Experts Decry CDC's Long Pause on Tropical Disease Testing

The Centers for Disease Control and Prevention (CDC) has long been the premier reference lab for the United States and, for some diseases, internationally. But the agency stopped testing for parasites more than 6 months ago, and public health experts say that's putting vulnerable populations even more at risk.

In September 2021, the CDC stated on its website that it would stop testing for parasites, herpesvirus encephalitis, human herpesvirus 6 and 7, Epstein-Barr virus, and other viruses, saying, "We are working diligently to implement laboratory system improvements."

At the time, the CDC said testing would be halted only for a few months.

In response to a Medscape query, a CDC spokesperson replied, "While at present we are unable to share a detailed timeline, our highest priority is to resume high-quality testing operations in a phased, prioritized approach as soon as possible and to offer the same tests that were available before the pause."

Several global health clinicians told Medscape Medical News that they were not aware of the halt and that they are now uncertain about the specific diagnosis and best treatment for some patients. Other patients have been lost to follow-up.

In response, a group of tropical disease specialists who focus on neglected tropical diseases (NTDs) wrote an editorial, "Neglected Testing for Neglected Tropical Diseases at the CDC," which recently appeared in The American Journal of Tropical Medicine and Hygiene (AJTMH).

NTDs are caused by viruses, bacteria, and parasites. They include leprosy and worms; many such diseases are disfiguring, such as filariasis (which causes the hugely swollen extremities of elephantiasis) and onchocerciasis (river blindness). They also include some viral and bacterial diseases. Their common denominator is that they are diseases of poverty, primarily in Africa, Asia, and Latin America, so they garner little attention from "first world" countries.

The loss of testing for two devastating parasites — Chagas and Leishmania — was particularly significant. Few other labs in the US test for these, and the tests can be expensive and of variable quality, experts said.

Dr Norman Beatty

Norman Beatty, MD, a global health physician at the University of Florida, told Medscape Medical News, "Chagas confirmatory testing is only available at the CDC and is the most reliable testing we have access to in the US. Leishmania species identification is also only available at the CDC and is important in determining which antiparasitic medications we will use."

Chagas disease is caused by the parasite Trypanosoma cruzi and is transmitted by triatomine bugs, also known as kissing bugs. Chagas is a major cause of an enlarged heart and congestive heart failure, as well as a dramatically enlarged esophagus or colon.

Prior to the cuts and before COVID-19, the CDC reported that they ran 10,000 to 15,000 tests for parasitic diseases annually. Testing requests declined during COVID. In 2021, they ran 1003 tests for Chagas.

Beatty said that he first became aware of the CDC's testing cuts last fall when he sought care for a patient. He was first told the delay would be 2–3 weeks, then another 2–3 weeks. It's now been 7 months, and only three tests have been resumed.

Beatty added that for Chagas disease in particular, there is urgency in testing because cardiac complications can be life-threatening. He said, "A lot of these diseases can be considered rare, but they also have a tremendous ability to cause morbidity and mortality."

Leishmania infections are also serious. Following the bite of an infected sandfly, they can cause disfiguring skin infections, but, more importantly, they can affect the liver, spleen, and bone marrow. Beatty said that since testing was dropped at the CDC, some colleagues had to send specimens outside of the country.

Beatty emphasized that the cuts in testing at the CDC highlight disparities in our society. "There are other commercial reference laboratories who may have some of these tests available, but the vast majority of people who suffer from diseases are underserved and vulnerable. [My patients] most definitely will not have access to advanced testing commercial laboratories," Beatty said. Those laboratories include Associated Regional University Pathologists (ARUP) laboratories, Quest Diagnostics, and LabCorp Diagnostics. But for some parasitic infections, there will simply be no testing, and patients will not receive appropriate therapy.

The CDC's website says, "USAID and CDC work together on a shared agenda to advance global progress towards the control and elimination of NTDs that can be addressed with preventive chemotherapy.... CDC has strong working relationships with WHO, regional reference laboratories/bodies, [and] national NTD programs...working with these partners through the provision of unique laboratory, diagnostic, and epidemiological technical assistance."

The WHO Roadmap for 2030 aims to prevent and control many NTDs, in part by "providing new interventions and effective, standardized, and affordable diagnostics." Last year, the CDC said that they "will continue working with WHO and other global partners to meet the established goals."

But testing for a number of NTDs is not currently available at the CDC. In response to questions from Medscape, a CDC spokesperson said the agency "supports the development of country capacity for NTD testing required...but does not perform testing related to the WHO Roadmap."

A group of CDC officials wrote an editorial response that was published in ASTMH, saying the agency has "three main priorities: reducing parasitic disease-related death, illness, and disability in the United States; reducing the global burden of malaria; and eliminating targeted neglected tropical diseases."

In response to Medscape's interview request, a CDC spokesperson wrote, "CDC is unwavering in our commitment to provide the highest quality laboratory diagnostic services for parasitic diseases. We understand the concerns expressed in the editorial and the challenges the pause in testing for parasitic diseases presents for healthcare providers, particularly those treating people at elevated risk for parasitic diseases."

Michael Reich, PhD, Beatty's co-author, is an international health policy expert at Harvard. He and the physicians had approached CDC about the elimination of services. He told Medscape Medical News, "We're still unable to get clear responses except for something along the lines of, 'We are working on it. It is complicated. It takes time. We're doing our best.' "

Reich added, "For me, this raises troubling issues both of transparency and accountability ― transparency about what is going on and what the problems are, and accountability in terms of who's being held responsible for the closures and the impacts on both public health and patient treatment."

Beatty concluded, "I think the goal of our group was to bring more awareness to the importance of having a national laboratory that can service all people, even the most underserved and vulnerable populations." He added, "Chagas disease is a disease of inequity in Latin Americans. Without having access to an appropriate laboratory such as the CDC, we would be taking a backwards approach to tackle neglected tropical diseases in our country and worldwide."

Beatty and Reich report no relevant financial relationships.

Am J Trop Med Hyg. doi.org/10.4269/ajtmh.22-0222. Editorial, Editorial response

Judy Stone, MD, is an infectious disease specialist and author of Resilience: One Family's Story of Hope and Triumph Over Evil and of Conducting Clinical Research, the essential guide to the topic. You can find her at drjudystone.com or on Twitter @drjudystone.

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