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. Also, blood drawing must be performed by trained
personnel, whereas urine and saliva sampling do not. The
study was published online in the Nov. 8 edition of
Malaria Journal.
"Testing urine or saliva could be an easier and safer
way to collect the information needed for studying malaria
in communities," said David J. Sullivan, senior author of
the study and a professor in the Malaria Research
Institute. "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."
The test uses polymerase chain reaction, 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 institute's research hospital in Macha,
Zambia. Urine and saliva samples were obtained from 47
volunteers with malaria and four 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.
Lead author Sungano Mharakurwa, a researcher with the
Malaria Research Institute in Macha, said, "Programs for
monitoring antimalarial drug and vaccine efficacy could
therefore adopt such a bloodless method, while maintaining
high sensitivity for clinically significant infections."
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