Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Contrasting patterns of malaria drug resistance found between humans and mosquitoes

A study conducted by researchers at the Johns Hopkins Malaria Research Institute and their Zambian colleagues detected contrasting patterns of drug resistance in malaria-causing parasites taken from both humans and mosquitoes in rural Zambia.

Parasites found in human blood samples showed a high prevalence for pyrimethamine-resistance, which was consistent with the class of drugs widely used to treat malaria in the region.

However, parasites taken from mosquitoes themselves had very low prevalence of pyrimethamine-resistance and a high prevalence of cycloguanil-resistant mutants indicating resistance to a newer class of antimalaria drug not widely used in Zambia. The findings are published November 7 in the online edition of the journal PNAS and will be discussed at the November 16 seminar, "The Forever War: Malaria versus the World," held in New York City by the Johns Hopkins Bloomberg School of Public Health and the New York Academy of Sciences.

Surveillance for drug-resistant parasites in human blood is a major effort in malaria control. Malaria in humans is caused by the parasite Plasmodium falciparum, which is spread from person to person through the feeding of the Anopheles mosquito. Over time, through repeated exposure to medications, the parasites can become less susceptible to drugs used to treat malaria infection, limiting their effectiveness.

"This contrast in resistance factors was a big surprise to us," said Peter Agre, MD, an author of the study and director of the Johns Hopkins Malaria Institute. "The contrast raises many questions, but we suspect that the malaria parasite can bear highly host-specific drug-resistant polymorphisms, most likely reflecting very different selection preferences between humans and mosquitos."

For the study, Sungano Mharakurwa, PhD, lead author and senior research associate with the Johns Hopkins Malaria Research Institute in Macha, Zambia, conducted a DNA analysis of P. falciparum found in human blood samples to those found in mosquitoes collected inside homes in rural Zambia. In samples taken from human blood, pyrimethamine-resistant mutations were greater than 90 percent and between 30 percent to 80 percent for other polymorphisms. Mutations of cycloguanil-resistance were 13 percent.

For parasites found in the mosquito midgut, cycloguanil-resistant mutants were at 90 percent while pyrimethamine-resistant mutants were detected between 2 percent and 12 percent.

"Our study indicates that mosquitoes exert an independent selection on drug resistant parasites—a finding that has not previously been noticed. If confirmed in other malaria endemic regions, it suggests an explanation for why drug resistance may appear so rapidly," said Mharakurwa.

Worldwide, malaria afflicts more than 225 million people. Each year, the disease kills approximately 800,000, many of whom are children living in Africa.

Authors of "Malaria antifolate resistance with contrasting Plasmodium falciparum dihydrofolate reductase (DHFR) polymorphisms in humans and Anopheles mosquitoes" are Sungano Mharakurwa, Taida Kumwenda, Mtawa A. P. Mkulama, Mulenga Musapa, Sandra Chishimba, Clive J. Shiff, David J. Sullivan, Philip E. Thuma, Kun Liu and Peter Agre.

The Johns Hopkins Malaria Research Institute is a state-of-the-art research facility at the Johns Hopkins Bloomberg School of Public Health. It focuses on a broad program of basic science research to treat and control malaria, develop a vaccine and find new drug targets to prevent and cure this deadly disease.

Funding was provided by the Johns Hopkins Malaria Research Institute, the Bill & Melinda Gates Foundation and the National Institutes of Health.

Tim Parsons | EurekAlert!
Further information:

More articles from Studies and Analyses:

nachricht Diagnoses: When Are Several Opinions Better Than One?
19.07.2016 | Max-Planck-Institut für Bildungsforschung

nachricht High in calories and low in nutrients when adolescents share pictures of food online
07.04.2016 | University of Gothenburg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>