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| | **[[Psychodidae|Sand flies]] biting infected dogs may spread the disease to other dogs, humans and wildlife | | **[[Psychodidae|Sand flies]] biting infected dogs may spread the disease to other dogs, humans and wildlife |
| | **There is a slight possibility of transmission to humans by direct contact | | **There is a slight possibility of transmission to humans by direct contact |
| − | | + | <big> |
| − | ==''Trypanosoma''==
| + | '''[[Trypanosoma|''Trypanosoma'']] |
| − | [[Image:Trypanosoma.jpg|thumb|right|150px|''Trypanosoma cruzi'' - CDC/Dr. Myron G. Schultz]] | + | </big> |
| − | [[Image:T.cruzi in monkey heart.jpg|thumb|right|150px|''T. cruzi'' in monkey heart - Dr. L.L. Moore, Jr.]]
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| − | [[Image:T.cruzi Life cycle.jpg|thumb|right|150px|''T. cruzi'' Life Cycle Diagram - Wikimedia Commons]]
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| − | [[Image:Triatoma infestans.jpg|thumb|right|150px|''Triatoma infestans'' the Kissing bug - WHO Wikimedia Commons]]
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| − | [[Image:Chagas endemic zones 2005.jpg|thumb|right|150px|Chagas endemic zones 2005 - Wikimedia Commons]]
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| − | [[Image:Ndama.jpg|thumb|right|150px|N'dama - Trypanotolerant West African Bos taurus - Wikimedia Commons]]
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| − | *Protozoal parasites found in the blood and tissues of vertebrates
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| − | *Worldwide distribution
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| − | *Causes sleeping sickness in humans
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| − | *Particularly seen in sub-Saharan Africa
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| − | **Affects cattle production
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| − | **Causes Nagana (Wasting disease)
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| − | *Divided into two groups depending on the mode of development in the insect vector
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| − | **'''Salivarian'''
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| − | ***Multiply in the foregut and proboscis
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| − | ***Transmitted via inoculation during feeding
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| − | ***Transmitted by [[Glossinidae|''Tsetse'' flies]]
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| − | ***Also known as '''anterior station development'''
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| − | **'''Stercorarian'''
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| − | ***Multiply in the hindgut
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| − | ***Infective form migrates to the [[Rectum - Anatomy & Physiology|rectum]]
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| − | ***Transmitted via contamination of wounds with insect faeces
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| − | ***Also known as '''posterior station development'''
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| − | *All ''Trypansomes'' except for ''T. equiperdum'' have arthropod vectors
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| − | **''T. equiperdum'' is a venereally transmitted disease
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| − | *'''Non-cyclical''' transmission can also occur
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| − | **Mechanical transmission
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| − | **Transferred by interrupted feeding from one host to another
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| − | **Usually transmitted by [[Biting Flies|biting flies]], e.g. [[Tabanidae|''Tabanidae'']] and [[Stomoxys calcitrans|''Stomoxys'']]
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| − | | |
| − | '''Recognition'''
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| − | *Elongated, spindle shaped protozoa
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| − | *Between 8 and 39 μm in length
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| − | *Flagellate
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| − | **Flagellum runs the length of the body attached to the pellicle which forms an undulating membrane
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| − | *Kinetoplast present which contains the DNA of the single mitochondrion
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| − | | |
| − | '''Life Cycle'''
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| − | *Undergo morphological transformations in intermediate host before becoming infective for the next host
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| − | | |
| − | *Blood-sucking [[Biting Flies|flies]] ingest trypanosomes whilst taking a blood meal from an infected animal
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| − | **Trypanosomes multiply first in the gut of the [[Biting Flies|fly]]
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| − | *Salivarian trypanosomes are transmitted by [[Glossinidae|Tsetse flies]]
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| − | **Trypanosomes pass forward to the salivary glands where they transform into the infective stage
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| − | **Inoculated with saliva when [[Glossinidae|Tsetse fly]] next feeds on a host
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| − | *Stercorarian trypanosomes are transmitted by triatomid bugs, [[Tabanidae|tabanids]] and [[Biting Flies#Melophagus spp.|keds]]
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| − | **Trypanosomes pass back to the rectum
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| − | **Next host is infected when skin wounds are contaminated with infected [[Insecta|insect]] faeces
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| − | '''Pathogenesis'''
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| − | *Salivarian
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| − | **Causes wasting disease in cattle (nagana)
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| − | **Sleeping sickness in humans
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| − | *Stercorarian
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| − | **''T. cruzi'' most important in veterinary medicine
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| − | ***Occurs in South America
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| − | ***Infects armadillos, possums and humans
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| − | ***Causes Chagas' Disease
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| − | **Transmitted by a triatomid (kissing) bug
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| − | **Chronic infections are often fatal causing heart failure
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| − | **Non-pathogenic species are transmitted by [[Tabanidae|tabanids]] and [[Melophagus spp.|keds]]
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| − | ***''T. theileria'' and ''T. melophagium''
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| − | *Enlarged [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] and [[Spleen - Anatomy & Physiology|spleen]]
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| − | **Causes lymphoid exhaustion
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| − | **Associated with plasma cell hypertrophy and hypergammaglobulinaemia
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| − | ***Due to an increase in [[Immunoglobulin M - WikiBlood|IgM]]
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| − | **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
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| − | *Anaemia
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| − | **Red blood cells are removed from circulation ('''haemolytic''')
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| − | **Is a cardinal feature of the disease
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| − | *Degeneration and inflammation of multiple organs
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| − | **E.g. Skeletal muscle, myocardium and CNS
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| − | '''Clinical Signs'''
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| − | *In ruminants:
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| − | **Anaemia
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| − | **Enlargement of the [[Lymph Nodes - Anatomy & Physiology|lymph nodes]]
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| − | **Progressive loss of body condition
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| − | **Fever and appetite loss occur during parasite peaks
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| − | **Chronic disease usually terminates in death of the animal if untreated
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| − | **Can cause abortion, infertility and decreased growth in herds
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| − | *In horses:
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| − | **Acute or chronic infections of ''T. brucei''
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| − | **Oedema of the limbs and genitalia
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| − | *In pigs:
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| − | **''T. congolense'' infections are mild or chronic
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| − | **''T. simiae'' infections are hyperacute usually leading to death from pyrexia in a few days
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| − | *In dogs and cats:
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| − | **''T. brucei'' and ''T. congolese''
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| − | **Acute infections
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| − | **Fever, anaemia, myocarditis, corneal opacity
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| − | **Occasionally neurological signs present, such as increased aggression, ataxia and convulsions
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| − | *In donkeys:
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| − | **''T. brucei'' in [[Protozoal Skin Infections - Donkey|skin infections]]
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| − | '''Epidemiology'''
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| − | *Vector distribution
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| − | **[[Glossinidae|Tsetse flies]] found in riverine, savannah and forest habitats
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| − | **Up to 20% [[Biting Flies|flies]] infected
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| − | **[[Biting Flies|Flies]] infected for life
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| − | *Parasite virulence
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| − | **Some parasitaemic animals survive for long periods of time
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| − | ***E.g. ''T. brucei'' and ''T. congolense''
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| − | ***Increases the opportunity for infection of [[Biting Flies|flies]]
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| − | **Some trypanosomes kill their host in 1-2 weeks
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| − | ***E.g. ''T. vivax''
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| − | ***Decreases the chances of [[Biting Flies|fly]] infection
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| − | **Trypanosomes avoid host immune defences by altering glycoprotein coat (surface antigen) before host [[Immunoglobulins - WikiBlood|antibody]] response
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| − | ***'''Antigenic variation''' can occur many times over several months causes relapsing parasitaemia
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| − | *Host response
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| − | **Trypanotolerant wild animals remain parasitaemic for prolonged periods without showing clinical signs of disease
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| − | ***Cause lasting reservoirs of infection
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| − | **Most domestic livestock are susceptible to trypanosomosis
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| − | **Some local breeds of sheep, goats and cattle are trypanotolerant
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| − | ***E.g. ''Bos indicus''
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| − | '''Diagnosis'''
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| − | *Demonstrate trypanosomes in blood
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| − | **Giemsa stained smears
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| − | **Fresh blood films
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| − | ***Motile trypanosomes
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| − | **Haematocrit tube
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| − | ***Motile trypanosomes at the plasma/buffy coat interface
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| − | '''Control'''
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| − | *[[Glossinidae|Tsetse fly]] control
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| − | **Spraying and trapping
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| − | *Prophylactic drug treatment
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| − | **Change drug group periodically to decrease the chances of resistance occurring
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| − | **May lead to protective immunity but livestock will still be susceptible to heterologous challenges
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| − | *Barrier fences and buffer zones
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| − | **Separate livestock and wild animals
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| − | *Trypanotolerant livestock
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| − | '''Other trypanosomes'''
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| − | *Mechanically transmitted by [[Biting Flies|biting flies]]
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| − | **E.g. Surra affecting horses and camels in North Africa, Asia and South America
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| − | **''T. equinum'' in South America
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| − | **''T. evansi'' in Asia
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| − | *Venereally transmitted
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| − | **E.g. Dourine
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| − | ***Transmitted by ''T. equiperdum''
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| − | ***Causes genital and abdominal oedema, emaciation and CNS signs
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| − | ***Affects horses and donkeys in Africa, Asia, Central and South America
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| − | *Non-pathogenic species occur in the UK
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| − | **In sheep caused by ''T. melophagium''
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| − | **In cattle caused by ''T. theileri''
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| | ==[[Protozoa Flashcards - Wikibugs#Tropical Protozoa|Tropical Protozoa Flashcards]]== | | ==[[Protozoa Flashcards - Wikibugs#Tropical Protozoa|Tropical Protozoa Flashcards]]== |