Aug. 28, 2025:
The Maryland Department of Health said the patient with the first human infection of a travel-associated New World screwworm in the U.S. has recovered from the flesh-eating parasite. There was also no sign of transmission to other people or animals.
The U.S. Health and Human Services Department said the disease was confirmed on August 4, 2025, in a person who traveled to El Salvador. The CDC then reported it on August 24 after a three-week delay.
R-CALF USA CEO Bill Bullard issued the following statement in response to the Reuters report indicating that neither the CDC nor the USDA had disclosed to the public the detection of a case of New World Screwworm, but instead, one or both agencies had selectively notified only certain industry participants of the detection, thereby according them insider information regarding an issue with potentially severe financial ramifications:
“We are deeply concerned that if the publicly disseminated Reuters report is accurate, including its implication that only select industry participants were timely informed of the detection of this devastating pest in the United States, then our governmental system is fundamentally broken.
“Independent U.S. livestock producers rely exclusively on the USDA to protect the health and safety of their livestock herds against the introduction of foreign pests and to protect the integrity of their U.S. livestock markets by preventing manipulation.
“Without transparency and symmetrical information dissemination to all industry participants – including to producers whose livelihoods could be severely impacted by not receiving information selectively provided to others – there can be no trust between industry participants and the government.
“If a human case of New World Screwworm was confirmed on or about Aug. 20, and if that fact was secretly disseminated to only a select group of industry insiders, but not simultaneously shared with all organizations representing independent livestock producers, or even with state veterinarians instrumental in disease and pest surveillance, then we ask for a full investigation of this incident and the establishment of a New World Screwworm task force comprised of representatives of each sector of America’s livestock industries to ensure future transparency and the proper allocation of resources to protect America from this devastating pest.”
Aug. 27, 2025:
U.S. Department of Health and Human Services (HHS) and the U.S. Centers for Disease Control and Prevention (CDC) recently identified an instance of a traveler-associated human case of New World screwworm (NWS) in the United States. The U.S. Department of Agriculture (USDA) reaffirmed its robust surveillance and trapping strategy, confirming there have been no detections of NWS in U.S. livestock.
USDA, HHS, CDC, FDA and other federal partners have led a government wide response to combat the New World Screwworm (NWS) in Mexico and prepare for all scenarios if it enters the United States.
On August 4, 2025, CDC, in coordination with the Maryland Department of Health, investigated a confirmed case of travel-associated NWS in a patient who returned from travel to El Salvador. As this is a human case, CDC is the lead response agency and is conducting an epidemiological assessment in coordination with local health authorities. Currently, the risk to public health in the United States from this case is very low. In support of CDC’s activities and out of an abundance of caution, USDA initiated targeted surveillance for NWS within a 20-mile radius of the affected area, encompassing portions of the District of Columbia, Maryland, and Virginia. To date, all trap results have been negative for NWS. There have been no detections of NWS in the U.S. in livestock or other animals since the last outbreak of NWS in the Florida Keys was resolved in 2017. There have been previous instances of traveler-associated cases of NWS in the United States in years past. In all cases, these instances were isolated and designated as closed after precautionary targeted surveillance in the vicinity was negative. We may continue to see traveler-associated cases of NWS and USDA, in coordination with HHS and CDC, will conduct targeted surveillance to ensure there is no active spread of NWS in the United States. This is not cause for alarm as human risk is low and we have seen several isolated cases in recent years that have not resulted in livestock transmission.
In June 2025, Agriculture Secretary Brooke Rollins announced a comprehensive five-part plan to strengthen the U.S. Department of Agriculture’s efforts to detect, control, and eliminate New World screwworm, pushing the pest back from Mexico to the biological barrier in Eastern Panama. A key part of this plan is trapping along the U.S.–Mexico border to proactively monitor for the pest out of an abundance of caution and it includes building a domestic sterile fly production and dispersal facility to increase our readiness and response efforts. Public health and safety and our joint effort to combat the northward spread of NWS from Mexico into the United States is the top priority of USDA and HHS.
Aug. 26, 2025:
A human case of New World screwworm was reported by the Centers for Disease Control after being discovered earlier this month (Aug. 2025) in a person from Maryland who had recently returned from Central America.
Colin Woodall, CEO of the National Cattlemen’s Beef Association, says while it’s something the cattle industry needs to monitor, at this point it isn’t a risk to the U.S. livestock industry.
“From what we understand, it was an individual who had made a trip to one of the countries in Central America that has New World screwworm, which are all the countries in Central America right now, came back, had some pain, went to seek treatment, and discovered that they were infested with New World screwworm larvae. I think the key is that the CDC protocols work. They identified it. CDC is not a PR agency. I can’t speak as to why they make the decisions about what they announce or don’t announce, but we do know that the protocol worked in that individual, who was treated, and the larvae were destroyed. And while, yes, it’s surprising to see that particular story, it’s not shocking.”
Woodall says there have been cases of New World screwworm in the U.S. in the last couple of years.
“There was a human case in the United States last year in 2024. There was one in 2023. We also know of one that happened in 2014, and all of them were very similar. These were individuals who traveled to a country that had New World screwworm, brought the larvae back with them, and then, when the pain got unbearable, went to seek treatment, and the CDC was engaged. It was identified, and those larvae were destroyed. So, in the NCBA, we’re not shocked to see that there is a human case.”
Woodall says the protocols for protecting humans and livestock from NWS worked as intended.
“I think, for us, as we are taking a serious approach to protecting ourselves from New World screwworm, the things that we’re looking at are, one, did the protocols work? And it’s obvious that the protocols worked. Let’s think about this for a minute from a human standpoint. If you go traveling, and somehow the New World screwworm female lays its eggs somewhere in your body, you come back to the United States, and you’re going to have excruciating pain because these larvae, these maggots, are going to be eating you alive. So, you’re going to go seek some sort of treatment.”
Woodall says the human infection had no chance to spread because of how quickly the person went to the doctor.
“This is not a situation where it’s a tick bite or a mosquito bite, and you might scratch it, and not necessarily think twice about seeking treatment until further down the line. This is not a situation where those larvae are going to then exit the human, pupate, and become the fly, because that pain is just so excruciating. So, the CDC approach, CDC protocols, and the information that they have out there in the medical community obviously works. So, that is probably the biggest takeaway we need to understand.”
Aug. 25, 2025:
The Department of Health and Human Services reported the first human case of New World screwworm in the U.S. The diagnosis was confirmed by the Centers for Disease Control.
The disease appeared in a traveler who’d been returning to the U.S. from Central America, where the disease is already present. State veterinarians learned of the human case during a call last week with the CDC.
Oklahoma State Veterinarian Dr. Rod Hall said the patient lives in Maryland, where officials said they’re confident it is contained. Dr. Hall added that he believes the U.S. is probably more likely to get it in a person or pet than in livestock, at least in the short term.
South Dakota State Veterinarian Beth Thompson was quoted in a Reuters article as saying that when NWS was confirmed in Maryland, the CDC worked with local physicians to identify the larvae. No livestock movement restrictions are in place.
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