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Scientists are warning that a species of malaria could switch from targeting monkeys to humans. Macaques in south east Asia are a vast source of Plasmodium knowlesi which can spread to people, they write in PLoS Pathogens. They believe that growing human populations and increased deforestation in the region could lead to the parasite switching host. But those changes could also reduce the spread of the disease. Around one million people die each year as a result of malaria. It is caused by parasites and is spread by mosquitoes when they drink blood.
'Huge reservoir'
P. knowlesi is known as the fifth malarial parasite in humans. It mostly exists in monkeys, however, there have been human cases and it has been shown in the laboratory to be able to spread from human to human. In south east Asia, the macaques are the second most common primate after humans. Blood tests on 108 wild macaques showed that more than three quarters were infected with the malaria parasite.
Professor Balbir Singh, from the Malaria Research Centre at Universiti Malaysia Sarawak, told the BBC: "they are a huge reservoir of Plasmodium knowlesi." Genetic analysis showed that P. knowlesi had existed in monkeys since before humans settled in south east Asia. The researchers said humans were being infected from the 'reservoir', rather than the disease spreading between humans. Prof Singh raised concerns about what could happen in the future: "We don't know how mosquito behaviour will change. "With increasing human populations and deforestation we may get a shift to humans. The number of malaria cases is coming down so there is also decreased immunity. Or would deforestation reduce numbers? It could go either way."
Dr Hilary Ranson, from the Liverpool School of Tropical Medicine, said: "It seems a very reasonable thing to speculate. "Deforestation or any perturbation of the ecosystem frequently leads to humans being exposed to an expanded range of biting insects and the pathogens they transmit, yellow fever is a good example of this." She said if humans catch the parastite more often then P knowlesi may evolve to target humans. "To me the important message is that disruption of the environment exposes people to a range of known and potentially unknown pathogens transmitted by blood feeding insects that do not typically feed on humans" she added.
BBC News - Monkeys 'harbour malaria threat'
Researchers have discovered a bacterium in the gut of the Anopheles mosquito which may someday be used to destroy and, therefore, prevent the spread of the disease-causing parasite. The World Health Organization estimates 800,000 people die of malaria each year. The parasite that causes the disease is transmitted by the Anopheles mosquito. After the mosquito feeds on the blood of an infected individual, the parasite matures into an infectious stage in the insects gut. From there, the parasite, known as Plasmodium falciparum, takes up residence in the mosquitos salivary glands so it can infect the next person thats bitten.
Researchers at Johns Hopkins School of Public Health in Baltimore, Maryland found the bacterium in the gut of the Anopheles mosquito among hundreds of so-called microbial flora that live harmlessly in the stomach of a group of Anopheles mosquitoes collected in an area of southern Zambia where malaria is rampant. The microbe, which was in the guts of a small percentage of the mosquitoes, protected those insects against infection with the parasite. Lead researcher George Dimopoulos says the protection seems to be a side-effect of the bacteriums normal bodily function, adding that scientists would like to figure out a way to use the microbe as a weapon against malaria.
Our study has shown that this bacterium produces free radicals, molecules that contain oxygen and that can cause damage to cells. So, we believe thats how this bacterium is killing the malaria parasite in the mosquito gut. But we need to understand that mechanism in greater detail. To demonstrate the beneficial effect, the researchers used antibiotics to kill the bacterium in mosquitoes that contained it, and were then able to infect those mosquitoes more easily with the Plasmodium parasite. They also introduced the bacterium into the guts of mosquitoes that didnt have it. When they fed this group infected blood, the parasite was destroyed in nearly all of the insects.
Dimopoulos says researchers goal now is to figure out a way to introduce the microbe into large populations of Anopheles mosquitoes - perhaps through bait laced with their favorite snack. Mosquitoes need to feed on sugar every day. And one can potentially expose mosquitoes in the field to these bacteria through sugar bait. The researchers noted that mosquitoes with the bacterium in their guts die sooner than those without it - when both groups are infected with the parasite. Since the malaria parasite lives in mosquitoes for about two weeks before maturing to an infectious stage, Dimopoulos says its good news that the stomach bacterium seems to shorten the insects lifespan, before it could potentially transmit the parasite to humans.
Source
The malaria parasite can ensure it keeps a host body all to itself by preventing further malarial infections, according to international researchers. The parasite initially reproduces in the liver and moves into the blood. A study on mice, published in Nature Medicine, showed the parasite can trigger iron deficiency in the liver and therefore prevent more infections.
An expert said the research was "very cool and very interesting", and improved understanding of infection. The researchers were looking at super-infections, when a patient already infected with malaria is infected with another batch of malaria parasites. People in high-risk areas can be bitten by up to 700 different malaria-infected mosquitoes each year.
Protecting turf
In experiments on mice, researchers showed that parasites in the blood were able to stimulate the production of the hormone hepcidin, which regulates iron levels. This reduced the level of iron in the liver, preventing other malaria parasites from reproducing in the organ. Dr Hal Drakesmith, from the Weatherall Institute at Oxford University, who was part of the research team, said: "Now that we understand how malaria parasites protect their territory in the body from competitor parasites, we may be able to enhance this natural defence mechanism to combat the risk of malaria infections." Malaria is often accompanied by anaemia, which is treated with iron supplements.
In this study, mice given iron supplements were more susceptible to additional infections. Dr Drakesmith said: "We may need to look again at the advisability of iron supplementation programmes in malaria-endemic regions, as possible increased risk of infection may need to be weighed against benefits." Dr Rita Tewari, a malaria researcher at the University of Nottingham, said: "It's very cool and very interesting. "It tells us a bit more about the mechanism of malaria infection and gives us some sort of tool, this molecule hepcidin, that you can manipulate which can affect infection."
BBC News - Malaria blocks 'super-infection'
Children with the unusual, or variant, gene have a 30 percent lower risk of developing cerebral malaria than those without the gene. Cerebral malaria is the most serious form of the parasitic illness that causes very high fever and coma, and leads rapidly to death in the 20 to 50 percent of people whose brains become infected. The mosquito-borne illness affects almost 300 million people every year. But most of the one million deaths occur in children under the age of five.
Researchers at Germanys Bernhard Nocht Institute for Tropical Medicine and Kumasi University in Ghana identified the protective gene in a study involving more than 6,000 children. Called FAS, the gene is responsible for a molecule involved in the programmed cell death of some white blood cells, which are immune system cells that attack and destroy microbes that invade the body. Researchers think that children who develop a life-threatening form of malaria have a hyper-immune response to the parasite. But youngsters with the FAS variant have increased expression of the molecule, called CD95, which appears to promote a greater number of immune system cell suicides - thus a less intense and ultimately survivable immune reaction to malaria.
At least thats the theory, according to Kathrin Schuldt, a biologist and co-author of the study. Schuldt says children who are vulnerable to cerebral malaria are constantly bitten by mosquitoes that carry the parasite. So the immune response is constantly on a very high level trying to eliminate the pathogen from the body. And so what we found with this naturally occurring variant, these children probably have a regulation in their immune response which down-regulates the immune response to a certain level and therefore is kind of protective, Schuldt said.
Humans never develop full immunity against malaria, but they can gain a partial immunity to the parasite, which is why the disease is less severe in adults. But children can become quite sick because they have had less exposure to the disease. Schuldt says her goal now is to figure out the underlying mechanism for the protective effect of the genetic variant. Then, Schuldt says, it may be possible to develop drugs to protect children from this fatal form of malaria. An article on the protective malaria gene is published in the on-line journal PLoS Genetics.
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Organic farmers in Africa complain that insecticides used to control mosquitos that carry the malaria parasitecontaminate their crops and hurt sales. And this Ugandan nurse says the insecticide of choice is no longer effective. "It was realized that the mosquito had already developed resistance against the DDT," said Sam Dick Kale. So in malaria-prone regions, bed nets treated with insecticides, and drug treatment, also are used. That has helped to cut the number of cases nearly in half, but some 800,000 Africans still die from malaria each year, most of them children under five.
Dr. Christian Loucq explains the challenges facing vaccine researchers. He is director of the PATH Malaria Vaccine Initiative that's conducting human trials in sub-Saharan Africa. It is difficult to develop a malaria vaccine because we are dealing with a complex organism a parasite which has many, many components and that parasite organism can change, its very versatile," said Dr. Loucq. "Its quite difficult to develop immunity against that parasite. Dr. Loucq is hopeful the World Health Organization will approve the new vaccine by 2015. It will reduce the number of times a child is going to have malaria, clinical malaria, and it means reducing the number of opportunities for that child to die from malaria," he said.
The Malaria Vaccine Initiative also is trying to develop a second generation vaccine to prevent mosquitos from carrying the malaria parasite. "Once the mosquito will come to take the blood meal - the mosquito will take the antibodies that are going to stop the cycle in the mosquito," said Loucq. "Therefore the mosquito will not be in a position to transmit malaria to another child, and that would be a fantastic way to stop the transmission of malaria." Dr. Loucq says the new vaccine, called RTS,S, will be a major step toward getting rid of malaria. But for that to happen, he says, greater investment in research will be essential.
Source
Can you kill a mosquito when its biting you [with] something thats in your blood," asked Brian Foy. Malaria researcher Brian Foy of Colorado State University found out that yes, you can. He is working on a malaria control program and says there are many benefits to killing mosquitos as they bite their hosts. Foy says that this not only is a clever way of getting a toxin directly to the malaria-causing parasite living in mosquitos, but it also saves the environment from harmful insecticides. In a field study done on malaria transmission in Senegalese villages, Foy and his colleagues found that a drug already widely used for treating the two most common parasitic diseases in Africa - river blindness and elephantiasis - also has insecticidal properties. We are repurposing a really cheap and important drug for worm control potentially to control malaria," he said.
The study shows that after single doses of the drug Ivermectin were administered to residents of several Senegalese villages, there was a 79 percent reduction in mosquitoes found to be carrying the malaria parasite. In villages where the drug was not given, the malarial mosquitoes increased by 246 percent. Researchers found that the drug circulating in peoples blood killed the mosquitoes. Ivermectin is given once every year in many countries in sub-Saharan Africa to fight common infections. But researchers say that if the drug is given more often, it can provide other benefits. If you give it more often, [as] we are proposing for malaria transmission control, it will start to have an effect against the soil-transmitted illness that people have in their guts - things like whip worm, round worm and maybe even hookworms, which cause a lot of hidden illnesses in people," said Foy.
Peter Hotez, president of the American Society for Tropical Medicine and Hygiene, calls Foy's study groundbreaking. He says it proves what many public health researchers have long suspected - that drugs used to combat neglected tropical diseases have important collateral health benefits. It opens up a new pathway for discovering an additional class of drugs specifically for this purpose - maybe a drug that can circulate in the body longer and then be better targeted for malaria specifically," said Hotez. Malaria kills almost 800,000 people around the world each year. Experts say Ivermectin would be a welcome addition to the anti-malaria arsenal of bed nets, pesticides, drugs and, perhaps one day soon, a vaccine. Public health experts say all these weapons will be needed in the years ahead to eradicate malaria permanently.
Source
There has been a fall of just over 20% in the number of deaths from malaria worldwide in the past decade, the World Health Organization says. A new report said that one-third of the 108 countries where malaria was endemic were on course to eradicate the disease within 10 years. Experts said if targets continued to be met, a further three million lives could be saved by 2015. Malaria is one of the deadliest global diseases, particularly in Africa.
In 2009, 781,000 people died from malaria. The mosquito-borne disease is most prevalent in sub-Saharan Africa, where 85% of deaths occurred, most of them children under five. An earlier report here incorrectly referred to a 40% drop in deaths. It has been eradicated from three countries since 2007 - Morocco, Turkmenistan and Armenia. The Roll Back Malaria Partnership aims to eliminate malaria in another eight to 10 countries by the end of 2015, including the entire WHO European Region.
Robert Newman, director of the WHO's Global Malaria Programme, said "remarkable progress" had been made. "Better diagnostic testing and surveillance has provided a clearer picture of where we are on the ground - and has shown that there are countries eliminating malaria in all endemic regions of the world," he told an international Malaria Forum conference in Seattle. "We know that we can save lives with today's tools."
Global eradication
The analysis was published in The New England Journal of Medicine. The Guardian newspaper says the trial, which involved almost 15,500 babies, shows that the vaccine could potentially save 800,000 lives a year. It is being carried out in seven countries – Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique and Tanzania.
The vaccine has been in development for two decades – the brainchild of scientists at the British drug company GlaxoSmithKline, which has promised to sell it at no more than a fraction over cost-price, the newspaper says. Andrew Witty, GSK's CEO, tells the newspaper that some of the scientists who began working on a vaccine 25 years ago broke down in tears when the trial data were revealed.
"It was the emotion of what they had achieved -- the first vaccine against a parasitic form of infection," says Witty. "They were overwhelmed. It says something about the amount of heart that has gone into this project." The Guardian reports that the World Health Organization has said that if the results of the study were satisfactory, it would issue a recommendation for its use as early as 2015. WHO says any such vaccine should be part of a program that includes the use of bed netting and insecticide spraying.
Source
The malaria parasite is spread by mosquitoes, and mosquitoes like to breed in standing water. So when a previously dry area is irrigated, the disease can take hold. What happens is that when you irrigate, there is more, in a sense, more breeding habitats for the mosquito, explains University of Michigan scientist Mercedes Pascual. She and her colleagues studied areas in northern Indias Gujarat state, where irrigation was introduced at various times. They analyzed how malaria progressed along with the spread of irrigation.
What they found was that after farmers began irrigating their crops, the malaria risk increased dramatically. The researchers thought maybe the malaria cases surged because there was little effort to control the mosquitoes that spread the disease. In fact, we saw the opposite, Pascual said in a telephone interview. This transition stage was characterized not just by heightened malaria risk, but also by more intervention to control the mosquito vector. Eventually, the mosquito control efforts take hold, but the researchers found high rates of malaria persist for a decade or more - longer than had been previously thought.
A laborer sleeps on a bed covered with a net on a hot summer morning
Pascual suggests that the irrigation project managers need to focus more on reducing places where mosquitoes might breed. And health officials may need to ramp up their approach, which she says has mostly focused on indoor insecticide spraying. And what we are saying is that those measures have to be sustained, and sustained and also planned for, for the long term.
In areas with low rainfall, the researchers write in their research paper, irrigation offers considerable rewards. But as University of Michigan scientist Mercedes Pascual and her team point out, irrigation can also bring with it years of high rates of malaria unless better planning and control measures come along with the water supply. Their findings are published online by the Proceedings of the National Academy of Sciences.
Irrigation Brings Malaria Along with Water
Researchers focused on a 3,000-square-kilometer area of Sabah state in Malaysia, with a population of 120,000 people. Much of the forest is being cleared to produce palm oil and other commodities. Using hospital data and satellite mapping, scientists found the changes in land use were closely associated with a rise in the number of human cases of a type of malaria called Plasmodium knowlesi.
Professor Chris Drakeley, who was part of the research team, said the malaria's normal host, "the thing that it normally grows in, is long- and pig-tailed macaques. And in recent years in that part of Malaysia, northern Borneo, they have shown an increase in the number of cases in individuals with this malaria, presenting themselves to hospitals.” Researchers said this was most likely explained by humans coming in close contact with the forest inhabited by the macaques, and the mosquitoes that transmit malaria. Many local villagers are employed in tree clearance and agricultural expansion.
The Plasmodium knowlesi strain is now the most common form of human malaria in many areas of Malaysia, and it has been reported across Southeast Asia. “It can rapidly reproduce in your blood, and that means you get very high levels of infection," Drakeley said. "The case fatality rate, the number of people that die per infection, is quite high. We don’t think there’s going to be a very big expansion of it, but we’re very concerned as a general public health problem.” So far there is no evidence of this strain of malaria being transmitted from human to human. But the report authors said their research suggested that deforestation has distinct public health consequences, which need to be urgently addressed.
Scientists: Malaysian Deforestation Driving Spike in Malaria Strain
Some Monkeys have Mad Cow disease. And some of them have AIDS too.Another good reason not to be eatin' monkey meat...
Monkeys 'harbour malaria threat'
8 April 2011 - A type of malaria could move from monkeys to humans, say scientists
Scientists are warning that a species of malaria could switch from targeting monkeys to humans. Macaques in south east Asia are a vast source of Plasmodium knowlesi which can spread to people, they write in PLoS Pathogens. They believe that growing human populations and increased deforestation in the region could lead to the parasite switching host. But those changes could also reduce the spread of the disease. Around one million people die each year as a result of malaria. It is caused by parasites and is spread by mosquitoes when they drink blood.
'Huge reservoir'
P. knowlesi is known as the fifth malarial parasite in humans. It mostly exists in monkeys, however, there have been human cases and it has been shown in the laboratory to be able to spread from human to human. In south east Asia, the macaques are the second most common primate after humans. Blood tests on 108 wild macaques showed that more than three quarters were infected with the malaria parasite.
Professor Balbir Singh, from the Malaria Research Centre at Universiti Malaysia Sarawak, told the BBC: "they are a huge reservoir of Plasmodium knowlesi." Genetic analysis showed that P. knowlesi had existed in monkeys since before humans settled in south east Asia. The researchers said humans were being infected from the 'reservoir', rather than the disease spreading between humans. Prof Singh raised concerns about what could happen in the future: "We don't know how mosquito behaviour will change. "With increasing human populations and deforestation we may get a shift to humans. The number of malaria cases is coming down so there is also decreased immunity. Or would deforestation reduce numbers? It could go either way."
Dr Hilary Ranson, from the Liverpool School of Tropical Medicine, said: "It seems a very reasonable thing to speculate. "Deforestation or any perturbation of the ecosystem frequently leads to humans being exposed to an expanded range of biting insects and the pathogens they transmit, yellow fever is a good example of this." She said if humans catch the parastite more often then P knowlesi may evolve to target humans. "To me the important message is that disruption of the environment exposes people to a range of known and potentially unknown pathogens transmitted by blood feeding insects that do not typically feed on humans" she added.
BBC News - Monkeys 'harbour malaria threat'
