06/17/2026
New World Screwworm (NWS) Information.
In response to the re-emerging threat posed by NWS we want to provide the following information:
Maryland and Delaware to date are unaffected. However we want our clientele to take this threat seriously. We are not as far from infestation as it may feel.
Interstate movement of animals to Maryland from states with cases is presently affected. Animals from Texas or New Mexico currently require additional inspection requirements. We anticipate other states will be included in the future.
NWS is not an ordinary fly producing an ordinary maggot. Typical fly control measures are encouraged and should be used to reduce risks however, products like Fly Predator will not effect the life cycle of this parasitic host that deposits its eggs directly in the wounds of warm-blood species including: cows, goats, sheep, dogs, cats, birds and rarely humans. The maggot is capable of killing calves within 2 weeks. While the maggot may be visible when the animal is infested it is difficult to identify prior. Umbilical cords are a very vulnerable site of infestation. All wounds should be treated to prevent infestation.
It is NOT business as usual at CSVS. We have no interest in profiteering from this problem and we have no interest in peddling fear. That said, we are now implementing strategies to prevent this pest from affecting our clientele as it is our assessment that for now, this threat is unlikely to be contained. Surgical protocols will include applied topicals to prevent NWS whenever appropriate. We have stocked additional preventive medications and treatments enabling us to respond and treat animals that may be affected.
We are confident that this pest will be eradicated from the United States in the future but we are increasingly concerned the re-emergence of this pest will affect the entirety of the continental United States and we have begun employing all epidemiological principles available to us to safeguard our clientele and their livestock. This is a joint effort and requires open communication.
Please do not hide an infestation. Report unusual wounds and fly-strike immediately. This is not a disease that can be isolated to an individual operation. It is not a disease that will result in state officials destroying infected animals. Isolation and Quarantine of affected areas and animals is inevitable and it is important that veterinarians and health officials can do their work to minimize the impact to all producers once it is identified. Infested animals are going to require veterinary treatment in most circumstances.
Consider taking the following steps on your operations to safeguard them:
1. Control fly populations through multiple modes including legal pesticide applications on premises. Appropriate manure management and animal applications.
2. Manage seemingly minor wounds differently. apply fly repellants frequently. Screwworm spray is an over the counter option and labeled to cover superficial wounds. Protect umbilical cords!
3. Encourage and utilize mechanical and natural fly control strategies near your operations.
4. Keep dogs and cats current on flea and tick control, many of which can prevent screwworm infestation.
5. Inspect animals frequently and please do not transport animals with wound infestations. Treatments do exist.
**We can and will prescribe flea and tick preventions to small animals on farms and will work to make the products available at the lowest possible prices to encourage their use. (many of these products can prevent screwworm)
There is no need to panic but please take seriously the threat of this parasitic fly. Recognize there are very few practicing veterinarians today with any real-world experience regarding this disease last eradicated from the USA in the 1960s. This is a real threat and we must take it seriously. While it is highly likely lessons will be learned and some pain will exist in the intervening period we can and we are 100% confident that we will beat this pest back together. We are not resigning our future to one along side NWS. For now, we must all focus our efforts on fortifying our operations in every way possible against this emerging threat that IS ON OUR DOORSTEP.
This is veterinary medicine. It is science based and we are not going to tolerate political ponderance or polarizing commentary on this page. We will work to answer questions in the comments.
Learn how the U.S. Government prevents New World screwworm and what to know about risks, surveillance, sterile-fly control, travel, and more.