Federal and state animal health officials have confirmed that the first case of New World Screwworm (NWS) has been detected in the state of Arizona. NWS maggots were discovered in a wound on the back of a domestic dog in Cochise County. The dog was examined by a local veterinarian, according to Arizona health officials. 

The month of October has seen 22 cases in domestic animals so far – an increase from only three in September, and from 14 total in the month of July, when NWS was first detected in the United States. There are 1,959 active cases in Mexico, 113 of which are in horses. 

Please refer to the U.S. Department of Agriculture’s page here for the latest information on active and inactive cases by state. 

“We are monitoring the overall case count in addition to the location of new cases,” said Dr. Katie Flynn, senior staff veterinarian at US Equestrian. “We have always said this situation could continue to change and evolve, and while the case count number still sounds small, we are concerned about that increase.”  

In total, there have been four detected cases of NWS in horses since the first equine detection on Sept. 9. 

Horse owners should inspect their horses every day for wounds, swelling, drainage, foul odor, or maggots. Pay close attention to small cuts, surgical sites, the umbilical area of foals, and moist areas such as the lips, nostrils, eyes, and genital areas. If you see maggots or anything unusual in a wound, contact your veterinarian right away. Early reporting helps animal health officials respond quickly with eradication tools like sterile fly release in your area. 

US Equestrian has protocols in place for licensed competition organizers and participants to reduce the opportunities for the fly to spread.  

If your horse lives in or has been in a state with active NWS cases (Texas, New Mexico, or Arizona), you will need to know whether the horse has been in what the USDA terms an “infested zone,” which is a perimeter of 20 kilometers around the infested premises. You can find state maps of infested zones for Texas here, and New Mexico and Arizona here. 

Required steps for horses from infested zones coming to USEF-licensed shows may include checking horses for wounds when they arrive and continuing to monitor horses during the competition. Finding and reporting suspect cases early helps protect horses and competition grounds from screwworm threats, including infestation and resulting quarantines. Remember that state animal health officials set policy for animals in their state, as well as animals coming in from states or geographic zones with screwworm cases, so you should remain aware of your state’s requirements as well as those of the Federation. You should be aware of the requirements in both your state of origin and state of destination when shipping out of state to a competition. 

You can find USEF protocols and links to state and federal resources at usef.org/screwworm. 

If you have questions about USEF protocols or NWS, please email [email protected].