INDUSTRY NEWS News and Information for Digital Health Professionals
Smartphone Microscope Diagnoses Deadly African Parasite The second leading cause of infectious blindness in the world is river blindness, or onchocerciasis, caused by a parasitic worm transmitted through bites from blackflies that live and breed near fast-flowing rivers. The World Health Organization estimates at least 25 million people have the infection, primarily among sub-Saharan African countries, with a couple pockets of Latin America and the Middle East. Among those infected, 300,000 are blind and 800,000 have some visual impairment, and another 123 million people are at risk for infection. For millions of people in central Africa, being infected with the microscopic worm Loa loa is not a big deal: just a bit of mild itching and swelling. But if they take a dose of ivermectin— a drug that’s being widely distributed around the continent in an attempt to wipe out other parasites—L. loa can cause more severe complications: hemorrhaging, neurological problems, and even death. Now, for the first time, scientists have developed a prototype for a handheld, mobile phone–based platform to screen for L. loa in a matter of minutes that could help health care workers decide who can safely receive the drug. “There is screening, but it is a long, tedious business,” says physician and public health researcher Adrian Hopkins, director of the Task Force for Global Health’s Mectizan Donation Program in Decatur, Georgia, who was not involved in the new work. The number of miniscule worms in a blood sample must be counted manually by a trained technician, he says, to determine if there are enough worms to cause the serious ivermectin reaction. “There’s no way you could go into a village and do it on everyone.” For programs like his, which oversees the administration of hundreds of millions of Mectizan (ivermectin) doses per year in Africa to treat river blindness and elephantiasis— both caused by parasitic worms—that’s a problem, because of the odd and poorly understood interactions between ivermectin and loiasis.
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Ivermectin is actually so good at killing Loa loa worms that killing them all at once in someone with too many in their blood – more than 30,000 parasites per millilitre – can
June 2015
potentially cause fatal encephalopathy, said Daniel Fletcher, a professor of bioengineering at the University of California at Berkeley. This risk has slowed or even suspended ivermectin administration programs because each person infected with river blindness or lymphatic filariasis has to be tested for Loa loa first to determine whether they can safely take the drug. That testing requires a trained technician using a conventional light microscope to manually count the Loa loa larvae in a blood smear, a process that usually takes at least a day. Researchers had previously tried developing ways to test blood for L. loa antibodies or to stain L. loa parasites for easier identification under a microscope, but the techniques were never fast, cheap, or effective enough. Fletcher wondered whether an automated computer program could instead detect the worms in blood samples by sensing their telltale wiggling. “It was really an effort to make it as simple Continued on page 8