An international team of researchers said Wednesday they have developed a mobile phone microscope that can rapidly and accurately detect parasitic worms in the blood, an advance that may aid efforts to eradicate neglected tropical diseases such as river blindness and elephantiasis in Africa.
"We previously showed that mobile phones can be used for microscopy," lead author Daniel Fletcher, professor at the University of California, Berkeley, said in a statement. "But this is the first device that combines the imaging technology with hardware and software automation to create a complete diagnostic solution."
A drug called ivermectin has been used to treat and control the spread of the debilitating parasitic diseases river blindness and elephantiasis. However, while ivermectin is safe and effective for these two diseases, it has proven dangerous to individuals also infected with the parasitic worm Loa loa, which causes another disease, loiasis, or African eye worm.
In patients with high blood levels of the worm's larval form, called microfilariae, the drug causes brain damage and even death.
Mass public health campaigns to administer the medication have been suspended in certain areas of West and Central Africa where Loa loa infections are common, leaving millions left untreated for the two diseases.
A strategy to identify and exclude people highly infected with Loa loa from treatment has been recommended. However, the current gold standard method requires a conventional light microscope to manually count the worms in a blood smear, which can take a trained technician at least a day to complete.
To rapidly screen for Loa loa infections in community settings, the team developed CellScope Loa, a video microscope integrating an Apple iPhone 5s.
With the help of a custom iPhone app, the device automatically captures and analyzes videos of the characteristic "wriggling" motion of microfilariae, enabling quantification of microfilariae in blood from a finger prick in less than two minutes.
No special preparation of the blood is required, limiting potential error and sample loss, and healthcare workers need minimal training to use the automated device, they said.
When used to screen 33 potentially Loa loa-infected individuals in Cameroon, the device closely matched results from standard microscopy.
Although additional work is needed, the researchers predicted that a team of three workers could screen up to 200 people during the four-hour midday window when Loa loa circulates at its peak in the blood.
"This research is addressing neglected tropical diseases," said Fletcher. "It demonstrates what technology can do to help fill a void for populations that are suffering from terrible, but treatable diseases."
The researchers are now expanding the study of CellScope Loa to about 40,000 people in Cameroon.
The study, also involving researchers from the U.S. National Institute of Allergy and Infectious Diseases and collaborators from Cameroon and France, was published in the U.S. journal Science Translational Medicine.
