1. Ectoparasitic Arthropods: lice, fleas, ticks and mites

2. Biology of Louse- Anoplura
Lice are highly specialized insects based on the host species and many species specifically only feed on certain areas of their host's body. As lice spend their whole life on the host they have developed adaptations which enable them to maintain a close contact with the host.

3. These adaptations are reflected in their size (0
These adaptations are reflected in their size (0.5–8 mm), stout legs, and claws which are adapted to cling tightly to hair, fur and feathers, wingless and dorsoventrally flattened.

4. Types of Lice
Three types of lice infest humans: the body louse, Pediculus humanus humanus Linnaeus, also known as Pediculus humanus corporis; the head louse Pediculus humanus capitis De Geer; and the crab louse (or pubic louse), Pthirus pubis (Linnaeus) .

5. Head louse

6. Pubic louse

7. Body Louse

8. Head lice and body lice are morphologically indistinguishable, although head lice are smaller than body lice. Head lice and pubic lice are highly dependent upon human body warmth and will die if separated from their host for 24 hours. Body lice are more hardy since they live on clothing and can survive if separated from human contact for up to a week without feeding.

9. Biology
Lice have simple or gradual metamorphosis. The immatures and adults look similar, except for size. Lice do not have wings or powerful jumping legs so they move about by clinging to hairs with claw-like legs. Head lice prefer to live on the hair of the head although they have been known to wander to other parts of the body.

10. Head lice do not normally live within rugs, carpet, or school buses
Head lice do not normally live within rugs, carpet, or school buses. Body lice live in the seams of clothing, generally where it touches the skin, and only contact the body to feed, usually holding on to the clothing while they do this. However, sometimes they will move to the body itself.

11. The eggs of lice are called nits
The eggs of lice are called nits. They are oval white cylinders (1/16 inch long). The eggs of head lice are usually glued to hairs of the head near the scalp. The favorite areas for females to glue the eggs are near the ears and back of the head. The eggs of body lice are laid on clothing fibers and occasionally on human body hairs.

12. Nits- Eggs of Louse

13. Under normal conditions the eggs will hatch in seven to 11 days
Under normal conditions the eggs will hatch in seven to 11 days. The young lice which escape from the egg must feed within 24 hours or they will die. Newly hatched lice will periodically take blood meals and molt three times before becoming sexually mature adults. Normally a young louse will mature in 10 to 12 days to an adult (1/8 inch in length). Adults range in color from white to brown to dark gray.

14. Female lice lay six to seven eggs (nits) per day and may lay a total of 50 to 100 eggs during their life which may last up to 40 days. Adults can only survive one to two days without a blood meal. The nymphs and adults all have piercing-sucking mouthparts which pierce the skin for a blood meal. The reaction of individuals to louse bites can vary considerably.

15. Both the immature or nymphal forms and adult lice feed on human blood
Both the immature or nymphal forms and adult lice feed on human blood. To feed, the louse bites through the skin and injects saliva which prevents blood from clotting; it then sucks blood into its digestive tract. Bloodsucking may continue for a long period if the louse is not disturbed. While feeding, lice may excrete dark red feces onto the skin.

16. Head lice should be suspected when there is intense itching and scratching of the scalp and the back of the neck or when there is a known infestation in the community. Close examination of the scalp will reveal small, whitish or dark eggs (nits) firmly attached to hair shafts, especially at the nape of the neck and above the ears.

17. Inspection may reveal active lice and many itchy, red marks resulting from irritation caused by the saliva of the louse. Although dandruff may resemble eggs, it can be removed easily from hair, whereas louse eggs are attached firmly to the hair with cement secreted by the louse and cannot be removed easily by pulling.

18. When an infestation becomes known, it is advisable to examine all members of the family, especially other children, and others who have been in contact with the infested person within recent weeks to be sure that they have not become infested.

19. Body lice are found in tight-fitting sites or seams of clothing, usually close to the skin. Only in heavy infestations will body lice be seen on other layers of clothing. Infestations usually occur where humans continuously wear several layers of clothing due to inadequate heating or during periods of war or natural disasters.

20. Louse infestations may also occur in poorly managed nursing homes, and among the poor and homeless. The main reasons for these infestations are the failure to change garments and/or inadequate laundering.

21. Disease Transmission
The body louse is the vector of three human diseases -- epidemic or louse-borne typhus, caused by Rickettsia prowazeki de Rocha-Lima; trench fever, caused by Rochalimaea quintana (Schmincke) Krieg (long known as Rickettsia quintana); and louse-borne relapsing fever, caused by Borrellia recurrentis

22. Although head lice have been experimentally infected with Rickettsia prowazeki, neither head lice nor pubic lice have been implicated directly in active disease transmission (Roy and Brown 1954). Although body lice may pose the most serious health threat in many countries, head lice appear to be the greatest nuisance, particularly among school children in highly developed countries where their presence is considered intolerable.

23. Lice feed on skin (epidermal) debris, feather parts, sebaceous secretions and blood. A louse's colour varies from pale beige to dark grey; however, if feeding on blood, it may become considerably darker.
A louse egg is commonly called a nit. Lice attach their eggs to their host's hair with specialized saliva which results in a bond that is very difficult to separate without specialized products.

24. Lice and humans
Humans are unique in they host three different kinds of lice: head lice, body lice (which live mainly in clothing), and pubic lice. The DNA differences between head lice and body lice provides corroborating evidence that humans started wearing clothes approximately 72,000 years ago [1].

25. Recent DNA evidence suggests that pubic lice spread to the ancestors of humans approximately 3.3 million years ago from the ancestors of gorillas by sharing the same bed or other communal areas with them, and are more closely related to lice endemic to gorillas than to other lice species infesting humans [2].

26. Fleas B. Siphonaptera: fleas ( Pulgas )
Characteristics Fleas are small, wingless insects ranging in size from approximately 1-10 millimetres in length depending on the species. Almost everybody, especially those with cats or dogs will be familiar with these small biting insects and will have either seen them or the effects of their nuisance bites. Fleas can be recognised by the following features

27. A Typical Flea

28. Laterally compressed bodies
Piercing-sucking mouthparts
Enlarged hind legs adapted for jumping
Strong tarsal claws adapted for holding onto their hosts
Backward pointing hairs and bristles for ease of movement through the hair of a host
Small antennae which tuck away into special groves in the head

29. Life Cycle Fleas mate on their host animal and lay their eggs either onto the animal where they fall to the nest or directly in the nest. The small larvae hatch from the eggs and do not begin to feed on blood like that of their parents but consume the dead skin and other dirt and dust from the host animal.

30. The larvae develop through 3 instars and when fully grown spin a silken cocoon and pupate in the nest of the host. The vibrations of a host often trigger the emergence of the adult flea from the pupal case, enabling it to immediately find a host and begin feeding. The complete life cycle may take from several weeks to many months depending on the species.

31. Feeding Adult fleas feed on the blood of their host and although most fleas are adapted to one particular animal, many are not host specific and will move to other animals if their preferred host is unavailable. Fleas are very adaptable and are also able to withstand unfavourable conditions and can live for many days without food.

32. Habitat Fleas are always found close by their hosts, either in direct contact such as among the feathers or hair or within their nests. Fleas are found in almost all habitats in Australia where there is a ready host and many native species of flea are closely associated with native marsupials and rodents.

33. The main introduced species are also associated with animals that have been introduced to the country such as the cat flea (Ctenocephalides felis) the dog flea (Ctenocephalides canis) and the rat flea (Xenopsylla cheopis).

34. TICKS- GARAPATA

35. TICKS (GARAPATA) C. Ticks ( Garapata )
Ticks are blood feeding external parasites of mammals, birds, and reptiles throughout the world. Approximately 850 species have been described worldwide (Furman and Loomis 1984). There are two well established families of ticks, the Ixodidae (hard ticks), and Argasidae (soft ticks)

36. Both are important vectors of disease causing agents to humans and animals throughout the world. Ticks transmit the widest variety of pathogens of any blood sucking arthropod, including bacteria, rickettsiae, protozoa, and viruses.

37. Some human diseases of current interest in the United States caused by tick-borne pathogens include Lyme disease, ehrlichiosis, babesiosis, rocky mountain spotted fever, tularemia, and tick-borne relapsing fever.

38. Hard Ticks: Family Ixodidae
Hard ticks have three distinct life stages. Larvae which emerge from the egg have six legs. After obtaining a blood meal from a vertebrate host, they molt to the nymphal stage and acquire eight legs. Nymphs feed and molt to the next and final stage - the adult, which also has eight legs

39. After feeding once more, the adult female hard ticks lay one batch of thousands of eggs and then die. Only one blood meal is taken during each of the three life stages. The time to completion of the entire life cycle may vary from less than a year in tropical regions to over three years in cold climates, where certain stages may enter diapause until hosts are again available.

40. The mouthparts of hard ticks are readily visible from above
The mouthparts of hard ticks are readily visible from above. There are three visible components: the two outside jointed parts are the highly mobile palps; between these are paired chelicerae, which protect the center rod-shaped structure, the hypostome.

41. The palps move laterally while the tick is feeding and do not enter the skin of the host. The rough hypostome has many beak-like projections on it. This is the structure which plunges into the host's skin while feeding.

42. The backward directed projections prevent easy removal of the attached tick. In addition, most hard ticks secrete a cement-like substance produced by the salivary glands which literally glues the feeding tick in place; the substance dissolves after feeding is complete.

43. Hard ticks seek hosts by an interesting behavior called "questing
Hard ticks seek hosts by an interesting behavior called "questing." Questing ticks crawl up the stems of grass or perch on the edges of leaves on the ground in a typical posture with the front legs extended, especially in response to a host passing by.

44. Certain biochemicals such as carbon dioxide as well as heat and movement serve as stimuli for questing behavior. Subsequently, these ticks climb on to a potential host which brushes against their extended front legs

45. Hard ticks are most commonly collected for research by the use of "flags" or "drags" which are made from 1 m square pieces of roughly textured fabric such as fleece or flannel attached to a rod handle.

46. The flags are slowly dragged across the surface of vegetation to collect questing ticks. Hard ticks feed for extended periods of time on their hosts, varying from several days to weeks, depending on such factors as life stage, host type, and species of tick. The outside surface, or cuticle, of hard ticks actually grows to accommodate the large volume of blood

47. SOFT TICKS -ARGASIDAE
The life stages of soft ticks are not readily distinguishable. The first life stage to come out of the egg, a six legged larva, takes a blood meal from a host, and molts to the first nymphal stage.

48. Unlike hard ticks, many soft ticks go through multiple nymphal stages, gradually increasing in size until the final molt to the adult stage. Some soft ticks pass through up to seven nymphal molts before they become adults

49. Soft ticks feed several times during each life stage, and females lay multiple small batches of eggs between blood meals during their lives. The time to completion of the entire life cycle is generally much longer than that of hard ticks, lasting over several years. Additionally, many soft ticks have an uncanny resistance to starvation, and can survive for many years without a blood meal

50. The mouthparts of soft ticks are are not readily visible from above
The mouthparts of soft ticks are are not readily visible from above. There are three visible components: the two outside jointed parts are the highly mobile palps; between these are paired chelicerae, which protect the center rod-shaped structure, the hypostome.

51. The palps move laterally while the tick is feeding and do not enter the skin of the host. The rough hypostome has many beak-like projections on it. This is the structure which plunges into the host's skin while feeding. The backward directed projections prevent easy removal of the attached tick.

52. Some soft ticks seek hosts by questing on low-lying vegetation, but the vast majority are nest parasites, residing in sheltered environments such as burrows, caves, or nests. Certain biochemicals such as carbon dioxide as well as heat and movement serve as stimuli for host seeking behavior. Soft ticks feed for short periods of time on their hosts, varying from several minutes to days, depending on such factors as life stage, host type, and species of tick

53. The feeding behavior of many soft ticks can be compared to that of fleas or bedbugs, as once established, they reside in the nest of the host, feeding rapidly when the host returns and disturbs the contents.

54. The outside surface, or cuticle, of soft ticks expands, but does not grow to accommodate the large volume of blood ingested, which may be anywhere from 5-10 times their unfed body weight

55. MITE-BIOLOGY
Mites are not insects; they are more closely related to ticks and spiders. Most mites are visible to the unaided eye and usually measure 1/8" or less in length. Their life cycle has four basic stages: egg, larva, nymph and adult.

56. The egg hatches into a larval stage, which molts to the nymphal stage
The egg hatches into a larval stage, which molts to the nymphal stage. After 1-2 more times, the nymph matures to an adult. Mites, like ticks, have three pairs of legs as larvae and four pairs of legs as nymphs and adults.

57. Sarcoptes scabie- a typical mite

58. SARCOPTES SCABIE
Sarcoptes scabiei, commonly known as the scabies, mange or itch mite, is a parasite of humans and other animals. Scabies mites are host-specific. The varieties of scabies that infest domestic animals can penetrate the skin of humans and cause the typical itching and rash, but they cannot complete their life cycles there. The adult female burrows into the outer layer of the skin (epidermis) where she feeds on tissue fluids and lays eggs that she cements to the floor of the burrow

59. Females lay eggs at a rate of up to 3 per day for a period of 8 weeks, producing about 200 eggs over her lifetime. These eggs hatch in 3-4 days and the newly-hatched larvae emerge from the burrows onto the surface of the skin and molt to form the first nymphal stage.
The rash and intense itching associated with scabies occurs when the nymphs burrow into the skin and begin feeding

60. These symptoms usually appear several weeks to a month after the initial infestation. The majority of mites are found in lesions in folds of skin between the fingers, on the sides of the feet, on the wrists and genitals, and in the bends of the knees and elbows. After feeding on tissue fluids, the nymphs molt to become adults

61. The life cycle, from egg to adult, can be completed in about two weeks
The life cycle, from egg to adult, can be completed in about two weeks. Scabies mites are readily transmitted within families and within institutions such as nursing homes. Personal contact, particularly holding or shaking the hands of an infested person, is a principal method by which the mites are spread. Intimate contact and sleeping with an infected person can also spread the mites.