A new mobile phone microscope uses video to detect and quantify infection by parasitic worms in a drop of blood.
The CellScope Loa device was developed by a research team led by engineers at the University of California, Berkeley, US.
This use of UC Berkeley’s CellScope technology could help revive efforts to eradicate diseases in Africa by providing critical information to health providers.
“We previously showed that mobile phones can be used for microscopy, but this is the first device that combines the imaging technology with hardware and software automation to create a complete diagnostic solution,” associate chair and professor of bioengineering Daniel Fletcher said in a statement.
“The video CellScope provides accurate, fast results that enable health workers to make potentially life-saving treatment decisions in the field.”
The engineers teamed up with Dr Thomas Nutman from the US National Institute of Allergy and Infectious Diseases, and collaborators from Cameroon and France, to develop the device. They conducted a pilot study in Cameroon, which has been battling the filarial, or parasitic worm, diseases onchocerciasis (river blindness) and lymphatic filariasis.
The video CellScope, which uses motion instead of molecular markers or fluorescent stains to detect the movement of worms, was as accurate as conventional screening methods, the researchers found. The results of the pilot study are reported in Science Translational Medicine.
River blindness is transmitted through the bite of blackflies. Lymphatic filariasis is spread by mosquitoes and leads to elephantiasis, which causes painful, disfiguring swelling in parts of the body.
The antiparasitic drug ivermectin, or IVM, can be used to treat these diseases, but mass public health campaigns have been stalled because of potentially fatal side effects for patients co-infected with Loa loa, which causes loiasis, or African eye worm.
When there are high circulating levels of microscopic Loa loa worms, treatment with IVM can lead to brain or other neurologic damage that can be severe or fatal.
Standard screening for levels of Loa loa involves technicians counting the worms in a blood smear using conventional laboratory microscopes.
The side effects of Loa loa and the difficulty of rapidly quantifying levels in patients make it too risky to broadly administer IVM.
The CellScope Loa combines a smartphone with a 3D-printed plastic base in which a sample of blood is positioned. The base includes LED lights, microcontrollers, gears, circuitry and a USB port.
Control of the device is automated through an app. The phone communicates via Bluetooth to controllers at the base to process and analyse the blood. Gears move the sample in front of the camera, and an algorithm analyses the ‘wriggling’ motion of the worms in video captured by the phone. The worm count is then displayed on the screen.
The procedure takes about two minutes or less, starting from the time the sample is inserted to the display of the results. This short processing time allows health workers to quickly determine whether it is safe to administer IVM.
The researchers are now expanding the study of CellScope Loa to about 40,000 people in Cameroon.