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| − | Also Known As | + | Also Known As — '''''Nagana'''''—'''''Typanosomiasis''''' |
| | | | |
| | + | ==Introduction== |
| | [[File:Trypanosoma brucei.gif|thumb|300px|right|Schematic diagram of Trypanosoma brucei]] | | [[File:Trypanosoma brucei.gif|thumb|300px|right|Schematic diagram of Trypanosoma brucei]] |
| | + | Trypanosomosis is a disease caused by [[Protozoa | protozoan]] pathogens of the genus Trypanosoma. |
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| | + | Trypanosomosis causes a wasting disease in cattle and sleeping sickness in humans. |
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| − | [[File:Trypanosomes blood.gif|thumb|200px|right|Trypanosomes in blood]]
| + | T. cruzi is the most important species in veterinary medicine. |
| | + | |
| | + | ==Causative Organisms== |
| | + | ''T. cruzi'' occurs in '''South America''' where it is transmitted by a triatomid bug and infects armadillos, possums and humans. It is known as ''Chagas’ Disease''. |
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| | + | ''T. brucei'' and ''T. Equiperdum'' affect horses, the latter causing venereal '''dourine'''. |
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| | + | ''T. simiae'' causes fatal pyrexia in '''pigs''' while ''T. Congolense'' is milder in the same species. |
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| − | '''Pathogenesis''' | + | ''T. brucei'' and ''T. Congolense'' can also affect '''dogs and cats''' causing acute fever, anaemia and neurological signs. |
| − | *Salivarian
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| − | **Causes wasting disease in cattle (nagana)
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| − | **Sleeping sickness in humans
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| − | *Stercorarian
| + | ''T. brucei'' causes [[Protozoal Skin Infections - Donkey|skin infections in donkeys]]. |
| − | **''T. cruzi'' most important in veterinary medicine
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| − | ***Occurs in South America
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| − | ***Infects armadillos, possums and humans
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| − | ***Causes Chagas' Disease
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| − | **Transmitted by a triatomid (kissing) bug
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| − | **Chronic infections are often fatal causing heart failure
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| − | **Non-pathogenic species are transmitted by [[Tabanidae|tabanids]] and [[Melophagus ovinus|keds]]
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| − | ***''T. theileria'' and ''T. melophagium''
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| | | | |
| − | *Enlarged [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] and [[Spleen - Anatomy & Physiology|spleen]]
| + | ''T. melophagum'' and ''T. Theileri'' are '''non-pathogenic''' species present in the '''UK'''. |
| − | **Causes lymphoid exhaustion
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| − | **Associated with plasma cell hypertrophy and hypergammaglobulinaemia
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| − | ***Due to an increase in [[Immunoglobulin M|IgM]]
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| − | **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
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| − | *Anaemia
| + | ==Transmission== |
| − | **Red blood cells are removed from circulation ('''haemolytic''')
| + | Trypanosomiasis is spread by [[Glossinidae|Tsetse flies]]. |
| − | **Is a cardinal feature of the disease
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| | | | |
| − | *Degeneration and inflammation of multiple organs
| + | ==Clinical Signs== |
| − | **E.g. Skeletal muscle, myocardium and CNS
| + | Clinical disease varies widely with death occurring from 1 week to months after infection. ''T. vivax'' is known for is rapid mortality while ''T. brucei'' and ''T. congolense'' hosts often survive for prolonger periods. Infection of large numbers of insect vectors is common in these circumstances |
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| − | '''Clinical Signs''' | + | ===Ruminants=== |
| − | *In ruminants:
| + | Enlarged '''[[Lymph Nodes - Anatomy & Physiology|lymph nodes]]''' and '''[[Spleen - Anatomy & Physiology|spleen]]'''. |
| − | **Anaemia
| + | Later in the disease course the [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] and [[Spleen - Anatomy & Physiology|spleen]] shrink due to '''lymphoid exhaustion'''. |
| − | **Enlargement of the [[Lymph Nodes - Anatomy & Physiology|lymph nodes]]
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| − | **Progressive loss of body condition
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| − | **Fever and appetite loss occur during parasite peaks
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| − | **Chronic disease usually terminates in death of the animal if untreated
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| − | **Can cause abortion, infertility and decreased growth in herds
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| − | *In horses:
| + | Haemolytic anaemia is a cardinal feature. |
| − | **Acute or chronic infections of ''T. brucei''
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| − | **Oedema of the limbs and genitalia
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| − | *In pigs:
| + | Chronic infection causes '''heart failure''' and associated signs and death. |
| − | **''T. congolense'' infections are mild or chronic
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| − | **''T. simiae'' infections are hyperacute usually leading to death from pyrexia in a few days
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| | | | |
| − | *In dogs and cats:
| + | Plasma cell hypertrophy and hypergammaglobulinaemia are evident on haematology and biochemistry. |
| − | **''T. brucei'' and ''T. congolese''
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| − | **Acute infections
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| − | **Fever, anaemia, myocarditis, corneal opacity
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| − | **Occasionally neurological signs present, such as increased aggression, ataxia and convulsions
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| − | *In donkeys:
| + | Emaciation |
| − | **''T. brucei'' in [[Protozoal Skin Infections - Donkey|skin infections]]
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| − | '''Epidemiology'''
| + | Abortion and infertility |
| − | *Vector distribution
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| − | **[[Glossinidae|Tsetse flies]] found in riverine, savannah and forest habitats
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| − | **Up to 20% [[Biting Flies|flies]] infected
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| − | **[[Biting Flies|Flies]] infected for life
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| − | *Parasite virulence
| + | ===Horses=== |
| − | **Some parasitaemic animals survive for long periods of time
| + | '''Oedema''' of the '''limbs''' and '''genitalia'''. |
| − | ***E.g. ''T. brucei'' and ''T. congolense''
| + | '''Dourine''' – genital and abdominal oedema and neurological signs. |
| − | ***Increases the opportunity for infection of [[Biting Flies|flies]]
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| − | **Some trypanosomes kill their host in 1-2 weeks
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| − | ***E.g. ''T. vivax''
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| − | ***Decreases the chances of [[Biting Flies|fly]] infection
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| − | **Trypanosomes avoid host immune defences by altering glycoprotein coat (surface antigen) before host [[Immunoglobulins|antibody]] response
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| − | ***'''Antigenic variation''' can occur many times over several months causes relapsing parasitaemia
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| − | *Host response
| + | ===Donkeys=== |
| − | **Trypanotolerant wild animals remain parasitaemic for prolonged periods without showing clinical signs of disease
| + | [[Protozoal Skin Infections - Donkey|Skin infections]] |
| − | ***Cause lasting reservoirs of infection
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| − | **Most domestic livestock are susceptible to trypanosomosis
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| − | **Some local breeds of sheep, goats and cattle are trypanotolerant
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| − | ***E.g. ''Bos indicus''
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| − | '''Diagnosis''' | + | ===Dogs and Cats=== |
| − | *Demonstrate trypanosomes in blood
| + | '''Pyrexia''', myocarditis, '''myositis''', corneal opacity and '''neurological signs'''. |
| − | **Giemsa stained smears
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| − | **Fresh blood films
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| − | ***Motile trypanosomes
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| − | **Haematocrit tube
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| − | ***Motile trypanosomes at the plasma/buffy coat interface
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| − | '''Control'''
| + | ==Diagnosis== |
| − | *[[Glossinidae|Tsetse fly]] control
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| − | **Spraying and trapping
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| − | *Prophylactic drug treatment
| + | [[File:Trypanosomes blood.gif|thumb|200px|right|Trypanosomes in blood]] |
| − | **Change drug group periodically to decrease the chances of resistance occurring
| + | Microscopic identification on trypanosome parasites in the host blood on a '''smear''' with Giemsa staining. |
| − | **May lead to protective immunity but livestock will still be susceptible to heterologous challenges
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| − | *Barrier fences and buffer zones
| + | Motile trypanosomes may be demonstrable in a haematocrit tube at the '''plasma: buffy coat''' interface. |
| − | **Separate livestock and wild animals
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| − | *Trypanotolerant livestock
| + | ==Treatment== |
| | + | A variety of drugs can be used to treat trypanosomiasis including '''diminazene''', '''homidium''', '''isometadium''', '''suramin''' and '''melarsomine'''. |
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| − | '''Other trypanosomes'''
| + | ==Control== |
| − | *Mechanically transmitted by [[Biting Flies|biting flies]]
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| − | **E.g. Surra affecting horses and camels in North Africa, Asia and South America
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| − | **''T. equinum'' in South America
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| − | **''T. evansi'' in Asia
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| − | *Venereally transmitted
| + | Separation of livestock and wild animals is effective but difficult. |
| − | **E.g. Dourine
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| − | ***Transmitted by ''T. equiperdum''
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| − | ***Causes genital and abdominal oedema, emaciation and CNS signs
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| − | ***Affects horses and donkeys in Africa, Asia, Central and South America
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| − | *Non-pathogenic species occur in the UK
| + | Use of trypanotolerant livestock breeds. |
| − | **In sheep caused by ''T. melophagium''
| + | [[Glossinidae | Tsetse fly]] control by sprays, traps etc |
| − | **In cattle caused by ''T. theileri''
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| | + | Prophylactic drug therapy with quinapyramine or homidium is effective. |
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| − | *Myositis
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| − | **Infrequent muscle lesions with mononuclear infiltrates
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| − | **Dogs, cats and pigs are affected
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| − | **Parasites lie between myofilaments
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| − | **May cause fibre degeneration
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| | + | ==References== |
| | + | <references/> |
| | + | Animal Health & Production Compendium, datasheet, accessed 02/06/2011 @ http://www.cabi.org/ahpc/ |
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| − | [[Category:To Do - Steph]] | + | [[Category: To Do – CABI Review]] |