Difference between revisions of "Trypanosoma"

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{{OpenPagesTop}}
 
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{{Taxobox
 
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|name              = ''Trypanosoma sp''
 
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|kingdom            = Protista
 
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|sub-kingdom        =
 
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|phylum            = [[Protozoa]]
 
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|super-class        =
 
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|class              =
 
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|sub-class          =
 
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|super-order        =
 
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|order              = Kinetoplastida
 
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|sub-order          =
 
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|super-family      =
 
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|family            = Trypanosomatidae
 
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|sub-family        =
 
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|genus              = Trypanosoma
 
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|species            =
 
−
}}
 
−
[[File:Trypanosoma brucei.gif|thumb|300px|right|Schematic diagram of ''Trypanosoma brucei'']]
 
 
[[Image:Trypanosoma.jpg|thumb|right|150px|''Trypanosoma cruzi'' <br> CDC/Dr. Myron G. Schultz, WikiMedia Commons]]
 
[[Image:Trypanosoma.jpg|thumb|right|150px|''Trypanosoma cruzi'' <br> CDC/Dr. Myron G. Schultz, WikiMedia Commons]]
−
[[Image:T.cruzi in monkey heart.jpg|thumb|right|150px|''T. cruzi'' in monkey heart <br> Dr. L.L. Moore Jr., WikiMedia Commons]]
+
[[Image:T.cruzi in monkey heart.jpg|thumb|right|150px|''T. cruzi'' in monkey heart - Dr. L.L. Moore, Jr.]]
 +
[[Image:T.cruzi Life cycle.jpg|thumb|right|150px|''T. cruzi'' Life Cycle Diagram - Wikimedia Commons]]
 
[[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]]
−
==Introduction==
+
[[Image:Ndama.jpg|thumb|right|150px|N'dama - Trypanotolerant West African Bos taurus - Wikimedia Commons]]
−
Trypanosomes are '''elongated unicellular [[Protozoa |protozoal]]''' organisms with an undulating membrane and anterior flagellum.
+
*Protozoal parasites found in the blood and tissues of vertebrates
  
−
==Lifecycle==
+
*Worldwide distribution
−
The trypanosomes are transmitted by '''haematophagous insect''' vectors including the '''[[Glossinidae |tsetse fly]]''' and '''triatomid''' kissing bug.
 
  
−
===Stercorarian===
+
*Causes sleeping sickness in humans
−
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.
 
  
−
They can then '''penetrate''' the tissues, gaining access through skin abrasions or mucous membranes. The metatrypanosomes then multiply within the reticulo-endothelial system of the host, later '''disseminating''' throughout the organs invading host cells residing within parasitophorous vacuole. These vacuoles acidify and subsequently release '''trypomastigotes''' into the cell cytoplasm. These then develop into '''amastigotes''' which divide several times eventually transforming back into trypomastigotes that rupture the host cell. From here they may invade other cells or enter the bloodstream where the opportunity may arise to infect the insect vector. The amastigotes may also burst the host cell and invade other cells.
+
*Particularly seen in sub-Saharan Africa
 +
**Affects cattle production
 +
**Causes Nagana (Wasting disease)
  
−
'''''T. cruzi''''', the trypanosome of '''most human importance''', is a typical Stercorarian trypanosome and utilises the '''triatomid “kissing bug”''' as its vector among others. Disease in dogs may also occur.
+
*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 [[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'''
  
−
''T. theileri'' infects cattle and is transmitted by [[Tabanidae |tabanid flies]], [[Stomoxys calcitrans |stable flies]], [[Ticks |ticks]] and [[Culicidae |mosquitoes]].
+
*All ''Trypansomes'' except for ''T. equiperdum'' have arthropod vectors
 +
**''T. equiperdum'' is a venereally transmitted disease
  
−
===Salivarian===
+
*'''Non-cyclical''' transmission can also occur
−
Salivarian trypanosomes develop in the '''anterior gut''' of their vector, the '''[[Glossinidae |Tsetse fly]]'''.
+
**Mechanical transmission
 +
**Transferred by interrupted feeding from one host to another
 +
**Usually transmitted by [[Biting Flies|biting flies]], e.g. [[Tabanidae|''Tabanidae'']] and [[Stomoxys calcitrans|''Stomoxys'']]
  
−
Development occurs in the '''proboscis''' and midgut, forming '''epimastigotes''' which then invade the '''hypopharynx''' and develop into '''trypomastigotes''' and then '''infective metatrypanosomes''' form.
+
'''Recognition'''
 +
*Elongated, spindle shaped protozoa
  
−
These are then innoculated into the mammalian host through a '''bite''' before a blood meal.
+
*Between 8 and 39 μm in length
  
−
==Pathogenesis==
+
*Flagellate
−
Trypanosomes '''deplete''' carbohydrates, proteins, lipids and micronutrients from their hosts.
+
**Flagellum runs the length of the body attached to the pellicle which forms an undulating membrane
  
−
They cause '''haemolytic [[Anaemia |anaemia]]''' when present within the bloodstream.
+
*Kinetoplast present which contains the DNA of the single mitochondrion
  
−
==Diseases==
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'''Life Cycle'''
−
[[Trypanosomosis]] affects the lymphoid and haematopoeitic systems of a wide range of hosts.
+
*Undergo morphological transformations in intermediate host before becoming infective for the next host
  
−
===Salivarian Species===
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*Blood-sucking [[Biting Flies|flies]] ingest trypanosomes whilst taking a blood meal from an infected animal
−
''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]].
+
**Trypanosomes multiply first in the gut of the [[Biting Flies|fly]]
  
−
''T. vivax'' infects ruminants, horses and camels causing significant disease.
+
*Salivarian trypanosomes are transmitted by [[Glossinidae|Tsetse flies]]
 +
**Trypanosomes pass forward to the salivary glands where they transform into the infective stage
 +
**Inoculated with saliva when [[Glossinidae|Tsetse fly]] next feeds on a host
  
−
''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.
+
*Stercorarian trypanosomes are transmitted by triatomid bugs, [[Tabanidae|tabanids]] and [[Biting Flies#Melophagus spp.|keds]]
 +
**Trypanosomes pass back to the rectum
 +
**Next host is infected when skin wounds are contaminated with infected [[Insecta|insect]] faeces
  
−
''T. simiae'' causes fatal pyrexia in '''pigs''' while ''T. congolense'' is milder in the same species.
+
'''Pathogenesis'''
−
+
*Salivarian
−
''T. congolense'' can also affect '''dogs and cats''' causing acute fever, anaemia and neurological signs.
+
**Causes wasting disease in cattle (nagana)
 +
**Sleeping sickness in humans
  
−
''T. evansi'' also affects all domestic mammals.
+
*Stercorarian
 +
**''T. cruzi'' most important in veterinary medicine
 +
***Occurs in South America
 +
***Infects armadillos, possums and humans
 +
***Causes Chagas' Disease
 +
**Transmitted by a triatomid (kissing) bug
 +
**Chronic infections are often fatal causing heart failure
 +
**Non-pathogenic species are transmitted by [[Tabanidae|tabanids]] and [[Melophagus spp.|keds]]
 +
***''T. theileria'' and ''T. melophagium''
  
−
===Stercorarian Species===
+
*Enlarged [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] and [[Spleen - Anatomy & Physiology|spleen]]
−
'''''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'''''.
+
**Causes lymphoid exhaustion
−
A similar acute disease is thought to be caused by ''T. cruzi'' in dogs in the USA.
+
**Associated with plasma cell hypertrophy and hypergammaglobulinaemia
 +
***Due to an increase in [[Immunoglobulin M|IgM]]
 +
**With infections of increased duration, the [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] and [[Spleen - Anatomy & Physiology|spleen]] shrink due to exhaustion of their cellular elements
  
−
''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''.
+
*Anaemia
 +
**Red blood cells are removed from circulation ('''haemolytic''')
 +
**Is a cardinal feature of the disease
  
 +
*Degeneration and inflammation of multiple organs
 +
**E.g. Skeletal muscle, myocardium and CNS
  
−
{{Learning
+
'''Clinical Signs'''
−
|flashcards = [[Trypanosoma Flashcards]]
+
*In ruminants:
−
[[Protozoa_Flashcards#Tropical_Protozoa|Tropical Protozoa Flashcards]]  
+
**Anaemia
−
|Vetstream = [https://www.vetstream.com/canis/search?s=protozoa Protozoa]
+
**Enlargement of the [[Lymph Nodes - Anatomy & Physiology|lymph nodes]]
−
}}
+
**Progressive loss of body condition
 +
**Fever and appetite loss occur during parasite peaks
 +
**Chronic disease usually terminates in death of the animal if untreated
 +
**Can cause abortion, infertility and decreased growth in herds
  
−
==References==
+
*In horses:
−
<references/>
+
**Acute or chronic infections of ''T. brucei''
−
{{CABI source
+
**Oedema of the limbs and genitalia
−
|datasheet = [http://www.cabi.org/ahpc/?compid=3&dsid=96918&loadmodule=datasheet&page=2144&site=160 ''Trypanosoma'']
 
−
|date = 6 June 2011
 
−
}}
 
−
<br><br><br>
 
  
−
{{Nick Lyons
+
*In pigs:
−
|date = October 29, 2011}}
+
**''T. congolense'' infections are mild or chronic
 +
**''T. simiae'' infections are hyperacute usually leading to death from pyrexia in a few days
  
−
{{OpenPages}}
+
*In dogs and cats:
 +
**''T. brucei'' and ''T. congolese''
 +
**Acute infections
 +
**Fever, anaemia, myocarditis, corneal opacity
 +
**Occasionally neurological signs present, such as increased aggression, ataxia and convulsions
 +
 
 +
*In donkeys:
 +
**''T. brucei'' in [[Protozoal Skin Infections - Donkey|skin infections]]
 +
 
 +
'''Epidemiology'''
 +
*Vector distribution
 +
**[[Glossinidae|Tsetse flies]] found in riverine, savannah and forest habitats
 +
**Up to 20% [[Biting Flies|flies]] infected
 +
**[[Biting Flies|Flies]] infected for life
 +
 
 +
*Parasite virulence
 +
**Some parasitaemic animals survive for long periods of time
 +
***E.g. ''T. brucei'' and ''T. congolense''
 +
***Increases the opportunity for infection of [[Biting Flies|flies]]
 +
**Some trypanosomes kill their host in 1-2 weeks
 +
***E.g. ''T. vivax''
 +
***Decreases the chances of [[Biting Flies|fly]] infection
 +
**Trypanosomes avoid host immune defences by altering glycoprotein coat (surface antigen) before host [[Immunoglobulins|antibody]] response
 +
***'''Antigenic variation''' can occur many times over several months causes relapsing parasitaemia
 +
 
 +
*Host response
 +
**Trypanotolerant wild animals remain parasitaemic for prolonged periods without showing clinical signs of disease
 +
***Cause lasting reservoirs of infection
 +
**Most domestic livestock are susceptible to trypanosomosis
 +
**Some local breeds of sheep, goats and cattle are trypanotolerant
 +
***E.g. ''Bos indicus''
 +
 
 +
'''Diagnosis'''
 +
*Demonstrate trypanosomes in blood
 +
**Giemsa stained smears
 +
**Fresh blood films
 +
***Motile trypanosomes
 +
**Haematocrit tube
 +
***Motile trypanosomes at the plasma/buffy coat interface
 +
 
 +
'''Control'''
 +
*[[Glossinidae|Tsetse fly]] control
 +
**Spraying and trapping
 +
 
 +
*Prophylactic drug treatment
 +
**Change drug group periodically to decrease the chances of resistance occurring
 +
**May lead to protective immunity but livestock will still be susceptible to heterologous challenges
 +
 
 +
*Barrier fences and buffer zones
 +
**Separate livestock and wild animals
 +
 
 +
*Trypanotolerant livestock
 +
 
 +
'''Other trypanosomes'''
 +
*Mechanically transmitted by [[Biting Flies|biting flies]]
 +
**E.g. Surra affecting horses and camels in North Africa, Asia and South America
 +
**''T. equinum'' in South America
 +
**''T. evansi'' in Asia
 +
 
 +
*Venereally transmitted
 +
**E.g. Dourine
 +
***Transmitted by ''T. equiperdum''
 +
***Causes genital and abdominal oedema, emaciation and CNS signs
 +
***Affects horses and donkeys in Africa, Asia, Central and South America
 +
 
 +
*Non-pathogenic species occur in the UK
 +
**In sheep caused by ''T. melophagium''
 +
**In cattle caused by ''T. theileri''
 +
 
 +
 
 +
*Myositis
 +
**Infrequent muscle lesions with mononuclear infiltrates
 +
**Dogs, cats and pigs are affected
 +
**Parasites lie between myofilaments
 +
**May cause fibre degeneration
  
 
[[Category:Tropical Protozoa]]
 
[[Category:Tropical Protozoa]]
−
[[Category:CABI Expert Review Completed]][[Category:CABI AHPC Pages]]
+
 
−
[[Category:Nick Lyons reviewed]]
+
[[Category:To_Do_-_Parasites]]

Revision as of 11:04, 22 July 2010

Trypanosoma cruzi
CDC/Dr. Myron G. Schultz, WikiMedia Commons
T. cruzi in monkey heart - Dr. L.L. Moore, Jr.
T. cruzi Life Cycle Diagram - Wikimedia Commons
Triatoma infestans the Kissing bug - WHO Wikimedia Commons
Chagas endemic zones 2005 - Wikimedia Commons
N'dama - Trypanotolerant West African Bos taurus - 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

Pathogenesis

  • Salivarian
    • Causes wasting disease in cattle (nagana)
    • Sleeping sickness in humans
  • Stercorarian
    • T. cruzi most important in veterinary medicine
      • Occurs in South America
      • Infects armadillos, possums and humans
      • Causes Chagas' Disease
    • Transmitted by a triatomid (kissing) bug
    • Chronic infections are often fatal causing heart failure
    • Non-pathogenic species are transmitted by tabanids and keds
      • T. theileria and T. melophagium
  • Enlarged lymph nodes and spleen
    • Causes lymphoid exhaustion
    • Associated with plasma cell hypertrophy and hypergammaglobulinaemia
      • Due to an increase in IgM
    • With infections of increased duration, the lymph nodes and spleen shrink due to exhaustion of their cellular elements
  • Anaemia
    • Red blood cells are removed from circulation (haemolytic)
    • Is a cardinal feature of the disease
  • Degeneration and inflammation of multiple organs
    • E.g. Skeletal muscle, myocardium and CNS

Clinical Signs

  • In ruminants:
    • Anaemia
    • Enlargement of the lymph nodes
    • Progressive loss of body condition
    • Fever and appetite loss occur during parasite peaks
    • Chronic disease usually terminates in death of the animal if untreated
    • Can cause abortion, infertility and decreased growth in herds
  • In horses:
    • Acute or chronic infections of T. brucei
    • Oedema of the limbs and genitalia
  • In pigs:
    • T. congolense infections are mild or chronic
    • T. simiae infections are hyperacute usually leading to death from pyrexia in a few days
  • In dogs and cats:
    • T. brucei and T. congolese
    • Acute infections
    • Fever, anaemia, myocarditis, corneal opacity
    • Occasionally neurological signs present, such as increased aggression, ataxia and convulsions

Epidemiology

  • Vector distribution
  • Parasite virulence
    • Some parasitaemic animals survive for long periods of time
      • E.g. T. brucei and T. congolense
      • Increases the opportunity for infection of flies
    • Some trypanosomes kill their host in 1-2 weeks
      • E.g. T. vivax
      • Decreases the chances of fly infection
    • Trypanosomes avoid host immune defences by altering glycoprotein coat (surface antigen) before host antibody response
      • Antigenic variation can occur many times over several months causes relapsing parasitaemia
  • Host response
    • Trypanotolerant wild animals remain parasitaemic for prolonged periods without showing clinical signs of disease
      • Cause lasting reservoirs of infection
    • Most domestic livestock are susceptible to trypanosomosis
    • Some local breeds of sheep, goats and cattle are trypanotolerant
      • E.g. Bos indicus

Diagnosis

  • Demonstrate trypanosomes in blood
    • Giemsa stained smears
    • Fresh blood films
      • Motile trypanosomes
    • Haematocrit tube
      • Motile trypanosomes at the plasma/buffy coat interface

Control

  • Prophylactic drug treatment
    • Change drug group periodically to decrease the chances of resistance occurring
    • May lead to protective immunity but livestock will still be susceptible to heterologous challenges
  • Barrier fences and buffer zones
    • Separate livestock and wild animals
  • Trypanotolerant livestock

Other trypanosomes

  • Mechanically transmitted by biting flies
    • E.g. Surra affecting horses and camels in North Africa, Asia and South America
    • T. equinum in South America
    • T. evansi in Asia
  • Venereally transmitted
    • E.g. Dourine
      • Transmitted by T. equiperdum
      • Causes genital and abdominal oedema, emaciation and CNS signs
      • Affects horses and donkeys in Africa, Asia, Central and South America
  • Non-pathogenic species occur in the UK
    • In sheep caused by T. melophagium
    • In cattle caused by T. theileri


  • Myositis
    • Infrequent muscle lesions with mononuclear infiltrates
    • Dogs, cats and pigs are affected
    • Parasites lie between myofilaments
    • May cause fibre degeneration
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