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"Newman, Robert D."
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A Research Agenda to Underpin Malaria Eradication
by
Newman, Robert D.
,
Chitnis, Chetan
,
Levine, Myron M.
in
Animals
,
Anopheles - parasitology
,
Antimalarials - pharmacology
2011
The interruption of malaria transmission worldwide is one of the greatest challenges for international health and development communities. The current expert view suggests that, by aggressively scaling up control with currently available tools and strategies, much greater gains could be achieved against malaria, including elimination from a number of countries and regions; however, even with maximal effort we will fall short of global eradication. The Malaria Eradication Research Agenda (malERA) complements the current research agenda--primarily directed towards reducing morbidity and mortality--with one that aims to identify key knowledge gaps and define the strategies and tools that will result in reducing the basic reproduction rate to less than 1, with the ultimate aim of eradication of the parasite from the human population. Sustained commitment from local communities, civil society, policy leaders, and the scientific community, together with a massive effort to build a strong base of researchers from the endemic areas will be critical factors in the success of this new agenda.
Journal Article
Epidemiology and burden of malaria in pregnancy
by
Brabin, Bernard
,
Asamoa, Kwame
,
McGready, Rose
in
Adult
,
Africa - epidemiology
,
Americas - epidemiology
2007
We reviewed evidence of the clinical implications and burden of malaria in pregnancy. Most studies come from sub-Saharan Africa, where approximately 25 million pregnant women are at risk of
Plasmodium falciparum infection every year, and one in four women have evidence of placental infection at the time of delivery.
P falciparum infections during pregnancy in Africa rarely result in fever and therefore remain undetected and untreated. Meta-analyses of intervention trials suggest that successful prevention of these infections reduces the risk of severe maternal anaemia by 38%, low birthweight by 43%, and perinatal mortality by 27% among paucigravidae. Low birthweight associated with malaria in pregnancy is estimated to result in 100 000 infant deaths in Africa each year. Although paucigravidae are most affected by malaria, the consequences for infants born to multigravid women in Africa may be greater than previously appreciated. This is because HIV increases the risk of malaria and its adverse effects, particularly in multigravidae, and recent observational studies show that placental infection almost doubles the risk of malaria infection and morbidity in infants born to multigravidae. Outside Africa, malaria infection rates in pregnant women are much lower but are more likely to cause severe disease, preterm births, and fetal loss.
Plasmodium vivax is common in Asia and the Americas and, unlike
P falciparum, does not cytoadhere in the placenta, yet, is associated with maternal anaemia and low birthweight. The effect of infection in the first trimester, and the longer term effects of malaria beyond infancy, are largely unknown and may be substantial. Better estimates are also needed of the effects of malaria in pregnancy outside Africa, and on maternal morbidity and mortality in Africa. Global risk maps will allow better estimation of potential impact of successful control of malaria in pregnancy.
Journal Article
Potential for reduction of burden and local elimination of malaria by reducing Plasmodium falciparum malaria transmission: a mathematical modelling study
by
Alonso, Pedro
,
Sinka, Marianne E
,
Cibulskis, Richard E
in
Agreements
,
Animals
,
Antimalarials - administration & dosage
2016
Rapid declines in malaria prevalence, cases, and deaths have been achieved globally during the past 15 years because of improved access to first-line treatment and vector control. We aimed to assess the intervention coverage needed to achieve further gains over the next 15 years.
We used a mathematical model of the transmission of Plasmodium falciparum malaria to explore the potential effect on case incidence and malaria mortality rates from 2015 to 2030 of five different intervention scenarios: remaining at the intervention coverage levels of 2011–13 (Sustain), for which coverage comprises vector control and access to treatment; two scenarios of increased coverage to 80% (Accelerate 1) and 90% (Accelerate 2), with a switch from quinine to injectable artesunate for management of severe disease and seasonal malaria chemoprevention where recommended for both Accelerate scenarios, and rectal artesunate for pre-referral treatment at the community level added to Accelerate 2; a near-term innovation scenario (Innovate), which included longer-lasting insecticidal nets and expansion of seasonal malaria chemoprevention; and a reduction in coverage to 2006–08 levels (Reverse). We did the model simulations at the first administrative level (ie, state or province) for the 80 countries with sustained stable malaria transmission in 2010, accounting for variations in baseline endemicity, seasonality in transmission, vector species, and existing intervention coverage. To calculate the cases and deaths averted, we compared the total number of each under the five scenarios between 2015 and 2030 with the predicted number in 2015, accounting for population growth.
With an increase to 80% coverage, we predicted a reduction in case incidence of 21% (95% credible intervals [CrI] 19–29) and a reduction in mortality rates of 40% (27–61) by 2030 compared with 2015 levels. Acceleration to 90% coverage and expansion of treatment at the community level was predicted to reduce case incidence by 59% (Crl 56–64) and mortality rates by 74% (67–82); with additional near-term innovation, incidence was predicted to decline by 74% (70–77) and mortality rates by 81% (76–87). These scenarios were predicted to lead to local elimination in 13 countries under the Accelerate 1 scenario, 20 under Accelerate 2, and 22 under Innovate by 2030, reducing the proportion of the population living in at-risk areas by 36% if elimination is defined at the first administrative unit. However, failing to maintain coverage levels of 2011–13 is predicted to raise case incidence by 76% (Crl 71–80) and mortality rates by 46% (39–51) by 2020.
Our findings show that decreases in malaria transmission and burden can be accelerated over the next 15 years if the coverage of key interventions is increased.
UK Medical Research Council, UK Department for International Development, the Bill & Melinda Gates Foundation, the Swiss Development Agency, and the US Agency for International Development.
Journal Article
The Threat of Artemisinin-Resistant Malaria
by
Guerin, Philippe J
,
Slutsker, Laurence
,
MacArthur, John R
in
Antimalarials - pharmacology
,
Antimalarials - therapeutic use
,
Artemisinin
2011
Since the 1970s, when Chinese researchers demonstrated the artemisinins' antimalarial potency, artemisinin-based combination therapy has become key to malaria control. But reduced susceptibility of
Plasmodium falciparum
to artemisinin is now being seen in some places.
In the 1970s, Chinese government scientists working on a secret “Project 523” developed a new class of potent antimalarial drugs, the artemisinins or qinghaosu derivatives. In mostly unpublished work that has just been recognized by a 2011 Lasker Award to Tu Youyou, researchers in China isolated the active compounds from the plant
Artemisia annua,
tested them in mice, analyzed the chemical structure of the artemisinins, and demonstrated their high potency and rapid efficacy in human trials. Although they were widely used in China during the 1980s, only in the 1990s did the artemisinins come to wider global attention in the . . .
Journal Article
Decision-making on malaria vaccine introduction: the role of cost―effectiveness analyses
by
MOORTHY, Vasee S
,
HUTUBESSY, Raymond
,
HOMBACH, Joachim
in
Adaptive immunity
,
Biological and medical sciences
,
Clinical research
2012
Policy-makers in countries where malaria is endemic are facing increasingly complex decisions about which vaccines and malaria prevention measures to include in national immunization and malaria control programmes. Several new vaccines and malaria preventive measures are already competing for limited financing in developing countries. African countries with endemic malaria should be ready to make a national policy decision on the introduction of RTS,S/AS01, a first-generation malaria vaccine, by 2015. If clinical trials progress according to schedule, that same year the World Health Organization will issue a policy recommendation on the public health use of this vaccine based on the findings of the full Phase III efficacy trial in progress, which will be available in late 2014. Cost-effectiveness is an important consideration in public health decision-making. This article summarizes critical parameters driving malaria vaccine cost-effectiveness predictions and discusses major uncertainties that remain in the cost-effectiveness modelling arena. It also highlights the need for ongoing work by modelling groups to further refine cost-effectiveness predictions.
Journal Article
Focused Screening and Treatment (FSAT): A PCR-Based Strategy to Detect Malaria Parasite Carriers and Contain Drug Resistant P. falciparum, Pailin, Cambodia
2012
Recent studies have shown that Plasmodium falciparum malaria parasites in Pailin province, along the border between Thailand and Cambodia, have become resistant to artemisinin derivatives. To better define the epidemiology of P. falciparum populations and to assess the risk of the possible spread of these parasites outside Pailin, a new epidemiological tool named \"Focused Screening and Treatment\" (FSAT), based on active molecular detection of asymptomatic parasite carriers was introduced in 2010. Cross-sectional malariometric surveys using PCR were carried out in 20 out of 109 villages in Pailin province. Individuals detected as P. falciparum carriers were treated with atovaquone-proguanil combination plus a single dose of primaquine if the patient was non-G6PD deficient. Interviews were conducted to elicit history of cross-border travel that might contribute to the spread of artemisinin-resistant parasites. After directly observed treatment, patients were followed up and re-examined on day 7 and day 28. Among 6931 individuals screened, prevalence of P. falciparum carriers was less than 1%, of whom 96% were asymptomatic. Only 1.6% of the individuals had a travel history or plans to go outside Cambodia, with none of those tested being positive for P. falciparum. Retrospective analysis, using 2010 routine surveillance data, showed significant differences in the prevalence of asymptomatic carriers discovered by FSAT between villages classified as \"high risk\" and \"low risk\" based on malaria incidence data. All positive individuals treated and followed-up until day 28 were cured. No mutant-type allele related to atovaquone resistance was found. FSAT is a potentially useful tool to detect, treat and track clusters of asymptomatic carriers of P. falciparum along with providing valuable epidemiological information regarding cross-border movements of potential malaria parasite carriers and parasite gene flow.
Journal Article
WHO and the future of disease control programmes
by
Dye, Christopher
,
Raviglione, Mario C
,
Savioli, Lorenzo
in
Acquired immune deficiency syndrome
,
AIDS
,
Alliances
2013
Huge increases in funding for international health over the past two decades have led to a proliferation of donors, partnerships, and health organisations. Over the same period, the global burden of non-communicable diseases has increased absolutely and relative to communicable diseases. In this changing landscape, national programmes for the control of HIV/AIDS, tuberculosis, malaria, and neglected tropical diseases must be reinforced and adapted for three reasons: the global burden of these communicable diseases remains enormous, disease control programmes have an integral and supporting role in developing health systems, and the health benefits of these control programmes go beyond the containment of specific infections. WHO's traditional role in promoting communicable disease control programmes must also adapt to new circumstances. Among a multiplicity of actors, WHO's task is to enhance its normative role as convenor, coordinator, monitor, and standard-setter, fostering greater coherence in global health.
Journal Article
Placental Malaria Increases Malaria Risk in the First 30 Months of Life
2008
Background. Plasmodium falciparum infection during pregnancy is associated with stillbirth, fetal growth restriction, and low birth weight. An additional consequence may be increased risk of malaria in early life, although the epidemiological evidence of this consequence is limited. Methods. A cohort of 527 children were observed actively every month for 30 months after delivery. Offspring of mothers with microscopically detectable placental P. falciparum infection at the time of delivery were defined as exposed. The outcome measure was malaria (parasitemia and fever). Analyses were performed using Cox proportional hazard models and were stratified by gravidity. Results. Overall, offspring of mothers with placental P. falciparum infection had a significantly higher risk of clinical malaria during the first 30 months of life (adjusted hazard ratio, 2.1; 95% confidence interval [CI], 1.2–3.7). The adjusted hazard ratio for offspring of multigravidae was 2.6 (95% CI, 1.3–5.3), and that for primigravidae was 1.5 (95% CI, 0.6–3.8). The offspring of placenta-infected primigravidae had no episodes of malaria during the first year of life. Conclusions. Our findings show that active placental P. falciparum infection detected at delivery is associated with an ∼2-fold greater risk of malaria during early life, compared with noninfection. The fact that persons born to infected multigravidae rather than primigravidae appear to be at greater risk emphasizes the importance of preventing malaria in mothers of all gravidities.
Journal Article
Comparison of Intermittent Preventive Treatment with Chemoprophylaxis for the Prevention of Malaria during Pregnancy in Mali
by
Kayentao, Kassoum
,
Mungai, Mary
,
Newman, Robert D.
in
Abortion, Spontaneous
,
Adolescent
,
Adult
2005
Background. Malaria during pregnancy contributes to maternal anemia and low birth weight. In East Africa, several studies have demonstrated that intermittent preventive treatment (IPT) with sulfadoxine-pyrimethamine (SP) is more efficacious than weekly chloroquine (CQ) chemoprophylaxis in preventing these adverse consequences. To our knowledge, there are no published trials evaluating IPT in West Africa. Methods. We undertook a randomized controlled trial of weekly CQ chemoprophylaxis, 2-dose IPT with CQ, and 2-dose IPT with SP; 1163 women were enrolled. Results. In multivariate analyses, when compared with weekly CQ, IPT/SP was associated with a reduction in third-trimester anemia (adjusted odds ratio [AOR], 0.49; P = .001), placental parasitemia (AOR, 0.69; P = .04), and low birth weight (<2500 g) (AOR, 0.69; P = .04). The prevalence of placental infection remained .04 Pp.04 unexpectedly high, even in the IPT/SP group (24.5%), possibly because of the intensity of seasonal transmission. There were no significant differences in stillbirths, spontaneous abortions, or neonatal deaths among the 3 groups. Conclusions. In Mali, IPT with SP appears more efficacious than weekly chloroquine chemoprophylaxis in preventing malaria during pregnancy. These data support World Health Organization recommendations to administer at least 2 doses of IPT during pregnancy. In intensely seasonal transmission settings in Mali, >2 doses may be required to prevent placental reinfection prior to delivery.
Journal Article
Protective Efficacy of Intermittent Preventive Treatment of Malaria in Infants (IPTi) Using Sulfadoxine-Pyrimethamine and Parasite Resistance
by
Chandramohan, Daniel
,
Newman, Robert D.
,
Grobusch, Martin P.
in
Alcohol Dehydrogenase - genetics
,
Alcohol Dehydrogenase - metabolism
,
Analysis
2010
Intermittent Preventive Treatment of malaria in infants using sulfadoxine-pyrimethamine (SP-IPTi) is recommended by WHO for implementation in settings where resistance to SP is not high. Here we examine the relationship between the protective efficacy of SP-IPTi and measures of SP resistance.
We analysed the relationship between protective efficacy reported in the 7 SP-IPTi trials and contemporaneous data from 6 in vivo efficacy studies using SP and 7 molecular studies reporting frequency of dhfr triple and dhps double mutations within 50 km of the trial sites. We found a borderline significant association between frequency of the dhfr triple mutation and protective efficacy to 12 months of age of SP-IPTi. This association is significantly biased due to differences between studies, namely number of doses of SP given and follow up times. However, fitting a simple probabilistic model to determine the relationship between the frequency of the dhfr triple, dhps double and dhfr/dhps quintuple mutations associated with resistance to SP and protective efficacy, we found a significant inverse relationship between the dhfr triple mutation frequency alone and the dhfr/dhps quintuple mutations and efficacy at 35 days post the 9 month dose and up to 12 months of age respectively.
A significant relationship was found between the frequency of the dhfr triple mutation and SP-IPTi protective efficacy at 35 days post the 9 month dose. An association between the protective efficacy to 12 months of age and dhfr triple and dhfr/dhps quintuple mutations was found but should be viewed with caution due to bias. It was not possible to define a more definite relationship based on the data available from these trials.
Journal Article