UMSOM Researchers Find that Silent Carriers of Malaria are Unlikely to Develop the Disease

Treating Those Who Have Malaria Parasite, But Don’t Have Symptoms, Could Help Stop Spread of Disease

In regions where malaria illness is widespread, it is common to find many individuals who are infected with malaria parasites (Plasmodium falciparum), but without symptoms. New research conducted by the University of Maryland School of Medicine (UMSOM) shows that treating these silent malaria cases could help stop the spread of malaria to others.

UMSOM researchers conducted a study of 114 participants in Malawi ranging from children to adults to better understand the role asymptomatic malaria infections have in the spread and occurrence of malaria illness. It is the first study to use prospective, longitudinal detection of asymptomatic malaria infection to examine subsequent risk of malaria illness among all ages.

These asymptomatic infections may never develop into illness, but they are an important contributor to the spread of malaria and pose a public health challenge.

“We know that in Malawi, like many parts of Africa, most of the malaria parasites are being carried by people who are not sick. They don’t get treatment for their infections, because their infections a silent, but when they get bitten by mosquitoes, they can transmit malaria” said Miriam Laufer, MD, MPH, Associate Professor of Pediatrics and Associate Director for Malaria Research in UMSOM’s Center for Vaccine Development and Global Health (CVD).

Researchers examined the association between asymptomatic malaria infections and subsequent risk of malaria illness and demonstrated that carrying P. falciparum infection without symptoms was associated with a 50% decrease in the risk of malaria illness.

Using a genotyping method to determine the molecular fingerprint of each parasite, they discovered when people who have asymptomatic malaria infection and get sick from malaria, it is because they acquire a new infection (from the bite of a mosquito) rather than having the asymptomatic infection develop into clinical disease.  With new infections, adults and children with and without asymptomatic infection were equally likely to get sick. The researchers concluded that asymptomatic infection did not protect against new infections that made them sick.

“We have always worried that if we give medicine to treat malaria to people with asymptomatic infection, they might get sicker the next time they get malaria. This has been a challenge to introducing new policies like mass drug administration or screening and treating campaigns to interrupt malaria transmission. Our results suggest that treating asymptomatic infection will not lead to increased risk of disease in the short term. Now we need to evaluate these new interventions to determine the long term impact both on the individual’s health and also on malaria transmission” said Dr. Laufer.

About the Study

Researchers enrolled participants seeking treatment for uncomplicated malaria at the Mfera Health Centre in Chikhwawa district in Malawi between June 2014 and March 2015. Subjects were eligible if they had symptomatic P. falciparum infection, detected by malaria rapid diagnostic test (RDT) and confirmed by microscopy, and were HIV-negative at time of screening. They were treated for their initial illness and then followed every month and evaluated every time they were ill.

This research was funded through the National Institutes of Health Malawi International Center of Excellence for Malaria Research and the National Institute of Allergy and Infectious Diseases (U19A1089683).

“Malaria is a serious disease impacting the most vulnerable populations. Dr. Laufer’s research is critical in our mission to help eradicate this disease,” said E. Albert Reece, MD, PhD, MBA, Executive Vice President for Medical Affairs at UM Baltimore, and the John Z. and Akiko K. Bowers Distinguished Professor and Dean, University of Maryland School of Medicine.

About the University of Maryland School of Medicine

Commemorating its 210^th Anniversary, the University of Maryland School of Medicine was chartered in 1807 as the first public medical school in the United States. It continues today as one of the fastest growing, top-tier biomedical research enterprises in the world -- with 43 academic departments, centers, institutes, and programs; and a faculty of more than 3,000 physicians, scientists, and allied health professionals, including members of the National Academy of Medicine and the National Academy of Sciences, and a distinguished recipient of the Albert E. Lasker Award in Medical Research.  With an operating budget of more than $1 billion, the School of Medicine works closely in partnership with the University of Maryland Medical Center and Medical System to provide research-intensive, academic and clinically-based care for more than 1.2 million patients each year. The School has over 2,500 students, residents, and fellows, and nearly $450 million in extramural funding, with most of its academic departments highly ranked among all medical schools in the nation in research funding. As one of the seven professional schools that make up the University of Maryland Baltimore campus, the School of Medicine has a total workforce of nearly 7,000 individuals. The combined School and Medical System (“University of Maryland Medicine”) has an annual budget of nearly $6 billion and an economic impact in excess of $15 billion on the state and local community. The School of Medicine faculty, which ranks as the 8^th-highest public medical school in research productivity, is an innovator in translational medicine, with 600 active patents and 24 start-up companies. The School works locally, nationally, and globally, with research and treatment facilities in 36 countries around the world. Visit medschool.umaryland.edu/

About the Malaria Research Program

The Center for Vaccine Development and Global Health’s Malaria Research Program aims to support global malaria eradication efforts by developing and deploying innovative tools for improved malaria treatment, prevention and surveillance. In the program’s molecular parasitology and immunology laboratories in Baltimore and at field research sites across Africa and Asia, researchers lead epidemiological studies and clinical trials of malaria drugs and vaccines. Researchers also investigate antimalarial drug resistance, molecular and genomic epidemiology, immunoepidemiology, pathogenesis, malaria in pregnancy and interactions between malaria and co-infections including HIV and schistosomiasis. Visit medschool.umaryland.edu/malaria/