Australian scientists have made a significant discovery that could lead to new tests for diagnosing malaria by identifying distinctive chemicals that can be detected in the breath of patients infected with the disease.
Researchers at the CSIRO, QIMR Berghofer Medical Research Institute and the Australian National University looked at the breath of volunteers, who had been given a controlled malaria infection as part of existing studies to develop new treatments.
The research found that the levels of some normally almost undetectable chemicals increased markedly in the breath of the volunteers during the malaria infection.
”What is exciting is that the increase in these chemicals were present at very early stages of infection, when many other methods would have been unable to detect the parasite in the body of people infected with malaria. In addition to its potentially better sensitivity, human breath offers an attractive alternative to blood tests for diagnosing malaria,” Dr Stephen Trowell, Research Group Leader at CSIRO, said.
The study, published today in the Journal of Infectious Diseases, was conducted in two independent studies where experimental drug treatments were being tested in volunteers who had been given a very small dose of infection.
Using a sophisticated analytical instrument, the researchers identified four sulphur-containing compounds whose levels varied across the time course of the malaria infection.
“The sulphur-containing chemicals had not previously been associated with any disease and their concentrations changed in a consistent pattern over the course of the malaria infection. Their levels were correlated with the severity of the infection and effectively disappeared after they were cured,” Professor James McCarthy, Senior Scientist in Clinical Tropical Medicine at QIMR Berghofer, said.
Malaria continues to place a huge health and economic burden on many of the poorest people in the world. In 2013, according to the WHO, there were almost 200 million cases and over half a million deaths due to this disease.
Currently, malaria diagnosis remains mostly based on using powerful microscopes to look for parasites in blood using a method discovered in 1880.
As the world starts to work towards elimination of malaria, there is an urgent need for more sensitive and convenient tests to detect early and hidden cases.
The name malaria originally came from the Italian words for “bad air” because it was thought that the disease was caught from the foul smelling air around swamps and marshes. (Now we know that these swamps were the breeding grounds of mosquitos that transmit the disease).
In an interesting twist, researchers have now detected foul-smelling compounds – albeit at levels far too low for humans to smell – in the breath of people with malaria.
Up to now, these chemicals have only been detected using very expensive, laboratory based instruments, and only in the breath of volunteers experiencing a controlled malaria infection in the clinic.
Dr Trowell added, “Now we are collaborating with researchers in regions where malaria is endemic, to test whether the same chemicals can be found in the breath of patients. We are also working with colleagues to develop very specific, sensitive and cheap “biosensors” that could be used in the clinic and the field to test breath for malaria.”