Insects of public health importance


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Insects of public health importance

  1. 1. Insects of Public Health Importance
  2. 2. 1. Mosquitoes Anophilines, Culicines1. Flies House fly, sand fly, Tsetse fly, black fly3. Human lice Head and body lice, crab lice4. Fleas Rat
  3. 3. Flies
  4. 4. Insecta or hexapoda • 6-7 cm long, hairy • Three body segments • Six legs • Two pairs of wings • Wings-transparent, no veins
  5. 5. House fly• A pair of compound eyes•Eyes are closer in males and far apart in females•Antenna - small & 3 segmented
  6. 6. House fly- life cycle• Egg- 150-200eggs/sitting 1mmlong, pearly white 2 longitudinal ridges in dorsal side• Larva (maggots)– white segmented(13) footles, worm like,1/2 inch. narrow anterior end & broad posteriror end no eyes / appendages
  7. 7. Contd…• Pupa- white in early stages, later it become dark brown. Barrel shaped
  8. 8. •2-6 d •2-7 d 8-24hr
  9. 9. Mechanical transmission of diseases• Viruses : Hepatitis, poliomyelitis.• Bacterial : Enteric fever, bacillary dysentery, wound infection & trachoma.• Parasitic : Mechanical transmission of Eggs: Ascaris ,Trichuris, Hymenolpis nana… Cysts: Entameba histolytica, Giardia
  10. 10. Fly control1. Environmental control clean house with clean surroundings1. Insecticidal control DDT (5%), lindane(0.5%), fenthion (2.5%), malathion(5%), diazinon (1-2%) etc as residual/space spray/Baits1. Fly papers –resin & castor oil2. Protection against flies-screening (14mesh/ in)3. Health education
  11. 11. Sand fly
  12. 12. Phlebotominae • Like a mosquito, except its body is hairy and the wings are feathery. • Tiny insects (1-3 mm) • Smaller than mosquitoes • Hairs on body and wings • Wings rest over body like “angel’s” wings • Only females suck blood
  13. 13. Sand flies Phlebotomus spp• Live in warm climates• Minute, hairy ,with wing kept erect while resting.• Breed in crack of soil and wall, rubbish heaps• Move in hops rather than fly .• Nocturnal ,during day time rest in cool damp places• Vector of leishmaniasis, sand fly fever.
  14. 14. Sand fly• Large compound eyes• Hairy legs• Long slender legs• Wings are vertical and pointed• Whole body is covered with hairs• All 10 segments are abdomen are visible
  15. 15. Sandfly• In males 2 claspers are seen in the 10th abdominal segment• In females ,10th abdominal segment has 2 small cerci
  16. 16. Sand flyVector for Leishmaniasis L.Donovani -visceral leishmaniasis. L. tropica -cutaneous leishmaniasis. L.braziliensis -mucocutenous. Transmission cyclopropagative . Sand fly fever viral disease mild fever like influenza propagative
  17. 17. Fleas of medical importance
  18. 18. Ctenocephalides• Ecto- parasites of dog and cat• Characterized by black teeth like structure on head known genetal comb and another set on first thoracic segment- pronotal comb
  19. 19. Dog flea, cat fleaHuman flea Trop. rat fleadog flea cat flea
  20. 20. Pulex irritanceCtenocephalides canis Rat flea
  21. 21. X. cheopes • Main vector for plague • Females have “C”shaped spermatheca with uniform thickness which is used for storing sperms • In males spermatheca is absent, the 9th abdominal segment dorsally has a sensory organ-pygedium • Anterior to this is anti pygedial bristles arise directly from the body • 9 th sternite is club shaped
  22. 22. X. astia• In female-spermatheca is bulbus at the middle –a shaped• In male- anti pygedial bristles arise directly from the body• 9 th sternite is ribbon shaped
  23. 23. X. braziliensis• In female-spermatheca is bulbus at one end –b shaped• In male- anti pygedial bristles arise from a conical base• 9 th sternite is absent
  24. 24. Fleas transmited• Plague (bubonic)• Endemic or murine typhus• Chiggerosis• Hymenolepis diminuta• Modeof transmission Biting-blocked flea Mechanical transmission Faecal
  25. 25. Control of fleas• Insecticides DDT(5-10%),γHCH, dieldrin, diazinon(2%) Applied in floors & walls up to 1ft Applied in rat burrows• Repellents Diethyl toluamide• Rodent control
  26. 26. Human lice
  27. 27. Lice• Small wingless insects• Three species that solely live on humans  Pediculus humanus occurs in two subspecies  the head louse (Pediculus capitis) and  the body louse (Pediculuscorporis)• The body louse lives mostly in the clothing and attaches its eggs to its fibers• The third species of human lice is Phthirus pubis the crab or pubic louse.
  28. 28. Head louse- Pediculus humanus capitis• The head louse lives in the hair and attaches eggs (nits) to the hair• Body - dorso-ventrally flattened, has head, thorax & abdomen• Head-pointed, bears a pair of 5 segmented antennae, Simple eyes.Head has a pair of antennae which is sucking & piercing type• Thorax(square shaped) has 3 pairs of appendages.Last segment of appendages ends with claws• Abdomen – 9 sements.Last segment imale it is pointed, females - bilobed
  29. 29. •In females lastHead louse abdominal segment is bifid •In males last abdominal segment is pointed not bifid. •Males posses a U shaped organ called ”aedeagus •Aedeagus is species specific and region specific
  30. 30. • Resembles a crab, about 2mmPthirus pubis - • Attached to pubic hair & eyePubic Louse lashes • Head, thorax, abdomen • Thorax has 3 pairs of legs & first pair is slender • Last segment of appendages ends with claws • Abdomen has lateral projections called lateral papillae • Females last abd.segment is bifid • In males last segment is not bifid.
  31. 31. Lice -PH importancedisease transmission :lice act as a vector for- Epidemic typhus- Epidemic relapsing fever,- Trench fever.Pediculosis, irritation and pruritus.
  32. 32. Control of lice• Insecticide s -Lotion with 0.5% malathion,toapplied and kept on for 24-48 hrs.• Personal hygiene
  33. 33. Ticks• Wingless insects• Ectoparasites of vertebrate animals• They all suck blood• Body is oval in shape ,and has two parts- head or Capitulum & Abdomen• Head is at anterior end• Has 4 pairs of appendages, no antennae• Hard tisks are covered on their dorsal surface by a chitinous schield called scutum
  34. 34. • Males are smaller thanHard ticks females • In males body is completely covered by scutum • In females anterior 1/3rd is covered by scutum • Vertical transmission from mother to egg
  35. 35. Hard tickFemale Male
  36. 36. Hard tickMale Female
  37. 37. Soft tick •Small, soft and leathery cuticula, •Mouthparts invisible from dorsal aspect •The scutum/dorsal schield is `absent • Abdominal wall is smooth • Dorsal surface has small dot like mamillary tubrercles
  38. 38. Soft and hard ticks(Agasidae/Ixodidae)
  39. 39. • Hard tick hard cuticle - Babesiosis,Tularemia - Quneensland fever, - Rocky mountain spotted fever, - Tick paralysis ,KFD• Soft tick soft cuticle - Relapsing fever Borrelia duttoni - Q fever - KFD
  40. 40. Mites – sarcoptes scabei • Tiny (0.1-0.3 mm) endo-parasitic mite • Lives in epidermal layer of skin • Body - Capitulum & Abdomen • Eyes, antennae & wings are absent • 2 pairs of legs in front 2 pairs behind.Front legs end in long tubular process- suckers • Hind legs end in long filamentous bristles • In females 4 th pair end in suckers
  41. 41. sarcoptes scabeiMale Female
  42. 42. sarcoptes scabei- Public health imp• Causes human scabies• Scabies is characterized by an intensely pruritic, erythematous, papular eruption caused by burrowing of adult female mites in upper layers of the epidermis, creating serpiginous burrows. Itching is most intense at night• Sites of lesion – hands & wrist (63%),extensor aspect of wrist (11%),
  43. 43. Preferred sites interdegital, popliteal fold and groin
  44. 44. • Class-crustaceaCyclops • Pear shaped semi transparent body, forked tail, 2pairs of antennae • Large cephalothorax & slender segmented abdomen • Single small pigmented eye • In females 1st abd. segment has apair of ovisac
  45. 45. Cyclops FemaleMale
  46. 46. Cyclops (water flea)• Vector for: Dracunculus medinensis
  47. 47. Control• Physical straining of water through a piece fine clothBoiling at 60 degree C• Chemical – chlorine 5ppm,alum 4gm/gallon, abate 1mg/l• Biological – gambusia fish• Abolish step well, promote sanitary well