Smartphone Microscope Detects Blood Parasites Quickly

A new smartphone microscope has been developed that is capable of detecting and quantifying infection by parasitic worms using video and a single drop of blood and it is hoped that this new technology could make a difference in the battle against neglected tropical diseases.

Diseases caused by the filarial nematodes Loa loa, Onchocerca volvulus, and Wuchereria bancrofti are a major public health and socioeconomic burden in co-endemic regions of Africa and the severity of symptoms and long-term consequences for patients depend on both the parasite and the parasitic load.

Scientists at the University of California, Berkeley (CA USA) and an international team of collaborators developed a mobile phone–based video microscope that automatically quantifies L. loa microfilariae (mf) in whole blood loaded directly into a small glass capillary from a finger prick without the need for conventional sample preparation or staining. They evaluated L. loa mf density in whole blood of 33 Loa-infected subjects from the region surrounding Yaoundé (Cameroon), using the mobile phone video microscope.

The mobile phone video microscope used in this study, which is referred to as the CellScope Loa, was built from a reversed iPhone camera lens module, a linear rail and carriage a hobby servo, an Arduino Micro, a Bluetooth communication board and a 3-D-printed plastic body. The investigators 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.

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 two 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 ivermectin to a patient.

Daniel A. Fletcher, PhD, an associate chair and professor of bioengineering and senior author of the study said, “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.” The study was published on May 6, 2015, in the journal Science Translational Medicine.

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University of California, Berkeley