Submitted to: Veterinary Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/15/2001
Publication Date: 12/1/2001
Citation: Interpretive Summary: Screwworms were once devastating pests for the U.S. livestock industry. The immatures, or maggots, develop in the wounds of animals and left untreated can lead to the death of the infested animal. Screwworm-infested wounds attract more screwworms and other flies to the wound, making it difficult at best to identify the species present. A highly successful eradication program has eliminated screwworms from the U.S. as well as Mexico and most of Central America. Now a burden exists to assure that screwworms do not re-invade these eradicated areas. Protecting against screwworm invasion relies on quick and accurate identification of infected wounds. Currently, identification relies on morphological traits that are difficult to evaluate, particularly in the youngest, smallest maggots. We developed monoclonal antibodies against the screwworm that can be used to identify all life stages. In a blind study where we evaluated screwworm samples against five other species of flies that can infest wounds, the antibodies showed high specificity, sensitivity and overall accuracy in identifying all life stages of screwworms. Further development of these antibodies should allow that a field identification kit, reliable and easy to use, could be available as another tool in the exclusion effort against screwworms.
Technical Abstract: Myiasis caused by screwworms, Cochliomyia hominivorax (Coquerel), is devastating to all warm-blooded animals and economically important to livestock producers. Immature screwworms are difficult to identify morphologically from immatures of other species of blow flies. We developed two monoclonal antibodies (MAbs) that are highly specific to the screwworm. Using a monoclonal antibody-based enzyme-linked immunosorbent assay (Mab-ELISA), screwworm eggs, larvae, pupae, and adults were identified from those of the secondary screwworm, Cochliomyia macellaria (Fabricius) and five other species of myiasigenic flies. In a blind study, the microplate MAb-ELISA displayed high specificity, sensitivity and overall accuracy in identifying all life stages of the screwworm. Electrophoresis results suggest that the two monoclonal antibodies probably recognized identical conformational epitopes present in all screwworm life stages. Although screwworms have been eradicated from the U.S., Mexico an most of Central America, there is a constant threat of reentry of this pest from regions in South America and the Caribbean through international trade and travel. The MAb-ELISA could be adapted to use in field-identification kits for this very important pest.