Medical Arthropodology Department of Parasitology Xiang-Ya School of Medicine.
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Transcript of Medical Arthropodology Department of Parasitology Xiang-Ya School of Medicine.
Arthropod species , about a few hundred million, accounting for
dynamic 87% of the total number of material types, hazard to
human health is only a tiny minority.
Medical arthropods (mainly medical insects) refer to those
arthropods with medical importance;
Parasitic arthropods are those being able to either directly impair
to human health by their toxic substances or indirectly harm
through spread of pathogens.
I Concepts
I Concepts
Medical arthropodology or Medical
entomology is to research on:
morphological characters, classification, life cycle,
ecology, geographical distribution, pathogenesis,
regularity of disease transmission and control
strategies of medical pests
The most harmful pests in China are mosquito, fly and cockroach.
Medical arthropods closely related with human
life include: mosquito, fly, sandfly, flea, louse,
cockroach, bed bug, hard tick, soft tick, gamasid
mite, itch mite, follicle mite, etc.
I Concepts
II Main conmmon characters of arthropods Bilaterally symmetric;
Segmented body with appendageson each segment;
Covered by exoskeleton made out of chitin, a
polysaccharide, and quinone tanned protein;
A dorsal heart with open circulatory system (also named
as hemocele) containing blood haemolymphand a nervous
system on the ventral side of body;
Molting (ecdysis ) and metamorphosis during
development history
Phylum Arthropoda
Arachnida: hard ticks, soft ticks, itch mites, chigger mites, gamasid mites, follicle mites, dust mites, etc;
Crustacea: crabs, shrimps, cyclops, diaptomus, etc;
Chilopoda: centipedes, etc;
Diplopoda: millipedes, etc.
III Classification of Arthropods
Insecta: mosquitoes, flies, sandflies, fleas, black flies, biting midges, tabanid flies, lice, cockroaches, bedbugs, etc;
2 Arachnida:
Cephalothorax and abdomen;
Or head, thorax and abdomen combining into a whole;
4 pairs of legs, without antenna and wing.
1 Insecta: Separated head, thorax and abdomen;
3 pairs of legs, 1 pair of antennae.
III Morphological characters
3 Crustacea: Cephalothorax;Abdomen ( 5 pairs of legs, 2 pairs of antennae ) ;
Mostly live in water.
shrimp, crab, cyclops
III Morphological characters
4 Chilopoda :
head and long, slender,
flat body segments;
1 pair of antennae,
1 pair of legs on every segment.
centipede
III Morphological characters
5 Diplopoda: head and long pipe-shaped body segments;
1 pair of antennae,
2 pairs of legs on every segment.
diplopod
III Morphological characters
IV Metamorphosis:
A series of changes on external
morphological characters, structures,
physiological functions, life habit,
behaviour and instinct during the
development of an insect from egg to
adult.
adultpupa
larva
eggs
IV Metamorphosis1 complete metamorphosis has pupa
stage
eclosion pupation
emergence
Annoyance resulted from sting and
bites
Envenomization and damage by
toxic substance
V Harmful effects on human
1 Direct harmful effects :
Allergic reaction : resulted from heterogeneous proteins, just as
saliva, secretions , excretions , and hull, etc. from arthropods
Direct parasitism :
myiasis: caused by larval flies parasiting in human body);
tungiasis: caused by tunga;
scabies: caused by itch mites;
demodicidosis: caused by follicle mite
V Harmful effects on human
1 Direct harmful effects :
Major diseases caused by direct injury of arthropods
Names of diseases
Arthropod pathogens Lesion sites Mechanisms
Allergic asthma and rhinitis
Dust mitesRespiratory system
Allergic reaction
Scabies Itch mites SkinDirect parasitism of itch mites
Demodicidosis Follicle mites Skin or visceraDirect parasitism of follicle mites
Tick paralysisSome hard tick species
Nerve system Nerve toxicity
Tungiasis Some flea species SkinDirect parasitism of fleas
MyiasisDipterous larvae (especially fly maggots)
Skin, eyes and digestive tracts, etc.
Direct parasitism of the larvae.
V Harmful effects on human
2 Indirect harmful effects
- disease transmision:
the major harmful effects of arthropods
*vectors:
arthropods capable of transmitting pathogens are called vectors
*vector-borne diseases:
the diseases transmitted by arthropod vectors
Mechanical transmission
transfer of a pathogen from an infectious source to a
susceptible host by an arthropod vector, without any
reproduction and development of the pathogen in the vector
biological transmission
the pathogen either reproduces or develops (or both) in the
vector, include developmental biological transmission,
propagative biological transmission, cyclopropagative biological
transmission (both developing and multiplying in the vector) and
transovarial biological transmission
V Harmful effects on human
2 Disease transmision :
a) developing : developmental biological transmission:
the pathogenic organisms having a period of
development in the arthropod vectors (eg, when
mosquitoes transmit filaria)
b) multiplying : propagative biological transmission: the
pathogens multiplying in the vectors (eg, when fleas
transmit plague)
V Harmful effects on human
2 Disease transmision :
c) developing and multiplying : cyclopropagative
biological transmission with the pathogens both
developing and multiplying in the vectors (eg, when
mosquitoes transmit malaria)
d) transmitting through eggs : transovarial biological
transmission with the pathogens being transferred to the
next generation of vectors through their eggs (eg, when
ticks and mites transmit some viruses)
V Harmful effects on human
2 Disease transmision :
Major pathogens mechanically transmitted by arthropods
PathogensArthropod
vectorsDiseases
Virus
Poliovirus Flies and cockroaches Poliomyelitis
Bacterium
Bacillus anthracis Tabanidae Anthrax
Salmonella Flies, cockroaches Salmonellosis
Shigella Flies Shigellosis
Vibrio cholerae Flies Cholera
Spirochete
Treponema pertenue Flies and eye gnats Yaws
Protozoa
Entamoeba histolytica Flies and cockroaches Amebic dysentery
Toxoplasma gondii Cockroaches Toxoplasmosis
Major pathogens biologically transmitted by arthropods
PathogensArthropod
vectorsDiseases
Virus
JEV Culex, Anopheles & Aedes
Epidemic type B encephalitis
Dengue virus AedesDengue fever & dengue hemorrhagic fever
YF virus Aedes Yellow fever
Sand fly fever virus Phlebotomus Sand fly fever
Forest encephalitis virus Ixodes Forest encephalitis (Russian spring-summer encephalitis)
CCHF virus (XHF virus) IxodesXinjiang haemorrhagic fever (XHF) or Crimean-Congo hemorrhagic fever
Hantaan virus Some gamasid mites and chigger mites
Hemorrhagic fever with renal syndrome (HFRS)
Rickettsia
Rickettsia prowazekii Pediculus humanus Epidemic typhus
Bartonella quintana Pediculus humanus Trench fever
Rickettsia typhi (R. mooseri)
Siphonaptera Endemic typhus
Rickettsia tsutsugamushi (R. orientalis)
Leptotrombidium Tsutsugamushi disease
Bacterium
Yersinia pestis Siphonaptera Plague
Spirochete
Borrelia recurrentis Pediculus humanus Epidemic relapsing fever (louse-borne relapsing fever)
Borrelia burgdorferi Ixodes Lyme disease
Borrelia persica, B. latyschevi & B. hermsii, etc.
Ornithodoros (soft tick)Endemic relapsing fever (Tick-borne relapsing fever)
Protozoa
Plasmodium (P. vivax, P. falciparum, P. malariae & P. ovale)
Anopheles Malaria
Trypanosoma Glossina Trypanosomiasis (sleeping sickness)
Leishmania Phlebotomus Leishmaniais
Nematode
Wuchereria brancrofti Culex, Anopheles & Aedes Bancroftian filariasis
Brugia malayi Anopheles & Aedes Brugian filariasis
Onchocerca volvulus Simulium Onchocerciasis
Loa loa Chrysops Loiasis
Dipetalonema perstans, D. streptocerca & Mansonella ozzardi
Culicoides Three types of filariasis
Thelazia callipaeda House flies Thelaziasis
piercing-sucking mouthpart
antennapalp
compound eye
Femur
Tibia
Tarsus
2 Morphological features
体分头胸腹,窄长翅一对
三对细长足,一根尖细喙
翅脉和翅缘,都有鳞片被
require water for development
females feed on blood30-300 eggs ovipositedadults
live 1-3 weeks
II Life cycle
wiggler
a) paddy-field type :
b) slow stream type :
c) jungle type :
d) sullage type :
e) container type :
III Ecological behaviors 1 Breeding places depend upon egg-laying behaviors
a) domestic roosting mosquitoes
b) semi-domestic roosting mosquitoes
c) wild roosting mosquitoes
humid and dark areas
III Ecological behaviors
2 Habitat
human blood
domestic animal blood
female mosquitoes: blood meal male mosquitoes : feed on the nectar of flowers or other suitable sugar source
III Ecological behaviors
3 Host preference
direct harm: disturbance, succking blood
indirect harm ( biological transmission) mosquito-borne disease malaria Anopheles
filariasis Anopheles, Culex and Aedes
epidemic encephalitis B Cx.tritaeniorhynchus
Dengue fever Aedes aegypti/ albopictus
Yellow fever Aedes aegypti
IV Medical significance
Malaria is transmitted by Anopheles
Filariasis is transmitted by Anopheles, Culex and Aedes
Epidemic encephalitis B transmitted by Gulex
Dengue fever transmitted by Aedes
IV Medical significance
Environment management
Physical control
Chemical control
Biological control
Genetic control
V Prevention and control
Insecta
Diptera
Cyclorrhapha
Muscidae Calliphoridae Sarcophagidae Oestridae
I Classification and morphology
1 Classification
2 morphological feature
I Classification and morphology
a) 2 large compound eyes separated to wider
spacing in female ,narrower spacing in male;
3 ocelli
b) 2 antennae with each has a special structure
called arista
c) lapping mouthpart
d) most developed mesothorax ,
2 wide and well developed wings
e) 3 pairs of legs, and each leg has a claw pad
with lots of tiny thin hairs
III Ecological behaviors
1 Breeding place
The larvae of most flies feed on organic
substance, and usually select the following
sites as their breeding places :
feces, garbage, putrid plants and
decaying flesh , etc.
a) unable to feed themselves: Oestridae
b) sucking blood: Stomoxys
calcitrans , tsetsefly
c) omnivorous: most flies with lapping
mouthparts are feeding on a variety of food,
including feces, decaying animals or plants,
excretory substance and humans’ food, etc.
vomit / excrete while eating
III Ecological behaviors 2 Feeding habit
mechanical transmission:
biological transmission:
tissue invasion and parasitism:
Myiasis
IV Medical significance