Universal anti-venom for snake bite planned by researchers


A universal life-saving anti-venom against the bite of every deadly snake is all set to become a reality.

Scientists from Liverpool School of Tropical Medicine are attempting to develop the first universal anti-venom in sub-Saharan Africa.
LSTM has more than 400 snakes in its institute using venom milked from up to 80 of the reptiles each week.

Snake bites kill an estimated 30,000 people a year in the region.

The current need to give many vials to treat a patient not only increases the risk of side-effects but often makes treatment unaffordable to the rural, impoverished subsistence farmers that are at greatest risk.

The current limitations to multi-species anti-venoms arise from the process used to make them. Venom is extracted from several species before being injected in low doses into horses or sheep. This does not cause illness in the animals bit induces an immune response causing the animals to produce antibodies. These antibodies are then purified from the blood to create anti-venom.

Using multiple snake species, however, means that the animals only make a small amount of antibody to any one species, and the resulting anti-venom is quite weak.

Dr Robert Harrison, the lead scientist for the research, said “Not only do we expect that our anti-venom will be cheaper, and safer and much more effective than anything else, but it will be able to be used anywhere south of the Sahara”.

“There are over 20 species of deadly snakes in Sub-Saharan Africa and doctors often rely on the victim’s description of the animal to help them decide which treatment to administer,” says Dr Harrison.

“The preferred option therefore is to give a broad-spectrum or poly-specific, anti-venom to cover all the possible snake species that could be responsible. Because these treatments are generally not very effective against any one species, the doctor therefore administers many vials. However, each dose carries a risk of serious side effects and this risk increases with each additional vial.”

The research team at LSTM, and their collaborators at the Instituto Clodomiro Picado, San Jose, Costa Rica and the Institute de Biomdedicina de Valencia, Spain, have devised a plan to vastly improve the potency of poly-specific anti-venom using a new technique called ‘antivenomics’ which will significantly expand the effectiveness of the anti-venom, covering all of the most medically-important snakes of sub-Saharan Africa.

Researchers will use the proteins from all of the collected venom to make the universal snake bite treatment. They will add stabilizing chemicals so that it can be stored in the African heat.

Study counters case for climate change-violence link


  • There was more conflict when temperatures were particularly high
  • But this link was inconsistent and less crucial than social and political issues
  • And the work fails to explain why certain areas have violence and others do not
 
Climate change is far from being solely to blame for violence in Sub-Saharan Africa, say researchers — other factors matter much more.

Their paper, published on 10 November in the journal Proceedings of the National Academy of Sciences, contradicts earlier studies that found that higher temperatures are a major risk factor in conflict.

For instance, last year a different group concluded that a shift towards hotter conditions by a single statistical unit known as a ‘standard deviation’ — equivalent to, for example, warming an African country by 0.4 degrees Celsius for a year — caused a four per cent rise in the likelihood of personal violence and a 14 per cent increase in conflict between groups.

“The effects of climate change on violence are actually quite modest compared to other factors.”

John O’Loughlin, University of Colorado

But now a team led by John O’Loughlin, a geographer at the University of Colorado Boulder in the United States, says that previous research may have overlooked other key triggers such as political instability, poverty and geographical conditions.

O’Loughlin’s team examined these factors alongside exceptionally hot or dry periods in Sub-Saharan Africa to assess the chances of increased violence. Breaking the area down into subregional grids, the researchers pinpointed 78,000 ‘conflict events’ from the past 33 years and matched them with weather conditions and social and geographical factors.

They found that conflicts such as riots, protests or violence against civilians were more common when temperatures were particularly high. But they also discovered an inconsistent relationship between temperature deviations on the one hand and different types of conflict and different subregions on the other.

Tim Forsyth discusses climate change and violence

And, more critically, they found that longer periods of higher temperatures and wet or dry conditions had less impact on conflict than other influences, such as recent nearby violence and a lack of democracy, says O’Loughlin.

“We were surprised to discover that the effects of climate change on violence are actually quite modest compared to other factors,” he says.

However, Tim Forsyth, an expert on the politics of environment and development at the London School of Economics and Political Science in the United Kingdom, says the paper also raises some questions.

“The problem with this approach is that there are many parts of the world experiencing climate change where violence doesn’t occur,” he says. “So instead of searching for linkage between climate change and violence, they should try to explain why certain places have conflict and others don’t.”

He believes that the approach taken will inevitably fail to explain the emergence of conflict in its complexity and help policymakers prevent it.

O’Loughlin agrees that other factors, such as conflicts over resources, play a major part in explaining conflict.

“Climate change is seen as a ‘threat multiplier’ that adds to the stresses and tensions over the distribution of resources in poor societies,” he says. “The scientific and public policy opinion is that it will be an indirect effect through this resource competition among groups.”

GM bacteria ‘could eliminate’ sleeping sickness


Speed read

  • Sleeping sickness affects 30,000 people and causes yearly loss of US$1 billion in Africa
  • Bacteria that live inside tsetse flies can be engineered to try curb infections
  • A study finds that in some areas such bacteria can help eliminate the disease

Releasing tsetse flies that carry genetically modified bacteria resistant to the parasite that causes sleeping sickness could eliminate the disease in Africa under certain conditions, a modelling study has shown.African trypanosomiasis or sleeping sickness — caused when the parasite is transmitted between livestock and humans via tsetse fly bites — infects 30,000 people, and causes losses of US$1 billion from livestock production a year in Sub-Saharan Africa, according to the study published in PLOS Neglected Tropical Diseases last month (15 August).

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Researchers have been considering genetically modifying bacteria that live inside tsetse flies, to try to eliminate the disease in the wild, a strategy called paratransgenesis.

A group of researchers in the United States modelled the spread of a bacteria (Wolbachia) to see if it could help drive another bacteria (Sodalis) carrying the resistance gene into the wild tsetse population.

Sodalis lives in the gut and Wolbachia lives in the reproductive organs [of tsetse flies]. But they are transmitted together to the tsetse progeny,” Serap Aksoy, co-author of the study and a researcher at the Yale School of Public Health, tells SciDev.Net.

Wolbachia gives the female tsetse flies in which it resides a reproductive advantage over female flies in which it does not, therefore becoming more common over time in the tsetse population. (But its presence in the population of flies also depends on different factors.)

It is this well-known feature of Wolbachia that made researchers think of it as a way to spread the resistance gene inserted into Sodalis, as the link in transmission between the two bacteria species had been shown to work in the laboratory in previous studies.

Sodalis is an ideal carrier of the resistance gene as it resides in the gut, which is where the sleeping sickness parasite first multiplies following infection, researchers say.

The study used data from Sub-Saharan Africa on the transmission of sleeping sickness among tsetse flies, humans and livestock, alongside data from Uganda on the number of wild tsetse flies carrying Wolbachia, to show that paratransgenesis is a promising technique for eliminating the disease.

It shows that a single release of tsetse flies, carrying both Wolbachia and genetically-modified Sodalis, could potentially eliminate sleeping sickness in between one-to-ten years, depending on the exact numbers of flies released.

But because several tsetse fly species exist in the wild, this can only be achieved if the species released comprises at least 85 per cent of the total population in the area of release.

Aksoy also warns that the model works under the assumptions that the anti-parasite gene is not lost from the tsetse population, the parasite does not gain resistance to it and the link between Sodalis and Wolbachia does not break.

François Chappuis, a medical advisor for Médecins Sans Frontières, an NGO involved in the fight against sleeping sickness, says: “Every new control method that is developed can be used alongside existing methods … If this technique of paratransgenesis is applicable on a large-scale while using limited resources, it may prove to be a very useful control method.

“But going from a mathematical model to a pilot study in infected areas and then applications in large, remote areas seems a long way off.”

Aksoy’s lab is now planning to insert the resistance gene into Sodalis, a feat that has been independently achieved by Jan Van Den Abbeele, a senior researcher at the Institute of Tropical Medicine in Antwerp, Belgium.

Van Den Abbeele plans to take the technique a step further by recolonising tsetse flies with genetically modified Sodalis to see if it protects flies from carrying the sleeping sickness parasite.

“So far, we were successful in genetically-modifying Sodalis to express an [anti-parasite gene] that specifically targets bloodstream [parasites]. With this we showed the proof-of-concept that indeed the Sodalis bacterium is able to express and release a sufficient amount of active, functional, parasite-targeting [compound],” Van Den Abbeele tells SciDev.Net.

His team is continuing to identify genes coding for proteins that target the parasite in the tsetse fly gut, and studying the inheritance of the genetically modified bacteria.

“We are now doing more basic research to understand better the mechanism of Sodalis mother-to-offspring transfer in order to use that knowledge to improve [its] transfer to the [tsetse] offspring,” he says.

The aim is to produce tsetse flies that are resistant to human and animal sleeping sickness , says Van Den Abbeele, but a similar approach is also being explored for malaria and Chagas disease, which are transmitted by mosquitoes and Triatoma bugs respectively.

50,000 kids to get self-adjusting eyeglasses.


Nearly 100 million near-sighted teenagers in developing countries may soon be able to see normally without the need for specialist eye care as a project starts distributing specially designed glasses costing just US$15.

The Child ViSion project, which will begin handing out the first 50,000 pairs of their self-adjusting glasses in Asia this year, aims to provide affordable vision correction to all children who need it in the developing world.

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The initiative, paid for by donors and sponsors, is run by the UK non-profit Centre for Vision in the Developing World. They hope that establishing long-term distribution schemes via schools will bring down the costs.

“There are roughly 100 million myopic children in the developing world who need eyeglasses to see the board in class. The Child Vision glasses are essentially an educational intervention to get them to see clearly,” says the project’s founder and director, Joshua Silver.

The prototype glasses are a smaller, lighter and more fashionable version of the adult model, Adspecs. Both work by the wearer pumping silicone oil into the lenses, which change shape, allowing the user to instantly adjust the glasses to their needs.

Self-adjusting lenses are not new. Companies such as Focus on Vision have developed glasses with specially designed lenses that are adjusted by sliding them back and forth.

But according to Silver, Child ViSion glasses are the only variable-power design based on clinically tested data.

In the tests Silver and colleagues measured how accurately around 1,500 near-sighted teenagers aged 12 to 17 in China and the United States used the self-adjusting lenses. They found 95 per cent of children achieved vision just short of normal when looking at the standard eye chart.

“That’s good enough to function in class,” says Silver.

But, Peter Ackland, chief executive officer of the International Agency for the Prevention of Blindness, which leads the VISION 2020 programme along with the WHO, says the glasses are not a replacement for professional eye care.

“Our approach is to try to develop local services where you can get an eye examination at the same time as specs. If you bypass that, you’re going to miss fundamental eye problems that can cause serious problems later in life.”

In places such as Sub-Saharan Africa, however, there can be as few as one optometrist for every million people. Until that number increases, Silver says the glasses can be a useful temporary solution.

Source: www.scidev.net

Extra-couple HIV transmission in sub-Saharan Africa: a mathematical modelling study of survey data.


Background

The proportion of heterosexual HIV transmission in sub-Saharan Africa that occurs within cohabiting partnerships, compared with that in single people or extra-couple relationships, is widely debated. We estimated the proportional contribution of different routes of transmission to new HIV infections. As plans to use antiretroviral drugs as a strategy for population-level prevention progress, understanding the importance of different transmission routes is crucial to target intervention efforts.

Methods

We built a mechanistic model of HIV transmission with data from Demographic and Health Surveys (DHS) for 2003—2011, of 27 201 cohabiting couples (men aged 15—59 years and women aged 15—49 years) from 18 sub-Saharan African countries with information about relationship duration, age at sexual debut, and HIV serostatus. We combined this model with estimates of HIV survival times and country-specific estimates of HIV prevalence and coverage of antiretroviral therapy (ART). We then estimated the proportion of recorded infections in surveyed cohabiting couples that occurred before couple formation, between couple members, and because of extra-couple intercourse.

Findings

In surveyed couples, we estimated that extra-couple transmission accounted for 27—61% of all HIV infections in men and 21—51% of all those in women, with ranges showing intercountry variation. We estimated that in 2011, extra-couple transmission accounted for 32—65% of new incident HIV infections in men in cohabiting couples, and 10—47% of new infections in women in such couples. Our findings suggest that transmission within couples occurs largely from men to women; however, the latter sex have a very high-risk period before couple formation.

Interpretation

Because of the large contribution of extra-couple transmission to new HIV infections, interventions for HIV prevention should target the general sexually active population and not only serodiscordant couples.

Funding

US National Institutes of Health, US National Science Foundation, and J S McDonnell Foundation.

Introduction

In the past 2 years, major research advances have been made in anti-HIV interventions. Antiretroviral drugs can help prevent HIV transmission, either by reducing infectiousness when given as antiretroviral therapy (ART) to HIV-positive individuals (treatment as prevention [TasP]),12 or by reducing the susceptibility of HIV-negative individuals when given as oral or topical pre-exposure prophylaxis (PrEP).34 These advances have led to debate about how best to use ART to further reduce HIV incidence.5 An approach that combines several biomedical and behavioural interventions will be needed,6 and policy makers are debating the criteria used to target interventions, including TasP and PrEP.

A serodiscordant couple, defined as an HIV-positive and HIV-negative individual in an ongoing sexual relationship, is a clear example of a susceptible individual being at risk of HIV infection from an infectious individual.78 Targeting of well defined, high-risk groups such as seronegative individuals in serodiscordant partnerships is expected to be resource-efficient. Thus, research of HIV transmission and intervention efficacy has tended to focus on cohorts of serodiscordant couples7 such that seronegative individuals in these partnerships are often the first group in which a new intervention is shown to work. For example, in response to the proven effectiveness of TasP in prevention of transmission in a cohort of serodiscordant couples,1 WHO has recommended this strategy to HIV-positive partners in serodiscordant couples, irrespective of immune status.9 However, not all transmission is within serodiscordant couples; routes also include infection of individuals who are single, and of those in couples by sexual partners outside their relationship (extra-couple relationships). Granich and colleagues10 propose a test-and-treat policy that would target all heterosexual routes of transmission. This approach consists of annual voluntary testing of the entire sexually active population, with immediate and sustained provision of ART to those who test HIV positive. This approach is more expensive and logistically difficult than are targeted approaches, and its value is strongly dependent on the proportion of new transmission events that occur between partners in serodiscordant couples versus those occurring by other routes.

We constructed a mathematical model to estimate rates of HIV transmission before couple formation, rates attributable to extra-couple intercourse, and rates within serodiscordant couples, to assess the proportional contribution of different routes of transmission to new HIV infections. Because the probability that an individual acquires HIV during any period is a function of the period’s duration,11 we disentangled routes of transmission by relating couple serostatus to information about couple duration, duration of sexual activity before couple formation, the population prevalence of HIV, and age-specific estimates of HIV survival.

Discussion

Our findings show three major conclusions. First, extra-couple transmission has played and still plays a major part in driving HIV incidence for both sexes, but particularly for men; second, within couples, HIV seems to be propagated more from men to women than vice versa; third, women have a period of high infection risk before entering a cohabiting partnership. We emphasise that the fitted transmission coefficients aggregate several behavioural and physiological processes and thus should be interpreted cautiously. Because the hazard of infection is the product of transmission coefficients and prevalence in the opposite sex, comparisons between male and female transmission coefficients should be made with consideration of the differing HIV prevalences for each sex. For example, although we estimate that more men than women are infected through extra-couple transmission, the estimated transmission coefficients are roughly similar because female infectious HIV prevalence is greater than that of the opposite sex. The transmission coefficients will also partially absorb unmodelled mixing patterns. For example, young women tend to mix with older men, who have a greater probability of being seropositive than do younger men. This effect would tend to increase female incidence before partnership formation, thus needing greater fitted female before-partnership transmission coefficients to fit the recorded data, but not necessarily biasing the estimate of incidence through this route.

Investigators of previous studies17—23 using DHS and similar cross-sectional couple data have come to diverse conclusions (panel). Analyses of DHS couples data have noted that slightly less than half of serodiscordant couples had seropositive women rather than men;1720 others used mathematical models to estimate the proportion of transmission that took place outside serodiscordant partnerships versus between partners.2122 These studies all conclude that the high prevalence of female-positive and male-positive serodiscordant partnerships suggests that, contrary to mainstream beliefs,20 both women and men often have risky extra-couple intercourse, with the modelling studies estimating that much of the transmission to both sexes is from outside rather than within the couple. These studies have largely overlooked that routes of infection cannot be directly inferred from cross-sectional data, such as DHS. Estimations of transmission from outside a couple combine infections occurring from extra-couple intercourse with those acquired before that couple’s formation when the individual was either single or in another couple. Thus, the existence of serodiscordant couples does not necessarily suggest extra-couple transmission, and estimates of the proportion of transmission from outside existing partnerships do not measure extra-couple transmission.

A second important factor largely overlooked in analyses of cross-sectional couple data is survival bias—ie, only couples in which both partners survive to be sampled are recorded. Median survival time after seroconversion is about 6—13 years, dependent on the age at seroconversion.12 Many couples in which one or both partners become infected are thus removed from the population before the sample is taken. This effect will be different for serodiscordant and seroconcordant couples. Studies analysing cross-sectional couple data while ignoring mortality17,20—22,28 could therefore yield biased conclusions for the proportional contribution of extra-couple intercourse to incidence.

Our findings show that extra-couple and within-couple transmission are both important routes of HIV infection and both account for many recorded infections in men and women; however, results vary substantially by country. We obtained this result despite finding that fitted extra-couple transmission coefficients were by far the smallest of the three routes of infection. This result is consistent with Chemaitelly and colleagues’28 finding that most infections in serodiscordant couples are due to within-couple transmission. The large contribution of extra-couple transmission at the population level is because most cohabiting couples are concordant negative and, on average, the surveyed individuals had spent most time in a couple since their sexual debut. Thus, the large amount of person-time spent at risk from extra-couple transmission more than compensates for its small transmission coefficients. Results from our analysis, which was only of couples, greatly contrast those of Dunkle and colleagues,19 who concluded that within-couple transmission accounts for most of the HIV incidence in sexually active urban populations (ie, in single individuals and those in couples) in Zambia and Rwanda. This contrast is probably because of the reliance of Dunkle and colleagues on downwards-biased self-reported rates of intercourse with non-cohabiting partners, which could lead to substantial underestimation of the contribution of extra-couple intercourse.29

When available, molecular evidence shows the importance of extra-couple transmission. In several cohort studies of serodiscordant couples,1,2,25—27 13—32% of incident infections were from virus not linked to that isolated from the seroconverter’s partner and were presumably due to extra-couple intercourse. Compared with cohort studies, we attributed a smaller proportion of transmission within serodiscordant couples to extra-couple intercourse, which might be because individuals enrolled in cohort studies differ systematically from the general population, which is more representatively sampled by DHS. Furthermore, seronegative individuals in cohort studies might engage in more extra-couple and less within-couple intercourse upon finding that their partner is seropositive.27 This behavioural effect could explain why our estimated rates of within-couple transmission are generally greater than those from cohort studies (table 2).1225

Our finding that, within couples, the directionality of HIV propagation is more from men to women than vice versa is because of the greater average duration of sexual activity in men before couple formation and additionally, for some countries, because of their greater hazard rate for extra-couple infection. Although the average duration of sexual activity before partnership formation is much shorter for women than for men, we noted that, as reported elsewhere,11 this difference is partly compensated by the greater risk of infection per unit time in women before partnership formation.

With use of relationship and serostatus data, country-specific trends for the prevalence of HIV, and estimates of HIV survival times to explicitly estimate the probability that infections were because of pre-couple, within-couple, or extra-couple transmission, our model addresses several limitations of previous studies, and advances estimations of transmission breakdown by behavioural routes from cross-sectional data. However, our model retains certain assumptions. We assumed homogeneous mixing between age groups for sexual partners chosen before couple formation or during extra-couple intercourse. Although this assumption might bias our results, to the extent that patterns of age mixing cause a consistent bias for overestimates or underestimates in the estimated prevalence that individuals are exposed to, this bias will be counteracted by underestimates or overestimates in transmission coefficients, with no effect on estimates of total hazard and per-route contributions to transmission.

We also assumed that the probability of infection via a particular transmission route is dependent on only the duration an individual is at risk by that route, the time-varying HIV prevalence in the population of the opposite sex (or partner seropositivity for within-partner transmission), and a transmission coefficient for each gender-route combination. In reality, the frequency of intercourse and the number and riskiness of partners also affect transmission. Other causes of heterogeneity not considered here include genetic and immunological factors, type of sexual exposure, sexually transmitted infections, viral loads, viral characteristics, tendency to seek care, male circumcision, and protected sex; many of these factors vary both between individuals and through time within individuals.716 Although we assumed that individuals were homogeneous, our results were robust to this assumption. Our sensitivity analysis shows that even with a large individual-level heterogeneity in hazard rates, the association between relationship histories and serostatuses was substantial enough for the model to accurately infer the proportional breakdown of infections by transmission routes.

Hazards can vary over time for reasons other than changing prevalence. Declines in HIV prevalence in several countries have been attributed to behavioural changes in response to interventions or overall HIV awareness.30 Such changes would lead to decreasing transmission coefficients during the epidemic, but how this decrease might be divided among the routes of transmission we considered is unclear; therefore, we were unable to assess this possibility. We did not include effects of ART on HIV survival times or within-couple transmission in our main analysis because DHS surveys do not provide the drug status of individuals, and because we believe that the within-couple effects of therapy were small. On the basis of policies created before WHO’s 2012 TasP recommendations, most treated individuals would have already exposed their partners to infection for a long time before they become ill, get tested, have CD4 counts decrease to less than 200 counts per μL, and start ART. Furthermore, coverage of ART in the countries analysed was negligible for most of the period covered by the couples in our survey.13 This factor explains why our results were robust in sensitivity analyses allowing for ART to affect within-couple transmission or relaxing the assumption that all individuals on ART are non-infectious.

Finally, in view of the range of the DHS and the relatively narrow scope of our study, we necessarily excluded many couples because of missing or inconsistent data. However, these exclusions are unlikely to cause major selection bias and our results are roughly generalisable to the couples in the population as sampled by DHS. In particular, our results are likely to be more representative of the general population than are those from virological linkage cohort studies, which have more specific selection criteria and alter the behaviour of participants.27

We have shown that substantial HIV transmission occurs through all transmission routes: within serodiscordant couples and before couple formation and from extra-couple intercourse. We make no assumptions about the morality31 or potential for mitigation32 of extra-couple sex. Extra-couple sex does not necessarily constitute a choice and could be motivated by basic needs or indicate large social support structures.33 However, policy choices should be made in view of our finding that extra-couple transmission by both sexes has a major role in the HIV epidemic in sub-Saharan Africa.

Offering of TasP to only HIV-positive individuals in stable, serodiscordant couples is tempting because the partner is identifiable, and clearly at risk. However, the aggregate risk to partners not in stable relationships with positive individuals is also high. This finding does not mean that TasP and PrEP programmes have no place in targeted treatment of serodiscordant couples. These programmes have been effective and represent major advances in HIV prevention strategy. PrEP, in particular, could change the gender power dynamics in serodiscordant couples by empowering women to prevent HIV transmission. In view of this fairly small proportion of populations constituted by serodiscordant couples, these approaches could be a good starting point for HIV control efforts, especially in the context of resource limitations. However, our results do imply that behavioural and biomedical interventions focused on serodiscordant couples will not be sufficient to cause major reductions in HIV incidence at the population level. Interventions should address all transmission routes to fight the HIV epidemic. Despite its expense and logistical demands, the universal test-and-treat strategy could reduce all forms of heterosexual transmission.

Source: Lancet

Tests find malaria vaccine useful.


A malaria vaccine tested on infants in seven African countries has shown a protective effect that is small but possibly enough to prove useful in areas where the infection is a serious threat to children.

The vaccine, known officially as RTS,S/AS01, reduced by 33 percent the number of cases of malaria suffered by infants in the year after they were immunized, according to a study presented in South Africa on Friday and published online by the New England Journal of Medicine.

The actual number of infections was small. About 2.3 percent of babies not getting the vaccine suffered a case of severe malaria in their first year. The vaccine reduced that by one-third.

Preventive measures and better treatment have driven down malaria mortality over the past 20 years. Nevertheless, the mosquito-borne infection still causes about 216 million cases of illness and 655,000 deaths — almost all of them of African children — each year.

“If you broadly implement this across sub-Saharan Africa, it is going to prevent millions of cases and save thousands of lives,” said David Kaslow, director of the malaria vaccine initiative at the Program for Appropriate Technology in Health (PATH), a nonprofit group in Seattle that is helping run the vaccine trials.

One of the more successful tools against malaria is the insecticide-treated bed net. Studies have shown that consistently sleeping under one reduces cases of malaria by 25 to 75 percent. About 85 percent of the children in the vaccine study slept under a net, so they were substantially protected. In addition, indoor spraying with long-lasting pesticides — another preventive tool — was common in four of the 11 study areas.

The study enrolled infants in Kenya, Tanzania, Mozambique, Malawi, Ghana, Burkina Faso and Gabon. Malaria transmission differed greatly from place to place. In the worst area, babies averaged two bouts of malaria a year. In the site with the least transmission, the figure was one-hundredth that rate.

About 6,500 babies were randomly assigned to get the malaria vaccine or an unrelated one that helps prevent bacterial meningitis. By design, twice as many were assigned to the malaria vaccine as to the other one. The malaria vaccine was given in three shots a month a part, starting at two months of age.

At least one episode of severe malaria occurred in 2.3 percent of the babies getting the meningitis vaccine, compared with 1.5 percent in those getting the malaria vaccine.

Death from any cause, including malaria, was rare. It occurred in 1.5 percent of the babies who got the malaria vaccine and 1.3 percent in those who got the meningitis vaccine.

Meningitis was twice as likely in the malaria-vaccine babies. Whether that was because they didn’t get the meningitis vaccine or happened by chance is unknown.

A study of the same vaccine in children 5 to 17 months of age was reported last year. It found a bigger protective effect — about 50 percent.

The vaccine is made by GlaxoSmithKline. The company has said the price of the vaccine will cover the cost of its production and a 5 percent margin, which will be reinvested in research on other vaccines for tropical diseases.

Source: http://www.washingtonpost.com

 

 

Novel Program Shows Strong Promise in Malaria Prevention.


BAMAKO, MALI/N’DJAMENA, CHAD/PARIS/NEW YORK

A large-scale malaria prevention program, consisting of intermittent distributions of anti-malaria medicines, appears to be drastically reducing the number of new cases of the disease among young children during peak transmission season, according to preliminary results from projects run by the international medical humanitarian organization Doctors Without Borders/Médecins Sans Frontières (MSF) in two African countries.

Antimalaria medicines have been administered prophylactically to approximately 175,000 children between three months and five years of age in Koutiala District in southern Mali and in two areas of Moïssala District in Chad, through an intervention known as seasonal malaria chemoprevention (SMC). Children in that age group are among the most vulnerable to death from malaria due to weaker immunity. Preliminary results show more than a two-thirds drop in the number of simple malaria cases in the intervention area in Mali and up to an 86 percent drop in Chad. A significant decrease of cases of severe malaria is also being recorded.

“While we need to continue evaluating the broader impact of SMC, in terms of its overall effect on a population’s health, the initial results of our intervention show a spectacular decrease in the number of malaria cases,” said Dr. Estrella Lasry, a malaria specialist at MSF. “The bottom line is that we are seeing a correlation with our intervention: more than half the beds in the pediatric ward of the hospital in which we work in Mali are empty, something we have never seen in prior years during peak malaria season, when bed occupancy was typically over 100 percent.”

The World Health Organization (WHO) recommended SMC in March, 2012, based upon research carried out in multiple countries in the Sahel region of Africa that experience high seasonal malaria. The intervention consists of the intermittent provision of a full course of treatment of an anti-malaria medication during peak malaria season, with the aim of preventing new cases of malaria. Different drugs are used to treat people in the area who test positive for malaria.

The MSF projects were launched in July and will last until October, the period of high malaria transmission, and mark the first time MSF has carried out a large-scale SMC program. Some 165,000 children in Mali and 10,000 in Chad take a total of three tablets of amodiaquine and one of sulphadoxine/pyrimethamine over a three-day period once a month. Children who are ill at the time of a distribution, and who test positive for malaria, receive artemisinin-based treatment and are excluded from that month’s distribution.

The areas in Mali and Chad were tested for resistance to the SMC drugs prior to the initiation of the intervention. No resistance was discovered among the representative sample tested. Further resistance surveys will be conducted periodically in Koutiala and Moïssala .

In Mali, MSF teams observed a 65 percent drop in the number of simple malaria cases in the weeks following the distribution of treatment. Additionally, the number of malaria-associated hospitalizations plummeted from an average 247 per week to 84. In southern Chad, results were equally encouraging; in two health zones in Moïssala, the decrease in the number of simple malaria cases was between 72 percent and 86 percent, compared to cases recorded in the weeks prior to the first SMC distribution.

“This prevention strategy could be an extraordinary public health tool, particularly for protecting children, who account for the vast majority of malaria deaths,” said Dr. Lasry. “We can draw on our projects in Chad and Mali to assess the feasibility of employing this strategy in other contexts.”

Additional malaria prevention methods, such as bed net distributions, insecticide spraying, and adequate diagnosis and management of malaria must continue to be supported and implemented in endemic countries, MSF said.

According to the WHO, an estimated 650,000 people die from malaria every year. Ninety percent of cases occur in Sub-Saharan Africa, mainly among young children.

MSF is running projects for the treatment and prevention of the most deadly diseases in young children in Mali and Chad. Since the beginning of 2012, more than 12,000 people have been treated for malaria as outpatients and 3,500 sick and/or severely malnourished children have been hospitalized in Koutiala district in southern Mali. In the Moïssala district in Chad, more than 18,000 people have received malaria treatment in MSF-supported facilities or from non-medical health workers in villages who have been trained by MSF.  

Related:

Source: MSF Newsletter.