Researchers at the Johns Hopkins Bloomberg School of Public Health's Malaria Research Institute have developed a new test for detecting the malaria parasite in human urine and saliva. Although not a diagnostic test for determining treatment, the method could potentially reduce the need for blood sampling in epidemiological studies where large-scale malaria screening is required. Drawing blood increases the risk of spreading HIV and other diseases, particularly in those developing countries where both HIV and malaria are prevalent. Blood drawing must also be performed by trained personnel, whereas urine and salvia sampling does not.
"Testing urine or saliva could be an easier and safer way to collect the information needed for studying malaria in communities. For instance, it could be used in studies to determine if a population is growing resistant to malaria drugs, which is a very serious problem," said David J. Sullivan, MD, senior author of the study and a professor in the Bloomberg School's Malaria Research Institute.
The test uses polymerase chain reaction (PCR), a technique for duplicating and then examining unique bits of DNA from a sample, thereby allowing DNA to be multiplied in the laboratory. The same PCR technique is used for examining malaria in blood, but has never been applied to urine and saliva samples.
The study was conducted in collaboration with colleagues at the Malaria Research Institute's research hospital in Macha, Zambia. Urine and salvia samples were obtained from 47 volunteers with malaria and 4 without, and were then examined with the PCR method. DNA from the Plasmodium falciparum, the parasite that causes malaria, was replicated at higher levels from the saliva compared to the urine samples. However, neither method was as sensitive as that using blood samples.
"Programs for monitoring antimalarial drug and vaccine efficacy could therefore adopt such a bloodless method, while maintaining high sensitivity for clinically significant infections," said Sungano Mharakurwa, PhD, lead author of the study and a researcher with the Malaria Research Institute in Macha.