The study of diseases caused by arthropods
Entomo (gr) = ‘segmented’
Arthron = ‘jointed’
Poda = ‘foot’
Arthropods: largest phylum in the animal
• B/L symmetrical segmented body, supported by
exoskeleton(chitin), do not have bones, but the
hard outer covering supports the muscles.
• The appendages are jointed.
• The body is formed of a number of segments.
Transmission of Arthropod borne diseases
From man to man
From man to man
Plague bacilli in rat
Plague bacilli in rat
Malaria parasites in
Malaria parasites in
• Body consist of 3 parts:
-Semi globular in outline
Pair of large compound eyes,
Needle like structure called
proboscis, with which it bites.
Palpi situated on either side
Pair of antennae or feelers.
bushy in male, not so in
Large & rounded in appearance.
Bears pair of wings dorsally which produces
Three pair of legs ventrally.
Long & narrow, composed of 10 segment,
last two segments are modified to form
Clasper in male n round in female
• Eggs are laid on the
surface of water,100 -250
• lays her eggs singly,
• boat shaped and
• possess lateral floats
• Cigar shaped,
• Laid down singly,
• no lateral floats
3. Culex small clusters
4. Mansonia lays her eggs
in star shaped clusters,
attached to the under
surface of certain aquatic
The period that elapses from the moment of blood
meal until the eggs are laid is called “gonotrophic
cycle” about 48 hours.
Egg stage of mosquito lasts for 1-2 days
• The larva is a free swimming creature
with an elongated body divisible into
head, thorax & abdomen.
• It feeds on algae, bacteria, and
• Passes through 4 stages of growth
called Instars with moulting between
• Exclusively surface feeder,
• Floats horizontally just below the
surface of water,
• very active with swift movement
• No siphon tube, but
• breathing apparatus consist of
parallel air tube at the tail end.
• suspended in water with head
• much slower with snake like
• Has long narrow siphon tube.
• Larva of Mansonia are
attached to rootlet of aquatic
plant by their siphon tube.
Larval stage occupies:
• 2 days in anopheles &
• 5-7 days in Culicines.
comma shaped in appearance
with large rounded cephalothorax
and a narrow abdomen.
Two small respiratory tubes or
trumpets project from the upper
surface of the thorax.
represents the resting phase in
the life history of mosquito.
Doesn’t feed & prefer to stay
quite at water surface.
The pupal stage lasts 1-2 days
• When development is complete, pupal skin
split along the back & adult mosquito
• It rests for a while on the pupal skin to allow
its wings to expand & harden & then flies
• The life cycle from the egg to adult is
complete within 7-10 days
• Normally adult mosquito lives for about 2
• Males are generally short lived.
• Identification features
When at rest,
inclined at an
angle of 45* to the
No buzzing sound
Palpi long In both
Anopheles male &
female and short in
Palps are as long as the
palps have white rings
• Food Preference: it is both anthropophilic &
zoophilic, a blood meal on the part of female
Anophelines is essential for maturation of the
• Resting Habit: Endophilic, i.e. indoor resting
habit for the purpose of digesting blood meal
& for the development of the ovum.
• Flight: can cover long distance, about 0.751.5 km, it significant for practical control of
• Life span: usually in India it lives for one
month, hibernating mosquito lives longer 31
Prefers clean water for • Time of biting :
Evening or early
• Irrigation channel,
part of night
Ponds, pools, lakes,
fruit & vegetable garden
and even s in Open
overhead tanks or in wells.
• Feeding Habits:
Only female bites,
male never bites.
Bio-Ecological Characteristics of Principal
Malaria Vectors in India
• About 45 species of anopheles
• 7 are vectors of malaria
It is most important vector in malaria
transmission in India & very widely distributed in
RURAL area of North, South and Central India
more zoophilic than anthropophilic,
bite in Dusk, peak time is 10.30pm to12.30
midnight, survives for 4 weeks.
• Resting Habits: Predominantly indoor rester-cattle
sheds and human dwellings and prefer pools with 34
low disturbance places.
2) An. Stephensi: it is normally vector for URBAN
area, particularly in coastal region and prefer
small collection of clean water,
prefer human dwelling & cattle sheds
bites soon after dusk,
peak at 4 to 6 am.
3) An. Minimus: in N.E. states, North West Bengal
4) An. Fluviatilis: seen along Himalaya range
seepage and in irrigation channels.
5) An. Dirus: deep forest in N.E. region.
6) An. Sundaicus: Andaman and Nicobar IslandSundaicus
breeds in brackish water.
7) An. Philippinensis: is the vector for the plains of
West Bengal and N.E. region.
• When at rest, the
body exhibits hunch
back(i.e. the thorax
makes an angle with
• Wings unspotted
• Buzzing noise
produce by beating of
Time of biting
• At night- enters the houses at dusk &
reaches maximum density at midnight
• Peak time of biting is at midnight
Site of biting – legs, below the knee
• Highly anthropophilic
• Dispersal is about 11 km, strong winged
• Average life span : 21 days
• The vector is mainly outdoor resting and
Bancroftian Filariasis ( Cu. Fatigans)
JE (Cu. Vishnui)
West Nile fever
• Sits parallel to the surface
• White stripes on black body
• Because it bites vigorously and fearlessly
to many persons, so it is also called as
• Adult seek dark and quit places to rest in
bedrooms, kitchen, on walls, furniture,
hanging articles like clothing, ropes and
• Average survival for male is 20 days and
for female 30 days.
Aedes aegypti profusely breeds in
Artificial accumulation of water
• Behind refrigetor &
• Broken glasses,
• Storage tanks,
• Plastic containers and
• Earthen pots and other
tins which have been
receptacles with rain
• In flower vases,
Time of biting
• Day biters
• Do not fly more than 100 meter
• Mostly found in rainy water
• A. aegypti and A. sentellaris :
breeds in peri- domestic
artificial collection of water.
• A. Albopictus : breeds in
natural rather than artificial
• Chikungunya fever
• Yellow fever
• A. vittatus : seen outside India,
not domestic mosquito.
• breed on aquatic plants ( Pistia straitiotes )
for the supply of oxygen
• Two species of the vector:
-Mansoniodes uniformis and M.
-transmit Brugia malayi infection of Filariasis
It is defined as an arthropod or any living
carrier that transport an infectious agent to a
susceptible individual by inoculating into or
through the skin/mucous membrane or by
depositing infected material on skin/food or
• Extrinsic incubation period:
It is the period of time required for the disease agent
to undergo multiplication or a phase of cyclic
development or both inside the body of arthropod
Eg. In malaria 10- 14 days
• Definitive host:
It is a one which the sexual phase of the development
or life cycle of the parasite takes place
Eg. Female anopheline mosquito in malaria
• Intermediate host:
It is one in which asexual phase of the development or
life cycle of the parasite takes place
Eg. Cyclops in dracontiasis
The lodgement, growth, development and
reproduction of the arthropod parasite on the
surface of the body Eg. Louse infestation
Changes that take place in size, shape and structure
during the different stages of life cycle of the
arthropod from the stage of egg to adult stage
Incomplete metamorphosis( Hemimetabola)
Stages: egg, nymph, adult..
Eg. Louse, ticks
Complete metamorphosis( Holometabola)
Stages: egg, larva, pupa, adult
Eg. Mosquito, fly and flea
• Infected Mosquito: A mosquito is said to
be infected when it has the disease agent
inside the body but may not be infective
• Infective Mosquito: A mosquito capable
of transmitting the disease agent. It
become so after the extrinsic incubation
Narrow tube like, having 10 segments.
Last 2 segments are modified into genitalia, a
pair of claspers in male & a pair of cerci in
Claspers are long and curved
Cerci are small and rounded
They are help for sex identification
Suspended downwards with lateral angles
Palmate hairs are scanty
Siphon tube open at surface for respiration
Siphon tube is short and
Siphon tube is long and
• Head and thorax is fused to form cephalothorax
and cylindrical abdomen is curved looks like tail.
• Thus this stage looks like comma shaped
• Bear a pair of eyes. Mouth is absent so does not
• Respiratory apparatus ( 2 siphon tubes for
breathing ) disappear from the last abdominal
segments of the larva and developed on the
cephalothorax of pupa
• Tip of abdomen has caudal paddles and caudal
• This stage is resting or quiescent stage
anopheline pupa, the siphon tube is
short and broad,
culicini pupa, it is long and narrow.
• Also called as imago stage
• When development is complete, pupal skin split along the
back & adult mosquito emerges.
• It rests for a while on the pupal skin to allow its wings to
expand & harden & then flies away.
• The life cycle from the egg to adult is complete within 7-10
• Adult male mosquito live for 2 weeks, the female live little
• Male mosquito smaller,slender and female are
• Male never feed on blood but on vegetable juice
• Female require blood meal for every 2-3 days for
• Before copulation the males collect in
swarms and engage in nupitial dance,
mating occurs in high up in air during
• Fertilization usually takes place 12- 24
hours after the emergence of the young
adults, the female lays eggs which marks
the repetition of life cycle
• Egg (2days )→ larva (6-8days) → pupa(2
days) → adult
• scutellum: Crescent shaped with
long hairs at regular interval
• Maxillary palpi: Long in both sexes,
tip is club shaped in male and not
club shaped in female
• Antennae: bushy and more hairy in
males and less in femal
INTEGRATED VECTOR MANAGEMENT
Evidence based implementation of one or
more, appropriate and effective, vector
control interventions (chemical and/or nonchemical), in a carefully managed operation to
limit disease transmission, with a view to
obtain maximum effect with minimal inputs
and also to minimize the excessive use of any
one method, thereby minimizing the risk of
emergence of resistance or environmental
3. Protection against mosquito-bite:
a) Mosquito net: ITBN treated with Deltamethrin
b) Screening: of windows, not >0.0475 inch in any
c) Repellants : DEET, indalone, diethyl benzamide,
More emphasis on IEC
using various media
• Increased budgetary
provisions for regular
• Observance of anti-malaria
June every year
• Life cycle: Egg, Larvae and Adult, i.e.
metamorphosis is incomplete.
• Life span of an adult is 3-5 weeks.
Breeding places (habitat): long hairs,
Overcrowding and poor personal hygiene
favours the transmission.
Places like hostels, prisons, beggar houses.
Dermatitis (Vagabond’s disease)
Epidemic typhus (Rickettsia Prowazeki)
Trench fever (R. quintana)
Relapsing fever (Borrelia recurrentis)
(pubic louse – Phthirus pubis)
found in pubic hair.
Short and stout, square shaped body,
Head impacted on the thorax
Powerful legs with claws
1st pair of leg is slender than others
Thorax is broader than abdomen
Abdomen has only five visible segment and
each segment has lateral protuberances
• Aedegus is small not clearly visible in male
and female 5th abdo segment bifid