Federal health officials are responding to two separate parasite-related threats that have raised concerns across the United States, prompting increased surveillance, emergency coordination, and warnings for both the public and the agricultural industry.
One threat involves a foodborne parasite sickening hundreds of people in multiple states.
At the same time, the other centers on the return of a flesh-eating fly that was eliminated from the United States decades ago but has now reappeared in livestock along the southern border.
Health officials are continuing to investigate a surge in cyclosporiasis cases, a gastrointestinal illness caused by the microscopic parasite Cyclospora cayetanensis, while also ramping up efforts to contain the New World screwworm, a destructive pest capable of causing life-threatening infestations in animals.
The Centers for Disease Control and Prevention said cyclosporiasis cases have climbed sharply this summer, with Michigan reporting more than 708 confirmed infections as of July 7 after typically seeing only about 50 cases during an entire year.
The illness is spread through contaminated food or water, most commonly fresh produce, and causes severe watery diarrhea, stomach cramps, nausea, vomiting, loss of appetite, and low-grade fever.
Health officials say the actual number of infections is likely much higher because many cases go undiagnosed or unreported.
At least 20 people have been hospitalized nationwide, although no deaths have been reported.
Michigan is not alone in seeing an increase.
Ohio has reported at least 170 cases since late June, while Indiana, New York, and North Carolina have each reported more than 100 recent infections.
The CDC, U.S. Food and Drug Administration and state health departments are working to identify the contaminated food responsible, although investigators say there is currently no evidence linking all of the reported illnesses to a single nationwide outbreak, Today reported.
While those investigations continue, federal officials have also intensified their response to the return of the New World screwworm, a flesh-eating fly that poses a serious threat to livestock and wildlife.
The CDC activated a Level 3 Emergency Operations Center in mid-June to coordinate with the U.S. Department of Agriculture and state officials after the first confirmed U.S. animal case was identified on June 3, 2026.
The USDA confirmed larvae were found in the umbilical area of a three-week-old calf in Zavala County, Texas.
Additional detections have since been reported in cattle, goats, sheep and at least one dog in Texas and New Mexico.
The New World screwworm, Cochliomyia hominivorax, lays eggs in open wounds or mucous membranes of warm-blooded animals.
After hatching, the larvae burrow into living tissue and feed on flesh, causing painful infestations known as myiasis.
If left untreated, the infestation can kill livestock, pets and wildlife and, in rare instances, infect humans.
Federal officials emphasize that no domestically acquired human cases have been reported and that the risk to the public remains very low, particularly when wounds are properly cleaned and protected.
The USDA eradicated the screwworm from the United States during the 1960s using sterile insect release programs, but the pest remained established in South America before steadily advancing north through Central America and Mexico.
By January 2026, officials reported more than 1,190 human cases and seven deaths across Central America and Mexico, along with hundreds of infected animals.
Following the recent U.S. detections, Texas Gov. Greg Abbott declared a statewide disaster, allowing additional resources to be deployed.
Federal authorities have established quarantine zones, expanded trapping operations near the southern border and dramatically increased the release of sterile male flies to interrupt the insect’s breeding cycle.
The Food and Drug Administration has also issued an Emergency Use Authorization for a generic treatment for pets as part of the containment effort.
Federal officials say the cyclosporiasis outbreak and the New World screwworm response are unrelated events, but both remain active investigations as health agencies continue working to protect public health and the nation’s food supply.
This article may contain commentary which reflects the author’s opinion.
