Medical Arthropods

1. Medical Arthropods

2. Most Successful Animals • The Phylum Arthropoda contains more than 85% of know animal species • Over one million modern species recorded. • They exist in marine, freshwater, terrestrial and even aerial areas.

3. Arthropods: A success story They have been around for more than 500 million years and are still evolving. They live on Earth in overwhelming numbers. There have come in all shapes and sizes. They have evolved to fill a variety of ecological niches — from tiny internal parasite to giant bird-eating predator.

4. Arthropods are the REAL rulers of the Earth Behold, thecrownprince of the animal kingdom

5. From delicious to disgusting

6. Some familiar faces

7. Definition Medical Arthropods are those animals that do harm to human health so as to have close relationship with medicine. Arthropods influence human being not only as hosts of parasitic organisms and vectors of a wide variety of pathogens but also as direct causes of tissue damage and disease.

8. Class insecta: mosquitoes ,fly,sandfly,flea,louse…… • Class Arachnia: tick(hard tick and soft tick),mite……

9. Bilateral (left/right) symmetry

10. Segmented body

11. Exoskeleton made of chitin

12. Exoskeleton restrains how much body weight can be allowed

13. To outgrow the exoskeleton, arthropods molt (Ecdysis)

14. Many pairs of appendages

15. Arthropods have open circulatory system

16. Which of the following are arthropods?

17. Life cycle • The life cycle of arthropods is metamorphosis. • This means "change of body form and appearance". An insect's outer coating is hard, so it can't stretch when an insect grows. The coating must split, with a new larger one appearing underneath. The new coating is sufficiently large to allow the animal to grow underneath. • There are two types of metamorphosis -- complete and incomplete

18. Life cycle 1. Incomplete metamorphosis: Egg → Nymph → Adult. • The insects hatch from their eggs looking like miniature adults. These young insects are called nymphs. As they grow, they shed their skin several times before they become adults.

19. Life cycle 2. Complete metamorphosis: Egg → Larva → Pupa → Adult. • As the insect grows, its shape changes completely. During the pupal (chrysalis) stage, the body undergoes a complete reorganisation, transforming into the adult. As the larva looks completely different from the adult, this is termed complete metamorphosis.

20. Direct damage Envenomization

21. Direct damage Hypersensitivity to cockroach allergen among children with bronchial asthma Asthma morbidity increase every year, especially among children. 160 children, age 4-17, with bronchial asthma, were participated in this study. The most common allergen (by skin test) was dust mite 51.3%, followed by pollen 48.8% and cockroach（蟑螂） allergen 24.3%. Children with cockroach hypersensitivity have severe asthma more often than children with dust and pollen sensitivity. Cockroach allergen is very important factor of sensitivity, next to dust mites and pollen.

22. Direct damage Scab mites– parasite

23. Global estimates of human mortality caused by arthropod-borne diseases Catherine AH,et al. Nature Review / Microbiology 2005; 3:262-268

24. Principles of control The control of arthropods is a complicated procedure. It must be the combination of several methods: 1. Environmentalprevention Reconstruction of environment so that the environment is not fit for the growth of the arthropods

25. Principles of control 2. Mechanical prevention – screening, nets. 3. Chemical prevention – insecticides (side effects) 4. Biological prevention – natural enemies, genetic measurement, introduction of insecticide-sensitive genes, pathogen-resistance gene, RNAi

26. INSECTS General Introductions: The class Insecta includes many forms that are blood feeders on man and can thus transmit many important parasitic and other infectious diseases. It is the most important part of Medical Arthropods.

27. INSECTA Ecto-morphology A pair of complex eyes A pair of antennae Head Biting mouth part Piercing and sucking mouth parts Lapping mouth parts mouth Insect Prothorax The thorax bears three pairs of legs and two pairs of wings Thorax Mesothorax Metathorax 11 segments. The ecto-reproduction organ also locate in the abdomen Abdomen

28. Life cycle Egg → Larva → Pupa → Adult

29. Ecology 1. Breeding places: All type of water 2. Hiding and resting places 3. Feeding: female suck blood 4. Seasonal distribution: >10℃.

30. Mosquito Control 1. Elimination of breeding place • The most effective method of mosquito control • modification of the aquatic sites in which the mosquitoes breed 2. Individual protection 3. Insecticides 4. Biological control

31. Fly • Morphology • 1) Head: a pair of compound eyes and three single eyes, a pair of antenna; the mouthparts is lapping type or sponging type, a few species have sucking type mouthparts. • 2) Thorax: The thorax bears three pairs of legs and a pair of wings. Each leg terminates has a pair of claws（爪） and a pair of pupvilli（爪垫）. These specific structures can carry the pathogens. • 3) Abdomen: There is external reproduction organ, which can be as a specific feature for identifying the species of fly.

32. Fly 1. According to their mouth parts, flies may be classified into: (1)piercing and sucking type- blood sucking, Glossina (2)sponging and lapping type- this type is much more common and important

33. There are 5 families of lapping flies that are important to human health.

34. Musca:no metallic colour, but there are 4 longitudinal striations on the dorsal side of thorax Lucilia:green metallic colour, white buccal regions Chrysomyia:metallic colour, a pair of red compound eyes Calliphora:blue metallic colour, covered by hairs Sarcophagidae :no metallic colour, the chessboard-like spots on the dorsal abdomen

35. Life cycle • It belong to complete metamorphosis, the development stages contains eggs, larvae, pupae and adults.

36. Habit They have dirt habits of feeding indiscriminately（不加区分） on both excreta and foods, and excreting and regurgitating（吐出） their partially digested meals over food. These specific eating behaviors are main causes of transmitting diseases by flies.

37. Principle of Control • Eradication of breeding places • Personal protection

38. Sandfly Morphology

39. Sandfly and Diseases • Transmit Leishimaniasis(利什曼病)

40. Human flea Without wings; Compressed laterally; Three pairs of legs

41. Louse (male) Head ,thorax,abdomen; Without wing; Flattened dorsaventrally; (male)The terminal segment is V-shaped

42. Louse (female) The terminal segment is W-shaped

43. Phthirus pubis (female ) Crablike; the thorax is broader than the abdomen; the two posterior pairs of legs are stronger , usually inhabit pubic hairs, eye lash, eyebrows.

44. Phthirus pubis(male)

45. Arachnida No antennae and no wings. They have a two-segmented body, cephalothorax（头胸部） and abdomen . In ticks and mites, the body consist of gnathosoma（颚体）and idiosoma（躯体）.

46. Hard tick (schematic diagram) The body is divided into two regions: the cephalic-thorax and abdomen region, or the two may be fused; Without antenna; With 4 pairs of legs in adult

47. Hard tick： male female Scutum is large and covers the entire dorsal surface of idiosoma in the male, while scutum is small and covers the anterior part in the female.

48. 软蜱示意图 Soft tick Gnathosoma is invisible in dorsal view Pedipalps(palps) :long, nimble Dorsal side of idiosoma :Without scutum Distinction between female and male: difficult

49. TICKS 2. Life and cycle Nymph Larvae Egg Adult Long life cycle, it may last for several years All the larvae, nymph and adult take blood meal Tick change host in their life cycle (mouse, cow, human ) One host tick; Two host ticks; Three host ticks

50. Trombiculid mite (Chigger) 1. Morphology of the larva Very small; reddish or orange in color Three pairs of legs Dorsal and ventral hairs Dorsal scutum Only larva stage is parasitic