The U.S. Centers for Disease Control and Prevention (CDC) has announced a temporary suspension of certain diagnostic tests, affecting those for rabies, human herpesvirus, and several other infectious diseases.

On Monday, the CDC published a list detailing over two dozen diagnostic tests that are currently unavailable. This move comes as part of an ongoing internal review that the agency began in late 2024, aiming to evaluate and improve its testing programs.

Typically, the CDC conducts a variety of pathogen tests to aid state and local health laboratories that may lack the necessary resources. The suspended tests include those for relatively common infections like the Epstein-Barr virus and the varicella zoster virus, responsible for chickenpox and shingles. However, the list also features tests for rarer organisms, such as the parasitic worms associated with “snail fever” and the virus linked to “sloth fever.”

In a statement to the Guardian, a CDC spokesperson explained: “Certain infectious disease tests are temporarily paused as part of our routine review process to ensure high-quality laboratory testing. We are in regular contact with state and local health departments and are prepared to coordinate testing through alternative labs if necessary.”

The spokesperson added, “We expect some tests to be reinstated in CDC labs in the coming weeks. Meanwhile, we remain committed to assisting our state and local partners in accessing the public health testing they require.”

“We anticipate some of these tests will be available through CDC labs again in the coming weeks. In the meantime, CDC stands ready to support our state and local partners to access the public health testing they need,” the statement said.

A combination of layoffs, hiring freezes and staff departures has reduced the number of experienced scientists available to assist laboratories. By July, the rabies team will have only one expert capable of providing clinical guidance to state and local officials, while the poxvirus team will have none, according to the New York Times.

The suspension of these lab services follows a period of major workforce reductions at the CDC over the past year, driven by layoffs, retirements, resignations and the expiration of temporary roles. Estimates from the Associated Press suggest that total staffing has dropped by 20% to 25%.

The poxvirus and rabies units have each lost roughly half of their staff, while the CDC’s malaria division has been cut even more severely, according to the National Public Health Coalition, a group composed of current and former CDC employees formed after the downsizing.

The CDC was thrown into upheaval last year when more than a thousand employees received notice from the Trump administration that they were losing their jobs in a move that erased entire offices within the agency. The move was then partly reversed days later, with hundreds of employees being offered their positions back.

In June, the Department of Health and Human Services (HHS) secretary, Robert F Kennedy Jr, controversially hand-picked new members of the advisory committee on immunization practices (ACIP) after firing all the previous members. Those appointments were later stayed after a federal judge ruled that the move probably violated federal law.

As a result, the US now has no functioning advisory committee, and several key vaccines are no longer recommended, including the latest version of the flu and Covid shots and the inclusion of the RSV shot for infants in the federal Vaccines for Children program, which covers immunizations for more than half of US children.

The Associated Press contributed reporting