Scientists decry USDA’s decision to end cat parasite research

For the past 37 years, a small research lab in Beltsville, Maryland, has been the world’s leading hub for scientists working on Toxoplasma gondii, a parasite that infects more than 1 billion people globally, causing death, blindness, and birth defects. Operated by the U.S. Department of Agriculture (USDA), the facility is a source of expertise and rare, sought-after materials for researchers working to stop the parasite, which can be transmitted by food and has no human vaccine and no cure.

But last week, the lab fell victim to pressure from animal welfare activists and members of Congress concerned about its use of cats, the only animal in which T. gondii completes the sexual stages of its life cycle. USDA abruptly announced it was shutting down the lab’s work, saying the program, which cost $625,000 annually to operate, had “reached its maturity” and “achieved” its agricultural research goals.

The 2 April decision, which lab chief Jitender Dubey learned about from media reports, has left researchers scrambling for alternatives. “I’m really angry about this,” says Laura Knoll, a parasitologist at the University of Wisconsin in Madison who relies on samples from the laboratory. During a December 2018 external review of the lab she took part in, she says, “The validity and necessity of the research never seemed to be in question.” (USDA declined to answer a list of questions from Science and denied a request to interview Dubey.)

The laboratory is “an incredible resource,” says Robert Yolken, a pediatric infectious disease specialist at Johns Hopkins University School of Medicine in Baltimore, Maryland. “It’s a loss for Toxoplasma research in the U.S. and around the world.”

But parasitologist Jim Keen, a former USDA scientist now at the University of Nebraska in Lincoln, sees things differently. Last month, he and the White Coat Waste Project, a Washington, D.C.–based advocacy group, released a report that argues the laboratory’s work is “unnecessary and unjustifiable.” The 14-page document, titled USDA Kitten Cannibalism, details how researchers fed infected meat, including cat meat, to kittens, in order to harvest parasite oocysts—infective, hardy forms of the organism—from their feces. Researchers then euthanized the animals, killing dozens each year, because they might spread the parasite if adopted as pets. Keen reviewed 121 Toxoplasma studies published between 1985 and 2018 that involved killing cats or dogs and had Dubey as a co-author. He concluded that much of the lab’s recent work is “irrelevant to American public health and the USDA’s mission.”

Outside scientists disagree. The lab has made several key contributions in the past decade, says David Sibley, a Toxoplasma researcher at Washington University in St. Louis, Missouri. One was developing a blood test that can inform parasite control strategies. The test indicates whether a person has become infected by eating undercooked meat or by ingesting parasite oocysts shed by cats.

The report marked the latest salvo in White Coat Waste’s efforts to end cat use at USDA’s Animal Parasitic Diseases Laboratory in Beltsville, which housed the Toxoplasma facility. The group has placed billboards attacking USDA on buses and this year persuaded 61 members of Congress to sponsor the Kittens In Traumatic Testing Ends Now (KITTEN) Act. One KITTEN Act co-sponsor, Representative Brian Mast (R–FL), called closing the program “a decisive victory against government animal abuse and wasteful spending.”

But many researchers say the lab’s demise will undermine efforts to fight the devastating parasite, which is the world’s leading infectious cause of blindness and causes roughly 190,000 babies to be born with defects each year. In the United States, which has about 1 million new infections annually, it is the second-leading food-borne killer, causing about 750 deaths.

“There is no laboratory in the world” that produces T. gondii oocysts with the same efficiency, says one U.S. researcher, who asked for anonymity to avoid being targeted by animal activists. “Centralizing production actually minimized waste and the number of cats required.” (Several scientists predict the closure will drive cat use to less-expert U.S. labs, or offshore.)

The loss of the lab will slow efforts to develop a vaccine to protect cats from infections, scientists say. That’s a top public health priority, and one that Dubey was pursuing, because it would stop the animals from shedding the oocysts that infect both livestock and people.

The closure will affect collaborations by U.S. and European researchers to develop better methods of detecting parasite oocysts in drinking water and soil. Other imperiled studies focus on keeping T. gondii out of the food supply. One—requested by USDA inspectors—is examining whether U.S. rules for curing hams are stringent enough. Another is testing methods for cleaning oocysts from fresh fruits and leafy greens. Other studies are probing why the parasite makes only some infected people very sick.

Scientists are also worried about the fate of the Beltsville lab’s unparalleled collection of more than 1000 T. gondii strains and its trove of tissue samples and reagents. “They can’t just throw them away,” says geneticist Chunlei Su of the University of Tennessee in Knoxville, who used the lab’s DNA samples to study the parasite’s global genetic diversity.

Knoll, for her part, says losing access to oocysts from the lab will disrupt her studies—which aim to find alternatives to cats in Toxoplasma research.