In a paradigm changing discovery, Plasmodium vivax (P. vivax) malaria has been identified in a population historically thought to be resistant to the disease, those who do not express the Duffy blood group protein on their red blood cells, according to researchers from Case Western Reserve University School of Medicine, Pasteur Institute, and the Madagascar Ministry of Health.
In a study of more than 600 individuals from eight communities covering the main malaria transmission areas of Madagascar, the researchers found that 10 percent of people experiencing clinical malaria were Duffy-negative and infected with P. vivax. These findings were published in an upcoming issue of the Proceedings of the National Academy of Sciences of the United States of America (PNAS).
Since the early 1920s, it has been widely accepted that people of African ancestry are resistant to P. vivax blood-stage infection and clinical malaria. The Duffy-negative blood group, one of the more than 30 blood types, is predominant in most African ethnic groups. In recent years, researchers have begun to suspect that P. vivax, the world's most abundant malaria parasite, had made its way into the blood of Duffy-negative people, but until now, confirming evidence that the parasite had entered the red blood cells remained elusive.
The Case Western Reserve-Pasteur Institute team has documented their novel discovery with the first photographic evidence of the parasite's presence within red blood cells of many Duffy-negative people experiencing malarial illness. It is understood that those with this blood type, can have P. vivax living dormant in their liver cells where it does not make people sick. What has distinguished Duffy-negatives from all others was that the malaria parasite was unable to cross the threshold from liver cells to blood cells. The lynchpin responsible for resistance to vivax malaria has been that when the Duffy antigen is missing the parasite is not able to invade the red blood cell and cause disease.
"The study confirms that P. vivax is not dependent on the Duffy antigen for establishing blood-stage infection and disease in Madagascar. Evolution of new parasite strains, infiltrating a new group of people who are Duffy-negative, seems to be occurring within a population of people from different ethnic backgrounds," says Peter A. Zimmerman, Ph.D., the study's senior author and Professor of International Health, Genetics and Biology in the Center for Global Health and Diseases at Case Western Reserve University School of Medicine. "These findings will have a major impact on efforts to eliminate malaria worldwide, particularly in large regions of Duffy-negative west, central and southern Africa."
The study's findings suggest that population mixing on the island of Madagascar increases the Duffy-negative's susceptibility to P. vivax. With ancestors of both Duffy-negative Africa and Duffy-positive Southeast Asia in Madagascar, P. vivax has steady opportunity to attempt infection of Duffy-negative red blood cells. Through these opportunities, and the lifecycle necessity of blood-stage infection, P. vivax strains in Madagascar may be optimizing an otherwise cryptic invasion pathway.
Malaria, one of the world's "big three" diseases, is a major health problem. Forty percent of the world's 6.5 billion people live in areas where malaria transmission occurs. As many as three million people are diagnosed with new cases of P. vivax malaria each year, which is one of the four types of malaria. "It will be imperative for the global health community to find ways to prevent the spread of these new strains of P. vivax to the continent of Africa," says Dr. Zimmerman.
In Madagascar, malaria is endemic to more than three-quarters of the island. With almost one million clinical cases reported each year, this disease is a major public health problem. Major efforts to fight malaria are focused on Plasmodium falciparum. While P. vivax is the second most prevalent malaria parasite, public health data on it is limited. "We did not anticipate such a widespread phenomenon when we started the study with our Malagasy colleagues from the National Malaria Control Programme. Finding vivax malaria in a group previously considered resistant adds yet another public health threat to this population. It was bad news. We need to understand how the parasite has evolved in Madagascar to spread disease to a broader population," says Dr. Didier Ménard from Pasteur Institute.
Dr. Odile Mercereau-Puijalon, Head of the Parasite Molecular Immunology Unit at the Pasteur Institute, commented, "The large numbers of P. vivax parasitized red blood cells in Duffy-negative patients shows an efficient invasion process in cells considered to be resistant to infection. This capacity is clearly not restricted to a single P. vivax strain in Madagascar and is a widespread phenomenon across the island. Our findings illustrate the extraordinary capacity of malaria parasites to overcome barriers. This calls for increased vigilance in the efforts to control malaria."
With these novel findings, the Case Western Reserve and Pasteur Institute researchers will examine how the malaria parasites successfully invade the cells and determine the molecular receptor involved in this process. Through their future studies the team hopes to determine how these parasites invade red blood cells and contribute to development of an effective vaccine against vivax malaria.
About Case Western Reserve University School of Medicine
Founded in 1843, Case Western Reserve University School of Medicine is the largest medical research institution in Ohio and is among the nation's top medical schools for research funding from the National Institutes of Health. The School of Medicine is recognized throughout the international medical community for outstanding achievements in teaching. The School's innovative and pioneering Western Reserve2 curriculum interweaves four themes--research and scholarship, clinical mastery, leadership, and civic professionalism--to prepare students for the practice of evidence-based medicine in the rapidly changing health care environment of the 21st century. Eleven Nobel Laureates have been affiliated with the school.
Annually, the School of Medicine trains more than 800 M.D. and M.D./Ph.D. students and ranks in the top 25 among U.S. research-oriented medical schools as designated by U.S. News &World Report "Guide to Graduate Education."
The School of Medicine's primary affiliate is University Hospitals Case Medical Center and is additionally affiliated with MetroHealth Medical Center, the Louis Stokes Cleveland Department of Veterans Affairs Medical Center, and the Cleveland Clinic, with which it established the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University in 2002.
Rutgers-led innovation could spur faster, cheaper, nano-based manufacturing
14.02.2018 | Rutgers University
New study from the University of Halle: How climate change alters plant growth
12.01.2018 | Martin-Luther-Universität Halle-Wittenberg
A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.
In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...
A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.
By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
23.02.2018 | Physics and Astronomy
23.02.2018 | Health and Medicine
23.02.2018 | Physics and Astronomy