Heat-seeking missile tech creates 4-minute malaria test (Wired UK)


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A system typically used to
detect enemy missiles has been modified to alert physicians to the
presence of early-stage malaria.

A team from the Monash University and the University of
Melbourne has published the find in the journal Analyst, revealing how the Focal Plane Array (FPA)
detector was used as the inspiration for the malaria test.

That system converts optical images into electrical signals, and
is used in the detection of anti-tank heat-seeking missiles — the
kind designed to destroy armoured vehicles in warfare. It can scan
an area in seconds to give a detailed break down of heat signals,
along with the shape and location of incoming targets. The
Australian team combined this technology with an infrared imaging
microscope in order to analyse red blood cells from a blood smear
for minute traces of the malaria parasite.

Associate Professor at Monash University, Bayden Wood, told Radio Australia: “What we’re actually detecting is the
vibration of molecules, because heat is essentially molecules
vibrating. In the case of the malaria-infected cells, these have a
specific signature, which enables us to detect the parasites within
the red blood cells.”

Wood and his team have achieved this at the single cell level,
with the test taking just four minutes to analyse many thousands of
cells and deliver a diagnosis. It does this by looking for the
infrared signature of fatty acids the parasite is made up of. The
team had already identified these fatty acids at the very early
stages of malaria. “The method relies on the detection of distinct
lipid signatures associated with the different stages of the
malaria parasite,” write the authors in Analyst.

With this diagnostic tip-off in mind, it was while on a trip to
the University of Wisconsin that the team used the IRENI (InfraRed
Environmental Imaging) system to try and seek out malaria. “Low and
beheld we could image cells and parasites,” said Wood.

“It enables us to detect the very low forms of the parasites
within the body — the advantage of that is in some remote
communities people might have malaria but don’t present the
classical symptoms like fever, because the [parasite levels] are so
low in their bodies.” These people, he says, pose a huge risk to
their communities.

Although the new test being proposed is swift, there is one
rather significant obstacle to this becoming the norm for testing
in the field. The equipment used is confined to the lab. Samples
would need to be sent back, and so results could not be provided
instantaneously on the spot. The team is however trialling a more
portable, battery-powered system in Thailand. Wood maintains that
the original lab-based scope is the “gold standard” in detection,
but the team has high hopes for its upcoming portable pilot
study.

Early diagnosis is key to treatment being effective. Currently,
malaria is either confirmed by microscope inspections or a rapid
diagnostic test (RDT). The latter seeks out antigens that are
expressed by the malaria parasites in the blood. These are — as
the name suggests — extremely rapid tests taking around 15-30
minutes. According to the World Health Organisation, 15 million
patients were tested for malaria using at RDT in 2012. In spite of
this, the global health body says that the majority of suspected
malaria cases do not undergo the test. On top of this, as
Wood points out, there is a period where patients are not
symptomatic, or simply do not show the classic symptoms that might
be expected. In the case of the former, it can take weeks for
symptoms to show. And it’s likely even at that stage there would be
a delay before heading for diagnosis.

“There are some excellent tests that diagnose malaria. However,
the sensitivity is limited and the best methods require hours of
input from skilled microscopists, and that’s a problem in
developing countries where malaria is most prevalent,” said
Wood.

The proposed new test could be administered at the earliest
stages. But that depends upon it being cheap enough and portable
enough to be used on people that are not exhibiting classic
symptoms.

Coauthor, professor Leann Tilley from the University of
Melbourne, said this could and should be a possibility in areas
where people are at risk, though.

“In many countries only people who display signs of malaria are
treated. But the problem with this approach is that some people
don’t have typical flu-like symptoms associated with malaria, and
this means a reservoir of parasites persists that can reemerge and
spread very quickly within a community,” she said. “Our test works
because it can detect the malaria parasite at the very early stages
and can reliably detect it in an automated manner in a single red
blood cell. No other test can do that.”

Wood hopes to get the diagnostic approach to clinical trials in
two to three years. 

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Source: wired.co.uk
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