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Created page with "'''Pathogenesis''' *Salivarian **Causes wasting disease in cattle (nagana) **Sleeping sickness in humans *Stercorarian **''T. cruzi'' most important in veterinary medicine ***O..."
'''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''
*Myositis
**Infrequent muscle lesions with mononuclear infiltrates
**Dogs, cats and pigs are affected
**Parasites lie between myofilaments
**May cause fibre degeneration
[[Category:To Do - CABI]]
*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''
*Myositis
**Infrequent muscle lesions with mononuclear infiltrates
**Dogs, cats and pigs are affected
**Parasites lie between myofilaments
**May cause fibre degeneration
[[Category:To Do - CABI]]