On the farm, arthropods like flies, mosquitoes, mites, and ticks can be more than a nuisance\u2014they can carry diseases, damage hides and wool, and even cause death. You\u2019ve probably heard about New World Screwworm (NWS) in the news. Once nearly eradicated from North America, NWS has been recently detected in Central America and Mexico. Northward migration to the United States is a major concern, as NWS threatens both animal and human health.<\/p>\n\n\n\n
NWS are the larvae (maggots) of a parasitic fly that feeds on living flesh. This differs from most other maggots, which consume dead or dying tissues. Female flies lay eggs in any open wound, no matter how small\u2014this can include:<\/p>\n\n\n\n
Most NWS cases are in cattle, goats, and sheep, but all warm-blooded animals, even birds, and rarely humans, can be affected.<\/p>\n\n\n\n
NWS infestations are difficult to detect at first. Slight movement might be seen inside a wound, but as the larvae feed and bury deeper, the wound gradually enlarges. A blood-tinged fluid with a decay smell may seep from the wound. Hundreds of larvae can be packed deep inside.<\/p>\n\n\n\n
NWS infestation is painful. Affected animals usually separate from the herd and lie down in shady areas. You may see head shaking, and animals may seem irritable. Decreased appetite and lowered milk production are common. Untreated animals can die in 7 to 14 days.<\/p>\n\n\n\n
In animals, contact your veterinarian immediately. Widespread outbreaks do not currently occur in the United States, although isolated cases do pop up, especially in southern states. Suspicion of disease requires immediate attention. In humans, contact your physician.<\/p>\n\n\n\n
Clean wounds as soon as possible, no matter how small. Check them closely for NWS eggs or larvae until healed. NWS eggs are creamy and white and deposited in a shingle-like manner on or near the edges of a wound. Larvae are cylindrical with one pointed end and one blunt end, with rings of dark brown spines around the body. Female flies are slightly larger than houseflies, with dark blue to blue-green bodies and reddish-orange heads.<\/p>\n\n\n\n
Even on small farms, one NWS case is too many. Stay informed, stay watchful, and don\u2019t hesitate to contact your veterinarian if you see anything unusual. Your animals\u2014and your neighbors\u2019 animals\u2014depend on it.<\/p>\n\n\n\n
Photo: Key Deer leg with NWS infestation. Mark Cunningham, USDA.
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On the farm, arthropods like flies, mosquitoes, mites, and ticks can be more than a nuisance\u2014they can carry diseases, damage hides and wool, and even cause death. You\u2019ve probably heard about New World Screwworm (NWS) in the news. Once nearly eradicated from North America, NWS has been recently detected in Central America and Mexico. Northward … Read more<\/a><\/p>\n","protected":false},"author":14,"featured_media":774,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[78,25,3,17,33,43,26,68,64],"tags":[82],"class_list":["post-770","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-animal-health","category-cattle","category-disease-prevention","category-foreign-animal-disease-fad","category-how-disease-spreads","category-humans-and-disease","category-sheep","category-wounds","category-youngstock","tag-screwworm"],"_links":{"self":[{"href":"https:\/\/www.cfsph.iastate.edu\/thelivestockproject\/wp-json\/wp\/v2\/posts\/770","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.cfsph.iastate.edu\/thelivestockproject\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cfsph.iastate.edu\/thelivestockproject\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cfsph.iastate.edu\/thelivestockproject\/wp-json\/wp\/v2\/users\/14"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cfsph.iastate.edu\/thelivestockproject\/wp-json\/wp\/v2\/comments?post=770"}],"version-history":[{"count":5,"href":"https:\/\/www.cfsph.iastate.edu\/thelivestockproject\/wp-json\/wp\/v2\/posts\/770\/revisions"}],"predecessor-version":[{"id":817,"href":"https:\/\/www.cfsph.iastate.edu\/thelivestockproject\/wp-json\/wp\/v2\/posts\/770\/revisions\/817"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.cfsph.iastate.edu\/thelivestockproject\/wp-json\/wp\/v2\/media\/774"}],"wp:attachment":[{"href":"https:\/\/www.cfsph.iastate.edu\/thelivestockproject\/wp-json\/wp\/v2\/media?parent=770"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cfsph.iastate.edu\/thelivestockproject\/wp-json\/wp\/v2\/categories?post=770"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cfsph.iastate.edu\/thelivestockproject\/wp-json\/wp\/v2\/tags?post=770"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}