Rapid, portable malaria diagnostic tool developed

Researchers have developed a new portable diagnostic instrument that can screen for all malaria strains within minutes.

The portable optical diagnostics system (PODS) prototype detects a byproduct generated by all species of the malaria parasite.

"With PODS, we can do rapid, broad population screening for malaria in low-resource environments," said Andrea Armani from the University of Southern California (USC) in the US.

"When combined with currently available therapeutics, this could represent a tipping point in the global fight against malaria," said Armani.

The PODS instrument was designed to solve the challenges limiting current systems, researchers said.

To minimise size, weight, and power requirements without sacrificing performance, every aspect was considered, they said.

The current prototype weighs fewer than 4.5kg, is 12 by 10 inches (the size of a large shoebox) and can be powered by a battery for eight hours.

In addition, PODS was designed to require minimal sample processing and handling, as well as eliminate the need for secondary chemicals with strict storage requirements.

This makes the device particularly suited to low-resource environments, researchers said.

The prototype can analyse an unprocessed, whole blood sample in 10-15 minutes.

With only 500 microlitres of blood (five to seven drops), it can achieve sensitivity levels needed for an early-stage diagnosis.

Malaria-infected mosquitoes infect human hosts with the parasite. Its primary nutrient source is hemoglobin, a component of red blood cells.

As the parasite digests hemoglobin, it creates what is known as heme as a byproduct.

"While heme is highly toxic to both the parasite and its host, the parasite has figured out a 'loophole' around this by aggregating heme into an insoluble nanocrystal known as hemozoin," said Samantha McBirney, a PhD graduate at USC.

PODS has three primary components: a laser, a detector (to detect light), and a magnet.

When a sample of blood is placed between the laser and the detector, the amount of light that makes it to the detector decreases as the blood blocks it.

If hemozoin is present, even less light shines through, researchers said.

At high concentrations even in blood, it is readily apparent if hemozoin is present because the nanocrystal is very good at blocking light, they said.