Trypanosoma

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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Tropical Protozoa Flashcards