Research Summary - 4
A needs assessment survey of dairy workers in the Midwest region: perceived fly burden, screwworm risk awareness, and on-farm wound management
| Date/Time: |
8/29/2026
14:45
|
| Author: |
Anna Rebeca Rodriguez Medina |
| Clinic: |
South Dakota State University |
| City, State, ZIP: |
Brookings, SD 57007 |
A. R. Rodríguez, DVM
1
;
N. Silva-del-Rio, DVM, PhD
2
;
M. Rovai, DVM, PhD
1
;
1South Dakota State University, Dairy and Food Science, SDS 113N, Box 2104 Brookings, SD 57007, USA.
2Department of Population Health and Reproduction, UC Davis School of Veterinary Medicine, Davis, CA 95616
3UC Davis Veterinary Medicine Teaching and Research Center, Tulare, CA 93274
Introduction:
Fly burden and wound management are important concerns in dairy production because open wounds can attract flies and, in areas where New World screwworm (NWS; Cochliomyia hominivorax) is present, can serve as sites for myiasis. NWS is an obligate parasitic fly whoselarvae invade living tissue after eggs are deposited in wounds or body openings, causing rapidly progressive lesions with serious consequences for animal health and productivity. Although NWS is not currently present in the United States, its re-emergence and northward spread
through Central America and Mexico have renewed concern about fly control, wound management, and preparedness on livestock operations. Dairy workers play a key role in early wound detection and on-farm response; however, little is known about their perceived fly burden, awareness of NWS risk, and wound management practices. Therefore, the objective of this study was to describe dairy workers’ perceived fly burden, NWS risk awareness, and on-farm wound management practices in the U.S. Midwest.
Materials and methods:
A Spanish-language cross-sectional survey assessed work roles, screwworm awareness, zoonotic risk prevention, and wound management practices. The survey was administered in person to attendees of Spanish-language educational sessions at the Central Plains Dairy Expo (March 2026), with participants given the option to complete it on paper or electronically using a Google Form accessed by QR code. Data was analyzed using descriptive statistics in Excel.
Results:
Descriptive statistics summarized responses from 61 dairy workers across the Midwest region. Participants primarily worked in large-scale production systems (mean ± SD: 5,500 ± 3,575 cows in lactation; range: 940–12,000). The most commonly reported roles were milkers (23%), managers (16%), breeders (12%), and health/prevention employees (12%). Most respondents were located in South Dakota (58%), followed by Minnesota (26%), Iowa (12%), and Kansas (4%). Respondents (39%) indicated that flies represented a high problem in their operations, especially in calf pens (36%), manure/drainage areas (36%), maternity areas (28%), lactating pens (26%), and feed areas (26%). Fly burden was perceived to peak during summer (90%) and spring (10%). To manage fly burden around wounds, workers reported using spray or topical products (64%), fly control in the area (61%), and frequent cleaning (43%), whereas only 11% isolated or monitored affected animals. Regarding screwworm risk awareness, prior NWS knowledge varied among respondents: 74% reported knowing about screwworm before the session, 16% had heard about it but lacked details, and 10% had no prior knowledge. Sick cows (49%) and newborn calves (46%) were identified as the animals most at risk for wounds attracting flies. Open wounds were most commonly associated with foot and hoof injuries (54%) and birth/umbilical cord wounds (43%). Regarding on-farm wound management, 84% of workers treated wounds the same day, and 82% of those always conducted wound follow-up.
The most common wound treatment steps reported were cleaning (75%), disinfection (69%), multi-day monitoring (44%), topical medication (43%), covering or protecting the wound (33%), injectable medication (25%), calling a veterinarian (13%), and photo or written records (7%).
When a wound was found to contain worms, 64% of workers reported it to the farm manager, 28% to the veterinarian, and 11% to the farm owner (n=59).
Significance:
Midwest dairy workers recognized flies as an important on-farm problem and generally reported prompt wound treatment. Although most respondents were aware of NWS, important gaps remained in preparedness, including limited veterinary involvement in wound management, low use of animal isolation, and inconsistent reporting of worm cases. These findings highlight the need for targeted Spanish-language training to strengthen early recognition, wound management, and reporting practices among dairy workers.
