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Medical Arthropodology
Department of Parasitology
Xiang-Ya School of Medicine
I
Concepts
 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
 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
I
Concepts
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.
The most harmful pests in China are mosquito, fly and
cockroach.
II Main conmmon characters of arthropods
insecta
arachnida
Morphological characters of arthropods
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
III Classification of Arthropods
Insecta: mosquitoes, flies, sandflies, fleas, black
flies, biting midges, tabanid flies, lice,
cockroaches, bedbugs, etc;
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 Morphological characters
1
Insecta:
Separated head, thorax and abdomen;
3 pairs of legs, 1 pair of antennae.
2 Arachnida:
Cephalothorax and abdomen;
Or head, thorax and abdomen combining into a
whole;
4 pairs of legs, without antenna and wing.
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 pipeshaped body segments;
1 pair of antennae,
2 pairs of legs on every
segment.
diplopod
fly
mosquito
sandfly
flea
black fly
biting midge
tabanid fly
2-4 mm
louse
1.5-2 mm
Cockroach
bed bug
hard tick
soft tick
itch mite
chigger mite
gamasid mite
dust mite
follicle mite
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.
IV Metamorphosis
1 complete metamorphosis has pupa
stage
emergence
adult
pupa
eggs
eclosion
pupation
larva
IV Metamorphosis
2 incomplete metamorphosis doesn’t
experience pupa stage
adult
nymph
egg
IV Metamorphosis
3 paurometamorphosis:
Larva
(six legs)
5-7 instar
blood meals
eggs
nymph
adult
V Harmful effects on human
1 Direct harmful effects :
 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
Major diseases caused by direct injury of arthropods
Names of
diseases
Arthropod
pathogens
Lesion sites
Mechanisms
Allergic asthma
and rhinitis
Dust mites
Respiratory
system
Allergic reaction
Scabies
Itch mites
Skin
Direct parasitism
of itch mites
Demodicidosis
Follicle mites
Skin or viscera
Direct parasitism
of follicle mites
Tick paralysis
Some hard tick
species
Nerve system
Nerve toxicity
Tungiasis
Some flea species
Skin
Direct parasitism
of fleas
Myiasis
Dipterous larvae
(especially fly
maggots)
Skin, eyes and
digestive tracts,
etc.
Direct parasitism
of the larvae.
Symptom of patients with scabies
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
V Harmful effects on human
2 Disease transmision :

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)
Major pathogens mechanically transmitted by arthropods
Pathogens
Arthropod
vectors
Diseases
Virus
Poliovirus
Flies and cockroaches
Poliomyelitis
Bacillus anthracis
Tabanidae
Anthrax
Salmonella
Flies, cockroaches
Salmonellosis
Shigella
Flies
Shigellosis
Vibrio cholerae
Flies
Cholera
Flies and eye gnats
Yaws
Entamoeba histolytica
Flies and cockroaches
Amebic dysentery
Toxoplasma gondii
Cockroaches
Toxoplasmosis
Bacterium
Spirochete
Treponema pertenue
Protozoa
Major pathogens biologically transmitted by arthropods
Pathogens
Arthropod
vectors
Diseases
Virus
JEV
Culex, Anopheles &
Aedes
Epidemic type B encephalitis
Dengue virus
Aedes
Dengue 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)
Ixodes
Xinjiang 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
Siphonaptera
Plague
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)
Bacterium
Yersinia pestis
Spirochete
Endemic relapsing fever
(Tick-borne relapsing fever)
Protozoa
Plasmodium (P. vivax, P. Anopheles
falciparum, P. malariae
& P. ovale)
Malaria
Trypanosoma
Glossina
Trypanosomiasis (sleeping
sickness)
Leishmania
Phlebotomus
Leishmaniais
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
Nematode
Section 1
Culicidae / mosquito
I Classification and morphology
1 Classification
Insecta
Diptera
Culicidae
Anopheles
Culex
Aedes
Anopheles sinensis
Culex pipiens pallens
Aedes albopictus
2 Morphological features
piercing-sucking mouthpart
palp
antenna
compound eye
Femur
体分头胸腹，窄长翅一对
Tibia
三对细长足，一根尖细喙
Tarsus
翅脉和翅缘，都有鳞片被
Piercing- sucking mouthparts
II Life cycle
females feed on blood
30-300 eggs
oviposited
adults live
1-3 weeks
wiggler
require water for development
Anopheles
Culex
Aedes
III Ecological behaviors
1 Breeding places depend upon
egg-laying behaviors
a) paddy-field type :
b) slow stream type :
c) jungle type :
d) sullage type :
e) container type :
III Ecological behaviors
2 Habitat
humid and dark areas
a) domestic roosting mosquitoes
b) semi-domestic roosting mosquitoes
c) wild roosting mosquitoes
III Ecological behaviors
3 Host preference
female mosquitoes: blood meal
male mosquitoes : feed on the nectar of flowers
or other suitable sugar source
human blood
domestic animal blood
IV Medical significance
 direct harm:
disturbance, succking blood
indirect harm ( biological transmission)
mosquito-borne disease
malaria
Anopheles
filariasis
epidemic encephalitis B
Dengue fever
Yellow fever
Anopheles, Culex and Aedes
Cx.tritaeniorhynchus
Aedes aegypti/ albopictus
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
V Prevention and control
Environment management
Physical control
Chemical control
Biological control
Genetic control
Fly
I Classification and morphology
1 Classification
Insecta
Diptera
Cyclorrhapha
Muscidae
Calliphoridae
Sarcophagidae
Oestridae
Chrysomyia megacephala
Boettcherisca peregrina
Lucilia sericata
Musca domestica vicina
I Classification and morphology
2 morphological feature
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
lapping mouthparts
claw pad (pulvillus)
II Life cycle
adult
pupa
egg
Larva (maggot)
egg
pupa
Larva of Chrysomyia megacephala spiracles of Chrysomyia megacephala
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.
III Ecological behaviors
2 Feeding habit
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
IV Medical significance
mechanical transmission:
biological transmission:
tissue invasion and parasitism:
Myiasis
dermamyiasis