Cochliomyia hominivorax

1. Karla Bennett May 2012 Cochliomyiahominivorax

2. Taxonomy • Kingdom: Animalia • Phylum: Arthropoda • Class: Insecta • Order: Diptera • Family: Calliphoridae • Genus: Cochliomyia • Species: Cochliomyiahominivorax

3. MMM! FLESH! Brief Information • It is called the “New World Screw-Worm Fly” • It is a parasitic fly whose larvae (maggots) feed on living tissue of warm-blooded animals. (Yes, it is a man-eating fly). • The infestation of a live vertebrate is called “myiasis” • There are 5 species of Cochliomyiabut only 1 species of screw worm fly. • They are unusual because they prefer healthy tissues and not putrid tissues.

4. Distribution • Range: Central and southern U.S. through mexico, Central America, Carribean Islands, and Northern South America. • U.S. and Mexico are using “sterile insect techniques”. Now the disease border is between Mexico, Guatemala, and Belize. • The red color on the map shows the New World distribution.

5. Life Cycle

6. Life cycle overview • Definitive Host= Humans or any warm-blooded animal • Intermediate Host= None • Fly lays its eggs in a wound • 24 hours later larvae emerge and feed and burrow their heads into the tissue. • Odor of wound attracts adult female to lay more eggs (3000 larvae/wound • 5-7 days larvae mature and drop to the ground, burrow, and become “pupates”. • Adults (8-10mm) emerge in the morning in 1-3 days. • They mate within 1-3 days. • Females then seek out a host to lay her eggs on (laid in a shingle-like batch).

7. Symptoms • Motion inside a wound • A wound becoming worse • Serosanguineous discharge and odor from the wound. • Larvae can be seen in the wound after 3 days (vertical orientation in the wound) • They burrow deeper if disturbed • Animals with it (specifically grazing animals) will lie down in the shade and show decrease in appetite and if milk producing will have decreased production.

8. Diagnosis • Identification of parasite under the microscope (can see distinctive larvae and eggs are laid in a particular pattern) • Cuticular hydrocarbon analysis • Analysis of mitochondrial DNA and random amplified DNA polymerase chain reaction (RAPD-PCR) assays. • Larvae resemble a wood screw with a pointed head and blunt back end. They have brown spines that encircle the body. • Eggs are laid in a shingle-like array near the edge of the wound.

9. Treatment • Wounds can be surgically excised • The best treatment is the use of larvacide. The treatment is repeated until the wound heals • Larvae must be destroyed otherwise they can leave and become adults.

10. Control • Reduced and then eradicated by repeatedly releasing sterilized male flies so that the flies mate and only produce unfertilized eggs.

11. Mini Quiz! • What phylum? • What is the common name of the parasitic fly? • Who is the intermediate host? • How did the U.S. eradicate this fly? • What stage is the fly in when it burrows into the ground? • Why shouldn’t you itch the wound being affected by the larvae? • Why are these flies so unusual as compared with other flies? (hint: has to do with where they lay their eggs).

12. Citations • http://www.fao.org/ag/aga/agap/frg/feedback/war/u4220b/u4220b07.htm#geographical%20distribution%20of%20new%20and%20old%20world%20screwworm%20flies • www.cfsph.iastate.edu/Factsheets/pdfs/screwworm_myiasis.pdf • Wikipedia (for picture only) http://en.wikipedia.org/wiki/Cochliomyia • http://www.naiaonline.org/guest_editorials_and_commentary/page/suffering-to-end-suffering-the-heroic-effort-to-eradicate-the-north-america • http://www.kmle.co.kr/search.php?Search=Cochliomyia+hominivorax&SpecialSearch=HTMLWebHtdig&Page=3 • http://www.sciencephoto.com/media/146978/enlarge • http://www.impactlab.net/2008/05/08/frightening-new-face-of-evil-the-screw-worm/