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==Introduction==
==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]].
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.
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 [[Glossinidae | tsetse flies]] and mammals are infected through bites.
Trypanosomosis causes a wasting disease in cattle and sleeping sickness in humans.
Trypanosomosis causes a wasting disease in cattle and sleeping sickness in humans.
T. cruzi is the most important species in veterinary medicine.
T. cruzi is the most important species in veterinary medicine.
Trypanosomosis is notifiable to the World Organisation for Animal Health [http://www.oie.int/ (OIE)]
==Causative Organisms==
==Signalment==
Some breeds appear trypanotolerant and able to resist clinical disease and anaemia, such as African buffalo and N’dama and Keteku cattle.
''T. brucei'' and ''T. Equiperdum'' affect horses, the latter causing venereal '''dourine'''.
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.
''T. simiae'' causes fatal pyrexia in '''pigs''' while ''T. Congolense'' is milder in the same species.
==Causative Organisms==
===Salivarian Species===
''T. brucei'' affects all domestic mammals, including small and farm species, and humans. It also causes a specific [[Protozoal Skin Infections - Donkey|skin disease in donkeys]].
''T. vivax'' infects ruminants, horses and camels causing significant disease.
''T. equiperdum'' causes venereal equine disease '''dourine'''. It is the only trypanosome that does not immediately require an insect vector for transmission, being spread through coitus.
''T. simiae'' causes fatal pyrexia in '''pigs''' while ''T. Congolense'' is milder in the same species
''T. Congolense'' can also affect '''dogs and cats''' causing acute fever, anaemia and neurological signs.
''T. evansi'' also affects all domestic mammals.
''T. brucei'' and ''T. Congolense'' can also affect '''dogs and cats''' causing acute fever, anaemia and neurological signs.
===Stercorarian Species===
''T. cruzi'' occurs in '''South America''' where it is transmitted by a triatomid (kissing) bug and infects armadillos, possums and humans. It is known as ''Chagas’ Disease''. A similar acute disease is thought to be caused by ''T. cruzi'' in dogs in the USA.
''T. melophagum'' and ''T. Theileri'' are '''non-pathogenic''' species present in the '''UK''' infecting cattle, buffalo and antelope. Stress and concurrent disease are thought to be contributors to the development of clinical disease from ''T. theileri''.
''T. brucei'' causes [[Protozoal Skin Infections - Donkey|skin infections in donkeys]].
==Transmission==
Trypanosomosis is spread by [[Glossinidae|Tsetse flies]] and other insect vectors.
[[Tabanidae | Horse flies]] and [[Stomoxys calcitrans | stable flies]] can also act as mechanical vectors for some [[Trypanosoma | ''trypanosoma'']] species, but the parasites can not undergo lifecycle development within these hosts.
''T. vivax and ''T. evansi'' are reported to achieve Transplacental transmission. <ref>Ikede and Losos, 1972>/ref>
''T. melophagum'' and ''T. Theileri'' are '''non-pathogenic''' species present in the '''UK'''.
==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.
==Clinical Signs==
==Clinical Signs==
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
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 pathognomic signs are evident.
===Ruminants===
===Ruminants===
Emaciation
Emaciation
Abortion and infertility
Abortion, premature births and infertility are features, and orchitis in males reduces fertility also.
===Horses===
===Horses===
'''Oedema''' of the '''limbs''' and '''genitalia'''.
'''Oedema''' of the '''limbs''' and '''genitalia'''.
'''Dourine''' – genital and abdominal oedema and neurological signs.
'''Dourine''' – genital and abdominal oedema, paraphimosis, urticarial plaques known as “silver dollar spots” and neurological signs. Disease is usually mild and recurrent but can be fatal.
===Donkeys===
===Donkeys===
Microscopic identification on trypanosome parasites in the host blood on a '''smear''' with Giemsa staining.
Microscopic identification on trypanosome parasites in the host blood on a '''smear''' with Giemsa staining.
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==
==Treatment==
A variety of drugs can be used to treat trypanosomiasis including '''diminazene''', '''homidium''', '''isometadium''', '''suramin''' and '''melarsomine'''.
A variety of drugs can be used to treat trypanosomosis including '''diminazene''', '''homidium''', '''isometadium''', '''suramin'' and '''melarsomine'''.
Diminazene acetrate 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==
==Control==
Separation of livestock and wild animals is effective but difficult.
Separation of livestock and wild animals is effective but difficult.
Use of trypanotolerant livestock breeds.
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 etc
[[Glossinidae | Tsetse fly]] control by sprays, traps, dips and release of sterile male flies is effective but expensive and time consuming.
Prophylactic drug therapy with quinapyramine or homidium is effective.
Prophylactic drug therapy with quinapyramine or homidium is effective.
==References==
==References==
<references/>
<references/>
Merck Veterinary Manual, '''Tetse-transmitted Trypanosomiasis''' accessed online 03/06/2011 @ http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/10413.htm
Merck Veterinary Manual, '''Tsetse-transmitted Trypanosomiasis''' accessed online 03/06/2011 @ http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/10413.htm
[[Category: To Do - Steph]]
[[Category: To Do - CABI review]]