Trypanosoma

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Trypanosoma cruzi
CDC/Dr. Myron G. Schultz, WikiMedia Commons
T. cruzi in monkey heart
Dr. L.L. Moore Jr., WikiMedia Commons
Triatoma infestans the Kissing bug - WHO Wikimedia Commons
Chagas endemic zones 2005 - Wikimedia Commons
  • Protozoal parasites found in the blood and tissues of vertebrates
  • Worldwide distribution
  • Causes sleeping sickness in humans
  • Particularly seen in sub-Saharan Africa
    • Affects cattle production
    • Causes Nagana (Wasting disease)
  • Divided into two groups depending on the mode of development in the insect vector
    • Salivarian
      • Multiply in the foregut and proboscis
      • Transmitted via inoculation during feeding
      • Transmitted by Tsetse flies
      • Also known as anterior station development
    • Stercorarian
      • Multiply in the hindgut
      • Infective form migrates to the rectum
      • Transmitted via contamination of wounds with insect faeces
      • Also known as posterior station development
  • All Trypansomes except for T. equiperdum have arthropod vectors
    • T. equiperdum is a venereally transmitted disease
  • Non-cyclical transmission can also occur
    • Mechanical transmission
    • Transferred by interrupted feeding from one host to another
    • Usually transmitted by biting flies, e.g. Tabanidae and Stomoxys

Recognition

  • Elongated, spindle shaped protozoa
  • Between 8 and 39 μm in length
  • Flagellate
    • Flagellum runs the length of the body attached to the pellicle which forms an undulating membrane
  • Kinetoplast present which contains the DNA of the single mitochondrion

Life Cycle

  • Undergo morphological transformations in intermediate host before becoming infective for the next host
  • Blood-sucking flies ingest trypanosomes whilst taking a blood meal from an infected animal
    • Trypanosomes multiply first in the gut of the fly
  • Salivarian trypanosomes are transmitted by Tsetse flies
    • Trypanosomes pass forward to the salivary glands where they transform into the infective stage
    • Inoculated with saliva when Tsetse fly next feeds on a host
  • Stercorarian trypanosomes are transmitted by triatomid bugs, tabanids and keds
    • Trypanosomes pass back to the rectum
    • Next host is infected when skin wounds are contaminated with infected insect faeces


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