MALARIA: Surface Layer Effectively Kills Malaria Mosquitoes in Rice Paddies

ScienceDaily (July 1, 2011) — A thin, liquid layer applied on the surface of inundated rice paddies effectively kills malaria mosquito larvae without having an impact on other aquatic life. Rice yield remains the same and water was saved because of the anti-evaporative properties of the layer. These conclusions were reached by scientists from Wageningen University and the Kenya Medical Research Institute who tested a silicone-based surface layer known as polydimethylsiloxane or PDMS, and commercially available as Aquatain. The results were published in this week's edition of PLoS ONE (Public Library of Science) and suggest that the surface layer is a suitable tool for controlling malaria mosquitoes in rice-agro ecosystems

http://www.sciencedaily.com/releases/2011/07/110701132254.htm
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0021713

MALARIA: Antimalarial Trees in East Africa Threatened with Extinction

NAIROBI 21 April 2011

Scientists call for more research, conservation of trees to harvest potential for next generation of malaria drugs
Research released in anticipation of World Malaria Day finds that plants in East Africa with promising antimalarial qualities—ones that have treated malaria symptoms in the region’s communities for hundreds of years—are at risk of extinction. Scientists fear that these natural remedial qualities, and thus their potential to become a widespread treatment for malaria, could be lost forever.
A new book by researchers at the World Agroforestry Centre (ICRAF) and the Kenya Medical Research Institute (KEMRI), Common Antimalarial Trees and Shrubs of East Africa, provides a detailed assessment of 22 of the region’s malaria-fighting trees and shrubs. While over a thousand plant species have been identified by traditional healers as effective in the prevention or treatment of malaria symptoms, the species in the book were assigned by both traditional medicinal practitioners and scientists as those that have potential for further study.
According to researchers, many species of trees in East Africa are at high risk of extinction due to deforestation and over-exploitation for medicinal uses. Scientists in the field have been able to identify at-risk tree species, including those that have antimalarial qualities, by monitoring deforestation in the region and by talking to herbalists and local communities. According to researchers, not all species of antimalarial trees are at risk, particularly those that grow wild in lowland and coastal areas.
ICRAF is doing its part preserving these trees and shrubs by holding samples of most of the species with antimalarial qualities in its genebank and growing these trees in plant nurseries at its headquarters in Nairobi. The ICRAF genebank holds close to 200 species, of which at least 30 are known to have antimalarial properties.
The field data was gathered by ICRAF scientists conducting research across Kenya, Uganda, and Tanzania, where they met with approximately 180 herbalists and 100 malaria patients in 30 separate communities. KEMRI supported the process by supplying the information about each plant’s chemical compound make-up—research that is the result of a sophisticated laboratory process developed by KEMRI for testing natural products.
“We’ve only scratched the surface on the potential value of these plants. Although widely used by farmers and people in rural communities, most of this information has never been collected in a comprehensive way by researchers,” said Dr. Geoffrey Rukunga, Director of KEMRI’s Centre for Traditional Medicine and Drug Research and one of the book’s co-authors. “Going forward, I’d like to see more investment and more research on the power of these plants to fight the scourge of malaria and other diseases.”
One of the drugs most widely used historically to treat malaria, quinine, was derived from the bark of the Cinchona tree in South America. Today, the world’s newest, most-effective therapeutic treatment for malaria also comes from a plant, the Artemisia annua shrub. However, access to malaria therapies based on artemisinin compounds remains low—around 15 percent in most parts of Africa and well below the World Health Organizations’ 80 percent target.
Additionally, the malaria parasite’s ability to resist artemisinin is already beginning to emerge in Southeast Asia. This comes years after the World Health Organization labeled the spreading resistance of malaria to cheap and widely available drugs such as chloroquine and sulfadoxine-pyrimethamine as a major public health problem. The increasing failure of once-effective malaria drugs has added urgency to the search for promising new targets.
Malaria still kills some 800,000 people per year, the majority of whom are children under five years of age in sub-Saharan Africa. A lack of access to doctors and drugs leaves many communities in Africa with few alternatives other than looking for natural remedies to address symptoms of malaria, including high fever, severe headaches, bone aches, nausea and vomiting.
“We’re not saying that using these medicinal plants is a replacement for common prevention treatments like bed nets or effective medicines like ACT,” said Dr Najma Dharani, a Consultant Research Scientist at the ICRAF in Nairobi, Kenya, who led the field research portion of the study. “But we believe that it’s worth learning from communities that have been treating malaria symptoms with plants for hundreds of years. We need to do more research because one of these plants could prove to be the next Artemisia, and we need to do our best to preserve the plants that are going extinct.”
Indeed, without clear research or proper guidance for their sustainable use, many of the plants with medicinal properties are being over-exploited and are in danger of extinction. One such plant, which is critically endangered in Kenya and threatened in other regions, is Zanthoxylum chalybeum, commonly known as “Knobwood.” It grows in dry woodlands or grasslands of eastern and southern Africa and has been found to have antimalarial properties that need to be further explored. An extraction process from leaves, bark or root is used to effectively treat a malarial fever in many communities. Other uses for the plant include infusing tea with the leaves, making toothbrushes, and using the seeds as beads in traditional garments.
The African wild olive (Olea europaea Africana), also threatened in East Africa due to over-exploited for timber, contains organic extracts with significant levels of antimalarial activity, and is used to treat malarial and other fevers. The plant also acts as a natural laxative to expel parasites or tapeworms.
“Throughout my eight years of research in Africa, I have seen that we have an entire pharmacy in our farms and in our forests. We have plants that should be used by scientific companies to develop more options for malaria drugs,” said Dr. Dharan. “And we cannot become complacent and rely on one herb, because we’ve learned that developing resistance is likely.”
Beyond the complicated process to extract and test antimalarial compounds from these trees, scientists have struggled to track or replicate the treatment process as it occurs in communities. Besides the plant itself, there may be other factors contributing to a malaria patient’s recovery. For example, a healer may combine one plant with another that changes its chemical compound and boosts its effectiveness. Unless more is done to understand these processes in the field, scientists in laboratories and researchers at major drug companies will lose that knowledge.
“While we’ve made scientific progress identifying these compounds over the last few years, the fact is that we may lose these important trees before we’ve had a chance to understand their ability to defend us against malaria, a disease that devastates Africa—killing hundreds of thousands of our children and costing us billions of dollars in productivity year after year,” said Dr. Rukunga. “We need to approach this as an opportunity on multiple fronts: to preserve the biodiversity that may hold the next cure, to strengthen the research done on the ground in communities, and to continue our diligent work testing our natural resources in the lab.”

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The World Agroforestry Centre (ICRAF) is an autonomous, non-profit research organisation whose vision is a rural transformation in the developing world resulting in a massive increase in the use of trees in rural landscape by smallholder households for improved food security, nutrition, income, health, shelter, energy and environmental sustainability. The Centre generates science-based knowledge about the diverse roles that trees play in agricultural landscapes, and uses its research to advance policies and practices that benefit the poor and the environment. We are one of the 15 centres of the Consultative Group on International Agricultural Research (the CGIAR). http://www.worldagroforestrycentre.org/

The Kenya Medical Research Institute (KEMRI) was established in 1979 as the national body responsible for carrying out health science research in Kenya. Since then, KEMRI has served as a centre of excellence for health research in Africa. It works closely with the Kenyan Ministry of Health and various national councils and committees on issues of policy and priorities. The institute accomplishes its mandate through research centres that are intended to focus on certain specific areas of national and/or strategic importance. The centre that conducts research on herbal medicines is the Centre for Traditional Medicine and Drug Research (CTMDR). This centre studies the chemical composition, efficacy and safety of traditional medicines, and the socio-cultural and anthropological basis of the use of herbal remedies. http://www.kemri.org/

MALARIA: Malaria vaccine hailed as a succes

Stephen Adams, 14 Jan 2011
A vaccine that almost halves the chance of catching malaria has the potential to save hundreds of thousands of lives a year, say scientists.
Research published online in The Lancet Infectious Diseases indicates that the vaccine reduces the risk of infection by the parasite that causes severe malaria by 46 per cent over 15 months.
Malaria, which is passed to humans via infected mosquitoes, is one of the biggest killers of children in Africa.
Of the 900,000 people killed by the disease across the continent every year, the majority are children under five.
While the vaccine does not give near total protection, as those for other diseases marketed for use in Western countries typically do, it still has the potential to save large numbers of lives.
In the phase II clinical trial, 447 children from Kenya and Tanzania, aged five to 17 months, were given the RTS,S/AS01E vaccine, while the same number were given the rabies vaccine as a 'control' group.
After 15 months, those who had the malaria vaccine were 46 per cent less likely to have been infected with the P Falciparum parasite than the control group. Only 11.4 per cent of those given the vaccine developed clinical malaria, compared to 19.7 per cent of the other group.
Dr Ally Olotu from the Kenya Medical Research Institute-Wellcome Trust Research Programme, who led the study, and fellow authors, concluded that the vaccine provides "sustained efficacy for at least 15 months and shows promise as a potential public health intervention against childhood malaria in malaria endemic countries".
The vaccine works by attacking the parasite when it first enters the bloodstream or liver cells, with the aim of completely preventing infection of red blood cells.
In 2008 results of a small-scale preliminary trial showed that it gave protection to 53 per cent of those vaccinated after eight months. However, the new study is larger, and shows only a small drop in the protection given after a further seven months.
The authors said more work was needed to see how well it worked in HIV-positive and malnourished children.
P falciparum is one of four species of malaria parasite that affect humans. It is found globally but is most common in Africa. It is the only one of the four species that can cause life-threatening malaria, according to the Wellcome Trust.
http://www.telegraph.co.uk/health/healthnews/8257496/Malaria-vaccine-hailed-as-a-success.html

MALARIA: Children with sickle cell suffer more severe malaria, researchers warn

6 September 2010
The sickle cell trait is known for its protective effect against developing malaria. But new research warns that children with sickle cell anaemia are more likely to die from severe malaria. Researchers from the Kenya Medical Research Institute (KEMRI) found that children with sickle cell anaemia have a "considerably higher" mortality rate than non-sickle cell sufferers when hospitalised with malaria.
Their findings indicate that sickle cell disease, which affects the shape of a patient's red blood cells, is very much a double-edged sword for children in Africa. Those with sickle cell trait (who carry one copy of the sickle cell gene) benefit from a protective effect against malaria. But those with full sickle cell anaemia (two copies of the sickle cell gene) not only suffer severe health problems, but also a "massively increased" risk of death if they do develop malaria.
"Much is known about sickle cell disease in Europe and North America, where children born with the condition can now expect to live long and relatively healthy lives," says Dr Tom Williams of KEMRI, who led the study. "Paradoxically however, little is known about the health problems of children with sickle cell disease in Africa - where more than 90 per cent of patients are born."
Malaria is actually considered a major cause of death for such children, but few studies have investigated this.
In the new study, researchers looked at data from four large-scale demographic studies conducted in the Kilifi district on the coast of Kenya, at various periods between 1996 and 2008.
The first part of the study looked at around 1000 children under the age of five admitted to hospital with uncomplicated Plasmodium falciparum malaria, compared with 1000 children admitted to hospital for other conditions.
The second part looked at 1700 children under five years of age with severe malaria (that is, malaria complicated by symptoms such as breathing difficulties or coma). In addition, the researchers also studied a group of 1800 children admitted with bacteraemia (bacteria in the blood).
Comparing the frequency of the sickle cell gene in the groups, they found that severe anaemia was "considerably more common" in those diagnosed with severe malaria. Moreover, mortality was considerably higher.
The researchers note that they didn't find any strongly increased risk of contracting malaria in children with sickle cell anaemia, but the high mortality makes it likely that such an association is there. They argue that a larger, more detailed study may provide the evidence needed. They also warn that susceptibility to malaria is likely to increase as a patient's spleen - which helps remove malaria parasites from the blood, but which is particularly vulnerable in sickle cell anaemia - deteriorates with age.
This comes on top of other severe health problems associated with the condition. The researchers found that four times as many sickle-cell children were admitted to hospital for nonmalarial illnesses than non-sickle cell children, rising to eight times for bacteraemia.
"Although sickle cell disease is relatively rare, affecting only about one per cent of African populations, it is likely to constitute a major health burden as mortality falls from other diseases in the years ahead," said Dr Williams. "It's critical that we gain a better understanding of the health needs of African children with sickle cell disease as soon as possible."



Image: Normal red blood cell (background, coloured red) and red blood cell affected by sickle-cell anaemia (foreground, coloured brown). Credit: EM Unit, UCL Medical School, Royal Free Campus, Wellcome Images

Reference
McAuley CF et al. High mortality from Plasmodium falciparum malaria in children living with sickle cell anaemia on the coast of Kenya. Blood 8 June 2010. Published online ahead of print.
http://www.wellcome.ac.uk/News/2010/News/WTX062604.htm

TUBERCULOSIS: TB vaccine trial in Kenya

By GEORGE OLWENYA
Trials for the first ever Tuberculosis (TB) vaccine to be conducted in four African countries has kicked off in Kenya’s Siaya District.
Ninety-six children aged between 16 to 26 weeks will be immunised in Boro Division. Research shows the area has the highest TB infection rate in the country.
Other countries where the trials are expected to take place are South Africa, Mozambique and Uganda.
The Kenya Medical Research Institute (Kemri) and the American funded Centres for Disease Control (CDC) will conduct the trials in partnership with the Global TB Foundation.
Kemri/CDC Field Research Station director Kayla Laserson said the trials will last six months before being moved to Karemo Division in Siaya.
Dr Laserson said this would bring to 192 the number of infants to be vaccinated for the next 12 months.
Speaking during the launch of the trials at Boro Primary School at the weekend, Laserson disclosed only those children not infected with the HIV virus would be covered and closely monitored for six months.
She said the vaccine developed by researchers from US and the Netherlands would help reduce TB infections, a major killer disease.
Laserson said Kenya was ranked 13 of 22 countries with the highest TB prevalence globally, hence the need to take a leading role in the search for an effective vaccine.
treatment success
The World Health Organisation (WHO) the estimated incidence rate of TB in sub-Saharan Africa is nearly twice that of the South-East Asia Region with over 350 cases per 100 000 population.
According to WHO, Kenya is the first country in sub-Saharan africa to achieve global targets for case detection and treatment success.
http://www.standardmedia.co.ke/sports/?cid=3&

MALARIA: Vaccine

The third phase of testing for the world's most clinically advanced malaria vaccine candidate began last year and researchers at the Kenya Medical Research Institutes and Centers of Disease Control believe it could lead to the nation's first malaria vaccine by 2015.The vaccine works by targeting two groups of children - one group from the age of six to 12 weeks and the other from five to 17 months - in different transmission settings across a wide geographic region.“If the vaccine is proved to be effective in the prevention of malaria, it will be introduced as part of the routine child vaccination series in Kenya by 2015,” said Dr Simon Kariuki, the principal researcher at the Kemri/CDC, told AllAfrica.com.The vaccine, known as Mall55 Study, began trials in 2009 with mandatory preliminary duties preceding the actual study.Eight hundred children have now been enrolled int he Mall 55 Malaria Vaccine Study for the five to 17 month age group, and the second phase of enrollment for the six to 12 week age group has already begun. The testing will continue for approximately one year and take place at 11 sites.“There is hope to have a first indication of how well the vaccine works in the older age group of children in approximately a year and a half," Kariuki said.Malaria kills more than 800,000 people annually in Africa, with the majority of those killed under the age of five.
http://vaccinenewsdaily.com/news/212872-malaria-vaccine-enters-third-phase-of-testing