A study of the arthropods of medical importance is known as medical entomology which is an important branch of preventive medicine.

1. MEDICAL ENTOMOLOGY
Dr. SASI KUMAR PJ, M.D.
Asst. Professor

2. Medical Entomology : It is the branch of
community medicine, which deals with
the study of arthropods of medical
importance.
Medical Entomology :

3. CLASSIFICATION OF ARTHROPODS
The phyllum arthropoda consists of three
important classes
1. Insecta
2. Arachnida
3. Crustacea

4. Insecta Arachnida Crustacea
Body shape Cylindrical Circular or Oval Pear shaped
Body division
Head, Thorax
and Abdomen
Cephalothorax
and Abdomen
Cephalothorax
and Abdomen
Antennae in
head
1 pair Absent 2 pairs
Wings
Some are
winged, some
are wingless
Absent Absent
Legs 3 pairs 4 pairs 5 pairs
Living On land On land In water
Examples
Winged -
Mosquito, Flies
Wingless -
Fleas, Lice,
Bugs
Ticks, Mites,
Spiders,
Scorpions
Cyclops,
Crabs,
Lobsters,
Prawns

5. VECTOR
1. Direct
2. Mechanical vector
3. Biological vector

6. ARTHROPOD BORNE DISEASES
Causative agent Disease Vector
Virus
Yellow fever, Dengue fever,
Chickengunya, Japanese
encephalitis
Mosquito
Rickettsiae
Epidemic typhus, Scrub
typhus, Q- fever, Rocky
mountain spotted fever
Louse
Rat flea
Tick
Tick
Bacteriae
Typhoid, Cholera, Shigellosis,
Plague
House fly
Rat flea
Spirocheta Relapsing fever Louse
Protozoa
malaria
Leishmaniasis
Mosquito
Sandfly
Nematoda
Filariasis
Dracunculosis
Mosquito
Cyclops

8. Extrinsic Incubation Period : The
period of time required for the
disease agent to undergo
multiplication or a phase of
cyclic development or both,
inside the body of the arthropod.

9. Definitive Host : It is the one in
which the sexual phase of the
development or life cycle of the
parasite takes place.

10. Intermediate Host : It is the one
in which asexual phase of the
development or life cycle of the
parasite takes place.

11. Infestation : It means the
lodgement, growth,
development and reproduction
of the arthropod parasite on the
surface of the body.

12. Principles of arthropod control
1. Environmental control
2. Chemical control
3. Biological control
4. Genetic control
Integrated Approach

13. MOSQUITO
1. Anopheles
2. Culex
3. Aedes
4. Mansonia

14. Morphology of Mosquito

19. Anopheles culex
Eggs are laid singly and
horizontally on
the surface of the water.
Eggs are vertically laid in
clusters on
the surface of the water.
Eggs are boat shaped. Eggs are cigar shaped.
Each egg has two lateral
air floats,
which help them in
floatation.
Eggs of culex mosquito are
not provided with
lateral air floats.
Eggs are laid on clean water. Eggs are laid on dirty water.

21. Anopheles culex
Larva of anopheles mosquito
is surface feeder.
Larva of culex mosquito
is bottom feeder.
The respiratory siphon is short.
The respiratory siphon is
long.
It remains parallel with
water surface.
It forms an angle inside water.

23. Anopheles culex
The pupa is green. The pupa is colourless.
The respiratory trumpets
are short and wide.
The respiratory trumpets are
long and narrow.
The abdomen is more bent. The abdomen is less bent.

25. Anopheles culex
Body is provided with
delicate legs.
Body is provided with
stouter legs.
Wings are spotted and
cannot fly for long distance.
Wings are transparent and
can fly for long distance.
The proboscis and palpi
have same length.
There is presence of small
palpi near proboscis.
At rest body is inclined at an
angle of 450 to the surface.
At rest body lies parallel
to the surface.
It transmits malarial parasite. It transmits filarial parasite.

28. HABITS

29. 1. FEEDING HABIT :
Males never bite (they subsist on plant juices)
Females - Haematophagous (once in 2-3 days)
2. TIME OF BITING : Evening
3. RESTING HABITS : Dark & Cool corners (endophila,
exophilia)
4. BREEDING HABITS:
Anopheles - Fresh water
Culex - Dirty & polluted water
Aedes - Artificial collection of water
Mansonia - Water containing aquatic vegetation

30. 5. HIBERNATION : Adult (not favourable)
6. DISPERSAL : Do not fly far, currents of wind, flight
range - 11 kms.
7. LIFE SPAN : Temperature & humidity, 8- 34 days,
males - short lived.

31. Type of mosquito Disease
Anopheles
Malaria
Filaria (not in India)
Culex
Bancroftian filariasis
Japanese encephalitis
West nile fever
Viral arthritis
Aedes
Yellow fever (not in India)
Dengue
Chickengunya
Filaria (not in India)
Mansonia
Malayan filariasis
Chickengunya fever
Mosquito borne diseases

32. MOSQUITO
CONTROL
MEASURES

33. Integrated Approach is recommended
Integrated approach means : Various combinations of
•Anti larval
•Anti adult mosquito
•Personal protection measures

34. 1) Anti-larval measures
a) Environmental control
b) Chemical control
c) Biological control
2) Anti-adult measures
a) Residual sprays
b) Space sprays
c) Genetic control

35. 3) Protection against mosquito bite
a) Mosquito net
b) Screening
c) Repellents

36. 1) Anti-larval measures
a) Environmental control
• Environmental control means reducing the
breeding places of mosquitoes
• Also known as source reduction
• It is the important method of mosquito control
a) Filling of breeding places
b) Levelling of breeding places with cement
c) Drainage of breeding places like dessert coolers
d) Water management e.g.;Intermittent irrigation
e) Changing the salinity of water
f) Covering water storage tanks

37. b) Chemical control
1) Anti-larval measures
a) Mineral oils : diesel oil, kerosene, MLO etc,
they forma thin film on the surface and
hence cut off the oxygen supply to the larvae
and pupae
Apply once a week - larval stage lasts for 8
days
Harms other water creatures too

38. b) Chemical control
1) Anti-larval measures
b) Paris green : Copper aceto - arsenite
Kills only if ingested by the larva
Mainly for anopheles larvae

39. b) Chemical control
1) Anti-larval measures
c) Synthetic insecticides : These are OP compounds
Fenthion
Chlorpyrifos
Abate
Temephos

40. c) Biological control
1) Anti-larval measures

42. 2) Anti-adult measures
a) Residual sprays :
• It is the application of insecticides to the inside of
dwellings, on walls and other surface that serves
as a resting place for mosquitoes.
• IRS kills mosquito when they come in contact with
treated surfaces.
• Disadvantage : Resistance
eg: DDT, Malathion etc

43. 2) Anti-adult measures
b) Space sprays (fogging)
• Insecticide is sprayed into the air as mist or fog of
spray
• No residual action
• Temporary reduction in number of mosquitoes
• Done mainly as emergency situations to
immediately reduce mosquito population
eg : pyrethrum extract

44. 3) Protection against mosquito bites
• Mosquito nets
• Screening of buildings
• Repellents

45. THANK YOU

46. THANK YOU