Biology of Phlebotomine Sand Flies (Diptera: Psychodidae)

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Biology of Phlebotomine Sand Flies (Diptera
Psychodidae)

• Bruce Alexander
• Molecular Biochemical Parasitology Group
• Liverpool School of Tropical Medicine, Pembroke
  Place, Liverpool L3 5QA, UNITED KINGDOM

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Female sand fly feeding on blood
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Characteristics

• Small (2-3 mm)
• Brown (but appear white when illuminated)
• Wings held in erect V-shape
• Nocturnal
• Do not hover
• Silent
• Painful bite

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Life cycle and developmental stages
Adult male
Fourth instar larvae
Adult female
Eggs
Life cycle
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Amazon Rain Forest
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Arabian Desert
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Peruvian Andes
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Brazilian city
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Global distribution of the leishmanaises
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Pathogens transmitted by sand flies

• Leishmania spp. (Cutaneous and visceral
  leishmaniases in 89 countries worldwide)
• Bartonella bacilliformis (Bartonellosis or
  Carrións disease in Peru, Ecuador and Colombia
• Phlebovirus spp. (Sand fly fever in Middle East
  and N. Africa)

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CYCLE OF LEISHMANIA TRANSMISSION
Intracellular amastigotes in mammal host ingested
by sand fly
Transformed into extracellular promastigotes in
gut of sand fly
Extracellular promastigotes injected into new
mammal host by sand fly
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Female sand fly biting
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Cerdocyon thous example of Leishmania reservoir
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Erythemas made by bites of Lu. longipalpis
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(No Transcript)
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MUCOCUTANEOUS LEISHMANIASIS resulting from
uncured chronic infection with Le. braziliensis
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DIFFUSE CUTANEOUS LEISHMANIASIS, due to
incurable infection with Le. amazonensis
parasites and related parasites all
leishmaniasis patients in Dominican Republic have
DCL why?
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Visceral leishmaniasis in man

• Anthroponotic cycle due to Le. donovani in India
  (kala-azar) humans generally represent dead-end
  host for Le. infantum
• Most cases in malnourished children
• Many asymptomatic
• subclinical cases AIDS in southern Europe

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Sand flies vital requirements

• Larvae breed in soil (not aquatic)
• Only females take blood, from a variety of
  vertebrate species
• Rest during the day in dark, humid microhabitats
• Both sexes require sugar as an energy source

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Sand flies resting on tree trunk during the day
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Extrafloral nectaries on Inga sp. - potential
sugar source for sand flies
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Sand flies resting on wall of a chicken house