All Mites


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Mites Presentation 2009
By Dr Mohammed Sarhan

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All Mites

  1. 1. MITES
  2. 2. Classification : <ul><li>Class : Arachnida </li></ul><ul><li>Order : Acarina </li></ul><ul><li>Families: </li></ul><ul><li>1- Sarcoptidae </li></ul><ul><li>2-Demodicidae </li></ul><ul><li>3-Trombiculidae </li></ul><ul><li>Genus : Sarcoptes </li></ul>
  3. 3. <ul><li>1- Family: Sarcoptidae </li></ul><ul><li>Sarcoptes scabiei var. humani </li></ul><ul><li>(Sarco: flesh, Ptes: cut) </li></ul><ul><li>Itch mite </li></ul>
  4. 4. <ul><li>There are several varieties of itch mites that can distinguished only by their host specificity and S. scabiei var. humani dependant on humans for its life cycle. There is a single species in the genus with a number of varieties named for the hosts on which they occur or live. Sarcoptes scabiei var. humani is on humans, S. scabiei var. suis is on swine and so on. </li></ul>
  5. 5. <ul><li>There is some cross transmission possible with many varieties, but usually the ability of the mites to survive and reproduce on an abnormal host is limited. </li></ul><ul><li>These mites are distributed worldwide and affect all socioeconomic groups. </li></ul>
  6. 6. General characters <ul><li>- Itch mite is about 0.4mm in length. </li></ul><ul><li>- Male smaller than female. </li></ul><ul><li>- It is whitish, has a body shaped like a tortoise rounded above and flattened below. </li></ul><ul><li>- Respiration via the skin. </li></ul>
  7. 7. <ul><li>- Mouth parts: </li></ul><ul><li>a) Hypostome: rudimentary, without teeth. </li></ul><ul><li>b) Chelicerae: end in pincer-like structure. </li></ul><ul><li>c) Pedipalps: short, 3-segments. </li></ul><ul><li>- Legs : </li></ul><ul><li>Female : </li></ul><ul><li>- 4 short pairs, 2 anterior and 2 posterior pairs. </li></ul><ul><li>- The anterior pairs end in sucker-like structure. </li></ul><ul><li>- The posterior pairs end in long bristles. </li></ul>
  8. 8. <ul><li>Male : - as female, but the 4th pair ends in suckers instead of bristles. </li></ul><ul><li>Larva: - 3 pairs, two anterior pairs ending in suckers. </li></ul><ul><li>- One posterior pair ending in bristles. </li></ul><ul><li>Nymph : as adult. </li></ul><ul><li>- Adult are eyeless. </li></ul><ul><li>- The cuticle is striated and carries several hairs. </li></ul><ul><li>Eggs : thin- shelled and ovoid. </li></ul>
  9. 9. Bionomics <ul><li>- Sarcoptes scabiei is a parasitic mite that live within the subcutaneous tissues of skin of human causing scabies. </li></ul><ul><li>- The female scabies mite selected places on the body where the skin is thin and wrinkled such between the fingers, wrists, elbows, feet, penis, scrotum, buttocks and axillae, breasts and nipples in women </li></ul>
  10. 10. <ul><li>The adult mites enter the skin, digging sinuous burrows in the upper layers of the epidermis. </li></ul><ul><li>When the females have burrowed into the superficial layers of the skin, they excavate winding tunnel at the rate of about 0.5-5mm/day, which are seen on the skin as very thin twisting lines a few millimeters to several centimeters long. </li></ul>
  11. 11. <ul><li>- Burrowing is activated by warmth especially during night. </li></ul><ul><li>- Males do not burrow into the skin but remain on the surface, along with nymphs. </li></ul><ul><li>- Each tunnel in the skin contains only one female, her eggs and feces, ecdysed cuticles. </li></ul>
  12. 12. <ul><li>- Female scabies mites may live about a month on human, away from their hosts, they live only 2-4 days. </li></ul><ul><li>- Mating occurs on the skin of the host and the male soon dies off. Newly fertilized female takes an hour to dig a tunnel in upper layer of the skin and begins forming a honey comb tunnels and dies after egg deposition. </li></ul>
  13. 14. <ul><li>- The life cycle can take place entirely within the tunnel in the skin. </li></ul><ul><li>- Female lays 1-3 eggs/ day in her tunnel. </li></ul><ul><li>- The eggs hatch within 3-5 days and small six- legged larvae emerge. </li></ul><ul><li>- These larvae crawl out of the tunnels onto the surface of the skin where a large number die, but a few succeed in either burrowing into the stratum corneum or entering a hair follicle to produce a small pocket called a molting pocket. </li></ul>
  14. 15. <ul><li>- After 2-3 days the larva molts in the pocket to produce an eight – legged </li></ul><ul><li>- A nymph molts to produce a sexually immature female which remains more or less quiescent in the molting pocket until she is fertilized by male. </li></ul>
  15. 16. <ul><li>- Mating occurs by the male either burrowing through the surface of the skin into the molting pocket containing the female or on the surface of the skin. </li></ul><ul><li>- Only after fertilization does the female commence to burrow through the skin. </li></ul><ul><li>- After about 3-5 days she starts to lay eggs in the tunnel. </li></ul>
  16. 17. <ul><li>- In life cycle of the male mite, the larva moults to become a nymph which stays in the moulting pocket until it changes into an adult male, this stage being reached 4-6 days after the eggs have hatched. </li></ul>
  17. 18. <ul><li>- Adult males spend most of their life wandering around on the surface of the skin seeking females. They can be found in either very short burrows or in small pockets in the skin. </li></ul>
  18. 19. Medical importance: <ul><li>Itch mite parasitizes human, causing a disease known as scabies. </li></ul><ul><li>Mode of transmission: </li></ul><ul><li>- Close contact with infected persons or with their clothing or bedding. </li></ul><ul><li>- The infection may also be acquired from infected domestic animals but is usually of short duration in humans. </li></ul><ul><li>- Spread of the infection to different parts of the body occurs through scratching </li></ul>
  19. 20. Clinical picture <ul><li>Incubation period: </li></ul><ul><li>2-6 or 1-4 days in persons sensitized by prior exposure. </li></ul><ul><li>- Rash is produced in response to allergic reaction produced by the mites. </li></ul><ul><li>- When a person is infected for first time with itch mites the rash does not appear until about 5-6 weeks later, but in individuals who have previously been infected a rash may develop with a few day after reinfection. </li></ul>
  20. 21. Scabies 1- burrow appear as fine scaly and wavy line 2- Severe pruritus  Vigorous, constant scratching  2ry bacterial infection
  21. 22. <ul><li>- Severe pruritus which results in vigorous and constant scratching, especially at night and this lead to secondary bacterial infections leading to boils, pastules, eczema, and impetigo contagiosa. </li></ul><ul><li>- The activities and secretions of the mites cause intense itching of the affected areas. </li></ul>
  22. 23. <ul><li>- A more severe from of scabies among immuno-compromised persons is called Norwegian scabies , characterized by vesicles and thick crusts over the skin accompanied by abundant mites and slight itching </li></ul>
  23. 24. <ul><li>N.B.: </li></ul><ul><li>Itch mite does not produce overwhelming infections in immunocompetent persons under ordinary circumstances. In the immunocompromised, however, so called Norwegian or crusted scabies may occur as a result of a decreased cutaneous immune responses. </li></ul>
  24. 25. <ul><li>The conditions is characterized </li></ul><ul><li>by widespread dissemination of massive numbers of mites, with thick, crusted lesions and inconsistent pruritus, from intense to absent. It is highly contagious, owing to the extraordinary numbers of mites present and is usually more difficult to treat. </li></ul>
  25. 26. Diagnosis: <ul><li>1- Clinically: (Presumptive diagnosis) </li></ul><ul><li>By history and clinical appearance. It is often difficult to find burrows. </li></ul><ul><li>2- Laboratory: (Definitive diagnosis) </li></ul><ul><li>Microscopic examination of skin scraping from burrows. Scrapings is cleared by adding one or two drops of a 20% solution of potassium hydroxide. However potassium hydroxide solutions will dissolve the mites and their eggs </li></ul>
  26. 27. <ul><li>Thus, alternatively, mineral oil may applied to the skin before scraping. This enables organisms and eggs to adhere better to the needle or blade and the microscopic slide and mineral oils will not dissolve mites or eggs . </li></ul>
  27. 28. <ul><li>3- Open the tunnel by a needle under a magnifying lens. The mites appear as highly retractile white organisms. </li></ul>
  28. 29. Treatment: <ul><li>Boiling of clothes and bed linen is necessary. </li></ul><ul><li>Washing the suspected sites with soap and warm water. </li></ul><ul><li>Rubbing the infected sites with brush to, open the tunnels following by application of one of following scabicide which should be applied to all skin surface from the top of head to the soles of the feet: </li></ul>
  29. 30. <ul><li>- 1% lindane in lotion or ointment. </li></ul><ul><li>- 25% benzyl benzoate emulsion (painted). </li></ul><ul><li>- 6% sulfur ointment . </li></ul><ul><li>- 0.5% Malathion. </li></ul>
  30. 31. <ul><li>N.B: Whichever drug is used should be applied for about 10hrs and then washed off, treatment should be repeated in 1 week if live mites or eggs are still present. </li></ul>
  31. 32. <ul><li>- Proper treatment of all fomites is essential. They may be washed and then dried for at least 10 minutes at 50 oC. dry cleaned or stored in closed plastic containers for 7 days. </li></ul><ul><li>- For patients, with crusted scabies permethrin, 5% is usually effective, but in those who are immunocompromised it may be necessary to combine the drug with the anthelmintic drug ivermectin. </li></ul>
  32. 33. Control <ul><li>- Personal cleanliness. </li></ul><ul><li>- Treatment of infected cases. </li></ul><ul><li>- Sterilization of clothes and bedding </li></ul>
  33. 34. 2- Family: Trombiculidae <ul><li>Genus: Leptotrombidium </li></ul><ul><li>Leptotrombidium akamushi </li></ul><ul><li>Leptotrombidium fletcheri </li></ul>
  34. 35. <ul><li>- L. akamushi and L. fletcheri and other species of leptotrobidium are vectors of scrub typhus ( Rickettsia tsutsugamushi ) in South Eastern Asia and Northern Australia. </li></ul>
  35. 36. <ul><li>- Other trombiculid mites, in Northern Europe Neotrombicula autumnalis, its larvae often attack people and are known as harvest mites . </li></ul><ul><li>- Larvae of trombiculids and often called red bugs, chiggers, scrub typhus mites or itch mites. </li></ul>
  36. 37. General characters: <ul><li>Adults: </li></ul><ul><li>- They are small mites (1-2mm) long. </li></ul><ul><li>- Reddish and covered dorsally and ventrally with numerous feathered hairs. </li></ul><ul><li>- There are 4 pairs of legs. </li></ul><ul><li>- The body is constricted between the third and forth pairs of legs. </li></ul><ul><li>- palps and mouth parts project in front of the body. </li></ul>
  37. 38. Trombicula akamushi larva and adult
  38. 39. <ul><li>Nymph: </li></ul><ul><li>- Resembles the adult but smaller and the body is less densely covered with feathered hairs. </li></ul><ul><li>- Neither the adults nor nymphs are of direct medical importance, they do not bite humans or animals but both are free living in the soil and feed on small arthropods and their eggs. </li></ul>
  39. 40. <ul><li>Larva: </li></ul><ul><li>- Very small (0.2mm) long. </li></ul><ul><li>- Reddish orange – rounded in shape. </li></ul><ul><li>- 3 pairs of legs. </li></ul><ul><li>- Mouthparts are large. </li></ul><ul><li>- Both legs and body are covered with fine </li></ul><ul><li>feathered hairs. </li></ul><ul><li>- It bears a dorsal plate or (scutum), at the level of the anterior two pairs of legs. </li></ul><ul><li>- A pair of eyes on either side of the scutum. </li></ul>
  40. 41. <ul><li>- Feathered hairs at its posterior margin. </li></ul><ul><li>- Larvae are ectoparasites of vertebrates (rodents, rabbits and occasionally man), feed on lymph, other fluid and semidigested materials. </li></ul><ul><li>- The larva feed on only one host in its life, it has no opportunity to transmit disease agent except to the next generation of mites </li></ul>
  41. 42. <ul><li>- mite live for about 6 months . </li></ul><ul><li>On people, larvae seek out areas where clothing is tight against the skin such as around the waist or the ankles. The leptotrombiduim vectors of scrub typhus remain attached to humans for about 2-10 days. </li></ul>
  42. 43. <ul><li>- Larva pierce the host's skin with their powerful mouthparts and inject saliva into the wound which causes disintegration of the cells. The repeated injection of saliva into the wound produces a skin reaction in the host and formation of a peculiar tube like structure which extends vertically downwards in the hosts skin which is known as the stylostome. The mite retains its mouthparts in the stylostome. </li></ul>
  43. 44. Life cycle: <ul><li>Eggs </li></ul><ul><li>Larvae </li></ul><ul><li>Nymphs </li></ul><ul><li>Adult </li></ul>
  44. 45. <ul><li>- Mating occurs in the soil. </li></ul><ul><li>- Female lays one to five spherical eggs/ day in the soil. </li></ul><ul><li>- In hot climates egg laying continues for a year or more, but in cooler areas of south-east Asia (Japan) oviposition ceases during the cooler months of the year and adults enter into hibernation. </li></ul>
  45. 46. <ul><li>- After about 4-7 days the egg shell split, but larva dose not yet emerge but remain within the eggshell and is called deutovum. </li></ul><ul><li>- After about 5-7 days the larva crawls out of the egg shell and usually becomes very active. </li></ul>
  46. 47. <ul><li>- Larva seek their hosts (birds, rodents and also people). </li></ul><ul><li>- The engorged larva drops to the ground and become inactive ( protonymph) </li></ul><ul><li>- After 7-10 days the protonymph moults to produce nymph. </li></ul><ul><li>- After a few day to about 2 weeks the nymph cease feeding and becomes inactive and is called a preadult, which after about another 14 days molts to give rise to an adult. </li></ul><ul><li>- The life cycle takes about 40-75 days. </li></ul>
  47. 48. Medical importance: <ul><li>(1) Chigger dermatitis: </li></ul><ul><li>- Several species of trombiculidae attack humans in many parts of the world. In northern Europe larvae of Neotrombicula autumnalis. Although such mites are not responsible for transmitting any disease, they can cause intense itching and irritation and a form of dermatitis known as scrub-itch or trombidiosis, commonly referred to as harvest-mite itch, autumnal itch </li></ul>
  48. 49. Chigger bite
  49. 50. <ul><li>- Larval mites commonly attack the legs. If they are forcibly removed their mouthparts, frequently remain embedded in the skin, cause irritation. </li></ul><ul><li>(2) Transmission of pathogens: </li></ul><ul><li>- Vector of scrub typhus ( tsutsu gamushi fever ) to man. </li></ul><ul><li>* Scrub typhus is limited to South Eastern Asia and Northern Australia. </li></ul><ul><li>* Organism : (Rickettsia tsutsu gamushi). </li></ul>
  50. 51. <ul><li>Mode of transmission: </li></ul><ul><li>- Bite of larva. - Transovarial transmission among mites. </li></ul><ul><li>Reservoir hosts : rodents and rabbits. </li></ul>
  51. 52. <ul><li>N.B . Larvae attach themselves to only a single host during their life cycle the disease cannot be spread by larvae feeding on one infected host (e.g. humans) and then another. The infection acquired by mites feeding on hosts with Rickettsiae is passed onto the free-living nymphal stages and then to the free-living adults. </li></ul>
  52. 53. <ul><li>When the female lays her eggs they are infected with Rickettsiae and this infection is passed onto the emerging larvae. So, larvae are infected and consequently transmit the disease to their hosts (humans or rodents) when they feed for the first and only time, this type of transmission called transovarial transmission. </li></ul>
  53. 54. Control: <ul><li>1 - Destroy breeding places by clearing grasses. </li></ul><ul><li>2- Spraying vegetation with acaricides to kill the adult and nymph. </li></ul><ul><li>3- Antirodent campaigns. </li></ul><ul><li>4- Personal protection using repellents as 1% lindane, ointment or pyrethrum. </li></ul>
  54. 55. 3- Family: Demodicidae <ul><li>Demodex folliculorum </li></ul><ul><li>Demodex infestation in human is known as demodecosis and occurs worldwide. </li></ul>
  55. 56. Characters and Bionomics: <ul><li>Adult </li></ul><ul><li>1 -Worm-like. </li></ul><ul><li>2 -is very minute (0.3 mm). </li></ul><ul><li>3 - The body is composed of a cephalothorax and an annulated abdomen. </li></ul><ul><li>4- The follicle mite of humans, is found particularly around the nose and eyes. </li></ul><ul><li>5 - All stages live in the same hair follicle and associated sebaceous gland. </li></ul><ul><li>6- They can move slowly in the skin especially during the night. </li></ul>
  56. 57. Life Cycle
  57. 58. Life cycle: <ul><li> The entire life cycle occurs within the follicles. </li></ul><ul><li> Female lays 20-24 eggs in hair follicles. </li></ul>
  58. 59. <ul><li> Eggs hatch to produce larvae. </li></ul><ul><li> Larva molt to nymphs. </li></ul><ul><li> Nymphs molt twice to become adults. </li></ul><ul><li> Life cycle is completed in 18-24 days </li></ul>
  59. 60. Pathogenesis: <ul><li>1 - Fibrous tissue reaction around the mites. </li></ul><ul><li>2- Dermatitis of the characteristic acne like appearance of hair follicles with black dots (due to the faces of mites) on the face. </li></ul><ul><li>3- It rarely cause pruritis. </li></ul><ul><li>4 - This mite is transmitted by direct contact. </li></ul>
  60. 61. Diagnosis <ul><li>By deep scraping and examining the extracted substance under the microscope. </li></ul>
  61. 62. Treatment: <ul><li>1- Cleanliness and washing. </li></ul><ul><li>2- Application of an acaricide as 1% lindane in cream massaged into the lesions. </li></ul>
  63. 64. <ul><li>House dust mites </li></ul><ul><li>( Dermatophagoides – skin eater) </li></ul><ul><li>- House dust mites are cosmopolitan in distribution. </li></ul><ul><li>House dust often contains allergenic mites. </li></ul>
  64. 65. <ul><li>General characters: </li></ul><ul><li>1- These mites are very small (0.2-0.3 mm long). </li></ul><ul><li>2- Adults are eight-legged creatures closely associated with us. </li></ul>
  65. 66. <ul><li>3- No eyes, no antennae, have mouth parts infront of the body and a tough , translucent shell, giving a &quot;fearsome appearance </li></ul><ul><li>4- The adult mite's cuticle has simple striations. </li></ul>
  66. 69. Bionomics: <ul><li>* House dust mites are not parasitic and do not bite. </li></ul><ul><li>* Dust mites prefer warm moisted surroundings such as the inside of a mattress, bedroom carpets, stuffed furniture and pillow. </li></ul>
  67. 70. <ul><li>Highest mite densities occur in hot humid summer months. They die at lower humidity less than 50%. </li></ul><ul><li>* They feed on human skin scales (shedding of dead skin during sleep). Also, feed on animal dander, pollen, fungi and bacteria. </li></ul><ul><li>* Life span of dust mite is one to three months. </li></ul>
  68. 71. <ul><li>Life cycle : </li></ul><ul><li>EGG LARVA NYMPH ADULT   </li></ul><ul><li>EGG </li></ul><ul><li>- Cream in colour </li></ul><ul><li>- Coated with a sticky substance </li></ul><ul><li>  </li></ul>
  69. 72. <ul><li>They breed in the skin scales that accumulate in human habitations. </li></ul><ul><li> Female lays 40-80 eggs singly or in small groups. </li></ul><ul><li> The whole life cycle takes about one month under optimal conditions. </li></ul>
  70. 73. <ul><li>Medical importance: </li></ul><ul><li>- It produce the most important allergens causing allergic diseases in human. </li></ul><ul><li>Causative agent: </li></ul><ul><li>Dust mites are strongly allergenic materials (their tiny faeces and body fragments). They are components of dust. </li></ul>
  71. 74. <ul><li>Mode of infection: </li></ul><ul><li>By airborne and inhalation of dust contains mites and their faeces when dust is disturbed. </li></ul><ul><li>Clinical picture: </li></ul><ul><li>Symptoms are usually respiratory in nature (Sneezing, itching, watery eyes and wheezing). </li></ul>
  72. 75. <ul><li>Diagnosis: </li></ul><ul><li>Laboratory: Collect dust samples from mattresses, carpets then examine microscapically to detect dust mites. </li></ul><ul><li>Control measures: </li></ul><ul><li>First: Reduction of dust mite populations: </li></ul><ul><li>1- Reduce humidity levels inside home especially in the bed room. In hot humid summer, air condition reduces both temperature & humidity, thus reduces house dust mites. </li></ul>
  73. 76. <ul><li>2- Wash all beddings weekly. </li></ul><ul><li>3- Exposure of bedlinen to sunrays. </li></ul><ul><li>4- treat the carpets and beds with insecticides, followed by thorough vacuum cleaning to remove dead mites and their faeces. </li></ul><ul><li>Second: Reduce exposure to dust by regular, thorough vacuuming of carpets, furniture and other home furnishings. </li></ul>
  74. 78. Immunology Of Scabies <ul><li>Introduction </li></ul><ul><li>Indirect evidence raised the possibility of cross-reactivity between scabies mites and the allergy-causing house dust mites Dermatophagoides pteronyssinus (DP) and Dermatophagoides farinae (DF) as some scabies patients who were RAST positive to DP and had high levels of serum IgE showed reduced concentrations of specific antibodies to DP and totoal IgE after treatment for scabies infestations . </li></ul>
  75. 79. <ul><li>Also, protective immunity against scabies mites was induced by vaccination with an extract of DP and DF . </li></ul><ul><li>This cross reactivity creates difficulties in understanding the immune response to scabies in humans since the prevalence of dust mite sensitivity is high and dust mites are common in homes in humid geographical areas . </li></ul>
  76. 80. Immune Reactions To Scabies Antigens <ul><li>The host's immune responses to antigens from scabies mites developing through five phases. These phases included : </li></ul><ul><li>Induction </li></ul><ul><li>Delayed hypersensitivity </li></ul><ul><li>Delayed and immediate and late phase hypersensitivity </li></ul><ul><li>Immediate hypersensitivity </li></ul><ul><li>Desensitization </li></ul>
  77. 81. Phase I Induction <ul><li>There is no response to skin test with scabies mite extract and clinical signs of scabies infestations are not evident, But antigen presenting cells have recognized and begun processing antigenic material. The first manifestations in human may not exhibit clinical signs for 4 to 8 weeks depending on the severity of the infestation . </li></ul>
  78. 82. Phase II Delayed hypersensitivity <ul><li>The cell mediated reaction to scabies antigens is characterized by amixed cellular infiltrate consisting of lymphocytes ( T cells, B cells, Plasma cells ) , histocytes ( macrophages ) , esinophils and neutrophils in the deep dermis, superficial dermis and prevascular areas . </li></ul><ul><li>Scabies induced a circulating IgE response, IgM, IgG and low secretory IgA in skin secretion . </li></ul>
  79. 83. Phase III Immediate, delayed and late hypersensitivity <ul><li>Immediate reactions are local allergic responses triggered by binding of antigen to IgE that is already bound to receptors on the surfaces of the mast cells in the dermis . </li></ul>
  80. 84. <ul><li>The Capacity to express delayed hypersensitivity reactions by skin testing develops earlier than the capacity to express immediate hypersensitivity phase reactions . </li></ul><ul><li>Histologically, late phase reactions are characterized by a mixed cellular infiltrate containing eosinophils, neutrophils and CD4+ T cells and no immunoglobulin or complement . </li></ul>
  81. 85. Phase IV Immediate hypersensitivity <ul><li>Skin tests result only in immediate reactions that are manifested within 10-20 minutes in sensitized individuals . </li></ul>
  82. 86. Phase V Desensitization <ul><li>Immunity has been induced so that no hypersensitivity occurs on exposure to the antigen . </li></ul><ul><li>Desensitization (protective immunity) occurs by down-regulating T-cell receptors . </li></ul><ul><li>And the cell mediated response is the primary mechanism responsible for protective immunity and Th1 system (cell mediated) is more up-regulated in protected hosts while Th2 system (humoral) is more up-regulated in non-resistant hosts . </li></ul>
  83. 87. Serum Antibody <ul><li>There is evidence that scabies infestations are associated with humoral immunological response . </li></ul><ul><li>Scabies antigens induce an IgM and IgG response in most cases and these are independent of an IgE response . </li></ul><ul><li>There may or may not be an IgE response to scabies . </li></ul><ul><li>Low serum IgA is associated with scabies infestation . </li></ul>
  84. 88. <ul><li>Circulating IgG or IgM antibody-antigen complexes have not been found . </li></ul><ul><li>Serum C3 and C4 concentrations are not increased during infestation . </li></ul><ul><li>Presence of C3 deposits and antibodies in the tissues near the scabietic lesions suggests that the alternative pathway is activated during scabies infestations . </li></ul><ul><li>Finding circulating antigen-antibody complexes after treatment for scabies suggests that the classical pathway is activated later . </li></ul>
  85. 89. Protective Immunity <ul><li>Resistance to reinfestation with scabies following an initial infestation has been demonestrated because secondary infestation showing lower antibody titres and concentrations of serum complement C3 paralleled to changes of circulating antibodies . </li></ul><ul><li>So, vaccination against scabies is possible . </li></ul>
  86. 90. THANK YOU