Author, Donkey, Bureaucrats, Administrators
53,803
edits
Changes
no edit summary
Line 57:
Line 57:
'''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 [[Tabanidae|tabanids]] and [[Melophagus ovinus|keds]]
−***''T. theileria'' and ''T. melophagium''
−*Enlarged [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] and [[Spleen - Anatomy & Physiology|spleen]]
−**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
−*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 - 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:
−**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 [[Protozoal Skin Infections - Donkey|skin infections]]
−'''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
−*Parasite virulence
−**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
−*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'''
−*[[Glossinidae|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|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
**Next host is infected when skin wounds are contaminated with infected [[Insecta|insect]] faeces
**Next host is infected when skin wounds are contaminated with infected [[Insecta|insect]] faeces
−==Test yourself with the Protozoa Flashcards==
==Test yourself with the Protozoa Flashcards==
Line 184:
Line 65:
[[Category:Tropical Protozoa]]
[[Category:Tropical Protozoa]]
−[[Category:To_Do_-_Parasites]]
+[[Category:To_Do_-_CABI]]