DPDx: 15 Years of Strengthening Laboratory Capacity for Parasitic Disease Diagnosis

Posted on by Alexandre J. da Silva, PhD, CDC DPDx


CDC’s DPDx helps labs around the world identify parasites like Taenia saginata. (Photo courtesy of David Snyder/CDC Foundation)
CDC’s DPDx helps labs around the world identify parasites like Taenia saginata. (Photo courtesy of David Snyder/CDC Foundation)

The inquiries and images come from almost every state in the United States, and often with a sense of urgency. Still others arrive from Argentina and Germany, Italy, Japan, China, New Zealand, India—and dozens more countries around the globe. Each time the question for CDC’s parasite identification laboratory, known as DPDx, is the same: What is it?

Alexandre J. da Silva, PhD, CDC DPDx
Alexandre J. da Silva, PhD, CDC DPDx

The diagnostic parasitology experts on CDC’s Division of Parasitic Diseases and Malaria’s DPDx team provide answers.

DPDx is the effective merger of technology, laboratory science, and CDC’s unparalleled expertise in parasite identification and the diseases they cause.

DPDx is a unique online educational resource that includes visual depictions of parasite lifecycles, a reference library of free images of parasites, and guidance on proper laboratory techniques for diagnostic parasitology. But it is much more than a Web site.

The primary role of DPDx is reference diagnosis, wherein CDC laboratory scientists confirm diagnoses or discover that the diagnosis is something altogether different from what was originally thought. In both cases, but especially in the latter cases, DPDx impacts treatment. For example, Babesia microti is one of the parasites that cause the tick-borne disease babesiosis; it can be misidentified as Plasmodium falciparum, which causes malaria. The two diseases require different treatments and on many occasions, the DPDx team has corrected a misdiagnosis, ensuring that the patient is appropriately treated.Definition of telediagnosis: noun. A process whereby a diagnosis is made by the electronic transmission of data between distant medical facilities. ORIGIN: Greek; tele, 'far off' + dia, 'through' + gnosis, 'knowledge'Another principal component of DPDx is telediagnosis—using information technology to link DPDx experts to those laboratory partners who need help, often almost in real time. DPDx connects partners who are able to take advantage of microscopes connected to digital cameras and computers with Internet access to take pictures of specimens, send the images to CDC electronically, and ask for help identifying the parasite they may be seeing under their microscope many miles away. In this way DPDx serves as a “virtual reference laboratory.”

U.S. states and other countries look to CDC to provide this service, especially for some of the rarest or least well-known diseases.

Since its launch in 1999, DPDx has provided diagnostic and other assistance more than 3,300 times.

In addition to providing online resources and diagnostic assistance, DPDx also serves as a training resource in diagnostic parasitology. The DPDx team conducts at least three annual training workshops for public health and clinical laboratory staff across the country and world. From 2008 through 2011, CDC experts conducted a series of parasitic disease training workshops in Angola and Mozambique on malaria diagnosis to support the President’s Malaria Initiative. Members of the DPDx team also conducted hands-on workshops in Brazil, Dominican Republic, Haiti, India, Kenya, Mexico, and Rwanda, as well as on-site workshops throughout the United States.

In 2012, CDC’s parasitic diseases laboratory tested 10,678 specimens; DPDx scientists responded to 549 telediagnosis inquiries from states, countries, and private laboratories and physicians; and our laboratory staff responded via a 24/7 hotline to more than 6,000 inquiries, many of them urgent requests related to life-saving diagnosis and treatment.DPDx also offers training opportunities online. For example, each month DPDx offers a Monthly Case Study Quiz. The purpose of this service is to provide distance training on diagnosis to professionals engaged in identifying parasites associated with human disease. In addition, the DPDx team recently worked to produce a training video to provide guidance around procedures for and interpreting results of a rapid diagnostic test (RDT) for malaria, called Binax NOW Malaria. The training is available as an e-learning tool on CDCTrain.

To improve the DPDx experience for our laboratory partners, the DPDx Web site got a new home and a facelift in November, offering those in need of diagnostic information even more content and a better user experience. DPDx now is easier to navigate, features enhanced image galleries, and offers updated information about laboratory procedures.

Building public health capacity by strengthening laboratory systems and diagnostic response is a key element of CDC’s strategies to improve the public’s health. DPDx allows medical doctors and laboratory scientists in the United States and other countries to access expert assistance in much less time and at less cost—a critically important role given an accurate diagnosis is often the first step to making sure people get better, faster.  With faster diagnosis, we can better prevent diseases from spreading, thereby protecting more people around the world.


Babesia microti (left) causes babesiosis but is sometimes misidentified as Plasmodium falciparum (right), which causes malaria. DPDx experts help laboratorians clarify confusing diagnoses such as this.
Babesia microti (left) causes babesiosis but is sometimes misidentified as Plasmodium falciparum (right), which causes malaria. DPDx experts help laboratorians clarify confusing diagnoses such as this.


Henry Bishop, DPDx
Henry Bishop, DPDx. CDC’s DPDx helps labs around the world identify parasites.


Since 1999, CDC's DPDx has fulfilled more than 3,300 requests for telediagnosis from around the globe.

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Posted on by Alexandre J. da Silva, PhD, CDC DPDxTags , , , , ,

4 comments on “DPDx: 15 Years of Strengthening Laboratory Capacity for Parasitic Disease Diagnosis”

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

    What would you guys do if Tom Frieden’s family started complaining that they all had Morgellons Disease. Would they all be considered delusional? Or would you do intense investigative diagnostics for them. Really, what would you do.

    I have a handheld microscope that blows away most traditional microscopes. I also have morgellons. I take the most professional pictures through this microscope with my cell phone. The detail is unbelievable. I have done this for 3 years now. My photos are so clear on some of them you can see their eyes. Professional is interested in looking at these photos please feel free to contact me. You never know it may help. Thank you, Dee

    in March 2014 a group of researchers and doctors from around the world held a two-day conference comparing notes and doing live examinations. It was discovered that three bacterias are involved.Helicobacter, Borrelia & Bartonella. ZI lost my food assistance because I cannot hold down a regular job because there wasn’t proof of a disease. The conference was 7 months ago. Why hasn’t the CDC changed their ruling from delusional to a legitimate disease. 7 months is long enough suck it up fake a facts.

    I have Morgellon disease & have had it for 5 yrs, many Dr.’s and they say its mental !!!!!!
    Its real just ask any of us that has it BUT we need something to stop it, cure it… where did it come from?
    I have bloody bites on my arms & try everything but still nothing works, some changes slow them down but they regroup… Any help will be appreciated. I’ve had a heart attack, lost both legs & hang on hoping for a resolution.

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Page last reviewed: May 11, 2021
Page last updated: May 11, 2021
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