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They have confirmed that resistant strains of the malaria parasite on the border between Thailand and Burma, 500 miles (800km) away from previous sites. Researchers say that the rise of resistance means the effort to eliminate malaria is "seriously compromised". The details have been published in The Lancet medical journal. For many years now the most effective drugs against malaria have been derived from the Chinese plant, Artemisia annua. It is also known as sweet wormwood. In 2009 researchers found that the most deadly species of malaria parasites, spread by mosquitoes, were becoming more resistant to these drugs in parts of western Cambodia. This new data confirms that these Plasmodium falciparum parasites that are infecting patients more than 500 miles away on the border between Thailand and Burma are growing steadily more resistant.
The researchers from the Shoklo Malaria Research Unit measured the time it took the artemisinin drugs to clear parasites from the bloodstreams of more than 3,000 patients. Over the nine years between 2001 and 2010, they found that drugs became less effective and the number of patients showing resistance rose to 20%. Prof Francois Nosten, who is part of the research team that has carried out the latest work, says the development is very serious. "It would certainly compromise the idea of eliminating malaria that's for sure and will probably translate into a resurgence of malaria in many places," he said.
'Untreatable malaria'
Another scientist involved with the study is Dr Standwell Nkhoma from the Texas Biomedical Research Institute. "Spread of drug-resistant malaria parasites within South East Asia and overspill into sub-Saharan Africa, where most malaria deaths occur, would be a public health disaster resulting in millions of deaths." The scientists cannot tell if the resistance has moved because mosquitoes carrying the resistant parasites have moved to the Burmese border or if it has arisen spontaneously among the population there. Either way the researchers involved say it raises the spectre of untreatable malaria. "Either the resistance has moved and it will continue to move and will eventually reach Africa. Or if it has emerged, now that artemisinin is the standard therapy worldwide then it means it could emerge anywhere," Prof Nosten told the BBC. "If we were to lose artemisinin then we don't have any new drugs in the pipeline to replace them. We could be going back 15 years to where cases were very difficult to treat because of the lack of an efficacious drug."
Artemisinin is rarely used on its own, usually being combined with older drugs to help fight the rise of resistance. These artemisinin based combination therapies are now recommended by the World Health Organization as the first-line treatment and have contributed substantially to the recent decline in malaria cases in many regions. Prof Nosten says the current spread of resistance could be similar to what happened in the 1970s with chloroquine, a drug that was once a front-line treatment against the disease. "When chloroquine resistance reached Africa in the middle of the 1970s it translated into a large increase in the number of cases and the number of children who died increased dramatically." In a separate paper published in the journal Science researchers have identified a region of the malaria parasite genome that is linked to resistance to artemisinin.
Dr Tim Anderson, from Texas Biomed who led this study, says that while mapping the geographical spread of resistance can be challenging it may be hugely beneficial. "If we can identify the genetic determinants of artemisinin resistance we should be able to confirm potential cases of resistance more rapidly. This could be critically important for limiting the further spread of resistance." According to the World Malaria Report 2011 malaria was responsible for killing an estimated 655,000 people in 2010 - more than one every minute. A majority of these were young children and pregnant women.
BBC News - Resistance spread 'compromising' fight against malaria
Italian researcher Dan Cojoc said that was the primary motivation behind his recent project to develop a new screening technique for the mosquito-born illness. He said a friend from Ivory Coast provides a good example of why faster tests are needed. He told me about his kid who was touched by malaria, Cojoc explained. And when he was at the hospital, the father was dispirited, because the doctors said you will have the [diagnosis] in 12 hours. In 12 hours, the person can die. Cojoc said his international team has developed a new technique that can get a diagnosis in minutes. He said the current standard method to test for malaria requires special training and expensive equipment. This actual technique can only be applied in hospitals, which are very few in Africa. Cojoc said his team wanted to create a device which can be used in every corner of a country.
Cojoc's technique involves taking a one-second video of a red blood cell, while shining a tinted light through it. The recording is done at a high frame rate, meaning that the second is broken down into many separate slides. The light shows up in the video in what he called a speckle pattern created by vibrations of the cell membrane. Cojoc said when viewed this way, the difference between a healthy cell and one infected with the malaria parasite is immediately obvious. A healthy cell vibrates in one way, and infected cells in a different way, because when a parasite enters into a cell, the cell [membrane] becomes stiffer. He is working on the final phases of developing a low-cost instrument that would implement this technique. He says he expects the final product will include a special, portable microscope, costing around $400, and disposable microchips to hold the blood sample, costing less than a dollar each.
Cojoc, a senior scientist at the Istituto Officina dei Materiali, added his team also hopes to apply his speckle pattern technique to other diseases. We do think that this technique can be applied also to characterize other types of cells, he said, the healthy cells and the cancer cells, for instance. According to the World Health Organization, a child dies from malaria every minute in Africa. The organization says prompt and effective treatment is a key component in controlling the disease.
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Researchers in London found resistance to artemether in test tube analysis of blood from 11 of 28 patients who had fallen ill after travelling in countries mainly in sub-Saharan Africa -- what they said was a "statistically significant" result. Artemether is one of the most effective drugs in the artemisinin group most commonly used in malaria cocktails known as ACTs. "Resistance in a test tube usually leads to resistance at some stage down the line in patients," study leader Sanjeev Krishna told AFP of the findings published in BioMed Central publishers' Malaria Journal. "The question is how far down the line." The study did not look at the patients' actual response to drugs, and "what that might mean in terms of treatment failure, we have yet to assess. We don't know." A statement said the resistance was caused by genetic mutations in a parasite transmitted by infected mosquitoes, and meant that "the best weapons against malaria could become obsolete."
The laboratory tests on the Plasmodium falciparum parasite, which causes the deadliest form of malaria and is responsible for 90 percent of deaths, showed artemether's effectiveness reduced by about half in the infected samples. "This study confirms our fears of how the parasite is mutating to develop resistance," said Krishna, adding the genetic changes "occurred relatively recently". "Drug resistance could eventually become a devastating problem in Africa, and not just in east Asia where most of the world is watching for resistance." Sub-Saharan Africa is home to 90 percent of people killed by malaria every year. The World Health Organisation (WHO) said Tuesday it was optimistic drug-resistant malaria that has emerged along Thailand's borders with Cambodia and Myanmar could be contained within the region.
While global campaigning and wide distributions of mosquito nets have helped curb malaria, it is still regarded as the worst parasitic disease in the world. The WHO says 655,000 people died of malaria in 2010, making it the world's fifth biggest killer in low-income countries. "What we should be doing is to use the drugs we have as effectively as we can, to make sure they are working and to stop using combinations that are not working," said Krishna. And the focus should be on monitoring and further research. "We must be very alert to the risk of there being increased treatment failures," the scientist warned. "We need to know more, we need to know it fairly quickly."
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Not long ago, malaria killed more Sudanese refugees than any other disease. But now, while it is still deadly, the U.N. reports it is only the fifth leading cause of death among the estimated 50,000 Sudanese refugees living in the Kakuma refugee camp in northern Kenya. The reason - a five-year campaign called Nothing-But-Nets run by The United Nations Foundation. Nothing-But-Nets is the largest grassroots campaign in the world and it hopes to end malaria deaths by 2015.
Now, Nothing-But-Nets has launched an emergency appeal to send 100,000 life-saving bed nets to help thousands of South Sudanese refugees fleeing conflict and violence along the Sudan border. Thirty-seven-year-old Achol Deng is a mother of three from Jonglei state. She is among thousands of new arrivals in the Kakuma refugee camp. Deng received mosquito nets that she will need to save her young family during the rainy season. Deng says the mosquito net she received will protect her children if she uses it the way she was instructed. She says she hopes because of the net, her family will be free from malaria.
Refugees free from the disease are what malaria campaigners, partners, and supporters want to see as they make a two-day visit to the Kakuma refugee camp to distribute mosquito nets. Chris Helfrich is the Director of the U.N. Foundations Nothing-But-Nets campaign. On a recent visit to the Kakuma camp he says life is tough enough for refugees, and they should not have to worry about dying from malaria. Its a tough situation here in Kakuma, obviously, but we are happy to bring hope and do a little of something; these people, they have very tough lives but we are happy to bring nets because with everything else they have to deal with, malaria shouldnt be one of them.
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Two million of the world's poorest children could be saved by introducing routine vaccination programmes against diarrhoea and pneumonia, says Unicef. It says focusing on these diseases would narrow the survival gap between the richest and poorest children. Pneumonia and diarrhoea account for one-third of all global deaths among children under five. Unicef's report, in advance of a child-survival initiative, calls for better access to vaccines and antibiotics.
Anthony Lake, its executive director, said it was a question of commitment and funding. "We know what works against pneumonia and diarrhoea - the two illnesses that hit the poorest hardest," he said. "Scaling up simple interventions could overcome two of the biggest obstacles to increasing child survival and help give every child a fair chance to grow and thrive."
New vaccines available
Nearly 90 per cent of deaths from pneumonia and diarrhoea occur in sub-Saharan Africa and South Asia. The report says that more than two million children's lives could be saved in the 75 countries with the highest death rate if the poorest children received the same care and treatment as the wealthiest 20% in those countries. New vaccines against the major causes of pneumonia and diarrhoea are already available.
While most low-income countries have introduced the Haemophilus influenza type b (Hib) vaccine and pneumococcal conjugate vaccines, they urgently need to introduce them into routine immunisation programmes, the report said. The prevention and treatments for both diseases include increasing vaccine coverage, encouraging breastfeeding, hand-washing with soap and expanding access to safe drinking water and sanitation. Giving oral rehydration salts to children with diarrhoea and antibiotics to children with bacterial pneumonia are also basic steps to combat the diseases, it says.
BBC News - Unicef: Tackling diarrhoea and pneumonia saves 2m lives
UNICEF said that while these two diseases kill more than two million children each year, making up 29 percent of child deaths under age five worldwide, some simple interventions could save lots of lives in the coming years. The report urges the 75 countries with the highest mortality rates to aim to treat poor children with diarrhea and pneumonia the same way they do those from the top 20 percent of households, a so-called "equity approach."
Key interventions include vaccinating against the major causes of pneumonia and diarrhea, encouraging infant breastfeeding, improving access to clean water and sanitation, offering antibiotics for pneumonia and rehydration solutions for diarrhea. "Modeled estimates suggest that by 2015 more than two million child deaths due to pneumonia and diarrhea could be averted across the 75 countries with the highest mortality burden," said the report. "If national coverage of key pneumonia and diarrhea interventions were raised to the level in the richest 20 percent of households in each country," it added.
About half of childhood deaths in the world due to diarrhea or pneumonia take place in five countries: India, Nigeria, Democratic Republic of the Congo, Pakistan and Ethiopia, said the report. There has been some progress in offering vaccines against Hemophilus influenza type b, as well as pneumococcal conjugate vaccines and rotavirus vaccines in the poorest countries, but more effort is needed, it said.
Water and sanitation is another key hurdle, with 783 million people globally not using an improved drinking water source, and 2.5 billion not using sanitation facilities. "Nearly 90 percent of deaths due to diarrhea worldwide have been attributed to unsafe water, inadequate sanitation and poor hygiene," said the report. "Hand washing with water and soap, in particular, is among the most cost-effective health interventions to reduce the incidence of both childhood pneumonia and diarrhea." Pneumonia is responsible for 18 percent of childhood deaths worldwide each year, and diarrhea is linked to 11 percent. In contrast, AIDS is responsible for two percent of global childhood deaths annually and malaria for seven percent, according to the report.
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"I've been suffering for more than two months now. I have headaches, fever, and I just feel very tired," said Lea Sadene, who has just been tested and diagnosed. She has Human African trypanosomiasis, commonly known as sleeping sickness, which is transmitted by tsetse flies found in 36 sub-Saharan African countries. Sadene is in the first phase of the often fatal illness. Without treatment in four months to a year, "the parasite penetrates into the brain, causing serious neurological symptoms, until death," said Doctor Benedict Blaynay, head of neglected tropical diseases at French pharmaceutical giant Sanofi. "The symptoms can cause a change in personality, mental deterioration, leading to a long sleep or coma," which gives the illness its name, he said.
Chadian health officials say around 3,300 people were infected between 2001 and 2011 in several areas of the landlocked central African nation, one of the poorest in the world. "With more than 100 cases per year Chad is considered an endemic country," said Doctor Peka Mallaye, who is in charge of the national programme to fight against sleeping sickness. In Kobitoi in southern Chad recently, village women lined up with their children, many with swollen bellies, in the scorching sun as temperatures hit 43 degrees Celsius (109 degrees Fahrenheit) to undergo tests for the disease organised with Sanofi. The team found 14 cases of sleeping sickness out of 120 people examined, Mallaye said. "This village is located next to a forest where the tsetse flies live. During the rainy season, people pass through the forest to go fishing or hunting," he said.
Fighting the disease, however, takes more than testing and drugs. For the people living in Chad's rural communities, the strange symptoms of sleeping sickness have long been shrouded in superstition about witchcraft and demonic possession. "Before we didn't know that it was the disease that was killing people. People died like flies, they blamed witches," said Alngar Legode, a village mother trying to comfort her eight-month child still crying after being pricked for the blood test for the disease. "Witchcraft is seen as a real phenomenon in traditional societies," said sociologist Serferbe Charlot. "They think that a man or a woman suspected of witchcraft is eating away at a person's soul."
In the advanced stages of the disease the infected person experiences severe neurological problems. "When this disease reaches the brain, the patient loses control of his life, he even becomes violent. That is when the villagers believe that the sick person is possessed by evil spirits," said Charlot. "It is up to the health specialists to prove" to the population that it is not witchcraft, he said, adding: "The fight against sleeping sickness calls for raising awareness."
More African sleeping sickness shrouded in superstition - Yahoo! News
In a study published in Nature Genetics, researchers said they had sequenced the genomes of four strains of Plasmodium vivax -- a parasite that infects about 100 million people every year. Other research had found that 10 to 20 percent of P. vivax cases occur in Africa south of the Sahara -- a region mainly affected by the P. falciparum parasite which causes the most malaria deaths worldwide. Outside of Africa, P. vivax accounts for half of all malaria cases, mainly in the Middle East, the Western Pacific and Central and South America.
Both parasite species are transferred by Anopheles mosquitos. P. vivax is more resilient than its deadlier, tropical cousin, and can stay in remission for longer and tolerate cooler climates. Yet much less is known about P. vivax, and less attention has been paid to unravelling its genetic code than that of P. falciparum. With their research, a team from India and the United States say they have tripled the number of genome sequences available for P. vivax.
They said they observed an "extremely high genomic diversity", suggesting it may be even harder than for P. falciparum to develop a single vaccine targeting several different strains of P. vivax. In 2010, malaria infected about 216 million people and claimed an estimated 655,000 lives -- mainly in Africa where a child dies of the disease every minute, says the World Health Organisation. Symptoms include fever, headache, chills and vomiting which if not treated within 24 hours can progress to severe illness and even death.
In a second Nature Genetics report, scientists in Japan and the United States said they had sequenced the genomes of three strains of P. cynomolgi -- a sister species to P. vivax and a cause of malaria in Asian Old World monkeys. Since it is so closely related, information on the DNA code of P. cynomolgi "provides the foundation for further insights into traits... that will enhance prospects for the eventual elimination of vivax-caused malaria and global malaria eradication," they wrote.
Scientists unravel 'other' malaria parasite's DNA code - Yahoo! News
Throughout the state 465 people have been sickened since the start of the year, putting it on track to have the most cases since the disease first emerged a decade ago, the Texas Department of State Health Services said. The county incorporating Dallas, the ninth-largest city in the United States, has been the hardest hit, prompting the mayor to declare a local state of disaster. "The city of Dallas is experiencing a widespread outbreak of mosquito-borne West Nile virus that has caused, and appears likely to continue to cause, widespread and severe illness and loss of life," Mayor Michael Rawlings said in a proclamation of emergency that took effect Wednesday. The virus has claimed ten lives in the county so far, local and state health authorities said.
First discovered in Uganda in 1937, the virus is carried by birds and spread to humans by mosquitoes. Severe symptoms of the virus include high fever, vision loss and paralysis, while milder symptoms range from headaches to skin rashes. At least 693 cases -- both confirmed and probable -- of the virus have been reported in the United States this year, including 26 deaths, according to the Centers for Disease Control and Prevention. Texas tops the list in both total cases and fatalities. In 2011, Texas saw a total of 27 cases and two deaths, the CDC said. Across the United States, 712 confirmed and probable cases and 43 fatalities were reported over that same 12-month period.
The worst year on record in Texas was 2003, with 40 deaths related to the West Nile virus, said Christine Mann, a spokeswoman for the Texas Department of State Health Services. Mann told AFP that the outbreak could be linked to a mild winter and rainy spring in the state. "It's really not clear at this point," she said. In an effort to stem the number of new infections, Texas authorities have urged residents to use insect repellent before heading outdoors, remain inside at dusk and at dawn, dress in protective clothing and drain standing water that could become a breeding ground for mosquitoes. Last month, officials in New York City said the West Nile virus had been detected on Staten Island, one of the city's five boroughs.
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The city of Dallas in the US state of Texas has declared a state of emergency as it struggles to contain an outbreak of mosquito-borne West Nile virus. At least 14 people have died after contracting the virus in the state so far this year. Almost 700 cases have been reported across the country - the highest number since 2004.
Texas residents have been urged to use insect repellent and avoid going out at dusk and dawn. "The city of Dallas is experiencing a widespread outbreak of mosquito-borne West Nile Virus that has caused and appears likely to continue to cause widespread and severe illness and loss of life," Michael Rawlings said. The move clears the way for aerial spraying to kill infected mosquitoes that transmit the disease.
Protective clothing
Aerial spraying is also being used elsewhere, including in New York City - where the virus was discovered on Staten Island last month - and Sacramento, California. There have been cases of infection reported in people, birds or mosquitoes in 42 US states, with 80% of the cases in Texas, Mississippi and Oklahoma. In Texas, the worst-affected state, residents have been urged to get rid of stagnant water, where the insect can breed, and to wear protective clothing.
Officials say it is too early to say what has caused the fresh outbreak, though some suggest that a mild winter and wet spring may have been a factor. The virus was first discovered in 1937 in Uganda. It is carried by birds and spread to humans by mosquitoes. In extreme cases, symptoms can include high fever, loss of vision and paralysis. Milder manifestations can include headaches and skin rashes. Those at greater risk of a serious case of the illness are those over the age of 50, or people who already suffer from a major health problem.
http://www.bbc.co.uk/news/world-us-canada-19276240
Two twin-engine planes loaded with 200 gallons of pesticide are set to spray Dallas, which has so far had 111 reported infections of West Nile virus that caused 65 hospitalizations, the Dallas Morning News reported. The planes are expected to take off Thursday night. "This is very much like a battle plan," Dallas County Judge Clay Jenkins said Wednesday. "We're going to hit them with this weapon, and we expect the result to be knocking them back in most places. But we'll do our reconnaissance and adjust our battle plan as necessary."
So far, 11 cities north of Interstate 30 have decided to spray pesticide to kill the mosquitoes. "I think this is the right thing to do," said Dallas Mayor Mike Rawlings. "I cannot have any more deaths on my conscience because we didn't take action." Jim Olson, a retired entomologist at Texas A&M University, said the pesticide being sprayed poses little risk to humans. "It's just like the disclaimer on medicine," he said. "Do you not take what the doctor prescribes for you because of the low chance you'll have a side effect? No, you take your medicine."
Nationwide, a total of 693 cases of West Nile virus disease in people have been reported, including 26 deaths, the Center for Disease Control reported. Of those cases, 406 of those cases were classified as neuroinvasive disease, such as meningitis or encephalitis, and 287were classified as non-neuroinvasive disease, the CDC said. More than 80 percent of the cases have been reported from six states -- Texas, Mississippi, Louisiana, Oklahoma, South Dakota, and California.
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Sierra Leone's President Ernest Bai Koroma has declared the outbreak there an "emergency issue," and has set up a task force to prepare the budget that will be needed to stem the outbreak. "All of this is the aftermath of the 11 years rebel war when we had a huge rural-to-urban migration and a huge population clustered in the urban area where adequate provision has not been made for water and sanitation. This is what we have been witnessing today," Minister of Health and Sanitation Zainab Hawa Bangura told The Associated Press.
She said that in the capital, Freetown, there have been about 100 deaths during the past month, especially in congested areas. That brings the total to at least 176 dead in Sierra Leone, while 82 deaths have been reported in neighboring Guinea. "It is important to request help from the international community in order to spread the mobilization of resources," she said. Cholera is an infection of the small intestine, contracted by eating or drinking contaminated food or liquids. It can cause acute diarrhea and vomiting and can kill within hours.
The International Federation of Red Cross and Red Crescent Societies said there has been a spike in reported cholera cases since mid-July and the onset of the rainy season. Over the past five weeks, 6,000 cases alone have been confirmed in Sierra Leone and many other cases might not been officially reported.
"This current outbreak of cholera has the potential to be devastating and is proving very difficult to control," said Amanda McClelland, IFRC emergency health coordinator. "We are particularly concerned by the rising numbers in Freetown, which suffers from overcrowding, poor sanitation and lack of safe water access - all factors which contribute to this deadly disease." Parts of Mali and Niger have also been affected by the outbreak, the Red Cross said.
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It's still too early to say how bad the year will end up because most infections are reported in August and September. But never before have so many illnesses been reported this early, said Dr. Lyle Petersen, of the Centers for Disease Control and Prevention. "We're in the midst of one of the largest West Nile outbreaks ever seen in the United States," said Petersen, who oversees the CDC's mosquito-borne illness programs. So far, 1,118 illnesses have been reported, about half of them in Texas. In an average year, fewer than 300 cases are reported by mid-August. There have also been 41 deaths this year, the CDC said. And cases seem to be accelerating: about 400 of the cases were reported in just the last week.
Experts think the mild winter, early spring and very hot summer helped stimulate mosquito breeding and the spread of the virus. Mosquitoes pick up the virus from birds they bite and then pass it on to people. CDC officials are also looking into the possibility that the virus mutated, but so far have no information showing that happened, Petersen said. West Nile virus was first diagnosed in Uganda in 1937, but no cases were reported in the U.S. until 1999 in New York. The virus gradually spread across the country.
It peaked in 2002 and 2003, when severe illnesses reached nearly 3,000 and deaths surpassed 260. Last year was mild, with fewer than 700 cases. Only about 1 in 5 infected people get sick. Early symptoms can include fever, headache and body aches. Some recover in a matter of days. But 1 in 150 infected people will develop severe symptoms including neck stiffness, disorientation, coma and paralysis. Many illnesses probably go unreported, especially milder cases. In this year's case count, more than half are severe, CDC officials said.
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The US Centers for Disease Control (CDC) said on Wednesday that 1,118 cases and 41 deaths had been reported so far this year, up from fewer than 700 cases and 26 deaths just one week ago. That is the highest number of West Nile virus infections reported through the third week of August since the virus was first detected in the US in 1999, the CDC said. The worst US outbreak occurred in 2003, with 9,862 cases and 264 deaths that year. “We’re in the midst of one of the largest West Nile virus outbreaks ever seen in the United States,” said Lyle Petersen, director of the division of vector-borne infectious diseases for the CDC. Federal officials are stumped by the severity of the outbreak.
Cases usually flare up in the summer because the illness is most often transmitted from infected birds to people by mosquitoes. Victims may suffer fever and aches that can become severe or even cause death, especially in the elderly, children and other at-risk groups. There is no specific treatment for the infection. Symptoms are often mild and many people stricken do not see a doctor, meaning cases are likely underreported. More than half of this year’s cases are in Texas, but the disease now has been detected in 47 states, and 38 states have reported cases in humans, with only Alaska, Hawaii and Vermont reporting no cases. About 75 percent of the cases have been in Texas, Mississippi, Louisiana, Oklahoma and South Dakota, officials said.
Nationwide, 56 percent of cases are of the more serious type that can cause paralysis, meningitis or encephalitis, the CDC said. The remaining 44 percent are the milder form of West Nile Fever. Officials said they were uncertain why this year’s outbreak had been so severe. A mild winter, a hot summer and other factors such as fluctuations in the bird population are contributors, officials said. “We don’t really know why it’s worse this year than in previous years,” Petersen said. “One observation that has occurred over many decades ... has been that hot weather seems to promote West Nile virus outbreaks.”
Dallas, where a health state of emergency was declared this month, is experiencing an unprecedented epidemic, Petersen said. Latest figures show there have been 640 cases of the disease in Texas. Texas state health officials said 23 people had died, including 15 in north Texas. “Dallas has been hardest hit,” Texas Department of State Health Services commissioner David Lakey said. So far, 11 deaths have been reported in Dallas County this year, compared with 10 in the period between 2003 — when the disease was first detected in Dallas — and last year.
US West Nile cases, deaths jump 60% - Taipei Times
Only female Anopheles gambiae mosquitos transmit malaria to humans and they are the principle vector for the disease. But chemistry professor Richard Baxter and his team at Yale University are focused on the males. Malaria mosquitos mate in airborne swarms. Unlike any other insect, the male inserts a gooey plug to seal its sperm inside the female during mating to ensure reproductive success.
At a meeting of the American Chemical Society in Philadelphia this week, Baxter and his colleagues announced a new approach for screening chemical compounds that would inhibit formation of the mating plug. This sterile insect technique has been successfully deployed in Africa against tsetse flies that transmit sleeping sickness, and in the United States to control the screwworm fly, which was once responsible for millions of dollars in losses in the cattle industry and has since been eradicated.
Baxter says this is important because malaria mosquitos are becoming resistant to insecticides and adapting to indoor control measures by biting outdoors, during the day. “So the idea is if we can actually suppress the mosquito, we will prevent the transmission of the disease and then eventually if you prevent transmission for several seasons, you will eradicate the parasite that itself causes the disease without eradicating the mosquito.”
Over the next several months, Baxter will test various chemicals to see which ones disable the proteins, so mating would be unsuccessful. “If that works in the lab, then we can move on to semi-field trails, where we have a large cage, which is outdoors," he says. "That would test the efficacy of the compound in a more realistic setting.” After mosquitos are fed the inhibiting compound, the modified males would be released to mate with wild females. With no resulting offspring, the population would be reduced without the use of pesticides.
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The problem is more severe in Cambodia than anywhere else in the world, says Steven Bjorge, the World Health Organization's malaria team leader in Cambodia. About 17 percent of all cases in the Cambodian-Thai border area of Pailin were drug-resistant in 2011, up from 10 percent the year before, according to Char Meng Chuor, director of the governments National Malaria Center. He says the drug-resistant disease has also spread to parts of Preah Vihear and Pursat, border provinces in Cambodias north and west. Drug-resistant malaria first evolved in Cambodia in the 1950s and 1960s, according to Bjorge.
Since then, every new drug seems to first become resistant in Cambodia or on the Thai-Cambodian border before anywhere else in the world, he said. Drug resistance occurs when a patient infected with the Plasmodium falciparum parasite takes an incomplete or incorrect course of anti-malarial drugs. This allows the parasite to evolve resistance to that medicine, so patients must take another course of drugs under the supervision of a doctor, says Char Meng Chuor.
Beyond Borders
The problem is greatest in border towns with a lot of traffic. Here, migrant workers might buy the wrong drugs without seeing a doctor, or misuse treatment in other ways, says Uth Sophal, Pailin field officer for the health group the Malaria Consortium. Migrant people move from one province to another, so when they come to Pailin, which already has resistant malaria, when the mosquitoes bite those people, they will get that parasite and pass it from one province to another province, from one country to another, he said. With some help, health workers are hoping that will change.
The Malaria Consortium has created a network of volunteers at Pailins border crossing to check and evaluate migrant workers and treat them if they have malaria. When Cambodians cross the border, we measure their temperature, Uth Sophal said. If they have any kind of illness, we have to immediately treat them. University Research, a global health company fighting drug-resistant malaria in sub-Mekong Region countries, is trying to ensure migrant workers are given bed nets before they move through malaria-prone areas. It is also training local people to provide malaria.
Global Ramifications
