Difference between revisions of "Trypanosomosis"

Revision as of 17:51, 30 May 2011

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

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

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

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

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

@@ Line 1: / Line 1: @@
-{{OpenPagesTop}}
+'''Pathogenesis'''
-Also Known As: '''''Nagana — Trypanosomiasis — Chagas' Disease — Sleeping Sickness — Parrot Sickness  —  Dourine'''''
+*Salivarian
+**Causes wasting disease in cattle (nagana)
+**Sleeping sickness in humans
-==Introduction==
+*Stercorarian
-[[File:Trypanosoma.jpg|thumb|200px|right|''T.cruzi''. Wikimedia Commons]]
+**''T. cruzi'' most important in veterinary medicine
-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.
+***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''
-Trypanosomes are divided into two categories depending upon their lifecycle:
+*Enlarged [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] and [[Spleen - Anatomy & Physiology|spleen]]
-'''Stercorarian trypanosomes''' develop within an '''insect''' vector and are transmitted to mammals in the faeces of the vector.
+**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
-'''Salivarian''' trypanosomes develop within '''[[Glossinidae |tsetse flies]]''' and mammals are infected through their bites.
+*Anaemia
+**Red blood cells are removed from circulation ('''haemolytic''')
-For more information about the various species see [[Trypanosoma]] page.
+**Is a cardinal feature of the disease
-Trypanosomosis causes a '''wasting disease''' in cattle and '''sleeping sickness''' in humans.
+*Degeneration and inflammation of multiple organs
+**E.g. Skeletal muscle, myocardium and CNS
-'''''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'''.
+'''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
-Trypanosomosis is '''notifiable''' to the World Organisation for Animal Health [http://www.oie.int/ (OIE)].
+*In horses:
+**Acute or chronic infections of ''T. brucei''
+**Oedema of the limbs and genitalia
-==Signalment==
+*In pigs:
-Some breeds appear '''trypanotolerant''' and able to resist clinical disease and anaemia, such as African buffalo and N’dama and Keteku cattle.
+**''T. congolense'' infections are mild or chronic
+**''T. simiae'' infections are hyperacute usually leading to death from pyrexia in a few days
-'''Calves''' less than a year old are more resistant than adults, but lambs and kids appear more susceptible to ''T. congolense'' infections.
+*In dogs and cats:
-Cattle 6-9yrs old appear most susceptible to trypanosomosis.
+**''T. brucei'' and ''T. congolese''
+**Acute infections
+**Fever, anaemia, myocarditis, corneal opacity
+**Occasionally neurological signs present, such as increased aggression, ataxia and convulsions
-==Transmission==
+*In donkeys:
-[[File:Tsetse fly.jpeg|thumb|200px|right|Tsetse fly]]
+**''T. brucei'' in [[Protozoal Skin Infections - Donkey|skin infections]]
-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.
-''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>
+'''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
-==Distribution==
+*Parasite virulence
-Worldwide
+**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
-''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.
+*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''
-==Clinical Signs==
+'''Diagnosis'''
-Clinical disease varies widely with death occurring from 1 week to months after infection.
+*Demonstrate trypanosomes in blood
-''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.
+**Giemsa stained smears
+**Fresh blood films
+***Motile trypanosomes
+**Haematocrit tube
+***Motile trypanosomes at the plasma/buffy coat interface
-Significant losses may also be caused by increased susceptibility and prevalence of other concurrent diseases where trypanosomosis is present.
+'''Control'''
+*[[Glossinidae|Tsetse fly]] control
+**Spraying and trapping
-Multisystemic signs can be seen in any species so diagnosis from clinical examination is often impossible as no pathognomonic signs are evident.
+*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
-===Ruminants===
+*Barrier fences and buffer zones
-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'''.
+**Separate livestock and wild animals
-'''Haemolytic anaemia''' is a cardinal feature. Chronic infection causes '''[[:Category:Heart Failure|heart failure]]''' and associated signs and death.
+*Trypanotolerant livestock
-Plasma cell hypertrophy and '''hypergammaglobulinaemia''' are evident on haematology and biochemistry.
+'''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
-Emaciation, '''abortion''', premature births and infertility are features, and '''orchitis''' in males reduces fertility.
+*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
-===Horses===
+*Non-pathogenic species occur in the UK
-'''Oedema''' of the '''limbs''' and '''genitalia''' is very common.
+**In sheep caused by ''T. melophagium''
+**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.
-===Donkeys===
+*Myositis
-See [[Protozoal Skin Infections - Donkey|donkey skin infections]] page for details.
+**Infrequent muscle lesions with mononuclear infiltrates
+**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.
-==Diagnosis==
+[[Category:To Do - CABI]]
-[[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]]

Difference between revisions of "Trypanosomosis"

Revision as of 17:51, 30 May 2011

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