This document discusses different types of blood-sucking lice that affect humans, including their morphology, life cycles, and public health importance. It covers three main types: body louse, head louse, and pubic louse. Key points include their worldwide distribution, feeding behaviors, egg-laying habits, and roles in transmitting diseases like epidemic typhus. Control methods include insecticidal treatments, combing, boiling clothes/water, and chemical disinfectants. The document also briefly overview Cyclops, a freshwater copepod genus that can act as an intermediate host for diseases like guinea-worm.

1. Medical Entomology
Louse & Cyclops
Dr Nishant Kumar
Assistant Professor
Department of Community Medicine
Madhubani Medical College , Madhubani
, Bihar

2. Introduction
Three types of blood sucking lice occurs in
humans
A. Body Louse ( Pediculus humanus)
B. Head Louse (Pediculus capitis)
C. Pubic or crab louse (Pthirus pubis)
All three species of lice have a more or less
world wide distribution but they are often more
common in template areas.

3. Body Louse (Pediculus
humanus)
A body louse is an ectoparasite of humans .
Away from human , unfed lice will die within 2-4 days
In its host it will live for about 30 days
They quickly abandon a dead person to seek new host
.
They also leave a person with high body temperature
People living in conditions of overcrowding , and in
situation where they rarely change clothes due to cold
weather are susceptible .
A person can harbour 400-500 lice , but less than 100
are found mostly.

4. Body Louse (Pediculus
humanus)
External Morphology
Adults are small , pale beige or greyish wingless
insects , with a soft leathery integument and are
flattened dorsoventrally
Male are 2-3 mm and female are 3-4 mm.
The head has a pair of small black eyes and a
pair of short five segmented antennae.
The three thoracic segments are fused together
and legs are stout and less well developed

6. The Body Louse (Pediculus
humanus)
Mouth parts of the louse differ from most blood
sucking insects in that they don’t form a
projecting proboscis but consist of a sucking
snout -like projection called the haustellum
which is armed on inner surface with minute
teeth that grip the skin during feeding.
Needle like stylets are thrust into the skin and
saliva injected into the wound to prevent blood
from clotting . Blood sucked up passes into the
stomach for digestion.

7. Life Cycle
Both sexes take blood meals and feeding occurs at any
time during the day or night .
Both adult and mature stages live permanently on
humans , clinging mainly to fibres of their clothing and
usually only on body hairs during feeding .
Female lice glue about 6-10 eggs per day very firmly on
the clothes especially to undergarments of the host.
The eggs are commonly called nits is oval , white ,1mm
long and has a distinct operculum (cap) containing
numerous perforations which give the egg the
appearance of pepper pots.

8. Life Cycle
Female lice live for 2-4 weeks and may lay upto 150-300
eggs.
The egg stage last for 5- 11 days except on discarded
clothes it may not hatch for 2-3 weeks or in cool
condition it may not
Eggs cannot survive longer than 4 weeks there is little
danger of acquiring body lice from clothes not worn for
over a month.
Louse hatchling are called nymph and resemble small
adult.
It takes blood meal and passes through three nymphal
instars and after 7- 14 days becomes adult male/female.

9. Head Louse (Pediculus
Capitis)
Morphologically similar to body louse only difference is it is
found on head
Life Cycle
The life cycle are similar excepts that (nits) are not laid
on clothes but are centred to the hair of the head
especially to the base and normally hatch after 6-7 days.
Eggs in long hair are near the or touching scalp.
Most individuals have 10- 20 head lice, but in sever
infection multiple stages may become matted with hair
and exudates from pustules from bite of the lice with
super impose bacterial and fungal infection.

10. Head Louse (Pediculus
Capitis)
Dissemination of head lice is only by close
contact such as children playing together and
their heads touching frequently .

11. The Pubic Louse (Pthirus
pubis)
The pubic louse is smaller ( 1.3-2mm) than
pediculus species.
They are less active and infestation is through
sexual intercourse and French called then
‘papillons d’amour’ ( The Butterly of Love’).
Other methods of transmission is though young
children getting infected from infected parents ,
infested discarded clothing , or even lavatory
seats
Adults survive two days or less away from host

13. Public Health Importance
The presence of body , head or pubic lice in a
person is called pediculosis
The skin of people who habitually harbour large
number of body lice may become pigmented and
tough and the condition is known as vagabond’s
disease , hobo disease , or morbus errorum .
Because lice feed several times their saliva has
toxic effect and may cause weariness , irritability
and pessimistic mood .Some people may
develop dermatitis , and have asthmatic
bronchitis .

14. Diseases
Louse borne epidemic typhus - Rickettsia
prowazeki
Louse borne epidemic relapsing fever -
Borrrelia recurrentis
Trench fever - Bartonella quintana

15. Control and
Prevention
Body lice - Clothes subjected to 70 C for one hour
kill the lice
Insecticidal dust - 5% carbaryl, 1% propoxur, 1%
Malathion, or 0.5% permethrin
Head Louse - Louse combs, malathion and
permethrin .4% dimeticone coats and kills the lice
Pubic lice - Aqueous not alcohol based insecticidal
solution
Oral Ivermectin can cure all kind of lice but under
study.

16. Cyclops
• Cyclops is one of the most common genera of
freshwater copepods, comprising over 400
species.
• The name Cyclops comes from the Cyclops of
Greek mythology which shares the quality of
having a single large eye, which may be either
red or black in Cyclops.

17. Morphology
• Cyclops individuals may range from ½–5 mm long
and are clearly divided into two sections. The broadly
oval front section comprises the head and the first five
thoracic segments. The hind part is considerably
slimmer and is made up of the sixth thoracic segment
and the four legless pleonic segments. Two caudal
appendages project from the rear.

19. Public Health Importance
Cyclops is intermediate host of dracunculiasis
(guinea-worm disease) and fish tapeworm
(Diphyllobothrium latum) infection

20. Control
Physical Method - Straining water though fine
cloth . Boiling the water above 70 C.
Chemical - Chlorination
Biological - Gambusia Fish

21. Thank You