David Smith, associate director of disease ecology at UF's Emerging Pathogens Institute, said the study will guide scientists and policy makers in extending the longevity of current artemisinin-based malaria drugs combined with partner drugs. Smith is a co-author of a report on the study, scheduled to publish online this week in the Proceedings of the National Academy of Sciences and in print on Sept. 16.
Smith collaborated with lead author Maciej Boni of Resources for the Future and Princeton University, and Ramanan Laxminarayan, also with RFF, to create mathematical models assessing the strategic effectiveness and clinical outcomes of using one, two and three first-line drug therapies to treat malaria within a population over a 20-year period. Their results show that using two or three drugs simultaneously reduced the total clinical cases and number of failed treatments , and slowed the rate at which drug-resistant genes spread within the parasites that cause malaria: Plasmodium falciparum, P. vivax, P. malariae and P. ovale.
"The models indicate that we can slow the evolution of resistance to current artemisinin-based therapies if nations use them in combination with two or more partner drugs," Smith said. "Currently, most nations don't do this. They use one therapy at a time, wait for it to fail, and then switch to a different therapy."
Artemisinin-combined therapies, or ACTs, are currently not widely implemented due to operational challenges and expense, Smith said. But he said the study offers compelling evidence for global leaders to collaborate and overcome these issues.
"This is not to say that implementing multiple first-line therapies solves all of our malaria problems," Boni said. "Anti-malarial drug development needs to continue so that we have novel and highly effective anti-malarials that can be plugged into the recommended strategy of deploying multiple therapies."
In the past century, chloroquine and sulfadoxine-pyrimethamine were widely used to combat malaria, but the parasites eventually evolved resistance leading to the drugs' failure. Artemesinin drugs, derived from the herb Artemisia annua, are relatively new and the malaria parasite does not yet appear to have a resistance to it. They work by triggering chemical reactions which damage the Plasmodium parasite.
"We don't have anything in the pipeline after ACTs, and it's basically just a matter of time until drug resistance evolves and artemisinin also fails," Smith said. "So the question becomes how do we keep ACTs in our arsenal for as long as effectively possible?"
The researchers' models also show that cycling through single drugs accelerated the rate at which malaria parasites evolved drug resistance. Smith said this occurred because cycling a single drug degraded the parasite's average fitness, which made it easier for drug-resistant genes to spread throughout the parasite population.
The cycling models predicted a declining therapeutic value of a single drug within 3.54 years, versus a longer effective therapeutic value of 9.95 years when three drugs were used in equal proportions within a population. The research was funded in part by grants from the Bill and Melinda Gates Foundation, and the National Institutes of Health.
"Using multiple first-line drugs reduces the selection pressure for resistance to a single drug," Smith said. "This is one way to make the ACTs last longer and benefit more people."
Co-author Laxminarayan, a senior research fellow at RFF, said ACTs are the best treatment option for malaria, now as well as in the foreseeable future.
"Novel treatment strategies improve our ability to delay the emergence of drug resistance without the need to deny treatment," Laxminarayan said.
Wil Milhous, associate dean for research at the University of South Florida's College of Public Health, said the research is "clearly a superb breakthrough in mathematical modeling applied to malaria drug deployment." Milhous has worked to develop new drugs for malaria for more than 25 years and is unaffiliated with the study.
"We have done the math in drug development, but only in terms of the cost of goods for drug combinations to include advanced preclinical and clinical testing. These are extremely time-consuming and costly but critical to regulatory approval," Milhous said. "Now we have a highly quantitative reality check that poor implementation strategies doom drugs to failure."
DeLene Beeland | EurekAlert!
Europe’s Demographic Future. Where the Regions Are Heading after a Decade of Crises
10.08.2017 | Berlin-Institut für Bevölkerung und Entwicklung
Scientists reveal source of human heartbeat in 3-D
07.08.2017 | University of Manchester
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
21.08.2017 | Life Sciences
21.08.2017 | Information Technology
18.08.2017 | Life Sciences