Difference between revisions of "Leishmania"

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==''Trypanosoma''==
 
==''Trypanosoma''==
 +
 +
*Protozoal parasites found in the blood and tissues of vertebrates
 +
 +
*Worldwide distribution
 +
 +
*Causes sleeping sickness in humans
 +
 +
*Particularly affect sub-Saharan Africa
 +
**Affect cattle production
 +
**Cause Nagana (depression)
 +
 +
*Divided into two groups depending on the mode of development of the insect vector
 +
**'''Salivarian'''
 +
***Multiply in the foregut
 +
***Transmitted via innoculation via feeding
 +
**'''Stercorarian''''
 +
***Multiply in the hindgut
 +
***Transmitted via contamination of wounds with insect faeces
  
 
'''Life Cycle'''
 
'''Life Cycle'''
 +
*Undergo morphological transformations in intermediate host before becoming infective for the next host
 +
 +
*Blood-sucking [[Biting Flies|flies]] ingest trypanosomes whilst taking a blood meal from an infected animal
 +
**Trypanosomes multiply first in the gut of the [[Biting Flies|fly]]
 +
 +
*Salivarian trypanosomes are transmitted by [[Biting Flies#Glossinidae|Tsetse flies]]
 +
**Trypanosomes pass foward to the salivary glands where they transform into the infective stage
 +
**Innoculated with saliva when [[Biting Flies#Glossinidae|Tsetse fly]] next feeds on a host
 +
 +
*Stercorarian trypanosomes are transmitted by triatomid bugs, [[Biting Flies#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
  
 
'''Pathogenesis'''
 
'''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 [[Biting Flies#Tabanidae|tabanids]] and [[Biting Flies#Melophagus spp.|keds]]
 +
***''T. theileria'' and ''T. melophagium''
 +
 +
*Enlarged [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] and [[Spleen - Anatomy & Physiology|spleen]]
 +
**Causes lymphoid exhaustion
 +
 +
*Anaemia
 +
**Red blood cells removed from circulation
 +
 +
*Degeneration and inflammation of multiple organs
 +
**E.g. Skeletal muscle, myocardium and CNS
  
 
'''Epidemiology'''
 
'''Epidemiology'''
  
 
'''Diagnosis'''
 
'''Diagnosis'''
 +
*Demonstrate trypanosomes in blood
 +
**Giemsa stained smears
 +
**Fresh blood films
 +
***Motile trypanosomes
 +
**Haematocrit tube
 +
***Motile trypanosomes at the plasma/buffy coat interface
  
 
'''Control'''
 
'''Control'''
 +
*[[Biting Flies#Glossinidae|Tsetse fly]] control
 +
**Spraying and trapping
 +
 +
*Prophylactic drug treatment
 +
**Change drug group periodically to decrease the chances of resistance occuring
 +
**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'''
 
'''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
 +
 +
*Venerally transmitted
 +
**E.g. Dourine
 +
***Transmitted by ''T. equiperdum''
 +
***Causes genital and abdominal oedema, emaciataion 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''
  
 
==''Leishmania''==
 
==''Leishmania''==

Revision as of 16:27, 23 November 2008


 This article is still under construction.


Infectious agents and parasitesWikiBugs Banner.png
PARASITES
PROTOZOA



Trypanosoma

  • Protozoal parasites found in the blood and tissues of vertebrates
  • Worldwide distribution
  • Causes sleeping sickness in humans
  • Particularly affect sub-Saharan Africa
    • Affect cattle production
    • Cause Nagana (depression)
  • Divided into two groups depending on the mode of development of the insect vector
    • Salivarian
      • Multiply in the foregut
      • Transmitted via innoculation via feeding
    • Stercorarian'
      • Multiply in the hindgut
      • Transmitted via contamination of wounds with insect faeces

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 foward to the salivary glands where they transform into the infective stage
    • Innoculated 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
  • Anaemia
    • Red blood cells removed from circulation
  • Degeneration and inflammation of multiple organs
    • E.g. Skeletal muscle, myocardium and CNS

Epidemiology

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 occuring
    • 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
  • Venerally transmitted
    • E.g. Dourine
      • Transmitted by T. equiperdum
      • Causes genital and abdominal oedema, emaciataion 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

Leishmania

Life Cycle

Pathogenesis

Leishmania involved in skin infections

Epidemiology

Diagnosis

Treatment and Control

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