Difference between revisions of "Trypanosomosis"

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'''Pathogenesis'''
+
{{OpenPagesTop}}
*Salivarian
+
Also Known As: '''''Nagana — Trypanosomiasis — Chagas' Disease — Sleeping Sickness — Parrot Sickness  —  Dourine'''''
**Causes wasting disease in cattle (nagana)
 
**Sleeping sickness in humans
 
  
*Stercorarian
+
==Introduction==
**''T. cruzi'' most important in veterinary medicine
+
[[File:Trypanosoma.jpg|thumb|200px|right|''T.cruzi''. Wikimedia Commons]]
***Occurs in South America
+
Trypanosomosis is a disease caused by '''[[Protozoa | protozoan]]''' pathogens of the genus [[Trypanosoma]]. They are '''obligate parasites''' and can infect mammals, birds, reptiles, amphibians and fish.
***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]]
+
Trypanosomes are divided into two categories depending upon their lifecycle:
**Causes lymphoid exhaustion
+
'''Stercorarian trypanosomes''' develop within an '''insect''' vector and are transmitted to mammals in the faeces of the vector.
**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
+
'''Salivarian''' trypanosomes develop within '''[[Glossinidae |tsetse flies]]''' and mammals are infected through their bites.
**Red blood cells are removed from circulation ('''haemolytic''')
+
**Is a cardinal feature of the disease
+
For more information about the various species see [[Trypanosoma]] page.
  
*Degeneration and inflammation of multiple organs
+
Trypanosomosis causes a '''wasting disease''' in cattle and '''sleeping sickness''' in humans.
**E.g. Skeletal muscle, myocardium and CNS
 
  
'''Clinical Signs'''
+
'''''T. cruzi''''' is the cause of Chagas disease in humans but can also  affect dogs, cats and pigs. ''T. vivax'' and ''T. congolense'' are the main pathogens of cattle. In horses, ''T. equiperdum'' is the cause of '''Dourine'''.
*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:
+
Trypanosomosis is '''notifiable''' to the World Organisation for Animal Health [http://www.oie.int/ (OIE)].
**Acute or chronic infections of ''T. brucei''
 
**Oedema of the limbs and genitalia
 
  
*In pigs:
+
==Signalment==
**''T. congolense'' infections are mild or chronic
+
Some breeds appear '''trypanotolerant''' and able to resist clinical disease and anaemia, such as African buffalo and N’dama and Keteku cattle.
**''T. simiae'' infections are hyperacute usually leading to death from pyrexia in a few days
 
  
*In dogs and cats:
+
'''Calves''' less than a year old are more resistant than adults, but lambs and kids appear more susceptible to ''T. congolense'' infections.
**''T. brucei'' and ''T. congolese''
+
Cattle 6-9yrs old appear most susceptible to trypanosomosis.
**Acute infections
 
**Fever, anaemia, myocarditis, corneal opacity
 
**Occasionally neurological signs present, such as increased aggression, ataxia and convulsions
 
  
*In donkeys:
+
==Transmission==
**''T. brucei'' in [[Protozoal Skin Infections - Donkey|skin infections]]
+
[[File:Tsetse fly.jpeg|thumb|200px|right|Tsetse fly]]
 +
Trypanosomosis is spread by '''[[Glossinidae|Tsetse flies]]''' and other insect vectors.
 +
[[File:Triatoma infestans.jpg|thumb|200px|right|Triatomid - "kissing bug". (WHO - Wikimedia Commons)]]
 +
[[Tabanidae | Horse flies]]  and [[Stomoxys calcitrans |stable flies]] can also act as mechanical vectors for some [[Trypanosoma | ''trypanosoma'']] species, but the parasites cannot undergo lifecycle development within these hosts.
  
'''Epidemiology'''
+
''T. vivax'' and ''T. evansi'' are reported to achieve transplacental transmission. <ref>Ikede, B. O., Loso, G. J.(1972). '''Hereditary transmission of Trypanosoma vivax'''. Brit Vet J, 128:i-ii</ref>
*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
+
==Distribution==
**Some parasitaemic animals survive for long periods of time
+
Worldwide
***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
+
''T. brucei'', ''T. uniforme'', ''T. congolense'' and ''T. simiae'' are found only in the tsetse fly belt of Africa due to the restricted spread of their vector. ''T. vivax'' is more widespread occurring in Sub-saharan Africa as well as South America.
**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'''
+
==Clinical Signs==
*Demonstrate trypanosomes in blood
+
Clinical disease varies widely with death occurring from 1 week to months after infection.
**Giemsa stained smears
+
''T. vivax'' is known for its rapid mortality while ''T. brucei'' and ''T. congolense'' hosts often survive for prolonged periods. Infection of large numbers of insect vectors is common in these circumstances.
**Fresh blood films
 
***Motile trypanosomes
 
**Haematocrit tube
 
***Motile trypanosomes at the plasma/buffy coat interface
 
  
'''Control'''
+
Significant losses may also be caused by increased susceptibility and prevalence of other concurrent diseases where trypanosomosis is present.
*[[Glossinidae|Tsetse fly]] control
 
**Spraying and trapping
 
  
*Prophylactic drug treatment
+
Multisystemic signs can be seen in any species so diagnosis from clinical examination is often impossible as no pathognomonic signs are evident.
**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
+
===Ruminants===
**Separate livestock and wild animals
+
Enlarged '''[[Lymph Nodes - Anatomy & Physiology|lymph nodes]]''' and '''[[Spleen - Anatomy & Physiology|spleen]]''' are the most common sign. Later in the disease course the lymph nodes and spleen shrink due to '''lymphoid exhaustion'''.
  
*Trypanotolerant livestock
+
'''Haemolytic anaemia''' is a cardinal feature. Chronic infection causes '''[[:Category:Heart Failure|heart failure]]''' and associated signs and death.
  
'''Other trypanosomes'''
+
Plasma cell hypertrophy and '''hypergammaglobulinaemia''' are evident on haematology and biochemistry.
*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
+
Emaciation, '''abortion''', premature births and infertility are features, and '''orchitis''' in males reduces fertility.
**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
+
===Horses===
**In sheep caused by ''T. melophagium''
+
'''Oedema''' of the '''limbs''' and '''genitalia''' is very common.
**In cattle caused by ''T. theileri''
 
  
 +
'''Dourine''' – genital and abdominal '''oedema''', paraphimosis, '''urticarial plaques''' known as “silver dollar spots” and neurological signs may all be present. The disease is usually mild and recurrent but can be fatal.
  
*Myositis
+
===Donkeys===
**Infrequent muscle lesions with mononuclear infiltrates
+
See [[Protozoal Skin Infections - Donkey|donkey skin infections]] page for details.
**Dogs, cats and pigs are affected
 
**Parasites lie between myofilaments
 
**May cause fibre degeneration
 
  
 +
===Dogs and Cats===
 +
'''Pyrexia''', myocarditis, '''myositis''', corneal opacity and occasionally '''neurological signs''' may all be present.
  
[[Category:To Do - Steph]]
+
==Diagnosis==
 +
[[File:Trypanosomes blood.gif|thumb|200px|right|Trypanosomes in blood]]
 +
Microscopic identification on trypanosome parasites in the host blood on a '''smear''' with Giemsa staining is commonly performed. Where low levels of parasitaemia are present, filtration or haemolysis of a whole blood sample may be required and motile trypanosomes may be demonstrable in a haematocrit tube at the '''plasma: buffy coat''' interface.
 +
 
 +
On '''post-mortem''' examination, carcasses are often pale and oedematous due to anaemia and emaciation. Degenerative lesions can be found on the heart, liver, lymph nodes, testes, brain, conjunctiva, cornea, spleen, kidney and endocrine organs.
 +
 
 +
Many other seroimmunological techniques are also available variably in laboratories.
 +
 
 +
==Treatment==
 +
A variety of drugs can be used to treat trypanosomosis including '''diminazene, homidium, isometadium, suramin''' and '''melarsomine'''.
 +
 
 +
'''Diminazene aceturate''' is most commonly used and is frequently '''curative'''. It however causes frequent local reactions in horses so should be given in multiple deep muscular sites and massaged well. The drug is also ''contraindicated in dogs and camels'' due to vascular damage. Diminazene also has a prophylactic effect for up to 3 months.
 +
 
 +
 
 +
'''Resistance''' is increasing in Africa to trypanosomicidal drugs so multiple treatments may be required in some areas.
 +
 
 +
==Control==
 +
'''Separation''' of livestock and wild animals is effective but difficult.
 +
 
 +
Use of '''trypanotolerant''' livestock breeds is the only option is some areas where economic restraints prevent constant treatment and control.
 +
 
 +
'''[[Glossinidae |Tsetse fly]] control''' by sprays, traps, dips and release of sterile male flies is effective but expensive and time-consuming.
 +
 
 +
Prophylactic drug therapy is also effective but costly.
 +
 
 +
{{Learning
 +
|flashcards = [[Trypanosomosis Flashcards]]
 +
}}
 +
 
 +
==References==
 +
<references/>
 +
 
 +
Merck Veterinary Manual, '''Tsetse-transmitted Trypanosomiasis''' accessed online 03/06/2011 @ http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/10413.htm
 +
 
 +
{{CABI source
 +
|datasheet = [http://www.cabi.org/ahpc/Default.aspx?site=160&page=2144&LoadModule=datasheet&CompID=3&dsID=60779  trypanosomosis]
 +
|date = 5 June 2011
 +
}}
 +
<br><br><br>
 +
 
 +
{{Nick Lyons
 +
|date = 15 October 2011}}
 +
 
 +
{{OpenPages}}
 +
 
 +
[[Category:Cardiovascular Diseases - Cattle]][[Category:Cardiovascular Diseases - Horse]][[Category:Lymphoreticular and Haematopoietic Diseases - Cattle]][[Category:Lymphoreticular and Haematopoietic Diseases - Horse]][[Category:Reproductive Diseases - Horse]][[Category:Reproductive Diseases - Cattle]]
 +
[[Category:CABI Expert Review Completed]][[Category:CABI AHPC Pages]]
 +
[[Category:Nick Lyons reviewed]]
 +
[[Category:Cardiology Section]]

Latest revision as of 17:35, 17 October 2013


Also Known As: Nagana — Trypanosomiasis — Chagas' Disease — Sleeping Sickness — Parrot Sickness — Dourine

Introduction

T.cruzi. Wikimedia Commons

Trypanosomosis is a disease caused by protozoan pathogens of the genus Trypanosoma. They are obligate parasites and can infect mammals, birds, reptiles, amphibians and fish.

Trypanosomes are divided into two categories depending upon their lifecycle: Stercorarian trypanosomes develop within an insect vector and are transmitted to mammals in the faeces of the vector.

Salivarian trypanosomes develop within tsetse flies and mammals are infected through their bites.

For more information about the various species see Trypanosoma page.

Trypanosomosis causes a wasting disease in cattle and sleeping sickness in humans.

T. cruzi is the cause of Chagas disease in humans but can also affect dogs, cats and pigs. T. vivax and T. congolense are the main pathogens of cattle. In horses, T. equiperdum is the cause of Dourine.

Trypanosomosis is notifiable to the World Organisation for Animal Health (OIE).

Signalment

Some breeds appear trypanotolerant and able to resist clinical disease and anaemia, such as African buffalo and N’dama and Keteku cattle.

Calves less than a year old are more resistant than adults, but lambs and kids appear more susceptible to T. congolense infections. Cattle 6-9yrs old appear most susceptible to trypanosomosis.

Transmission

Tsetse fly

Trypanosomosis is spread by Tsetse flies and other insect vectors.

Triatomid - "kissing bug". (WHO - Wikimedia Commons)

Horse flies and stable flies can also act as mechanical vectors for some trypanosoma species, but the parasites cannot undergo lifecycle development within these hosts.

T. vivax and T. evansi are reported to achieve transplacental transmission. [1]

Distribution

Worldwide

T. brucei, T. uniforme, T. congolense and T. simiae are found only in the tsetse fly belt of Africa due to the restricted spread of their vector. T. vivax is more widespread occurring in Sub-saharan Africa as well as South America.

Clinical Signs

Clinical disease varies widely with death occurring from 1 week to months after infection. T. vivax is known for its rapid mortality while T. brucei and T. congolense hosts often survive for prolonged periods. Infection of large numbers of insect vectors is common in these circumstances.

Significant losses may also be caused by increased susceptibility and prevalence of other concurrent diseases where trypanosomosis is present.

Multisystemic signs can be seen in any species so diagnosis from clinical examination is often impossible as no pathognomonic signs are evident.

Ruminants

Enlarged lymph nodes and spleen are the most common sign. Later in the disease course the lymph nodes and spleen shrink due to lymphoid exhaustion.

Haemolytic anaemia is a cardinal feature. Chronic infection causes heart failure and associated signs and death.

Plasma cell hypertrophy and hypergammaglobulinaemia are evident on haematology and biochemistry.

Emaciation, abortion, premature births and infertility are features, and orchitis in males reduces fertility.

Horses

Oedema of the limbs and genitalia is very common.

Dourine – genital and abdominal oedema, paraphimosis, urticarial plaques known as “silver dollar spots” and neurological signs may all be present. The disease is usually mild and recurrent but can be fatal.

Donkeys

See donkey skin infections page for details.

Dogs and Cats

Pyrexia, myocarditis, myositis, corneal opacity and occasionally neurological signs may all be present.

Diagnosis

Trypanosomes in blood

Microscopic identification on trypanosome parasites in the host blood on a smear with Giemsa staining is commonly performed. Where low levels of parasitaemia are present, filtration or haemolysis of a whole blood sample may be required and motile trypanosomes may be demonstrable in a haematocrit tube at the plasma: buffy coat interface.

On post-mortem examination, carcasses are often pale and oedematous due to anaemia and emaciation. Degenerative lesions can be found on the heart, liver, lymph nodes, testes, brain, conjunctiva, cornea, spleen, kidney and endocrine organs.

Many other seroimmunological techniques are also available variably in laboratories.

Treatment

A variety of drugs can be used to treat trypanosomosis including diminazene, homidium, isometadium, suramin and melarsomine.

Diminazene aceturate is most commonly used and is frequently curative. It however causes frequent local reactions in horses so should be given in multiple deep muscular sites and massaged well. The drug is also contraindicated in dogs and camels due to vascular damage. Diminazene also has a prophylactic effect for up to 3 months.


Resistance is increasing in Africa to trypanosomicidal drugs so multiple treatments may be required in some areas.

Control

Separation of livestock and wild animals is effective but difficult.

Use of trypanotolerant livestock breeds is the only option is some areas where economic restraints prevent constant treatment and control.

Tsetse fly control by sprays, traps, dips and release of sterile male flies is effective but expensive and time-consuming.

Prophylactic drug therapy is also effective but costly.


Trypanosomosis Learning Resources
FlashcardsFlashcards logo.png
Flashcards
Test your knowledge using flashcard type questions
Trypanosomosis Flashcards


References

  1. Ikede, B. O., Loso, G. J.(1972). Hereditary transmission of Trypanosoma vivax. Brit Vet J, 128:i-ii

Merck Veterinary Manual, Tsetse-transmitted Trypanosomiasis accessed online 03/06/2011 @ http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/10413.htm


CABIlogo

This article was originally sourced from The Animal Health & Production Compendium (AHPC) published online by CABI during the OVAL Project.

The datasheet was accessed on 5 June 2011.










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