PA10: Arthropod-borne protozoa Flashcards
(24 cards)
Why are arthropod-borne protozoa referred to as haemoprotozoa?
They affect the blood system of vertebrate hosts & have forms that develop in their blood.
What type of reproduction do arthropod-borne protozoa undergo?
Both sexual & asexual
Sexual reproduction can only occur in the arthropod host (if it even occurs at all).
What is cyclical/biological transmission with reference to arthropod-borne protozoa?
When the parasite develops within the arthropod host before being transmitted to another host
What are examples of arthropod-borne protozoa?
Babesia spp.
Trypanosoma spp.
Plasmodium spp.
Leishmania spp.
Theileria spp.
How is Babesia spp. transmitted?
By ixodid ticks
Which cell does Babesia spp. invade?
Erythrocytes
What disease is caused by Babesia spp.?
Babesiosis (also known as redwater).
What are the 2 important subspecies of Babesia spp.?
Babesia divergens is the main cause of babesiosis
Babesia major
Characteristics of Babesia divergens
Small
Paired
Found near the edge of RBC
Transmitted by Ixodes ricinus
Characteristics of Babesia major
Large
Paired
Less pathogenic than B. divergens
Transmitted by Haemaphysalis punctata
When must calves be infected by Babesia divergens to develop lifelong immunity?
Between 3-9 months of age
What are the clinical signs of babesiosis?
Haemolysis
Haemoglobinurea (red urine)
What control methods are available for Babesia spp.?
Treatment using imidocarb diproprionate & oxytetracycline
Reducing ticks
Vaccination with attenuated strains of Babesia
Characteristics of Babesia canis
Affects dogs
Transmitted by Rhipicephalus sanguineus
Causes severe inflammatory reactions, anaemia & pyrexia.
Characteristics of Trypanosoma spp.
Extracellular haemoflagellate
Wide host range
Problematic in the tropics
Causes trypanosomiosis
What species is affected by Trypanosoma theileri and how is it transmitted?
Affects cattle, transmitted by tabanids
What species is affected by Trypanosoma melophagium and how is it transmitted?
Affects sheep, transmitted by keds
What species is affected by Trypanosoma brucei evansi and how is it transmitted?
Affects all domestic animals but only fatal for horses, transmitted by tabanids
What species is affected by Trypanosoma equiperdum and how is it transmitted?
Horses & donkeys, venereally transmitted
What are the clinical signs of Trypanosoma brucei evansi in horses?
Lymphadenopathy, anaemia, recurrent fever, oedema
Characteristics of Plasmodium spp.
Cause malaria
Affects birds who are often asymptomatic
Intraerythrocytic
Transmitted by tabanids
Avian parasites do no affect humans
Characteristics of Leishmania spp.
Intracellular in tissue & blood macrophages
Transmitted by sandflies
Cause leishmaniosis
Clinical signs of leishmaniosis
Skin ulcers, hair loss, generalised inflammatory disease
Depends on parasite species, host & location in host
Describe the pathogenesis of leishmaniosis
Amastigote forms of Leishmania in macrophages are ingested by sandflies & develop in the gut to proliferative promastigote form.
Promastigote form migrates to the proboscis of sandflies & are transmitted to dogs when they are bitten by a sandfly.
Once in a macrophage, promastigote reverts to amastigote & divides.
