Difference between revisions of "Trypanosomosis"
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− | + | Also Known As | |
− | Also Known As | ||
− | + | [[File:Trypanosoma brucei.gif|thumb|300px|right|Schematic diagram of Trypanosoma brucei]] | |
− | [[File:Trypanosoma. | ||
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− | + | [[File:Trypanosomes blood.gif|thumb|200px|right|Trypanosomes in blood]] | |
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− | ''' | + | '''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 [[Tabanidae|tabanids]] and [[Melophagus ovinus|keds]] | ||
+ | ***''T. theileria'' and ''T. melophagium'' | ||
− | + | *Enlarged [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] and [[Spleen - Anatomy & Physiology|spleen]] | |
+ | **Causes lymphoid exhaustion | ||
+ | **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 | ||
− | + | *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 - 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 | ||
− | + | *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 | ||
− | + | *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'' | ||
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− | + | *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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− | [[Category: | + | [[Category:To Do - Steph]] |
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Revision as of 12:01, 3 June 2011
Also Known As
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
- T. cruzi most important in veterinary medicine
- 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
- In donkeys:
- T. brucei in skin infections
Epidemiology
- Vector distribution
- Tsetse flies found in riverine, savannah and forest habitats
- Up to 20% flies infected
- 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 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
- Some parasitaemic animals survive for long periods of time
- 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
- Trypanotolerant wild animals remain parasitaemic for prolonged periods without showing clinical signs of disease
Diagnosis
- Demonstrate trypanosomes in blood
- Giemsa stained smears
- Fresh blood films
- Motile trypanosomes
- Haematocrit tube
- Motile trypanosomes at the plasma/buffy coat interface
Control
- 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
- 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
- E.g. Dourine
- 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