Count Equine Parasites with a Cell Phone.

Equine veterinarians have lauded the benefits of fecal egg counts (or FECs) for designing targeted equine deworming programs. While these tests are already fairly simple; collect sample, submit to lab, and await results (which typically arrive in a few days to weeks, depending on the laboratory)—researchers have developed an even easier way: Collect the sample and let your veterinarian’s cell phone do the counting. At the 2015 American Association of Equine Practitioners’ Convention, held Dec. 5-9 in Las Vegas, Paul Slusarewicz, PhD, shared how he and colleagues determined this was possible and what steps went into developing the final product. Slusarewicz is an adjunct associate professor at the University of Kentucky’s (UK) Gluck Equine Research Center and the chief scientific officer and co-founder of MEP Equine Solutions, both in Lexington. The first step, he said, was to identify a universal egg marker (UEM), which is present on all parasite eggs that would allow software to detect the eggs amidst the rest of the debris in a sample. Slusarewicz determined that a carbohydrate called chitin—which is also present in shellfish, insects, and fungi, he said—could potentially serve as that UEM, but no one had suggested this could be a universal component of parasite eggs. To test chitin’s usefulness, the team attached fluorescein dye (the fluorescent green substance your veterinarian uses to check for abrasions in your horse’s eye) to a naturally occurring protein that can bind tightly to chitin. They then stained the eggs and viewed the fecal sample under a fluorescence microscope, using different optical filters to block out the background debris and see if the eggs stood out. The eggs appeared fluorescent, indicating that, indeed, chitin can be used as a UEM. The team had to consider cost of device if they really want it to be universal, so they opted for a cheaper alternative. They selected an iPhone with an added macro lens (designed for use in taking pictures of subjects up close) and found that it successfully captured usable images from a properly prepared sample. After confirming that their counting method was feasible, it was time to see how well the software worked. Slusarewicz and colleagues collected eight fecal samples, counted them manually using the traditional McMaster method, and then ran a count using their iPhone and software system. He said the two correlated rather well, but the iPhone method needed some streamlining. So the team designed and built an imaging unit that includes the macro lens and optical filters needed to obtain the image. They’ve tested the software and imaging unit on three phones with cameras of different megapixels, Slusarewicz said, and even the lowest-resolution device gave very good results. They also determined that the software can distinguish between different types of parasite eggs, “because horses have more than just strongyles,” Slusarewicz said, referring to ascarids, the other clinically important internal parasite of horses. He showed that the app could accurately count both strongyle and ascarid eggs in a sample containing both. McMaster tests, on the other hand, are used most commonly identify large and small strongyles. The team is carrying out full validation studies and finalizing the system—dubbed Parasight—before it becomes available for purchase. The Parasight System will not require specialized training and is anticipated to be available to veterinarians in the second half of 2016. Parasight System,” Slusarewicz said, “veterinarians will now have a portable, simple, rapid, and convenient test to replace the fecal egg count which can be conducted on-site. This will allow vets to once again take the lead in responsible parasite control strategies. Putting an end to the practice of prophylactic rotational deworming will not only reduce the amount of drugs given unnecessarily to horses, but also the alarming trend of increasing parasite resistance to all current classes of deworming medicines.” Read more at www.thehorse.com