Changes

Jump to navigation Jump to search

Trypanosoma (view source)

Revision as of 11:45, 6 June 2011

1,277 bytes added ,  11:45, 6 June 2011
no edit summary
Line 20: Line 20:  
[[Image:Triatoma infestans.jpg|thumb|right|150px|''Triatoma infestans'' the Kissing bug - WHO Wikimedia Commons]]
 
[[Image:Triatoma infestans.jpg|thumb|right|150px|''Triatoma infestans'' the Kissing bug - WHO Wikimedia Commons]]
 
[[Image:Chagas endemic zones 2005.jpg|thumb|right|150px|Chagas endemic zones 2005 - Wikimedia Commons]]
 
[[Image:Chagas endemic zones 2005.jpg|thumb|right|150px|Chagas endemic zones 2005 - Wikimedia Commons]]
−
*Protozoal parasites found in the blood and tissues of vertebrates
     −
*Worldwide distribution
+
==Introduction==
 +
Trypanosomes are '''elongated unicellular [[Protozoa | protozoal]]''' organisms with an undulating membrane and anterior flagellum.
 +
==Lifecycle==
 +
The trypanosomes are transmitted by '''haematophagous insect''' vectors including the '''[[Glossinidae | tsetse fly]]''' and '''triatomid''' kissing bug.
 +
===Stercorarian===
 +
Stercorarian trypanosomes develop in the '''posterior gut''' of the insect and infective '''metatrypanosomes''' are excreted in the '''faeces''' of the insect onto the '''skin''' of the host.
   −
*Causes sleeping sickness in humans
+
They can then '''penetrate''' the tissues. The metatrypanosomes then multiply within the reticulo-endothelial system of the host, later '''disseminating''' throughout the organs.
   −
*Particularly seen in sub-Saharan Africa
+
'''Trypomastigotes''' then enter the bloodstream and can reinvade new tissues as anastigotes as well as infecting insects during bloodfeeding.
−
**Affects cattle production
  −
**Causes Nagana (Wasting disease)
     −
*Divided into two groups depending on the mode of development in the insect vector
+
'''''T. cruzi''''', the trypanosome of '''most veterinary importance''', is a typical Stercorarian trypanosome and utilises the '''triatomid “kissing bug”''' as its vector.
−
**'''Salivarian'''
  −
***Multiply in the foregut and proboscis
  −
***Transmitted via inoculation during feeding
  −
***Transmitted by [[Glossinidae|''Tsetse'' flies]]
  −
***Also known as '''anterior station development'''
  −
**'''Stercorarian'''
  −
***Multiply in the hindgut
  −
***Infective form migrates to the [[Rectum - Anatomy & Physiology|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. theileri'' is transmitted by [[Tabanidae | tabanid flies]], [[Stomoxys calcitrans | stable flies]], [[Ticks | ticks]] and [[Culicidae | mosquitoes]]
−
**''T. equiperdum'' is a venereally transmitted disease
+
===Salivarian===
 +
Salivarian trypanosomes develop in the '''anterior gut''' of their vector, the '''[[Glossinidae | Tsetse fly]]'''.
   −
*'''Non-cyclical''' transmission can also occur
+
Development occurs in the '''proboscis''' and midgut, forming '''epimastigotes''' which then invade the '''hypopharynx''' and develop into '''trypomastigotes''' and then '''infective metatrypanosomes''' form.
−
**Mechanical transmission
+
These are then innoculated into the mammalian host through a '''bite''' before a blood meal.
−
**Transferred by interrupted feeding from one host to another
  −
**Usually transmitted by [[Biting Flies|biting flies]], e.g. [[Tabanidae|''Tabanidae'']] and [[Stomoxys calcitrans|''Stomoxys'']]
     −
'''Recognition'''
+
==Pathogenesis==
−
*Elongated, spindle shaped protozoa
+
Trypanosomes '''deplete''' carbohydrates, proteins, lipids and micronutrients from their hosts.
   −
*Between 8 and 39 μm in length
+
They cause '''haemolytic [[Anaemia | anaemia]]''' when present within the bloodstream.
 +
==Diseases==
 +
[[Trypanosomosis]] affects the lymphoid and haeatopoeitic systems of a wide range of hosts.
 +
===Salivarian Species===
 +
''T. brucei'' affects '''all domestic mammals''', including small and farm species, and humans. It also causes a specific [[Protozoal Skin Infections - Donkey|skin disease in donkeys]].
   −
*Flagellate
+
''T. vivax'' infects ruminants, horses and camels causing significant disease.
−
**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
+
''T. equiperdum'' causes '''venereal''' equine disease '''dourine'''. It is the only trypanosome that does not immediately require an insect vector for transmission, being spread through coitus.
   −
'''Life Cycle'''
+
''T. simiae'' causes fatal pyrexia in '''pigs''' while ''T. congolense'' is milder in the same species.
−
*Undergo morphological transformations in intermediate host before becoming infective for the next host
+
 +
''T. congolense'' can also affect '''dogs and cats''' causing acute fever, anaemia and neurological signs.
   −
*Blood-sucking [[Biting Flies|flies]] ingest trypanosomes whilst taking a blood meal from an infected animal
+
''T. evansi'' also affects all domestic mammals.
−
**Trypanosomes multiply first in the gut of the [[Biting Flies|fly]]
     −
*Salivarian trypanosomes are transmitted by [[Glossinidae|Tsetse flies]]
+
===Stercorarian Species===
−
**Trypanosomes pass forward to the salivary glands where they transform into the infective stage
+
'''''T. cruzi''''' occurs in '''South America''' where it is transmitted by a triatomid (kissing)  bug and infects armadillos, possums and humans. It is known as '''''Chagas’ Disease'''''.
−
**Inoculated with saliva when [[Glossinidae|Tsetse fly]] next feeds on a host
+
A similar acute disease is thought to be caused by ''T. cruzi'' in dogs in the USA.
   −
*Stercorarian trypanosomes are transmitted by triatomid bugs, [[Tabanidae|tabanids]] and [[Melophagus ovinus|keds]]
+
''T. melophagum'' and ''T. Theileri'' are '''non-pathogenic''' species present in the '''UK''' infecting cattle, buffalo and antelope. Stress and concurrent disease are thought to be contributors to the development of clinical disease from ''T. theileri''.
−
**Trypanosomes pass back to the rectum
  −
**Next host is infected when skin wounds are contaminated with infected [[Insecta|insect]] faeces
      +
==References==
 +
<references/>
 +
Animal Health & Production Compendium, '''Trypanosoma datasheet''', accessed 06/06/2011 @ http://www.cabi.org/ahpc/
    +
Animal Health & Production Compendium, '''Trypanosomiasis datasheet''', accessed 06/06/2011 @ http://www.cabi.org/ahpc/
    
==Test yourself with the Protozoa Flashcards==
 
==Test yourself with the Protozoa Flashcards==
Line 82: Line 78:  
[[Category:Tropical Protozoa]]
 
[[Category:Tropical Protozoa]]
   −
[[Category:To_Do_-_Steph]]
+
[[Category:To_Do_-_CABI review]]
Lwyasm1
1,433

edits

Retrieved from "https://en.wikivet.net/Special:MobileDiff/117294"

Navigation menu