Cell phones are being used as medical instruments in underdeveloped nations, extending highly cost-effective health care to underserved villages and rural areas.

A team led by Daniel Fletcher, a Bioengineering Professor at the University of California at Berkeley has developed inexpensive conversions of cell phones into medical instruments, using clip-on lenses that cost one dollar or less. Fletcher’s team has on-the-ground tests in Cameroon screening for parasitic worm infections and in Thailand screening for retinal diseases.

“By attaching a simple set of lenses to a Nokia phone borrowed from my sister,” wrote Fletcher, “we were able to image blood cells, malaria parasites and the bacteria that cause tuberculosis.” Indeed, according to Fletcher, these images are “similar to those captured on our $150,000 research microscope.”

In an interview, Fletcher told me cell phone images are perfectly adequate for a range of diagnostic tests, which can be performed very quickly.

Another team, from the London School of Hygiene and Tropical Medicine, is using a similar technology in Kenya to screen for cataracts, glaucoma and diabetes. Named PEEK, or Portable Eye Examination Kit, the devices can image a patient’s eye in a few seconds.

Unlike Fletcher’s clip-on lenses, each PEEK is a dedicated handheld that costs $500 and generates imagery similar to bulky equipment costing over $100,000, according to a BBC report. And PEEK handhelds can be used by anyone, not just medical professionals: teachers in Kenya now screen school students, according to the BBC. Thousands have been screened, and early tests showed ten percent of those screened needed treatment, according to a Voice of America report.

The potential for these devices is extraordinary: a wave of repurposed consumer devices as medical instruments are helping eradicate entire diseases in developing nations — and could be critical innovations in rural areas of the U.S. that are underserved by medical care facilities. As mobile phones become a new universal medium in America, the impact can be enormous.

If the patient has a cell phone equipped with a camera, doctors can see the patient from a distance. This is a gaining acceptance as a simple but effective diagnostic tool, according to the Wall Street Journal. And another spinoff from Dan Fletcher’s lab at Berkeley, Cellscope, lets patients use their cell phones to examine their ears. And still more mobile-based diagnostic tools are in development based on that technology, according to a Business Outlook report.

But even if a patient has the most inexpensive “dumb” cell phone, text messages can be critical. In Africa and Asia, sending text messages simply to remind patients to take their medicine has had a huge effect, with a recorded 30-70% improvement in tuberculosis treatment compliance, according to a 2012 study from the Boston Consulting Group and Telenor Group, and a 30% drop in maternal and perinatal mortality.

In the U.S., tests of health text messages have also shown dramatic results. For six weeks, the New York City Department of Health added text messages to its free stop-smoking program; the result was to double the program’s effectiveness among heavy smokers.

“People in the text messaging pilot were compared with a control who group did not receive the messages,” according to the Mobile Commons web site. “53% of heavy smokers quit vs. 25% of the control group.”

Now researchers and entrepreneurs are experimenting with new mobile phone apps ranging from monitoring the number of steps you take (10,000 per day is the recommended minimum) to helping you get to sleep.

The cost savings can be huge: Trials of mobile phone apps in Scandinavia “have shown 50 to 60% reduction in hospital nights and rehospitalization” (see page 8 of “Connected Life: The Impact of the Connected Life over the next five years”).

However, there are barriers to innovation in the U.S., among them legal restrictions from the pre-digital era. Last year, a mobile phone app for urinalysis was delayed by regulators, Bloomberg News reported. But today, more and more cell phones have health apps already built into the device: the new Samsung Galaxy S5 monitors users’ heart rates, motions and steps – all standard features.

Now Washington DC is taking note: Earlier this month, a government report proposed a new regulatory regime for health information technology, a regime which a Washington Post analysis indicated a “loose regulatory framework for some elements of health-care IT” is on the way.

“All told, it represents a relaxation of concerns for unexpected regulation,” analyst Wes Richel told the Post. “It represents a relaxation of concerns for the Nike wristbands, and the home market blood oxygen testers and things like that, that are sold at Best Buy.”

Millions of mobile phones are provided to low-income Americans by a program administered by the FCC and by many states, to enable everyone to be connected. But with cell phones, being connected takes on an entirely new dimension with health care.

This report is part of a CCLP/Sunnylands initiative on mobile telephones as platforms for public service, including health care, education and public safety. An earlier blog covered an agriculture innovation.