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Medical Parasitology

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Arthropod

Medical Arthropod Introduction

Class Insecta Class Arachnida End

Introduction • Arthropod ： 1 million species of Arthropods, occupying 85% of animal species ； most of them lead free living, very few are parasites • Medical Arthropods ： meaning those arthropods which do harm to human health in direct way or indirect way

1. Harms by Medical Arthropods （ 1 ） Direct way

• Sucking blood, annoyance, sting, poison, allergenic effects, parasitizing, etc. （ 2 ） Indirect way • Mechanical transmission • Biological transmission

2. Classification • • • • •

Class insecta: mosquito, fly, flea, lice, etc Class Arachnida: mite, tick,spider,scorpion Class Crustacea: crab, shrimp, crayfish Class Chilopoda: centipede Class Myriopoda: diplopod

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Class Insecta 1. Morphology • Head ： antenna, compound eyes,simple eyes, mouthpart • Chest ： 3 pairs of feet ， 0~2 pairs of wings • Abdomen ： segmented, no more than 11 S. 2. Life cycle • Complete metamorphosis • Incomplete metamorphosis

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蚊

(mosquitoes)

1. Morphology Head: antenna, compound eyes, mouthpart Chest: 3 pairs of feet, 1 pairs of wings Abdomen ： 11 segments Morphological difference of 3 genera

2. Life cycle Complete metamorphosis • • • •

egg larva pupa adult

3. Zoology • • • •

Breeding place: Feeding: Mating: group dancing Inhabiting: homekeeping, half-homekeeping, wild • Hibernation: • Life span: male,1-3 w; female longer • Rang of flight: 500 m long and 300 m high

4. Harms by mosquitoes • Sucking blood of man • Causing allergic reaction • Transmitting diseases Malaria, filariasis, cephalitis, dengue fever,etc

5. Control • Elimination of breeding places • Insecticides • Biological control (bat, fish, Bacillus thuringiensis) • Individual protection • Control with help of laws

蝇 (flies)

Flies 10 000 species in total, 1 600 in China

1. Morphology • Head ： 2 compound eyes ， 3 simple eyes ， 1 mouthpart • Chest ： a pair of wings, 3 pairs of feet, ungual mat • Abdomen: 4 – 5 segments

2. Life cycle Complete metamorphosis • • • •

Egg Larva (maggot) Pupa Adult

3. Zoology • Breeding place • Feeding • Habitat • Hibernation

4. Harms 4.1 Transmission of disease • Mechanical transmission ： dysentery, cholera, hepatitis, paratyphoid, parasitic infection, etc • Biological transmission ： tzetze fly transmits trypanosomiasis

4.2 Myiasis • • • •

Gastrointestinal myiasis: Housefly Ocular myiasis: Oestrus ovis Dermal myiasis: Hypoderma lineatum myiasis of ear, pharynx, mouth and nose ： Housefly, Chrysomyia megacephala • Genitourinary myiasis: housefly • Myiasis in cutaneous injury: housefly

蚤

(fleas)

Fleas 2500 species in total, 640 in China 1. Morphology • 3 mm long, brownish yellow • Head ： 2 simple eyes, a sharp mouthpart • Chest ： 3 pairs of feet • Abdomen ： 10 segments

2. Life cycle Egg

Adult

Larva

Pupa

3. Zoology • Breeding place • Habits: Sucking blood Great capacity of enduring hunger A talent for jump

4. Harms • • •

plague Murine typhus Tapeworm disease

虱 (lice)

1. Morphology 2 groups ： Pthirus pubis and Pediculus humanus

Pthirus pubis

P. humanus

2. Life cycle

(Incomplete metamorphosis)

Egg

Nympha

Adult

3. Habits • Breeding habit • Suck blood • Sensitive to temperature • Sensitive to humidity • Transmitted between persons

4. Harms 1. Dermal pruritus and papilla 2. Transmission of disease • Epidemic typhus (Ship fever) • Louse-borne relapsing fever

臭 虫 (bedbug)

Bedbug 1. Morphology • oval shaped ， reddish brown, 4 -6 mm long • having 1 pair of compound eyes, sharp mouthpart, no wings, 8 segments in abdomen

2. Life cycle and Habits • Incomplete metamorphosis • Like to infest in bed board, bedding, mat, and gaps in desk, wall, floor board during daytime, suck blood at night • Strong resistance against hunger • Not bear high temperature

3. Harms • Suck blood • Disturbance

白 蛉 (sandfly)

Sandfly 1. Morphology ： grayish white, 1.5-4.0 mm

long, having many hairs, a sharp mouthpart, 2 black compound eyes 2. Habits ： larvae in soil; female suck blood at night;housekeeping group and wild group; group dancing 3. Harms ： sting man and suck blood; transmit black fever Back

蜱 (ticks)

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Tick • Adult body ： 2 parts, idiosoma and gnathosoma; 2-10 mm long • 2 groups ： hard ticks and soft ticks Hard tick: 1 scutum,2 eyes Soft tick: no scutum, most no eyes

• Inhabitation ： bosk; bushwood; cavity • Life cycle: egg, larva, nymphae, and adult • Feeding: Larva, nymphae and adult • Attack object ： mammals and aves • Attack time ： daytime • Attack region ： perform selectivity

Harms by ticks • • • •

Sucking blood Local infection Tick paralysis Transmission of diseases Forest encephalitis, Xingjiang haemorrhagic fever, Q fever, relapsing fever, Lyme disease

蠕形螨 (follicle mite)

• Morphology: Cylindrical, milk white, semitransparent, 0.15-0.30 mm long • Life cycle: egg, larva, nymphae and adult • Habitat: Parasitize human follicle and sebaceous gland • Habits: Sensitive to temperature

Harms Cause folliculitis, acne, bottle nose (a nose to light candles), dermatitis, etc

Prevention • Diagnosis the cellophane tape method; skin scraping method • Treatment: external use of Metronidazole or take orally • Prevention

疥螨 (itch mite)

Sarcoptes scabiei • Morphology: Nearly round, milk white, female 0.3-0.5 mm long • Life cycle: egg, larva, nymphae and adult • Habitat: Live in keratoderma, dig tunnel • Feeding: on cutin and lymph fluid • Mating: at night • Habit: Enjoy low temperature, and high humidity

Harms and Prevention • Pathogenesis: mechanical irritation,allergic reaction, secondary infection • Symptom ： papilla, nodules,bleb, purulence, tunnels, itching (more serious at night) • Dignosis: found tunnel and adults • Epidemiology: children, live in collectivity, fans in internet • Treatment: Sulfureous ointment, Ivermectin • Prevention:

尘螨 (dust mite)

• Oval, slight yellow, 0.17-0.50 mm long

Dust mite • Life cycle: egg, larva, nymphae and adult; free living • Feeding habit: powder food supply, animal’s scurf, dust of flower, mycete,etc • Harms ： cause allergic reaction • Prevention ： reduce contact with these allergens; Back

The end ， thanks ！

蝎 (scorpion)

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蜈蚣 (centipede)

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Antenna

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Compound Eyes

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Proboscis 1: labrum 2,3: maxilla 5,7: mandible

1

4: labium 6: hypopharynx

2 3 4

5 7 6

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Mouthpart

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3 genera of mosquitoes

Anopheles

Culex

Aedes Back

Life cycle of mosquito

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Adult Egg Pupa Larva

Compound Eyes

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Compound Eyes

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Mouthpart

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Ungual Mat

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Life Cycle

Pupa

Egg

Maggot Back

Egg

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Maggot

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Pupa

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Housefly

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Chrysomyia megacephala

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Oestrus ovis

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Sarcoptes scabii

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Scabies

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Scabies

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Scabies

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Scabies

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