Exam 3 Bot flies and Myasis

Exam 3 Bot flies and Myasis - Bot flies and Myiasis 1)...

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Bot flies and Myiasis 1) Myiasis a. Invasion of living vertebrate by fly larvae i. Invasion may or may not involve feeding on tissues of host ii. Three types 1. Accidental a. Generally not parasitic, but may become so. b. Two methods i. Fly eggs or larvae contaminate foods ingested by host 1. About 50 species of flies 2. Pass through alimentary tract ii. Other invasion by anus 2. Facultative a. Larvae can be either free living or parasites b. Opportunistic c. Invasion of open sores on livestock by normally free living blow fly maggots d. Three types i. Primary – can initiate myiasis ii. Secondary – Species that continue myiasis but only after it is started by primary group iii. Tertiary – species which join primary and secondary just prior to host death 3. Obligatory a. Always parasitic b. Require living host i. Primary screwworms and bot flies
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c. Incidental myiasis = occasional parasitism of atypical hosts by obligate myiasis – producing flies i. Cattle grub on horses, sheep nose bot in human iii. Site Categorization 1. Gastrointestinal – can be accidental (larvae in fruit) or obligatory (horse bots) 2. Urogenital – invasion of urethra or genitalia by fly larvae, exposed openings or infection attracting flies 3. Ocular-invasion of eye tissues, often by sheep nose bot, occasionally by rodent bots 4. Nasopharyngeal – nasal and deep oral cavities, often associated with infections, but some specialize 5. Auricular – invasion of ears, usually by blow flies and flesh flies 6. Cutaneous – blow flies, flesh flies, screwworms, some bot flies, traumatic myiasis, when the skin is broken. b. Adaptations i. Overwintering – cuterebrids, - long pupal period, other bots, long larval stage ii. Adult longevity – few days for stomach bots, adults don’t feed, 1-2 weeks for other bots, 1 month for muscids, calliphorids, sarcophagids iii. Egg development - nose bots and flesh flies – retain fertilized eggs, larviposit. Others fertilize eggs as they oviposit, requires development. Cuterebrids oviposit at nest burrows, Dermatobia on other flies, others on host. c.
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Exam 3 Bot flies and Myasis - Bot flies and Myiasis 1)...

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