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Myiasis

Myiasis. By Karma Tiberg Biology 4800 Spring 2011. Outline. What is myiasis? Flies causing myiasis Life cycle Effects on livestock Effects on humans A few types of myiasis in humans Treatment options. What is Myiasis?.

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Myiasis

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  1. Myiasis By Karma Tiberg Biology 4800 Spring 2011

  2. Outline • What is myiasis? • Flies causing myiasis • Life cycle • Effects on livestock • Effects on humans • A few types of myiasis in humans • Treatment options

  3. What is Myiasis? • Myiasis is the disease caused by the feeding of larval dipterans on living and necrotic tissue, liquid body-substance, or ingested food • Described in two ways: • Location of the affected area • Relationship between the fly and its host (obligate, facultative, or accidental) • Can affect all vertebrates including humans!

  4. The Flies • There are three main families of flies that cause myiasis: • Oestridae (obligate parasites) • Calliphoridae (obligate or facultative) • Sarcophagidae (obligate or facultative)

  5. Life Cycle

  6. Effects on Livestock • Pests that cause huge economic losses worldwide (in the hundreds of millions annually) • Cause stress to the livestock and reduction in livestock health • High infection levels, or migration of larvae into important regions can lead to death • Damage to the hides

  7. Horse and Cattle Bots

  8. Screwworm Flies

  9. Effects on Humans • Mainly a problem for rural populations especially in tropical and subtropical regions • A problem of countries with a low socioeconomic status, limited access to health care, and poor hygienic practices • A problem for elderly people • Most commonly infected by obligate and facultative fly species • Humans may become infected if they spend extended periods of time around livestock • Depending on the species of fly and the type of infection, the effects can range from minor to severe and potentially fatal • Secondary infections are common

  10. Types of Myiasis in Humans • Cutaneous • Furuncular • Creeping • Wound • Nasopharyngeal • Opthamomyiasis • Oral • Intestinal • Cerebral

  11. Cutaneous • Furuncular • Infection of skin on the scalp, face and extremities • Swelling localized at the area of infection • Small opening is maintained in the skin to promote respiration, and waste excretion by the growing larvae • Mainly a problem in tropical locations, but can be a problem in the U.S. and Canada • Human botfly - Dermatobiahominis(family Oestridae) • Tumbu fly – Cordylobiaanthropophaga(family Calliphoridae) • *Wohlfahrtia vigil – (family Sarcophagidae)

  12. Furuncular myiais

  13. Cutaneous 2. Creeping Myiasis • Infection of humans by the larvae of horse bot flies (Gasterophilus) and cattle bot flies (Hypoderma) • Both in the family Oestridae • Larvae typically do not develop in humans • Travel around the epidermis looking for proper host cues • Painful “Migrating lumps” and the production of long tunnels • Gasterophilus tunnels are located in the epidermal layer • Hypoderma tunnels are located deep in subcutaneous tissue but may migrate to other tissues

  14. Cutaneous • Wound Myiasis • Flies deposit eggs or larvae on the outer margins of a wound or sore • Larvae feed and travel through living flesh • Can be fatal if left untreated • Wound myiasis can develop into other forms of myiasis depending on where the larvae migrate in the body • Screwworm Flies - Cochliomyiahominivorax, Chrysomyabezziana • Wohlfahrtiamagnifica (family Sarchphagidae) • Bluebottle flies

  15. Nasopharyngeal • Less common in humans • Occurs in people who spend extended periods of time around livestock • Sheep bot fly (Oestrus ovis) • Fly inserts larva into the nostril of host • Larvae can cause extensive damage to the nose, sinuses and pharynx due to the feeding on living and necrotic tissue • In some cases larvae can migrate out of the sinuses into the eyes, ears, mouth or brain causing myiasis in those locations

  16. Nasopharyngeal

  17. Opthalmomyiasis • Affects the eyes, orbits and periorbital tissue • Larvae cause the destruction of these tissues through feeding and migration • Often caused by migrating fly larvae or flies that preferentially infect soft and susceptible tissues • May lead to blindness if not treated

  18. Opthalmomyiasis

  19. Oral Myasis • Infestation of the oral cavity by fly larvae • Sheep bot fly • Migratory larvae, or opportunistic infection of a sore or lesion (wound myiasis) • varejeira fly - Cochliomya hominivorax

  20. Intestinal Myiasis • This is often a result of accidental infection • Ingestion of fly eggs or larvae in water or contaminated food and subsequent larval development within intestines • Can be a result of migration of larvae

  21. Cerebral Myiasis • Extremely rare • A traumatic skull fracture followed by the depositing of eggs or larvae into the wound • Human bot flies • Screwworm Flies • Migration of larvae into the brain originating from another area of the body • cattle bot flies (Hypoderma)

  22. Shoo fly, don’t bother me! • Preventative measures are usually the best way to minimize human (or livestock) infection with myiasis • Use of insect repellents with DEET • Improve hygienic practices • Limit exposure to livestock and other common hosts, or treatment of livestock with insecticides and larvicidal drugs (endectocides) • Introduction of coprophageous insect species • Suffocation of larvae within the skin and then careful extraction of the larvae (Furuncular) • Treatment with Ivermectin products • Surgery

  23. References • Caca, I., K. Unlu, S. Soker Cakmak, K. Bilek, B. Sakalar and G. Unlu. 2003. Orbital myiasis: case report. Japanese Journal of Ophthalmology 47: 412-414 • Colwell, D.D., D. Otranto and J. R. Stevens.2009. Oestrid flies: eradication and extinction versus biodiversity. Trends in Parisitology 25: 500-504 • Lucas, E. M., C. Diez, A. Gutierrez, F. Montiaga, J. Arnaiz, A. Gonzalez Mandly, E. Sanchez and N. Valle. 2008. Unusual MRI findings in a patient with history of frontal fracture and skin infestation by fly larvae, as a possible sign of intracerebral myiasis. Clinical Neurology and Neurosurgery.110: 725-728 • Robbins, K. and A. Khachemoune. 2010. Cutaneous myiasis: a review of the common types of myiasis. International Journal of Dermatology 49: 1092-1098 • Shinohara, E. H., M. Z. Martini, H. G. Oliveira Neto and A. Takahashi. 2004. Oral myiasis treated with ivermectin: Case report. Brazilian Dental Journal.15: 79-81 • 1999, Intestinal Myiasis caused by Eristalis tenax, Journal of Clinical Microbiology 37: 3082

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