A small company in the U.K. is developing an affordable, hand-held device that will not only diagnose malaria in the field, but will also read DNA markers that suggest which antimalarial drugs will be most effective for treatment. If fielded, such a device could help alleviate the 200+ million cases of malaria per year, as well as prevent some of the nearly one million deaths associated with malarial illness.
Malaria is a life-threatening disease caused by parasites acquired through the bites of infected mosquitoes, with roughly half the world's population in constant danger of infection. Over 200 million new cases of clinically significant malaria are reported yearly, causing between half a million and a million deaths. This makes malaria the fifth-most likely cause of death in low-income countries.
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Map of the world showing the primary range of malaria infestation with dark red regions indicating drug resistant malaria, lighter red regions resistance to older drugs, yellow regions showing no drug resistance, and grey regions being malaria-free (Photo: Percheire via Wikipedia)
The European Union-funded Nanomal project, involving researchers from St. George's University, the University of London, the Newcastle-based QuantuMDx Group, the University of Tuebingen, and the Karolinska Institute in Sweden, has taken on the challenge of developing a handheld device that can perform a full malaria screening panel, including identification of which of the five parasitic species is involved and what levels of drug resistance should be expected.
The NanoMal test is projected to take less than 20 minutes from start to finish, compared to a minimum of several days in a standard diagnostic laboratory. Such a device, projected to be available at costs similar to that of a smartphone, would be an important new tool in treating what in many areas is a malarial epidemic, and will be adaptable to the diagnosis and treatment of many other diseases.
The malaria-causing Plasmodium falciparum parasites in human blood cells (Photo: US Center for Disease Control and Prevention)
There is currently no approved malaria vaccine, although several experimental versions are currently in clinical trials. While several classes of antimalarial drugs exist, in the wild the malarial parasite is quickly developing resistance to their effects, including artemisinins, the most powerful class of anti-malarial drugs. As a result, combination therapies are increasingly being used to slow the process whereby malarial parasites gain resistance to a particular drug.
Ongoing research has established that certain combinations of genes in the parasite's DNA are associated with various types of drug resistance. The Nanomal unit will sample the DNA from a drop of blood with a MEMS-like apparatus then opening the cell walls of the blood cells and of the malarial parasites found within. The malarial DNA is selectively grown using PCR (Polymerase Chain Reaction) amplification, until enough material is available for analysis. The small scale of the reaction vessels on the chip allows sufficient analysis material to be grown in minutes rather than the hours required by table-top reactors.
The PCR material is then processed by a microscopic gene sequencer that is built to search for two things – genes identifying the parasite's species, and gene sequences corresponding to drug resistance. This is accomplished by unraveling the DNA into long straight sections that are passed through channels in proximity to nanowires.
These nanowires are treated along their length with regions of molecular probes which encode the DNA sequences being searched for. When they appear, the DNA adheres to the nanowires, driving an electrical signal that identifies the gene sequence that has been found. The Nanomal unit contains a large number of such nanowires, resulting in a gene sequencer that can perform a relatively thorough analysis that points away from the parasite's strengths, and toward an effective treatment regimen.
According to Elaine Warburton, CEO of QuantuMDx, "placing a full malaria screen with drug resistance status in the palm of a health professional's hand will allow instant prescribing of the most effective anti-malaria medication for that patient. Nanomal's rapid, low-cost test will further support the global health challenge to eradicate malaria."
To be effective in the poorer nations suffering from malarial epidemics, the cost of a diagnostic and treatment analysis must be affordable. A single-test diagnostic cartridge is currently expected to cost about US$18, although plans are underway to provide the units through donations where necessary. Clinical trials of the device should begin within three years.View gallery - 4 images