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Pthirus pubis Pubic or Crab Louse

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Nocturnal feed on hosts while they sleep (bed bugs), painful bite disrupts sleep ... Insect defecates when feeds. ... Sudden appearance in winter of 1346-1347 ... – PowerPoint PPT presentation

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Title: Pthirus pubis Pubic or Crab Louse


1
Pthirus pubis - Pubic or Crab Louse
2
Pig Louse
3
Hemiptera - the true bugs
  • Some 55,000 species
  • Hemielytra type of wing. Anterior half is
    leathery while the posterior portion is
    membranous. Some are wingless

4
Cimex lectularius - the bed bug
  • Cosmopolitan - in the temperate zones
  • Not a major transmitter of human pathogens.
    Mechanically transmit Hepatitis B virus and
    source of much misery to man.
  • Can live without food for as long as 18 months (4
    months is common)
  • Nocturnal feed on hosts while they sleep (bed
    bugs), painful bite disrupts sleep

5
Cimex lectularius - the bed bug
  • Dorsoventrally flattened - allows them to hide in
    tight places, cracks, under loose materials, in
    thatch houses.
  • Control is use of insecticides and remove hiding
    places.

6
Reduviidae - The Assassin Bugs
  • The assassin bugs - most feed on other insects.
  • One Subfamily Triatominae contain important
    vectors of Trypanosoma cruzi which causes Chagus
    disease.
  • Called Kissing bugs often bite on tender parts
    of the body (lips) and have a bite that does not
    hurt while feeding. Hurts sometime later.

7
Reduviidae - The Assassin Bugs
  • The most common vectors of T. cruzi are
    Panstrongylus megistus, Triatoma infestans, and
    Rhodnius prolixus
  • Dogs, cats, rodents are important reservoir hosts
    in the urban setting and in the Sylvantic cycle
    the opossum is very important. .

8
Reduviidae - Kissing Bugs
  • Rhodnius prolixus Triatoma infestans

9
Chagus Disease
  • Caused by the protozoan Trypanosoma cruzi.
  • Develops in the posterior of the insect infective
    forms passed out in insect feces.
  • Insect defecates when feeds.
  • Feces with infected forms rubbed into break in
    skin or into membranes of eyes.

10
Pathogenesis of Chagus Disease
  • Acute phase - most common in children under 5
    years
  • Romana's sign
  • Pseudocysts can form in almost any tissue Heart
    muscle ganglion cells are very susceptible and up
    to 80 of them may be destroyed.
  • Death may occur within 3-4 weeks after infection.

11
Epidemiology
  • Reduviidae bugs are the most important link to
    human transmission
  • wild mammals may serve as reservoir hosts, dogs
    and cats are more important reservoirs for human
    disease.

12
Siphonaptera - the fleas
  • The combined effects of Nero and Kubla Khan, of
    Napoleon and Hitler, all the Popes, all the
    Pharoahs, and all the incumbents of the Ottoman
    throne are as a fuff of smoke against the typhoon
    blast of fleas rabages through the ages.
  • Quote by B. Lehane

13
Siphonaptera - the fleas
  • Important in the transmission of many organisms
    especially the the plague.
  • Morphology - see figures page 554-555. These
    will used in lab to identify fleas.
  • Jumping mechanism -
  • Can jump more than 100 times body length.
  • Resulin is a specialized protein that releases
    97 of its stored energy.

14
Siphonaptera - the fleas
  • In general, fleas lack significant host
    specificity.
  • Most fleas do have preferred hosts.
  • Fleas are grouped as to how much time they spend
    on the host.

15
Types of Fleas
  • Spend little time on host (feeding) spend most of
    time in nest. Some rodent fleas.
  • Spend most of time on host but can transfer from
    host to host. Most fleas.
  • Sticktight flea attaches permanently to skin of
    fowl.
  • Chigoe (Tunga penetrans) buries under skin on
    feet and hands - (see fig 37.12).

16
Some Important Fleas
  • Nosopsyllus fasciatus - northern rat flea -
    Usually not considered an important plague vector
    because it seldom bites man.
  • Pulex irritans - the human flea - see page 557.
    Is not host specific and commonly appears on dogs
    (80 of fleas on dogs were Pulex irritans in
    Georgia study). Can transmit plague

17
Some Important Fleas
  • Echidnophaga gallinacea is the sticktight flea of
    poultry. Buries its mouthparts under the skin
    and remains attached.
  • Ctenocephalides canis and C. felis are the dog
    and cat fleas. Often bite humans. Can be
    distinguished from other fleas by the presence of
    genal ctenidium with more than 5 teeth.

18
Some Important Fleas
  • Xenopsylla cheopis - The oriental or tropical rat
    flea - most important vector for plaque and
    murine typhus
  • Tunga penetrans (chigoe, jigger, chigger, chique,
    sand flea) commonly penetrates the skin around
    the base of nails on feet and hands. (See fig
    37.12, page 560)

19
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20
Ctenocephalides felis (cat flea)
21
Pulex irritans - the Human Flea
22
Xenopsylla cheopis - oriental rat flea
23
Tunga penetrans
24
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25
Fleas as Vectors
  • Plague
  • Commonly known as the black death
  • Caused by bacterium Yersinia pestis (Pasturella
    pestis)
  • Releases toxins that act on the mitochondrial
    membranes inhibiting uptake of ions and thus
    normal functioning of the cellular respiration.
  • Primarily a disease of rodents. Infected flea
    bites man and he becomes infected.

26
Three Types of Plague
  • Bubonic - primary plague in epidemics,
    demonstrates buboes (large swollen areas in lymph
    nodes of the groin area or armpits (see fig
    37.13, page 561). Fatal in 25-50 of untreated
    cases.
  • Pneumonic plague involves heavy infection of
    lungs. Is highly contagious and can be spread by
    breathing, coughing. Often fatal
  • Primary septicemic - generalized blood infection.
    Is often fatal.

27
Murine Typhus
  • Murine typhus
  • Endemic or flea-borne typhus caused by Rickettsia
    mooseri (prowazekii).
  • Usually rather mild in humans fever, head and
    body aches, and rash of 14 days or so duration.
  • Xenopsylla cheopis is most important vector.

28
Following info from Dr. Glenn Songers Webpage at
http//microvet.arizona.edu/Courses/MIC420/lecture
_notes/yersinia/yersinia_p_history.html
  • History of the Plaque- problem since early
    recorded history- Justinian Pandemic 6th century
  • Began 540 A.D. in Egypt, spread to Alexandria
    then on to Palestine, and to the rest of the
    world
  • 10,000 deaths per day at peak in Byzantium
    lasted 50 years, killed 100 x 106 people

29
Black Death Pandemic - From Asia to Europe on the
Silk Road
  • 14th century social conditions poor, rat
    population high, rats and humans lived in close
    proximity
  • First use of "Black Death" probably because of
    severe cyanosis in terminal plague victims.
  • China, India, Syria, ArmeniaMoved via the trade
    routes to Europe

30
The Black Plague
  • Probably first use of biological weapons bodies
    of plague victims catapulted into enemy camp.
  • Sudden appearance in winter of 1346-1347 in
    Europe- suspect black rat (Rattus rattus) and
    its flea Xenopsylla cheopsis. Throughout 14th
    century, upto 55 million died. (1/3 population)

31
The Black Death
32
Great Plague of London - 1665
  • Began 1664 - "Just before Christmas
  • Peak mortality 7000/week Total mortality of
    100,000 (Total population 500,000) Not isolated
    to London or England
  • May have given rise to children's rhyme
  • "Ring Around The RosiesA Pocket Full Of
    PosiesAshes, Ashes, All Fall Down"

33
Prevention of Diseases Carried by Fleas
  • Control of fleas - Use of insecticides and light
    traps that attract fleas.
  • General sanitation
  • Conditions conducive to high rat and flea
    populations and human overcrowding contribute to
    plague outbreaks.

34
Diptera - the Flies
  • More members of this group are involved in the
    transmission of pathogens than any other
    Arthropod group.
  • General features
  • These organisms have two wings (Diptera) and a
    second pair of halters which function in
    equilibrium
  • Have complete or Holometabolous development (egg,
    larvae, pupae, adult)

35
Family Psychodidae - Subfamily Phlebotominae -
Phlebotomus
  • The sand flies
  • Weak flies that can fly only short distances and
    can not fly when wind is blowing.
  • Transmits Leishmania causing Kala azar disease
    and tropical sore.
  • Carrions disease (Oroya fever). Caused by the
    bacterium Bartonella bacilliformis. It is a
    visceral form that causes muscle and joint pains,
    anemia, jaundice, and is sometime fatal.

36
Culicidae - Mosquitos
  • Mosquitos are the most Important insect vectors
    of human disease?
  • Have scales on the wing veins and posterior
    margin
  • Have an elongate proboscis
  • Life cycle includes eggs, larvae (wiggler) pupa
    (tumbler), and adult.
  • Larval forms use siphon tube to breath.

37
Some Important Mosquitos
  • Culex tarsalis - main vector of western equine
    encephalitis (WEE) and St. Louis encephalitis
  • Culex pipiens - are important vectors for
    filarial worms (Wucheria bancrofti and
    Dirofilaria immitis).
  • Aedes aegypti - the yellow fever mosquito - also
    dengue, (breakbone fever).

38
Anopheles sp
  • At rest, the head, thorax, and abdomen form a
    straight line. When they feed, there is a sharp
    angle toward the host
  • Vectors for Plasmodium falciparium, the most
    important of the human malarias
  • Female Anopheles mosquitos are the vectors
    Anopheles freeborni is a common example.

39
Anopheles feeding on person
40
Mosquito Control
  • Control of mosquitos comes from two major methods
  • Destruction of breeding sites - drainage of
    swamps, changing water levels, removal of trash
    (cans, tires, etc.) Mud puddles in Honduras.
  • Destruction of the organism - Insecticides,
    Gambusia (mosquito larvae eating fish), oil on
    the water.

41
Mosquito eating fish
42
Culex pipiens Male
43
Aedes aegypti - yellow fever mosquito
44
Culex pipiens and Anopheles punctipennis
45
Simulidae
  • Black flies, buffalo nats
  • Immature stages aquatic found in cold rapid
    flowing streams.
  • Transmitts Onchocerca volvolus which causes river
    blindness among other things

46
Simulium larva
47
Tabanidae
  • Transmitts Trypanosoma evansi which causes surra
    in horses, cattle, dogs, etc.
  • The deer fly, Chrysops is important in
    transmission of Loa loa - the African eye worm.
  • Often cause significant blood loss.

48
Tabanidae
  • Tabanids as transmitters of pathogens.
  • Anautogeny - must have blood meal for development
    of eggs
  • Telmophagy feeding habit - pool of blood that can
    receive pathogenic organisms.
  • Large blood meals (feed for long time)
  • Intermediate feeding (from organism to organism)

49
Black Deer Fly Chrysops
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