Parasitic Flies Class Hexapoda Order Diptera

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Parasitic Flies Class HexapodaOrder Diptera
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Flies - Diptera

• The key distinguishing adult structure two
  wings.
• All Flies are Holometabolous (having a complex
  metamorphosis
• i.e. egg, larvae pupa, and adult)

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One of Great Adaptations of of Flies - The
Habitat of larval stage

• The habitat of the larval stage is basically
  aquatic or semi-aquatic, and they have adapted
  to live in very, very challenging environments.

Allows them to invade Dead and Living tissues
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Diptera Flies as parasites

• Ectoparasites
• Adults are free living but blood feeding with the
  larvae stages aquatic or in moist semi-aquatic
  habitats. (Nematocera and Brachycera)

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Diptera Flies as parasites

1. Adults ectoparasites (or blood feeding) but
   larvae develop within female and essentially
   pupate after emerging from mother (Glossina,
   Hippoboscidae)

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Diptera Flies as parasites

• Endoparasites
• Adults free living but larvae are internal or
  partially internal (flesh feeding) parasites of
  vertebrates (Oestrus, Gasterophilus, Cochliomyia
  hominovorax)

Gasterophilus intestinalis
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Suborders of Diptera

• Nematocera
• Adults are mosquito like.
• Adults have long antennae with more than 6
  segments.
• Larvae have a well developed head capsule,
  usually with mandibles.

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Suborders of Diptera

• Brachycera
• Antennae shorter three to five segments
• Larvae have reduced mandibles and head capsule.
• Adults emerge from puparium from
  T-shaped slit.

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Suborders of Diptera

• Cyclorrhapha
• Antennae short, usually a club with an arista
• Larvae have mouth hooks and no head capsule.
• Within this group are the muscamorpha flies that
  emerge from puparium using a ptilinum

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Families of NematoceraNon-parasitic

• Tipulidae crane flies.
• Chironomidae - Midges

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Families of NematoceraParasitic forms

• Psychodidae Sand flies
• Many are not blood sucking (Psychodinae) although
  some can be nuisance flies around sewage
  treatments plants
• Phlebotominae (Bloodsuckers)

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Psychodidae

• Phlebotominae were discussed as vectors of
  Leishmania.
• Also vectors of several other minor diseases

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Sand flies as Vectors Genus Lutzomyia

• Carrions disease (baronellosis, Oroya fever,
  verruga peruana).
• Named for Daniel Carrion who made the ultimate
  graduate student sacrifice.
• Two forms 1) a severe anemia, and 2) a
  cutaneous swelling or ulcer.
• Peru, Equador or Colombia

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Phlebotomus as Vectors

• Gulf War Development
• Sand fly fever (pappataci fever, three day fever,
  and Phlebotomus fever).
• Viral fever occurring in Mediterranean, South
  China, India, and the Near East.
• Causative agent Sandfly Fever Viruses of the
  Bunyaviridae family.
• Symptoms may include fever, frontal headache,
  lethargy, malaise, retroorbital pain,
  conjuctivitis, photophobia, neck rigidity, low
  back pain, myalgia, meningitis, encephalitis,
  confusion.
• Bite from female sandflies, Phlebotomus papatasi,
  Phlebotomus perniciosus, Phlebotomus perfiliewi

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Families of NematoceraParasitic forms

• Ceratopogonidae (biting midges, punkies,
  no-see-ums, jejenes).
• lt 1 mm long!!
• Can go through most window screens
• Because of small size, they cannot orientate with
  even the slightest of winds.

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Ceratopogonidae

• Ceratopogonidae (biting midges, punkies,
  no-see-ums, jejenes).
• Larvae breed in moist substrates wet soil,
  cattle dung, and especially in salt marshes,
  mangrove swamps and brackish waters
• Ferocious biters despite their size.

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Ceratopogonidae

• Ceratopogonidae Minor Vectors of several
  parasites
• The nonpathenogenic filarioid nematodes Mansonia
  persitans and M. streptocerca.
• Bluetongue a virus causing a hemorrhagic
  desease of ruminants.

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Ceratopogonidae as Vectors

• Bluetongue is a viral disease to which all
  species of ruminants are susceptible, although
  sheep are most severely affected.
• It is characterized by changes to the mucous
  linings of the mouth and nose and the coronary
  band of the foot. .
• Bluetongue is caused by a virus within the
  Orbivirus genus of the family Reorvirades.

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Bluetongue Symptoms
Nasal Discharge
Blue tongue is rare but Notorious symptom
Mortality 5-20 some virus strains 70
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Families of NematoceraParasitic forms

• Culicidae covered later

Aedes albopictus
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Mosquitoes as vectors of Viruses and other
non-protozoan or non-metazoan diseases
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SARS virus is a new corona virus.
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Standing Water or Container-breeding Mosquitoes

• All Anopheles species lay single eggs on the
  water surface and the egg has a built in set of
  floats (on the side) to prevent it from sinking.
• Culex lay eggs on water surface as well, but
  in rafts.

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Flood water mosquitoes

• Aedes lays single eggs on moist ground. When
  rains come they are already in position.
  Sometimes the can wait out long periods of dry
  weather.

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Yellow fever

• Yellow fever is caused by a virus and is spread
  by the yellowfever mosquito, Aedes aegypti (L.).
• The disease, which originated in Africa and
  spread to the New World during the slave trade in
  the 1500s, affects humans as well as monkeys.
  Typically, yellow fever is expressed within one
  week of infection.
• Mild symptoms include headaches, fever, muscular
  pains, and nausea.
• Severe symptoms include dangerously high fevers,
  severe headaches, muscular pains, jaundice, and
  vomiting (characterized by black material and
  fluid). Yellow fever can lead to delirium, coma,
  and death.

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Dengue

• Dengue is presently the most important
  mosquito-borne virus affecting humans (CDC 2003)
• Causes more than 50 million cases of infection
  and 24,000 deaths worldwide

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Dengue

• The Pathogen is the Virus, Togaviridae,
  Flavivirus
• The flavivirus family includes a number of
  dangerous insect-borne diseases such as dengue,
  West Nile, yellow fever, tick-borne encephalitis
  and St. Louis encephalitis.

The dengue virus the first flavivirus structure
to be determined
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Dengue

• The Reservoir of dengue is Humans
• Geographic Distribution coincides with that of
  A. aegypti
• A debilitating illness, (two months under the
  weather and 1 week prostrate) but generally not
  fatal although a small and significant percentage
  of acses results in death, especially children.
• Other Names hemorrhagic fever, dengue shock
  syndrome, epidemic hemorrhagic fever,
  breakbone fever.

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• Principal vector is Aedes aegypti the
  yellowfever mosquito

Lyre pattern on prothorax
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Aedes aegypti

• Most important vector of dengue
• Why?
• greatly reduced the humming' sound
• Normally lives less than ninety meters from
  dwellings
• attacks from below or behind, usually from
  underneath desks or chairs and mainly at the feet
  and ankles
• Painless bite
• Prefers humans

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Dengue

• Currently, more than 100 countries have
  experienced dengue. Each year there are tens of
  millions of cases, and as many 95 are children

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Distribution of Aedes aegypti (red shaded areas)
in the Americas in 1970, at the end of the
mosquito eradication program, and in 1997.
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American countries with laboratory-confirmed
hemorrhagic fever (red shaded areas), prior to
1981 and from 1981 to 1997
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Encephalitis

• Def. Inflammation of the brain
• Effects can be like Multiple Sclerosis (MS), or
  stroke often have long-term consequences such as
  lameness or impairment of the intellectual
  faculties.
• The excessive inflammatory reaction of the brain
  can damage its sensitive nerve tissue or even
  lead to the death of a person.

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St. Louis Encephalitis.

• Like Dengue, St. Louis encephalitis is a
  flavivirus.
• Transmitted by mosquitoes (primarily the Culex
  species)

Culex spp.
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St. Louis Encephalitis

• Mosquitoes become infected by feeding on birds
  infected with the St. Louis encephalitis virus.
  Infected mosquitoes then transmit the St. Louis
  encephalitis virus to humans and animals during
  the feeding process.

Birds
Human- Dead end
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St. Louis Encephalitis

• The St. Louis encephalitis virus grows both in
  the infected mosquito and the infected bird, but
  does not make either one sick.
• Human to Human infection does not occur

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St. Louis Encephalitis

• The symptoms of St. Louis encephalitis are
• Mild infections occur without apparent symptoms
  other than fever with headache.
• More severe infection is leads to encephalitis
  which is marked by headache, high fever, neck
  stiffness, stupor, disorientation, coma, tremors,
  occasional convulsions (especially in infants)
  and spastic (but rarely flaccid) paralysis.
• The mortality rate of St. Louis encephalitis Is
  from 3 to 30 (especially higher in the aged).
• There is no specific therapy and Intensive
  supportive therapy is indicated.

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Eastern Equine Encephalitis

• CLINICAL FEATURES
• Symptoms range from mild flu-like illness to
  frank encephalitis, coma and death
• ETIOLOGIC AGENT
• Eastern equine encephalitis virus, member of the
  family Togaviridae, genus Alphavirus. Closely
  related to western and Venezuelan equine
  encephalitis viruses
• INCIDENCE
• 153 confirmed cases in the U.S. since 1964
• TRANSMISSION
• Mosquito-borne

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Other mosquitoe borne Encephalitides

• Western Equine Encephalitis
• Eastern Equine Encephalitis
• Venezuelan Equine Encephalitis
• Japanese B Encephalitis
• Murray Valley Encephalitis

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Other Mosquito-borne viruses

• West Nile Virus
• Rift Valley fever
• Rabbitt myxomatosis
• Fowl pox