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Fighting Malaria Requires New Diagnostic Tools

Dr. Sanjeev Krishna, Professor of Molecular Parasitology and Medicine at St George's, University of London, has written an interesting article on the need for developing better diagnostic tools for fighting malaria. The following is an excerpt of his paper.

Malaria hits rural dwellers in poor countries the hardest. Those bitten by the wrong mosquito often do not know for many days that they have contracted malaria. Some have little or no access to doctors. There are times when, even if the tests confirm the disease soon enough, standard treatments may not help because they may be suffering from the drug-resistant strain of the parasite. 

The World Health Organisation recommends diagnosis of malaria before treatments are begun, because if drug-resistant varieties are on the rise. Despite support from big funding agencies, such as the Global Fund to fight AIDS, Tuberculosis and Malaria, such diagnoses are not happening often enough.

With more than 200 million cases and over 660,000 deaths reported annually, the need to develop a more reliable, cheap and effective tool to detect malaria without the need for trained personnel has never been higher.

Catch ‘em Quick

Rapid diagnostic tests (RDTs) developed for malaria in recent years have made it much easier to diagnose without using the conventional method of staining blood films and then examining them under a microscope.

RDTs still suffer from limitations, though. They need trained personnel to generate reliable results. Even though these test can be performed without the need for electricity, other field conditions such as high ambient temperatures encountered during transport and storage can interfere with the quality of results.

Access to trained personnel in rural places is difficult. Could we develop a method that does not require trained personnel? A recent large-scale experiment suggests we can. In the experiment, 1000 untrained individuals across 60 countries were able to diagnose malaria as accurately as experts.

There are a number of efforts to build better diagnostic tools. For example, a group of students at Makerere University in Uganda have developed a new needleless malaria-testing application that uses a light sensor connected to a tablet device to detect the infection. This could perhaps be used to screen large groups of patients quickly before suspected infections are confirmed.

Another tool comes from researchers at Michigan State University. They have identified a test that can determine which children with malaria are likely to develop cerebral malaria, a much more life-threatening form of the disease. Only about 1% of children with malaria develop the life-threatening form of the disease, yet thousands of African children die from it each year.

One More Solution

Researchers at St. George’s University of London where I work, along with researchers in Sweden and German, have been working on the Nanomal project to build another tool that could make malaria diagnosis cheap and more effective. The handheld device can diagnose malaria on-site in less than 15 minutes.

Successful diagnosis depends on reliable and detailed results based on a patient’s blood sample. Fortunately, each parasite has specific DNA markers that differentiates them. This device consists of a nanowire (billionths of a metre thick) that changes how much electricity it conducts based on which DNA marker it comes in contact with.

The diagnosis, which can be completed in a few minutes, is made by analysing a blood sample of a patient obtained by a small prick on the finger. Parasite’s DNA is then extracted from this sample and analysed by the nanowire.

If, say, the malaria is caused by Plasmodium falciparum, then it is likely that it is a drug-resistant variety. A doctor or nurse on site can then give more personalised prescription, helping increase chances of successful treatment while also reducing the chances of drug-resistance buildup.

The device will be tested in the field this year. If successful, the price of each device is expected to be about the same as a smartphone initially. A single-test cartridge will be around £10 to begin with.

In addition to improving immediate patient outcomes, the project will allow the researchers to build a better picture of levels of drug resistance in stricken areas. It will also give them information on population impacts of antimalarial interventions.

There are other challenges such as ensuring that the device can be quickly modified to include new DNA markers as more drug-resistant parasites are selected. And the price of each device and its cartridges need to be cut further, so that those in poor countries can afford it on a large scale.

When all these tools are put together, there is great hope that they will help cut down the number of those who die from malaria every year. The sooner this happens the better.

Source: The Conversation

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