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==Introduction==

==Introduction==

Trypanosomosis in equines is caused by [[Tropical Protozoa#Trypanosoma|trypanosome protozoans]], of which there are five pathogenic to livestock. Most common are:

Trypanosomosis in equines is caused by [[Trypanosoma|trypanosome protozoans]], of which there are five pathogenic to livestock. Most common are:

* '''''Trypasnosoma equiperdum''''', the cause of '''dourine''', which is '''transmitted venereally'''

* '''''Trypasnosoma equiperdum''''', the cause of '''dourine''', which is '''transmitted venereally'''

* '''''T. evansi''''' the cause of '''surra''', which is '''transmitted by several species of [[Biting Flies#Tabanidae|tabanid flies''']]

* '''''T. evansi''''' the cause of '''surra''', which is '''transmitted by several species of [[Tabanidae|tabanid flies''']]

As with many other domestic livestock, [[Biting Flies#Glossinidae|tsetse-transmitted]] '''''T. vivax, T. congolense''''' and '''''T. brucei''''' can also affect equines in tsetse-infested areas. ''T. vivax'' can also be transmitted mechanically by biting flies, which extends its

As with many other domestic livestock, [[Glossinidae|tsetse-transmitted]] '''''T. vivax, T. congolense''''' and '''''T. brucei''''' can also affect equines in tsetse-infested areas. ''T. vivax'' can also be transmitted mechanically by biting flies, which extends its

occurrence outside the tsetse belt.

occurrence outside the tsetse belt.

* Blood samples may be taken from the peripheral ear vein and either examined as a '''wet smear or as a stained thin/thick smear'''. But, because levels of parasitemia fluctuate and in chronic cases can be low, it is often necessary to use a concentration method such as centrifugation and then look for trypanosomes in the blood buffy coat layer. Even this method

* Blood samples may be taken from the peripheral ear vein and either examined as a '''wet smear or as a stained thin/thick smear'''. But, because levels of parasitemia fluctuate and in chronic cases can be low, it is often necessary to use a concentration method such as centrifugation and then look for trypanosomes in the blood buffy coat layer. Even this method

may detect as little as one third of cases

may detect as little as one third of cases

* '''Serology tests''' such as CFT and ELISA have been used

* '''Serology tests''' such as [[CFT]] and [[ELISA testing|ELISA]] have been used

* Animal inoculation is not recommended as a diagnostic method on ethical grounds and in any case is not practicable in the field

* Animal inoculation is not recommended as a diagnostic method on ethical grounds and in any case is not practicable in the field

* ''T. equiperdum'' can be isolated from genital discharge or urticarial plaques. However, as many cases are asymptomatic, serology is the most reliable and practicable test. CFT has been the standard test used for ''T. equiperdum'', but should not be used where ''T. brucei spp.'' are present as crossreactions occur. In approximately 50% of cases donkey and mule sera show anti-complementarity. This can be reduced by dilution of the serum by half and heat inactivation at 60-63ºC for thirty minutes (OIE, 2004)

* ''T. equiperdum'' can be isolated from genital discharge or urticarial plaques. However, as many cases are asymptomatic, serology is the most reliable and practicable test. CFT has been the standard test used for ''T. equiperdum'', but should not be used where ''T. brucei spp.'' are present as crossreactions occur. In approximately 50% of cases donkey and mule sera show anti-complementarity. This can be reduced by dilution of the serum by half and heat inactivation at 60-63ºC for thirty minutes (OIE, 2004)

* Trypanocidal drugs can be used for chemo-therapy/prophylaxis

* Trypanocidal drugs can be used for chemo-therapy/prophylaxis

* Resistance has been documented in donkeys (Assefa, 2001)

* Resistance has been documented in donkeys (Assefa, 2001)

* The drugs shown in <font color='green>Table 2 (page 281) </font color>have been suggested for equines. They should be used with great caution, preferably after determining the trypanosome chemosensitivity and as part of integral approach to the disease

* The drugs shown in the table below have been suggested for equines. They should be used with great caution, preferably after determining the trypanosome chemosensitivity and as part of integral approach to the disease

* Deep muscle injection divided through the day is recommended for some drugs, ''e.g.'' quinapyramine, because of tissue necrosis and toxicity. Adverse reactions are common with many trypanocides

* Deep muscle injection divided through the day is recommended for some drugs, ''e.g.'' quinapyramine, because of tissue necrosis and toxicity. Adverse reactions are common with many trypanocides

* Diminazene at therapeutic doses can produce severe nervous signs and sometimes death in donkeys. It has been used as a preventative at low dosage every three months. Its success with mules for surra has been documented, as has the mild to severe toxicity observed when it was used (Tuntasuvan, 2003)

* Diminazene at therapeutic doses can produce severe nervous signs and sometimes death in donkeys. It has been used as a preventative at low dosage every three months. Its success with mules for surra has been documented, as has the mild to severe toxicity observed when it was used (Tuntasuvan, 2003)

* If quinpyramine is used, donkeys should be well-rested beforehand, as heat, stress, and fatigue can precipitate acute  curare-like reactions after treatment

* If quinpyramine is used, donkeys should be well-rested beforehand, as heat, stress, and fatigue can precipitate acute  curare-like reactions after treatment

* <u>Once nervous signs occur, treatment for trypanosomosis is unlikely to be successful</u>, as trypanocides do not cross the blood-brain barrier

* <u>Once nervous signs occur, treatment for trypanosomosis is unlikely to be successful</u>, as trypanocides do not cross the blood-brain barrier

* [[Donkey - Euthanasia|Euthanasia]] is often recommended for dourine where there is an ongoing eradication programme, as treatment may improve clinical signs but will not sterilise the infection and the animal will remain as a carrier. A more widely applicable strategy for dourine is a combination of treatment and castration

* [[Euthanasia - Donkey|Euthanasia]] is often recommended for dourine where there is an ongoing eradication programme, as treatment may improve clinical signs but will not sterilise the infection and the animal will remain as a carrier. A more widely applicable strategy for dourine is a combination of treatment and castration

[[Image:Trypanosomosis drugs donkey.jpg|center|thumb|500px|<small><center>Drugs that have been used to treat equine trypanosomosis. (Image courtesy of  [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary])</center></small>]]

[[Image:Trypanosomosis drugs donkey.jpg|center|thumb|500px|<small><center>Drugs that have been used to treat equine trypanosomosis. (Image courtesy of  [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary])</center></small>]]

Dourine has been successfully eradicated from many areas by testing and slaughter. Where this is not feasible, the presence of fences and prevention of indiscriminate breeding may control spread of the disease. If possible, breeding animals should be tested serologically as the sperm and vaginal discharge of ''T. equiperdum'' infected donkeys is very virulent and can be a

Dourine has been successfully eradicated from many areas by testing and slaughter. Where this is not feasible, the presence of fences and prevention of indiscriminate breeding may control spread of the disease. If possible, breeding animals should be tested serologically as the sperm and vaginal discharge of ''T. equiperdum'' infected donkeys is very virulent and can be a

source of infection to other donkeys and horses.

source of infection to other donkeys and horses.

==References==

==References==

{{toplink

{{toplink

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|linkpage =Protozoal Skin Infections - Donkey

|linkpage =Exotic Infections - Donkey

|linktext =Protozoal Skin Infections - Donkey

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|sublink1 = Protozoal Skin Infections - Donkey

|subtext1 = Exotic Infections - Donkey

|subtext1 = Protozoal Skin Infections - Donkey

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