Cochliomyia hominivorax Screwworm

1. Cochliomyia hominivoraxScrewworm MAN eater Allaa` Hassan

2. Parasitic fly • Known for the way its larvae(maggots) eat the living tissue of warm blooded animals.

3. Causes • Myiasis: damage of animal tissues (by larva) • Infestation causes serious loss of livestock production

4. Geography • “New world” tropics and Neoartic regions of western hemisphere • Eradicated in the United States, (except Southern Texas) Mexico, Guatemala, Belize, El Salvador, Honduras., and Libya. • Throughout Africa, ME, India, and SE Asia. • Central and South Americas.

6. MONSTERS inside me: • http://animal.discovery.com/videos/monsters-inside-me-the-screwworm.html

7. Definitive Host • All warm blooded animals • Including livestock, wildlife, pets, zoo animals, & even humans! • Cattle, sheep, and goats • Experience the greatest economic losses • No intermediate host

8. Morphology • Adults • Dark, shiny, bluish green • 10mm long • Reddish yellow face & 3 black stripes on upper thorax between the wings. • Larva • 17mm • resembles the spiraled “screw” • shape their common name is based on • cranial end of the larvae has two sharply-curved hooks, • generally dark in color • caudal end: distinctive spiracle patterns • distinctly pigmented tracheal trunks

10. Life cycle • ~20 days • Females lay 250-500 eggs on edge of exposed flesh of an animal. • Eggs are in a tight row that overlap on the edge of the wound, resembling shingled roof. • Egg mass is characteristically white and compact . • After 12-21 hours, larva hatches, crawls into wound, and burrow into surrounding tissue as they feed • first stage • They get their name “screwworms” because if the wound is disturbed during their burrow and feeding time, they burrow or “screw” deeper into the flesh. • Larva feeds on wound fluids and live tissue

11. Life cycle contd • Within 24 hours of hatching: • larvae penetrate wound and molt into second stage. • 42-45 hours after hatching: • larvae enter third and final stage • ~7 days after hatching: • the grown larva exit from the wound and fall to the ground • They burrow in the soil and pupate (7-10 days) depending on the temperature • Form hard sclerotised pupal case • Freezing /sustained soil temperatures <46 F kills the pupa • After they pupate, the adult stage develops • Females mate 4-5 days after hatching • Females can lay up to 3,000 eggs and fly up to 125 miles during her life time.

12. Clinical signs • May be readily missed • Even with close examination • With suitable environment and host circumstances; • Infestations can be dramatic and devastating • Enlarging the wound makes the host vulnerable to bacterial infections • Screwworm fly is an obligate wound parasite and requires soft tissue of living warm-blooded animal to develop its larva. • Related to the site and severity of infestation • Severe infestation will cause systematic disease • Light infestation may go unnoticed • They infest umbilical regions of newborn animals. • Infestations are associated with traumatic injury, erosive or ulcerative lesions of the skin, or hemorrhage • In sheep • Strikes the inner corner of the ye and perineal region of ewes without obvious trauma

13. Signs of infestation • Procedures like: • dehorning • castration • branding • tail docking • ear tagging can lead to infestation. • Foul –smelling lesion containing larval screwworm flies • Frequent licking of the lesion by an animal • Restlessness of affected animal • Fever • Lethargy • Loss of appetite • Debilitation • Decreased growth rate • Anemia • Hypoproteinanemia • Peritonitis following navel infestation • Sinusitis following dehorning • Pleuritits following thoracic infestation • Restricted movement following muscle infestation • Tissue irritation

15. Screwworm maggots have toxic saliva which promotes infection of wounds and thus the cause of foul smelling pus • The pus is what attracts more screwworm flies and other species of flies. • If tissue is necrotic, it attracts even MORE flies! • This increased level of infestation becomes greatly enlarged unless treated. • If untreated, results in death of animal.

16. Prevention • Early detection • Public awareness • Widespread targeted surveillance • Concentrate on areas at higher risk • Like: ports of entry for returning livestock vessels • Traps • Sticky boards • Regularly inspect animals for wounds

17. Treatment • Chemical pesticide to treat infestations and to protect animals from a strike by the screwworm flies. • Myiasis(humans and animals) • Clean the wound and surroundings with warm water • Remove (using forceps) as many larva as possible • Collect and destroy removed larva using hot water or insecticide • (may or may not retain larva for identification) • Apply topical treatment to the wound to kill any remaining larva • Treat animal with longer acting systemic insecticide for prophylaxis • For animal: Invermectin is administered by subcutaneous injection and is the only active constituent of any product with claim against Old World SWF. • Provides protection against new infestations in cattle for 16-20 days. • No vaccine

18. Human infestations • Rare but very common in endemic areas. • Causes Myiasis that usually occurs on the neck or scalp. • Serious complications including death • Resulted from infestation of the nose, eyes, ears, and mouth. • Tissue inflammation

19. Control & Eradication • (SIT) • Sterile Insect Technique • U.S officially eradicated the Screwworm in 1982. • Method of biological control • Mass number of sterile males are released. • Why males? • Overwhelming number of sterile males and they compete with the wild males for female kissy time. • What happens when a female mates with a sterile male? • Keep in mind that the screwworm fly only mates once during her life time while the men are a bit more…promiscuous.

20. Why is this technique so successful if the female can only mate once during her life time? • This is quiet possibly the most ingenious technique because it reduces the next generation’s population. • When it’s repeated, you can eventually have a strong control or fully eradicate a species in a location.

21. Problems with technique • Species specific. If you eradicate one species that is in a genus that contains 25 species, you must do every single species separately. • Cost involved in producing large number of sterile insects, especially in poorer countries

22. Why get rid of it? • NUISANCE! • These “man-eaters” prey on warm blooded animals, especially cattle and are capable of killing a full grown cattle within 10 days of infection. • In the 1950’s, screwworms caused lots of loss to American meat and dairy supplies that were projected at above $200 million!

23. References • http://animal.discovery.com/videos/monsters-inside-me-the-screwworm.html • http://www.fao.org/ag/aga/agap/frg/feedback/war/u4220b/u4220b0a.htm • http://docs.google.com/viewer?a=v&q=cache:QZcwLnugCPcJ:www.animalhealthaustralia.com.au/fms/Animal%2520Health%2520Australia/AUSVETPLAN/SWF3_0-16FINAL(11Jul07).pdf+screwworm+fly+life+cycle&hl=en&gl=us&pid=bl&srcid=ADGEESiu63Elqf5Sf4tbZEQDQQjI_2hOMUTD8imimIMm5jk49LSEnfYgn-nrGcX06PY5iMbpq2HkgMHMivy5MQGglTELDOZy9UnFeHm1-FDTdOBHgk8SyRTm5zeGn_MQXKgLFQA8ZXb_&sig=AHIEtbQ4EhpxIV20qJsvhS9-vIvLRBwwgQ&pli=1 • http://en.wikipedia.org/wiki/Cochliomyia • http://www.everythingabout.net/articles/biology/animals/arthropods/insects/flies/screwworm/