Mosquitoes are found worldwide and transmit many diseases. They undergo complete metamorphosis with four stages - egg, larva, pupa, and adult. Females of many species bite humans to obtain blood meals required for egg production. Control methods include reducing breeding sites, biological controls, traps, and insecticides targeting larvae or adults.

1. Mosquitoes

2. Introduction
• Mosquito is a flying insect which belong to the
Culicidae family and the order Diptera,
• Mosquitoes are found all over the world.
occur throughout the tropical and temperate
regions and northwards into the Arctic Circle.
• Mosquitoes are widely known for transmitting
diseases such as yellow fever, dengue and
most notorious disease caused by mosquitoes
in Africa is malaria

3. Mosquitoe identification

4. Geographical location

5. Identification
• Possess only one pair of functional wings, the
fore-wings
• Hind-wings are represented by a pair of small,
knob-like halteres.
• Distinguished from other flies by;
– possession of a conspicuous forward-projecting
proboscis;
– presence of numerous appressed scales on the thorax,
legs, abdomen and wing veins
– fringe of scales along the posterior margin of the
wings

6. Adult mosquitoes
• Different species of mosquitoes differ in
appearance, location, feeding habits and their
threats to human.
• Structurally, mosquitoes have a pair of scaled
wings, a pair of antennae, a pair of long legs and
slender body.
• There are whorls of hair on the antennae which
are short in the female but long and bushy in the
male.
• An average mosquito weighs about 2-2.5 mg and
can fly at about 1.5 -2.5 km/hr

7. Aedes mosquito

8. Classification of mosquito
• Kingdom:Animalia
–Phylum:Arthropoda
•Class:Insecta
–Order:Diptera
»Family:Culicidae
• Genus:Anopheles

9. Distribution
• There are approximately 41 genera and about
2500 species of mosquitoes worldwide.
• Only 30–40 commonly transmit parasites of
the genus Plasmodium which cause malaria in
humans in endemic areas.
• Culex, Anopheles,Mansonia and Aedes genera
are the most common genera worldwide

10. Life cycle of mosquito

11. Reproduction
• Most mosquitoes mate shortly after emergence
from the pupa
• Sperm, in the spermatheca, usually serves to
fertilize all eggs laid during her lifetime;
• when a female mosquito bite a host and take a
blood-meal to obtain the necessary nutrients for
the development of the eggs in the ovaries.
• This is referred to as anautogenous
development.

12. Fed

13. • Few species however can develop the first
batch of eggs without a blood-meal, and more
rarely subsequent batches.
• This process is called autogenous
development
•

14. • After a blood-meal the mosquito’s abdomen is
dilated and bright red in colour, but some hours
later the abdomen becomes a much darker red.
• As the blood is digested and the white eggs in the
ovaries enlarge, the abdomen becomes whitish
posteriorly and dark reddish anteriorly.
• This condition represents a mid-point in blood
digestion and ovarian development, and the
mosquito is referred to as being half-gravid

15. • Blood is digested and the abdomen becomes dilated
and whitish due to the formation of fully developed
eggs
• The female is gravid searches for suitable larval
habitats in which to lay her eggs.
• After oviposition the female mosquito takes another
blood-meal a further batch of eggs is matured.
• This process of blood-feeding and egg maturation,
followed by oviposition, is repeated several times
throughout the female’s life and is referred to as the
• gonotrophic cycle.

16. LIFE CYCLE OF THE MOSQUITO
• Undergo complete metemorphosis
• EGG STAGE
– All species of mosquitoes lay their eggs on
STANDING water.
– Culex eggs are stuck together in rafts of hundreds
or more, Aedes and Anopheles species lay eggs
separately
– Adult females lay 50–200 eggs per oviposition.

17. Culex
Anopheles

18. Larvae
• Mosquito larvae have a well-developed head
with mouth brushes used for feeding, a large
thorax and a nine segmented abdomen
• Breathe through spiracles located on the 8th
abdominal segment.
• Larvae develop through 4 stages, or instars

19. PUPA STAGE
• dormant, non-feeding stage.
• takes about two days to fully develop into adult
• The pupa has a comma shaped body
– 1st region: head and thorax (cephalothorax), bears
pairs of respiratory trumpets on the upper surface
which must come to the surface occasionally to get
oxygen
– 2nd region is abdomen, has freely movable segments
with a pair of paddle-like appendages at the tip.

21. FEEDING BEHAVIOUR
• Male mosquitoes cannot bite but feed on the
nectar of flowers and other naturally occurring
sugary secretions.
• Female mosquitoe bite to suck blood but
some feed on nectar of flowers
Anopheles
Culex

22. Medical and Economic Importance
• Mosquitoes are important because the females of
many species are bloodsucking, they annoy humans
and other animals,
• Transmit the pathogens that cause human and animal
diseases.
• The pathogens transmitted by mosquitoes include
viruses (arboviruses), filarial worms (helminths) and
protozoa.
• Mosquitoes are the indirect cause of more morbidity
and mortality among humans that any other group of
organisms.

23. Control
• Source reduction (e.g., removing stagnant
water)
• Biocontrol (e.g. importing natural predators
such as dragonflies)
• Trapping, and/or insecticides to kill larvae or
adults
• Exclusion (mosquito nets and window
screening)

25. Sand fly :Phlebotomus spp
Leishmania: Infection and Treatment

26. Classification of Leishmania
• Leishmaniases is a complex of vector-borne
diseases, caused by more than 20 species of the
protozoan genus Leishmania, and ranging from
localized skin ulcers to lethal systemic disease.
• Leishmaniasis is classified as one of the "most
neglected diseases," based on the limited resources
invested in diagnosis, treatment and control, and its
strong association with poverty.

27. Phlebotomine Sand Flies…
Order: Diptera
Family: Psychodidae
Genera:
● New World ● Lutzomyia
● Brumptomyia
● Warileia
● Old World ● Phlebotomus
● Sergentomyia
(Aranasy et al., 1999 and Martin-Sanchez et al., 2000)

28. Morphology
• Adults –
– small (less than 5 mm long) with
conspicuous black eyes
– long narrowly obovate wings that form a V-
shaped out line above thorax, wing veins are
parallel to each other, slender with piercing
mouthparts and long antennae; There are
fine hairs on body, wings and legs.

29. Cutaneous leishmaniasis
Visceral leishmaniasis
Mucocutaneous leishmaniasis

30. Visceral

31. Cutaneous and
subcutaneous

32. Habits
• Only female sandflies are blood sucker and they are
nocturnal feeders.
• They are poor flier and fly in a characteristic hopping,
30-1000 m.
• Prevalent from May to September. Larvae survive
through the winter.

33. Hematophagous Diptera (flies) are of two
basic types :-
Capillary feeders : mouth parts are inserted
into the skin and blood is withdrawn directly
(solenophages) .
Pool feeders : mouthparts short and are used to
lacerate the skin then the blood flow and
ingested by the fly (temophages).

34. Female feed on blood at night.
Sand flies are pool feeder ( telmophages )
which suck blood from a small wound they
make in the skin.
Their bite is therefore relatively painful .

35. - Sand flies do not produce a buzzing or whining
noise before biting which again reduces the
perceived nuisance to man.
-Color of sand flies are brownish in day light ,
but their bodies are densely covered in oily hairs
which give them whitish appearance when
illuminated

36. ‫ذكر‬ ‫أنثى‬
Adult male and female sandfly

37. ‫ذكر‬ ‫أنثى‬
Pharynx
Maxillary
palp
Mouth parts of sandfly

38. B
A
‫أنثى‬
‫أنثى‬
Phlebotomus
Phlebotomus
A- Maxilla
B- Mandible
Notice the
saw like
structure

39. Life cycle (stages)
• Eggs are laid in dark humid animal burrows, cracks
or crevices, or under dead leaves (Egg laid on moist
dark place containing organic debris (under leaves on
the ground ,in damp mossy place ,in rank vegetation
or on hallow tree trunks).
• 4 larval instars, lasting 4-6 weeks
• pupa requires 10 days for development
• Life cycle requires 40-50 days
• Only adult females suck blood
• Adult life span 2-3 weeks, 30-50 eggs/female.

40. Sand fly
(
Phlebotomas papatasi
)
Egg
Larva

41. - Sand fly bite: The bite is inflamed with a wheal of 1-2
cm. and accompanied by pruritus lasting for hours or
weeks and sometimes with systemic allergic reaction
(fever, nausea, malaise swelling of the bitten member).
- Treatment: Topical application of phenolated
camphor in mineral oil or anesthetic ointment.

42. 1. Leishmaniasis is transmitted by the bite of female
phlebotomine sandflies. The sandflies inject the infective
stage, promastigotes, during blood meals.
2. Promastigotes that reach the puncture wound are
phagocytized by macrophages.
3.They transform into amastigotes.
4. Amastigotes multiply in infected cells and affect different
tissues.
5. Sandflies become infected during blood meals on an
infected host when they ingest macrophages infected with
amastigotes.
6. In the sandfly's midgut, the parasites differentiate into
promastigotes.
7. They multiply and migrate to the proboscis.

43. PROMASTIGOTES
AMASTIGOTES

44. LIFE CYCLE

45. inoculation
ingestion
Sand fly
Vertebrate host
Transformation
Attachment and
phagocytosis
Multiplication and
reinfection
Release from macrophages
Multiplication
Transformation
Protozoan parasites (proto = first; zoan = animal)
Small (usually microscopic) single-celled organisms
Life cycle can be divided into 2 stages depending on the host:
 Sand fly vector = Leishmania promastigotes
 Human or other vertebrate = Leishmania amastigotes
Leishmania fact sheet
What are Leishmania parasites?
Life cycle of Leishmania parasites
Form of Leishmania within human or other vertebrate host’s cells (have
resorbed their flagellum)
Size: 2-6 mm
Shape: ovoid
Characteristics: central nucleus
Leishmania amastigotes
Different parasites cause different forms of the disease
Flagellum
Form of Leishmania within sand fly vector:
• Can move in the direction of their flagellum
• Can be cultured
Leishmania promastigotes
Amastigotes
Promastigotes
Cutaneous lesihmaniasis Visceral lesihmaniasis

46. EARLY DIAGNOSIS
• L.D Bodies (Spleen, Bone Marrow,
Lymph Node)
• Aldehyde Test
• Elisa & Polymerize Chain Reaction
(Pcr)

47. Control
• 1. Elimination of breeding grounds
• 2. Application of insecticides.
• 3. Personal protection.

49. 49

50. SIMULIDAE (BLACK FLIES)
50

51. OUTLINE
• Introduction to Simulium
• External morphology of Simulium
• Life cycle
• Adult behaviour
• Medical importance of Simulium
• Control
51

52. Learning objective
• Describe the external morphology of black flies
• Explain the life cycle of black flies
• List the adult behaviour of black flies
• Describe the medical importance of black flies
• Discuss control measures of black flies
52

53. Family Simuliidae (Black flies)
• Suborder Nematocera and the family Simuliidae
• The family contains approximately greater than
1800 species in about 25 genera
• World wide distribution
• Common Name: Black Fly, Buffalo or Turkey Gnat
53

54. Simulidae....
• Generas of economic and medical
importance (bite people):
– Simulium (medically, the most important genus)
– Prosimulium
– Austrosimulium
– Cnephia
54

55. External Morphology:
Adult: Usually black in color (Black flies)
Size: Minute (1.5 – 4 mm) but bigger than
phlebotomus species
Thorax: humped when seen from the side like
phlebotomus
55

56. External…
Eyes: A pair of large compound eyes
dichoptic in females/holoptic in males

57. External…
• Antennae: short, stout, cylinderical, has 11
segments
• Mouthparts: Short
• Thorax, abdomen & legs are covered dorsally
by fine dense short hairs

58. Front veins thicker
The rest of the veins are indistinct
58

59. External…
• Wings: are short and broad unique to make it
fly and easily enter water without wetting
– Alary nipples
• Legs: 3 pairs

60. 4.2.Life Cycle
Has four stages
• Eggs:
– 0.1-0.4 mm long
– Brown or black and
– more or less triangular in shape but have rounded
corners
– Covered with a sticky substance
– Laid in flowing water (while females are in flight or
after alighting on partially immersed objects
– Hatches within 1-4 days
60

61. Life cycle…
• Larva:
– Instars: No fixed no of instars (rather 6 – 9)
– Head: Black and has prominent feeding
brushes(Cephalic fans)
– Body: cylinderical
• Feed on organic matter as Browsers or filter
feeders(most)
• Proleg & posterior circlets help for attachment
61

63. Life cycle…
• Mature larva spins silk around to form Cocoon.
• This cocoon attahced to submerged vegetation.
• Becomes pupa.
Pupa
• May be found grouped closely together or singly
• Age can be roughly assessed by its color
– Dark pupa--- adults are ready to emerge
• Pupa ruptures the larval cuticle and adults emerge
63

64. Larva
Pupa
Respiratory filaments
Pupa in coccoon
Many larvae
64

65. Adult behaviour
• Only females takes blood meals
• Outdoor biters
– Many-Any light hours
– S.damnosum- bimodal bitting hours
• Marked preference for feeding ondifferent parts
of the body:
– S.damnosum- mainly on legs
– S.ochraceum- Mainly head and torso
• Females may fly 15-30 km and up to 400-600
km if supported by wind
65

66. Medical importance
• Annoyance: painful bite & the pain may last
several days
• Onchocerciasis transmitted by:
• S. damnosum complex & S. neavei group in Africa
• S. ochraceum, S. metallicum & S. exiguum
complexes in Central & South America
• Mansonella ozzardi
• S. amazonicum
66

67. Control
• Some protection from repellents such as DEET
• Wearing pyrethroid – impregnated clothing
• Insecticidal fogging of vegetation harbouring resting
adult black – flies
• Application of insecticides to larval breeding places
• Specific measure for onchocerciasis:
– Onchocerciasis control programme(OCP)
67

68. Review questions
• What are the distinguishing morphological
features of the different stages of Black fly?
• List the diseases that can be transmitted by
Black fly
• What is the difference between browsers and
filter feeders?
68

69. • Describe the morphology of black flies, which
are typical to black flies?
• Mention the stages involved in the life cycle of
black flies by giving a brief description of each
stage?
• Explain why control of black flies is relatively
more difficult than other diptera of medical
importance?

70. Tsetse Flies, Oestrids

71. Tse Tse Flies
• Family Glossinidae
• One genus, Glossina, with 23
spp.
• All in subsaharan Africa
• Species are grouped by
generic habitat
– palpalis group of 5 riverine spp.
– fusca group of 5 forest spp.
– morsitans group of 5 savanna
spp.
• Vector of African
trypanosomiasis, “Sleeping
Sickness”

72. Tse Tse Fly Biology
• Both sexes blood feed
• Strong host preferences by species
– Humans are not preferred hosts of any species
• Female usually only mates once.
• Populations are often scattered at low
densities over wide areas.
• Flies congregate near hosts as a way of mate
location

73. Biggest Med/Vet Issue is
Trypanosmiasis
• Trypanosoma.
– 6 spp. cause sleeping sickness in wild/domesitic
animals.
– One of these, T. brucei, also infects humans
– It has two subspecies, each causing a different
disease
• T. b. gambiense – West African Sleeping Sickness
• T. b. rhodesiense – East African Sleeping Sickness

74. West African Sleeping Sickness
• Initially a skin lesion with swelling
• Winterbottom’s sign – swelling of
cervical lymph nodes
• Eventually parasite enters CNS
• CNS involvement often results in
wasting condition.
• Untreated patients lapse into
stupor, convulsions, death.

75. East African Sleeping Sickness
• Acute onset of fever, headache dizzyness
• Instead of lymphatic disease, this is a circulatory
disease
• Early heart problems (tachycardia [rapid beating] &
arrythmia [abnormal heart rate])
• Biochemical interaction between immune response
and trypanosomes kill blood cells, damage brain
tissue (other organs too)
• Trypanosomes migrate to the CNS
• From there, similar to WASS but faster

76. Like most arthropod borne pathogens,
vector control is important
• Flies are sparse in most of their range, location of
hotspots is known.
• Eradication technology is available but not the
resources.
• Instead, main plan is to:
– reduce fly populations via insecticides, habitat
manipulation, etc.
– reduce trypanosome burden via trypanotolerant livestock
– reduce human impact pharmacologically

77. Myiasis
• Invasion of body tissue by fly larvae – not other fly stages,
not other insects.
• Three kinds:
1. Accidental (pseudomyiasis) – unusual situation results in a non-
parasitic fly inside a vertebrate.
2. Facultative – opportunistic fly species, e.g. open wounds invaded by
carion flies
• Primary – A species initiates myiasis
• Secondary – A follow-on species continues myiasis after a primary
species
• Tertiary – Occurs when there is Primary + Secondary + Imminent host
death. Host is nearly indistinguishable from a corpse.
• Facultative species are “borderline parasites” attacking a weakened
host and continuing after host death as carion feeders.

78. 3. Obligatory Myiasis
• Fly larvae are always parasitic, parasitism is required to
complete life cycle
• Usually very host specific, fly larvae have developed
mechanisms for dealing with healthy host defenses (unlike
previous 2 forms)
• Related subtypes:
1. Temporary Obligatory Myiasis – Larvae spend most of their time off
of the host, come to host only to feed.
2. Incidental Obligatory Myiasis – Myiasis of an atypical host by an
obligate species. Eg. Sheep bot in a human.

80. Myiasis is also classified by the
affected host tissue
• Gastrointestinal – Digestive system, “Enteric” refers
to intestinal tract. Includes anus.
• Urogenital – urogenital openings to the outside.
• Ocular – eyes, esp. subconjunctival myiasis
• Nasopharyngeal – nasal & sinus passages
• Auricular – ear, inner & outer
• Cutaneous – generic skin
• Oral - mouth
• Furuncular – “boil-like” [Note not in text]

81. Gastrointestinal Myiasis
• Most human cases are
accidental (esp. from eating
uncooked fruit)
• Most veterinary cases are
from obligatory species
• cf. Table 18.1
• Most common in our area are
the horse bots, Gasterophilus
spp. (G. intestinalis is most
common).
• Lay eggs on hair, horse ingests
eggs when they groom
themselves.

82. Urogenital Myiasis
• Usually involve blow
flies & flesh flies
• Typically facultative,
often following trauma
• Also associated with
urogenital infection.

83. Ocular Myiasis
• Most human cases are incidental
infestation from non-human bot
flies
• Also called “Opthalomyiasis”
• Sheep bot is most common agent
and can cause epidemics
– 1977 - Benghazi, Libya, had 80
human cases.
– Usually a combination of poor sheep
AND human health in close
proximity.
Can superficially resemble Romaña’s sign

84. Nasopharyngeal Myiasis
• Very similar to
opthalomyiasis
• A particularly
dangerous form as
larvae can migrate to
brain tissue

85. Auricular Myiasis
• Typically incidental or
accidental.
• Most human cases are
with the Old World
Screwworm
• Lay their eggs in batches,
larvae stay together
Chrysomya bezziana larvae “en pabellón”

86. Cutaneous Myiasis
• The most common
form in humans
• In South/Central
America, mostly
caused by the
human bot fly,
Dermatobia hominis

87. Oral Myiasis
• Fairly rare pathology in
humans
• Associated with poor
oral hygiene,
alcoholism, senility,
trauma with lesions,
severe halitosis and
others conditions.
• Caused by a wide
variety of species

88. African Furuncular Myiasis
• Also called “Tumbu Dermal
Myiasis”
• “Furuncular” means boil-like or
“pustule-like”
• Caused by the Tumbu fly,
Cordylobia anthrophaga
• Common in eastern Africa,
Humans are incidental hosts
• Form of cutaneous myiasis but
prevalence is rapidly increasing
• Fly lays eggs on damp clothes on
clotheslines. Can be controlled by
ironing clothes (including bras).

89. Lotus seed pod

90. About the Flies:Calliphorid &
Sarcophagids
• Calliphoridae (Carrion & blow flies) & Sarcophagidae
(flesh flies)
– Most myiasis spp are necrophagous
– Only a few are obligate myiasis spp.
– Calliphorids include temporary myiasis spp. (Congo floor
maggot, nest blow fly).
– Tumbu flies are Calliphorids
– Most economically important spp are the Screwworms,
major livestock pests.
• Old World Screwworm Chrysoma bezziana
• New World Screwworm, Cochliomyia hominivorax

91. New World Screwworm
• Mostly a livestock pest
• Untreated myiasis results in
animal death
• Invasion produces more flies
that lead to more
infestation.
• Wounds become infected,
large number leads to
septicemia.
• Presence of flies leads to
gadding (stampedes). Does
not happen with bot flies
that use egg porters.
• Eradication has proven
possible with this species.

93. About the Flies: Oestrids (Bot Flies)
• Four Suborders
– New World Skin Bots, Cuterebrinae.
• Most are parasites of rodents & rabbits.
• Tórsalo, Human bot fly, Dermatobia hominis. S. Mexico
to Argentina
– Old World Skin Bots, Hypodermatinae
• Mostly parasitic on larger mammals.
• Most important species are the cattle grubs (northern
& southern).

94. About the Flies: Oestrids (Bot Flies)
• Four Suborders
– Nose Bots, Oestrinae.
• Sheep bot is the most common. Can
also infest human with very bad results.
– Stomach Bots, Gasterophilinae
• Horse bots previously mentioned

95. Tiny antennae, no mouths
Human bot fly, Dermatobia hominis