New World screwworm (NWS), \u201cgusano barrenador del Nuevo Mundo\u201d in Spanish, is a devastating pest. NWS myiasis occurs when NWS flies lay eggs in wounds or in other body cavities with mucus membranes, such as the nose, ears, eyes, or mouth. The eggs develop into parasitic larvae (maggots) that feed on and burrow into living flesh. Although they primarily affect livestock, such as cattle and horses, the flies can also lay eggs on people and other warm-blooded animals, both domestic and wildlife. Cases of NWS in people can be fatal if left untreated.<\/p>\n
An outbreak of NWS<\/a> infestations in people and animals has developed across Central America and Mexico. During this outbreak, more than 1,190 cases and seven deaths in people have been reported in Central America and Mexico as of January 20, 2026. Mexico has reported 24 hospitalizations among people<\/a> and 601 active cases among animals<\/a>. (An animal case is defined as \u201cactive\u201d at the time of diagnosis and becomes inactive if officials verify the absence of new wounds or larvae after 15 days.) The Mexican state of Tamaulipas, which borders the U.S. state of Texas, reported eight active animal cases<\/a>. The NWS fly has not been detected in the United States and risk to people remains low. For more information about the more than 148,000 animals affected by the outbreak, please see Current Status of New World Screwworm | Screwworm.gov<\/a>.<\/p>\n NWS was previously a significant economic pest of livestock in the United States. The United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) developed an eradication strategy<\/a> based on releasing sterile male flies. Since the female NWS fly only mates once in her 21-day lifespan, mating with a sterile male fly means any resulting eggs are not fertilized and no larvae can hatch. This strategy was successful in eradicating NWS from the United States, Mexico, and southward through Central America. The United States successfully used the strategy again in 2017 following a 2016 re-introduction of NWS into Key deer in the Florida Keys.<\/p>\n Since 2006, animal health and agricultural officials<\/a> had maintained a biological barrier at the Darien Gap along the Panama and Colombia border, where sterile flies were continuously released to prevent reintroduction into Central America. In 2023, Panama reported a spike in cases of NWS\u2014more than 9,300 in one year<\/a>. Unregulated cattle movement, increased movement through the Darien Gap, and new areas of farming contributed to rapid northward spread of NWS. In addition to this increased activity in Central America and Mexico, NWS has remained persistent in South America and the Caribbean, including in Cuba, Haiti, and the Dominican Republic.<\/p>\n The USDA\u2019s APHIS current strategy to control and re-eradicate NWS includes<\/p>\n Releasing sterile male flies. An additional and important part of this strategy includes rapid identification and appropriate clinical management of infestations in people. Timely public health response allows for prompt investigations and control measures to prevent onward spread outside of the area where sterile flies are being released. CDC is collaborating with federal, state, and local agencies and international organizations to assist with efforts to control the spread of NWS through public health action.<\/p>\n People might be at increased risk for developing NWS if they spend time in geographic areas where NWS flies are present and<\/p>\n Have an open wound, including scratches, cuts, insect bites, or surgical wounds.
\nDeveloping and enforcing animal movement controls.
\nIncreasing passive and active surveillance, outreach, and education in impacted areas.<\/p>\n
\nHave a medical condition that might affect how quickly a wound heals or that may cause bleeding or open sores (e.g., skin cancer, psoriasis, or eczema).
\nAre very old or very young.
\nExperience malnutrition.
\nSleep outdoors, especially during daytime hours when NWS flies are more active.
\nLive, work, or spend an extended amount of time near livestock or other warm-blooded animals in these areas.<\/p>\n","protected":false},"excerpt":{"rendered":"New World screwworm (NWS), \u201cgusano barrenador del Nuevo Mundo\u201d in Spanish, is a devastating pest. NWS myiasis occurs…\n","protected":false},"author":2,"featured_media":419878,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[59],"tags":[97,252,253],"class_list":{"0":"post-419877","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-health-care","8":"tag-health","9":"tag-health-care","10":"tag-healthcare"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/419877","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=419877"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/419877\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/419878"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=419877"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=419877"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=419877"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}