguing new way to fight malaria: turning people into human time bombs for mosquitoes.

A cheap deworming pill used in Africa for 25 years against river blindness was recently shown to have a power that scientists had long suspected but never before demonstrated in the field: When mosquitoes bite people who have recently swallowed the drug — called ivermectin or Mectizan — they die.

Other scientists caution that while the mosquito-poisoning trick is pretty nifty, it is not very practical: For it to work effectively, nearly everyone in a mosquito-infested area must take the pills simultaneously.

Getting thousands of villagers to do that even in annual deworming campaigns is a logistical nightmare, scientists said. The mosquito-killing effect appears to fade out within a month, so it would need to be repeated monthly.

Also, in rare cases, the otherwise safe drug can be lethal.

The new study, published last week by The American Journal of Tropical Medicine and Hygiene, was carried out by scientists from Senegal and Colorado State University. They vacuumed mosquitoes from the walls of huts in three villages whose inhabitants had recently been given ivermectin and three whose had not, and tested to see how many mosquitoes contained malaria parasites.

The ivermectin villages had almost 80 percent fewer.

The drug was shortening the mosquitoes’ lives, explained the lead author, Brian D. Foy, a Colorado State mosquito expert. Only older insects transmit malaria, since they must get it from humans first.

Dr. Peter Hotez, president of the American Society of Tropical Medicine and Hygiene, was enthusiastic about the study, saying it showed that deworming drugs “could have a lot of collateral effects.”

Dr. Lee Hall of the National Institutes of Health, which helped finance the study, was more cautious, saying a clinical trial might be warranted once more is known about how long ivermectin kills.

But a worm expert from the Carter Center in Atlanta was very skeptical.

At present, millions of free doses are given out to fight onchocerciasis, or river blindness, which is caused by tiny worms migrating into the eye.

“We hand it out once a year,” said the parasitologist, Dr. Frank O. Richards Jr. “I’m pushing for twice a year, and people want to kill me. It’s very difficult to imagine a once-a-month program anywhere.”

It might be useful, he suggested, in areas with brief, intense malaria seasons.

Also, when people with lots of worms are treated, they suffer fever and intense itching as the worms die. Though that might be bearable once a year, it discourages people from seeking treatment more frequently. And ivermectin is dangerous for a few people — those infested with large numbers of a relatively rare West African worm, the loa loa. These worms circulate in the blood and lungs and may jam capillaries when they die, potentially causing coma or death. Detecting them means drawing blood and viewing it under a microscope.

“It’s very difficult to say, ‘Let’s treat a million people’ — and then have to test each one for loa loa,” Dr. Richards said.

What’s that smell? Mosquitoes prefer the odor of stinky feet over that of a human.

 

 

 

Mosquitoes lured to traps using natural and artificial foot smell

 

 

 

By Jennifer Welsh

The old adage that you catch more flies with honey may be true, but researchers are betting that the scent of smelly feet will be the best lure to catch disease-spreading mosquitoes.

The researchers, led by Fredros Okumu at the Ifakara Health Institute in Tanzania, are developing traps using natural and artificial foot odors to lure mosquitoes and prevent them from spreading diseases like malaria. Their project was just awarded a grant from Grand Challenges Canada and the Bill & Melinda Gates Foundation.

 

A whiff of the trap odor may send humans in the other direction, but the scent is a pleasant one to mosquitoes, luring them into traps and keeping the pesky insects out of open-air houses. The researchers also found the trap could be used as a complement to bed nets and bug sprays to protect people from  mosquito-borne diseases, which are prevalent in many of the poorer areas of the world and cause millions of deaths a year. [ 10 Deadly Diseases That Hopped Across Species ]

Nearly 250 million new cases of malaria, which is transmitted by Anopheles gambiae mosquitoes, are reported each year, with almost 800,000 individuals dying each year from the disease, according to the researchers.

“Despite global progress in the fight against malaria, there is still work to be done,” Okumu said in a statement. “Malaria has claimed so many lives, including those of people close to me, and my hope is that this innovative device will be part of the solution.”

The stinky foot smell (either from smelly socks or similar smelling synthetic bait) is so attractive to mosquitoes that researchers found it draws about four times more of the insects than the smell of a human does. Once the mosquitoes are lured away from their human meal into the trap, they are poisoned or imprisoned there until they die.

The grant will fund Okumu’s team in further development and perfection of the device and test its cost-effectiveness and reliability. The team expects the optimized trap to be in communities in two years.

 

 

Fighting malaria with bed nets

Employees at a textile mill manufacture durable mosquito nets for distribution to high-risk areas for malaria. Fine mesh bed nets treated with long-lasting insecticides are an important method of protection against malaria infection. Partners, such as The Global Fund to Fight AIDS, Tuberculosis and Malaria, provide funding to national malaria control programs to procure and distribute nets. Arusha, Tanzania

Ivanhoe.com, July 14, 2011 — Killing over 780,000 people each year, malaria is one of the deadliest diseases in the world. Finding a cure has been the goal of scientists for many years. Now a cheap and common medication used to treat lice in children and heartworm in pets, could add malaria to the list of diseases it helps control.

According to the World Health Organization, new approaches to combat malaria are in constant demand. Current methods of avoiding transmission rely mainly on sleeping under insecticide-treated bed nets and spraying indoors with mosquito poisons. Scientists from Senegal and Colorado State University found that transmission of malaria parasites by mosquitoes fell substantially over two weeks among people living in several Senegalese villages who took the drug ivermectin. The drug appeared to kill malaria-carrying mosquitoes that fed on the blood of the villagers.

“There is no silver bullet for malaria control,” Brian D. Foy, Ph.D., a vector biologist at Colorado State University and the article’s senior author, was quoted saying. “But this could be an important tool that would also contribute to the fight against other neglected diseases. It’s clearly a multipurpose drug.”

Ivermectin is currently used to treat river blindness in Africa. It is also effective against variety of parasitic worms including those that cause elephantiasis. It can help prevent heartworm in animals and kills insects that commonly affect children, like lice.

“If using ivermectin works to reduce transmission, people will have a drug circulating in their blood that could kill mosquitoes anywhere and at any time of day,” Dr. Foy said.

Researchers collected mosquitoes from villages where people were taking Ivermectin and compared them to collections gathered at the same time from villages where people were not taking the drug. In locations where people were taking ivermectin, two weeks after the drug was administered there was a 79 percent decline in mosquitoes carrying Plasmodium falciparum—the world’s most deadly malaria parasite. In villages where ivermectin was not in use, malaria-bearing mosquitoes increased by 246 percent over the same period.

The study suggests it might be possible to use the drug to reduce malaria transmission during epidemics or in well defined transmission seasons. Larger, longer studies will be needed to show weather more frequent doses of ivermectin during malaria season have an important impact on the disease.

Source: American Journal of Tropical Medicine and Hygiene, July 2011

Malaria

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The life cycle of malaria parasites in the human body. A mosquito infects a person by taking a blood meal. First, sporozoites enter the bloodstream, and migrate to the liver. They infect liver cells (hepatocytes), where they multiply into merozoites, rupture the liver cells, and escape back into the bloodstream. Then, the merozoites infect red blood cells, where they develop into ring forms, trophozoites and schizonts which in turn produce further merozoites. Sexual forms (gametocytes) are also produced, which, if taken up by a mosquito, will infect the insect and continue the life cycle.

 

 

 

Malaria Overview

Malaria is an infection of the blood that is carried from person to person by mosquitoes. The disease has been recognized for thousands of years and once was found almost everywhere except in the most northern areas of the world. Malaria has been wiped out in North America, Western Europe, and Russia. It remains a serious problem in much of the tropical and subtropical world, however.

Millions of people continue to be infected every year, and probably up to 1 million of them die. Although the United States is malaria-free, hundreds of cases a year are still reported here. Most of these are people who acquired the disease overseas.

Malaria Causes

Malaria is caused by protozoan of the genus Plasmodium.

  • Infection begins with a bite from an infected mosquito.
  • The parasite travels from the mosquito to your liver, where the parasite begins to reproduce.
  • The parasite leaves the liver and travels to the bloodstream, where it infects red blood cells. The parasite reproduces in the red blood cells, which destroys the cells and releases more parasites into the bloodstream.
  • If another mosquito bites an infected person, that mosquito can then carry the infection to someone else.
  • There are 4 species of Plasmodium that infect humans:
  • P vivax – Most common in India and Central and South America but found worldwide. It has an incubation period of 8-13 days. Infections can sometimes lead to life-threatening rupture of the spleen. In people treated only with chloroquine (Aralen), this type of malaria can hide in the liver and return later.
  • P ovale – Rarely found outside Africa. This form of malaria has an incubation period of 8-17 days and can hide in the liver of partially treated people and return later.
  • P malariae – Found worldwide but less common than the other forms. This form of malaria has an incubation of 2-4 weeks. If untreated, the infection can last many years.
  • P falciparum – Common worldwide, this is the most life-threatening form of malaria. This parasite has an incubation period of 5-12 days. Resistance to many of the drugs used to treat or prevent malaria is becoming very common.

 

  • Although most people acquire malaria through mosquito bites, in some foreign countries the disease can have other sources.
  • Every year a handful of people are infected through blood transfusions or organ transplants.
  • IV drug users can develop malaria from sharing needles.
  • Each year a few babies are born to mothers who did not know they were infected. The babies then develop malaria.

A new manufacturing technique may allow for solar panels to be produced simply using nothing more than an ink-jet printer.

 

 

 

SmartPlanet.com, July 13, 2011, by Tuan C. Nguyen  —   The new technique, developed by MIT researchers, is a much gentler technology than what’s being used to manufacture solar cells. That’s because the process involves using vapors instead of liquid to bring down the temperature during manufacturing to less than 120 degrees Celsius, which allows it to be used on more delicate materials like paper, cloth or plastic.

The idea behind the MIT team’s approach is that if researchers can perfect a process in which cells can be printed on common everyday materials like cloth and paper, you would suddenly open the technology up to all kinds of possibilities for household use. Cells can be painted on wallpaper or companies can produce solar-powered curtains to harness energy anywhere the sun might shine.

The cells, which are quite durable, can be scrunched up, made into a paper airplane or even folded a thousand times over and still deliver solid performance. And if you wanted to harness energy outdoors, the paper can be laminated to protect it from harsh weather conditions.

Versatile and affordable solar cells would be a major boon to the industry. High manufacturing costs is one of the reasons why solar power hasn’t hit the mainstream as some renewable energy advocated had hoped. For instance, the glass that supports the active photovoltaic material coupled with installation can cost twice as much as the cells themselves. In contrast, paper costs one-thousandth as much as glass for a given area, according to the researchers.

Dynamic Folding of a Paper Solar Cell Circuit

MITNewsOfficeUploaded by MITNewsOffice on Jul 8, 2011

 

A paper solar cell circuit is dynamically folded and unfolded while the voltage is simultaneously measured on the meter. The paper photovoltaic is illuminated from below with simulated solar illumination.

 

 

The drawback is that paper-printed solar cells have an efficiency of about 1 percent, though researchers believe this can be improved significantly with further fine-tuning of the materials. Still, researchers say the amount of energy is supplied is “good enough to power a small electric gizmo.”

“We have demonstrated quite thoroughly the robustness of this technology,” says Vladimir Bulović, a professor of electrical engineering. “We think we can fabricate scalable solar cells that can reach record-high watts-per-kilogram performance.”

Image: MIT