New smartphone microscope able to detect blood parasites quickly

Researchers have developed a new smartphone microscope capable of detecting and quantifying infection by parasitic worms using video and a single drop of blood. The team hopes that this new technology could make a difference in the battle against neglected tropical diseases.

The new smartphone-powered device could provide diagnoses that were previously only obtainable in laboratories.

Results of a pilot study are published in Science Translational Medicine and suggest that the video provided by the device could help health workers make important treatment decisions in the field.

The researchers at the University of California, Berkeley,  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.

Rather than molecular markers or fluorescent stains, the new smartphone microscope utilizes motion to quickly provide results that were found to be just as accurate as conventional screening methods.

The research team was comprised of engineers from the University of California, Berkeley, and other researchers representing the National Institute of Allergy and Infectious Diseases (NIAID), the University of Montpellier in France and research centers in Yaoundé, Cameroon.

In Cameroon, health officials have been struggling with treating two parasitic worm diseases: river blindness (onchocerciasis) and lymphatic filariasis, spread by blackflies and mosquitoes respectively.

River blindness is the second-leading cause of infectious blindness worldwide. Lymphatic filariasis can lead to elephantiasis, characterized by painful swelling, which is the second-leading cause of disability worldwide. Both of these conditions can be successfully treated with an antiparasitic drug called ivermectin (IVM).

Unfortunately, the treatment process is complicated by another parasite - Loa loa, worms that cause loiasis, a skin and eye disease also referred to as African eye worm. Patients with high levels of Loa loa in their blood can develop severe brain and other neurologic damage if treated with IVM.

Quantifying the levels of Loa loa in patients is time-consuming and impractical, requiring technicians to count the worms in a blood smear manually using laboratory microscopes. These difficulties have proven to be major setbacks in public health campaigns to administer IVM widely.

'Ingenious, practical and highly needed'

The new microscope, named CellScope Loa, could change things. To create the device, the researchers combined a smartphone with a 3D-printed plastic base in which the blood sample is positioned.

An app controls the device, designed by the researchers to be automated in order to reduce human error. The blood sample is moved in front of a camera, and an algorithm analyzes the "wriggling" motion of any worms present, calculating how many there are and displaying the result on the phone's screen.

From the time a sample is loaded into the device, the calculating process takes up to 2 minutes. An additional minute is spent pricking the patient's finger and loading the blood into the device's capillary. Overall, CellScope Loa provides results swiftly and can inform health workers in the field whether or not it is safe to administer IVM to a patient.

"he availability of a point-of-care test prior to drug treatment is a major advance in the control of these debilitating diseases. The research offering a phone-based app is ingenious, practical and highly needed.

The researchers validated the performance and usability of the device by testing 33 patients who were potentially infected with Loa loa. The smartphone microscope's results correlated with those obtained with conventional manual thick smear counts.

Following these results, the researchers will look to trial the device further, expanding the study to around 40,000 people in Cameroon.

Earlier this year, we reported on the successful field testing of a new smartphone accessory capable of diagnosing HIV and syphilis. Tested in Rwanda, the device is the first instance of a device being created capable of replicating certain functions of a laboratory-based blood test.

References:

1.  Point-of-care quantification of blood-borne filarial parasites with a mobile phone microscope, Daniel A. Fletcher, et al., Science Translational Medicine, doi: 10.1126/scitranslmed.aaa3480, published online 6 May 2015, abstract.
2.  University of California, Berkeley news release, accessed 7 May 2015.