Mite Biology & Control

1. Mite Biology & Control Female Scabies Mite

2. Objective هدف • Relate the biology of mites to appropriate control measures.

3. Overview مرور • Characteristics and Habits • Life Cycle • Medical Importance • Control Measures

4. Mites • Not all mites are of medical importance. We will be concentrating on the following: • Scabies • Chiggers • Dust Mites • Rat Mites

5. Mites • Other mites of some Importance • Forage Mites • Straw Itch Mites • Poultry Mites • Follicle Mites • Cable Mites

6. Biology • Mites are arachnids closely related to ticks • Life cycle : egg, larva, nymph and adults • Nymphal stage s; protonymph, deutonymph and tritonymph (not present in all mites) • Considerably smaller than ticks • Three body segments • Mouthparts consist of fewer segments

7. Biology • Have varied appearances and food sources • free-living predators • external parasites (most) • internal parasites (very few) • plant feeders • stored-products pests

8. Medical Importance • Affect the health of man in three ways • By causing dermatitis e.g. scabies and chiggers • As vectors of diseases i.e. scrub typhus and Rickettsial pox • By causing allergic reactions in man e.g house dust mite

9. Sarcoptic Itch Mites • Sarcoptesscabiei • variety hominis causes scabies in humans • variety suis causes swine mange • variety equi causes horse mange

10. Scabies (Seven-year Itch) • Sarcoptesscabiei • Gravid females form burrows in the skin where they lay eggs • Larvae burrow out to the skin surface • they mature and mating occurs here • Eggs and debris are left within burrows

11. Scabies • Transmitted through intimate contact • Immunity appears to develop over time • Outbreaks occur sporadically • Initial effects usually not noticed for first month • Scratching leads to complications

12. Chiggers • A.k.a. called Red Bugs • Numerous species called chiggers in genus Trombicula • Larval mites wait on grass blades for a host to pass by • Only larvae feed on man • Nymphs and adults are predators

13. Behavior • They don’t burrow into the skin • Mouthparts are inserted into a pore or hair follicle • Inject digestive fluid into cell, then feed on ruptured cell contents • Mite feeds and then leaves host • Welt and itching occur after mite is gone

14. Behavior • Once on the host the mite crawls around looking for a suitable feeding site • They love elastic • socks • briefs • bras

15. Chiggers • Bites commonly cause • itching in about 3 to 6 hours after feeding • dermatitis develops in about 10 to 16 hours • secondary infections can occur if bite wounds are scratched

16. Scrub Typhus • Transmitted from Leptotromidium mites infected with Rickettsiatsutsugamushi • Found in South East Asia • Mites and disease are associated with • “fringe habits” transition line between wooded and maintained • “mite islands” patches of vegetation harboring large numbers of mites

17. Dust Mites • Dermatophagoidespteronyssinus • Tiny mites that feed on shed human skin • They DO NOT bite! • People suffer from allergic reactions to: • excreta • cast skins • secretions

18. Dust Mites • Higher humidity levels are more conducive to mite survival • Mite populations are present year round

19. Rat Mites • Blood feeding mites associated with rodents; several species are involved • They occasionally inflict painful bites • Can also transmit rickettsial pox (Liponyssoides spp. ) and possibly endemic typhus

20. Rat Mites • Most commonly found in buildings infested with rodents • Eliminate the rodents and the mites will not be a problem after about two weeks

21. Tropical Rat Mite Vector of Epidemic Hemorragic Fever Disease is probably viral Rodent population forms reservoir Cases documented in Korea

22. Forage Mites • Several species are involved • Normally infest grains, flour and cheese • Food handlers are occasionally attacked • AKA • Grocer’s Itch (Glycyphagusdomesticus) • Copra Itch (Tyrophaguscastellanii) • Vanillisme (Acarussiro)

23. Forage Mites • Allergic responses also can occur • Intestinal disturbances due to consumption of infested food can also be a problem

24. Straw Itch Mites • Pyemotestritici • A predator in agriculture crops • Bean, pea & boll weevils, grain moths • Workers come into contact with the mites while handling straw and other commodities

25. Poultry Mites • Blood feeding mites of chickens and other birds; several species are involved (Dermanyssusgallinae, Ornithonyssussylviarum) • Occasionally feed on people; AKA poultryman’s itch

26. Poultry Mites • Commonly associated with: • English sparrows • starlings • pigeons • Look for bird nests close to buildings • chimney • windows

27. Follicle Mites • Demodexfolliculorum • Most humans are infested • Occur in hair follicles around the eyes and nose • Cause no discomfort to the host • Similar mites cause demodectic mange in dogs

28. Cable Mites • Cause static to occur in TV broadcasts • Infest coaxial cable resulting in a degradation of the cable line

29. Cable Mites(the real story) • Not an actual species • Some people think they are infested with mites or other insects • Can be static electricity • Allergic responses to chemicals or medication • Delusory parasitosis

30. Surveillance for Mites • Very difficult to do • Doctors can do skin scrapings from patients • Black plate method • Look for hosts (rats and birds)

31. Control • Personal hygiene • Chemical (permethrin, lindane, crotamiton, gamma-BHC) • Chemical control presents problems due to dosage restrictions and development of resistance • Personal protection (deet, permethrin)

32. Summary • Characteristics and Habits • Life Cycle • Medical Importance • Control Measures

33. Questions? سوالات