Parasitology Flashcards
What are the major tick-borne diseases of cattle in the UK?
- Babesia
- Theileria
What is the life-cycle of babesia?
- Mature tick feeds and becomes infected
- Babesia sexually multiplies in the tick’s intestines
- Asexual multiplication also occurs in multiples tissues
- Vernicules formed (which also divide)
Either - In tick salivary glands
or - In tick ovary and eggs
- Tick feeds on the cow and transmits infection
- Asexual multiplication in Bovine RBCs
What is the pathogenesis of babesiosis?
Infected RBCs rupture leaving free antigen in the blood which then sticks to the surface of other RBCs missdirecting the host immune response while babesia parasites enter other RBCs
What are the consequences of Babeosiosis in naive animals?
Sudden Onset:
- Fever
- Anaemia
- Haemoglobinuria
- Continous diarrhoea
- May result in death (if survie may become a carrier)
What is the epidemiology of Babesiosis?
Mostly in defined endemic areas, sporadic, spring and autumn time affecting hill grazing, over 2 year old, often newly purchased or stressed animals
What is the epidemiology of babesiosis dependent upon?
- Vector (species, population etc)
- Host susceptibility (multi factorial)
What is the host susceptibility of babesiosis dependent upon?
- Age: calves under 9 months are refactory, infected but not sick or Adults are susceptible until infected
- Immunity develops rapidly but may ane
- Carrier state
- Stress
What is enzootic stability versus enzootic instability?
Enzootic stability = Continual re-infection resulting in consistent high level of herd immunity and less disease
Enzootic instability = Infrequent re-infection resulting in some animals with low immunity and more disease
What circumstances will lead to infection of susceptible animals?
- Susceptible animals moving to an infected area
- Infected ticks moving to a clean area
- Infected cattles added to area with clean ticks
- Reduction in tick numbers
- Stress
What is leishmania?
Intra-cellular, protozoan parasites of macrophages causing disease in humans, dogs and wild animals in S. Europe, Africa, Aia and S. america
What is the life-cycle of leishmania?
- Sandfly ingests leishmania
- Intermediate host of sandfly
- Transforms and multiplies in the fly gut and migrates to proboscis
- Dog infected when sandfly bites; leishamnia transforms in the macrophage
Two stages
What is the digenetic life-cycle of leishmania?
- Promastigote
- Amastigote
What is the pathogenesis of leishmania?
- Infection of the vertebrate host = foci of proliferating organisms in skin (cutaneous leishmaniosis) and internal organs (visceral leishmaniosis)
- Very long incubation period (months to years)
- Many dogs that are infected are asymptomatic
- Infection does not equal disease
What are the clinical signs of leishmaniosis in dogs?
Cutaneous:
Shallow skin ulcers e.g. lip, eyelid, ear pinna
Visceral:
- More common
- Chronic wasting condition
- Generalised eczema, hair loss around the yes
- Intermittent fever
- Generalised lymphadenopathy
What is the epidemiology of leishmania?
- Disease dependent on sandfly distibution
- Reservoirs of infection e.g. wild animals such as rats
- Mechanism of transmisson is sandlfy bites or direct contact
How is leishmaniosis diagnosed?
- Demonstrate leishmania organisms in skin smears/scrapings, lymph node/ bone marrow biopsies
- Serology
- PCR
How is leishmaniosis treated?
- Chemotherapy: prolonged, expensive, suppresses infection
- Prevent sandfly bites: colalrs/sprays
- Vaccination e.g. CaniLeish or Letifend
What is Dirofilaria immitis?
- Cause of canine heartworm disease
- Is a dilarial nematode
- Serious cause of canine morbidity and mortality
- Cats and ferrets are also susceptible
What are the presenting signs of canine heartworm disease?
Usually:
- Exercise intolerance
- Chronic heart failure
Sometimes:
- Acute collapse
What is the life-cycle of Dirofilaria immitis?
- No eggs, microfilariae (300 micrometers long)
- Found in 60% of infected dogs
- Microfilariae ingested by mosquito
- Develop into L1-L3 in 10-14 days under optimal conditions (14 centigrade)
- L3 transmitted by feeding mosquito
- L3 progresses to L4 and L5
- L5 migrates to the heart
How is dirofilaria controlled?
Prophylaxis is the basis of control:
All year round in the tropics and one month before mosquito season and two months after in temperate zones
How is dirofilaria detected?
- Blood: microscopy for microfilaria, serology
- Ultrasonography for adult worms
How is dirofilaria treated?
Doxycycline
Macrocyclic lactone
Is dirofilaria zoonotic?
- Man can be host to an aberrant infection
- No parasite development
- No microfilaria
- Larvae die in the pulmonary artery
