UC San Diego, San Diego County develop dashboard to track New World screwworm and forecast its spread

A new dashboard from University of California San Diego (UCSD) researchers and the County of San Diego Health and Human Services Agency is giving public health officials a way to track the spread of New World screwworm (NWS) and estimate where the parasite could pose a threat next, using information from more than just confirmed cases.

The tool combines reports of NWS detections with environmental conditions that could support the fly and its larvae, along with media reports about suspected or emerging cases. According to USCD, the information is being used to estimate risk at the county level across the United States. The dashboard is currently available only to project partners and public health officials, but the team hopes to eventually make a public version available, the university said.

The inclusion of media reports is a key part of the approach. Confirming a suspected NWS infestation through laboratory testing can take days or weeks, potentially leaving public health agencies with a significant delay between a case emerging and being reported through traditional channels.

"By incorporating media reports, we can identify potential threats sooner and stay one step ahead," Seema Shah, MD, MPH, medical director of the County of San Diego's Epidemiology and Immunization Services Branch, said in a USCD announcement.¹

That added lead time could be important as NWS moves into areas where it has not been detected in decades. The parasite cost US livestock producers tens of millions of dollars annually in the 1950s, reaching an estimated $50 million to $100 million a year in the hardest-hit parts of the Southwest. By the late 1960s, the US was able to eliminate the pest through the sterile insect technique, which involved releasing large numbers of radiation-sterilized male flies to prevent the population from reproducing. That same technique remains part of the response to the parasite's current return.

USDA confirmed the first US case in roughly 60 years on June 3, 2026, after NWS was detected in a 3-week-old calf in Zavala County, Texas. To date, as of August 12, the Animal and Plant Health Inspection Service (APHIS) has confirmed 45 domestic animal cases in the US, comprising 21 cattle, 13 sheep, 5 goats and 3 dogs. The cases were reported across 16 Texas counties and 1 New Mexico county. The FDA has also cleared multiple drug products for use against the parasite over the past year through the Emergency Use Authorization and conditional approval regulatory pathways.

Unlike other types of maggots, NWS larvae feed on the tissue of living, healthy animals. Female flies lay their eggs in wounds or natural body openings, and the larvae that emerge burrow into healthy tissue. The resulting wounds can become progressively larger and more susceptible to secondary infection. Without treatment, an infestation can cause severe injury or death. People can also become infested, although NWS is not transmitted from person to person.

According to Mark Beatty, MD, MPH, assistant medical director of the county's Epidemiology and Immunization Services Branch, officials were surprised by how quickly the parasite moved north.

"We knew in 2023 that New World screwworm was going to move northward, but I wasn't expecting it to move as fast as it has," Beatty said in an announcement.¹

"Once it entered Texas, we quickly saw an increase in detections. It's in a place where it used to live, so it's not surprising it's taking a hold again."

The dashboard's value, its creators argue, is lead time.

"The tool gives you a sense of where you might expect to see cases next," he said.¹

"Is the threat imminent, or do we have six months? We're in a very concerning phase right now, and the tool backs that up."

Veterinarians are also an important part of the surveillance effort, as NWS can affect any warm-blooded animal. Emily Trumbull, DVM, who leads the county's One Health Program, said the county is working with the California Department of Food and Agriculture to connect veterinarians with resources for identifying and reporting potential cases.

"The flies can affect any warm-blooded animal, so working together with veterinarians serving livestock, pets and wildlife is critical," Trumbull said.¹

The dashboard was developed through Resilient Shield, a UCSD initiative and CDC-funded center that builds public health tools in response to requests from government agencies. Rather than developing projects based solely on researchers' priorities, the program allows public health partners to submit requests, or "tickets," for specific tools they need, according to UCSD.

The screwworm dashboard is one example of that approach, bringing together public health, epidemiology and data modeling to address an emerging threat before it reaches additional regions.

References

1. As New World screwworm returns to the U.S., UC San Diego and San Diego County team up to track the risk. University of California - San Diego. August 11, 2026. Accessed August 12, 2026. https://www.eurekalert.org/news-releases/1139701
2. Bautista-Alejandre A. A veterinarian's guide to New World screwworm cases, treatment, reporting, response in the US & more. dvm360. July 2, 2026. Accessed August 12, 2026. https://www.dvm360.com/view/a-veterinarian-s-guide-to-new-world-screwworm-cases-treatment-reporting-response-in-the-us-more