Vector-Borne Protozoa

Question 1

what are the arthropod-borne protozoa of major importance in humans?

Answer 1

-plasmodium (malaria)
-trypanosoma (trypanosomiasis)
-leishmania (leishmaniasis)

Question 2

what are the arthropod-borne protozoa of major importance in animals?

Answer 2

-trypanosoma
-theileria (theileriosis)
-babesia (babesiosis)
-plasmodium (avian malaria)
-leishmania

Question 3

what are the vector, parasite and diseases for flagellates?

Answer 3

-tsetse flies, biting flied-trypanosoma-trypanosomiasis
-sand flies-leishmania-leishmaniasis

Question 4

what are the vector, parasite and diseases for apicomplexas?

Answer 4

-mosquitos-plasmosium-malaria
-ticks-babesia-babesiosis/theileria/theileriosis

Question 5

what are the vector, parasite and diseases for rickettsiales?

Answer 5

-ticks- ehrlichia-erlichiosis/anaplasma-anaplasmosis

Question 6

what are the stages of the life cycles in ticks?

Answer 6

-egg mass
-larva
-nymph
-adult (male and female)

Question 7

what is the basic tick life cycle?

Answer 7

1. Eggs laid by engorged female
2. Hatched into larvae that attach to host and feed on blood thorugh sepcialised mouth parts
3. Malt to become nymphs and feed
4. Then malt again to become males and females which both feed and mate
5. Adult females lay thousands of eggs in environment

Question 8

what are one-host ticks?

Answer 8

-all three life cycle stages feed on same host
-e.g. rhipicephalus microplus
-an important tropical cattle tick

Question 9

what are two host ticks?

Answer 9

-larvae and nymphs feed on same host
-e.g. hyalomma sp
-important mediterranean and subtropical livestock ticks
-adult ticks feed on another host

Question 10

what are three host ticks?

Answer 10

-each stage feeds on a different host
-e.g. ixodes ricinus
-the familiar UK sheep tick

Question 11

what is transstadial transmission?

Answer 11

-Transmission between stages - larva to nymph, nymph to adult
-tick cannot be a reservoir ‘pasture spelling’ eliminates disease from ticks if alternative tick hosts not susceptible

Question 12

what is transovarial transmission?

Answer 12

-Vertical transmission via eggs (so larvae are infected and infectious)
-tick may act as reservoir of disease in absense of disease susceptible vertebrate hosts
-ticks survive by feeding on non-susceptible hosts
-pathogen survives by vertical transmission within ticks

Question 13

what is ixodes ricinus?

Answer 13

-sheep tick, castor bean tick

Question 14

what is rhipicephalus sanguineus?

Answer 14

brown dog tick, kennel tick

Question 15

what is dermacentor reticulatus?

Answer 15

marsh tick, meadow tick, ornate cow tick
uncommon in UK, important vector in belgium

Question 16

what is babesia?

Answer 16

-tick-borne ampicomplexan parasite causing disease in domestic animals
-occasional zoonosis

Question 17

what are the properties of babesia?

Answer 17

-tick-borne protozoan parasites of red blood cells
-cause of babesiosis
-discovered by victor babes 1888 in romania
-a variety of species infect various host and vector species e.g. babesia canis

Question 18

where did texas fever arise?

Answer 18

-texas longhorne cattle trekked north along chisholm trail
-disease broke out in midwestern cattle close to trails
-splenic or redwater fever- pyrexia, splenomegaly and haemoglobinuria
-trekked cattle remained healthy

Question 19

what is the babesia life cycle?

Answer 19

1. In dog red blood cells, parasite may multiply by binary fission in merogeny and under microscope seen in pairs
2. Merozoites go on to infected further red blood cells
3. Ingested by tick
4. Within tick gut, undergoes sexual repro forming gametes which fuse to form zygotes and invade gut epithelial cells where they multiply
5. Motile chimete stage migrates to both ovary of female ticks thereby allowing transovarial transmission to next generation of ticks to the tick salivary gland
   - Further multiplication- sprorogony- occurs in epithelial cells giving rise to sporozoites in the saliva which are infective to dog RBCs when tick feeds

Question 20

what is babesia canis canis?

Answer 20

-transmitted by dermacentor reticularis
-main species in Europe

Question 21

what is babesia canis vogeli?

Answer 21

-transmitted by Rhipicephalus sanguineus
-mediterranean area
-less pathogenic than B.canis canis

Question 22

what is babesia gibsoni?

Answer 22

-probably transmitted by rhiphicephalus sanguineus
-sporadically reported in Europe

Question 23

what is babesia vulpes?

Answer 23

-AKA theileria annae, babesia microti-like species
-suspected vector: Ixodes hexagonus
-probably reservoir in foxes
-endemic in northern spain

Question 24

what is the pathogenesis of canine babesiosis?

Answer 24

-rapid division of parasite erythrocytes
-haemolytic anaemia
-splenomegaly

Question 24

what is the pathogenesis of canine babesiosis?

Answer 24

-rapid division of parasite erythrocytes -haemolytic anaemia -splenomegaly

Question 25

what are the clinical signs of canine babesiosis?

Answer 25

-1-2 weeks post tick-feeding -fever, haemogloinuria (redwater), jaundice, anaemia -neurological signs

Question 26

what is the treatment of canine babesiosis?

Answer 26

-antiprotozoal drugs -blood transfusion

Question 27

what are the features of babesia divergens in the UK?

Answer 27

-small -ixodes ricinus vector -all areas with ixodes ricinus -in endemic areas

Question 28

what are the features of babesia divergens?

Answer 28

-vertebrae host: cattle -vector: Ixodes ricinus -disease: redwater fever

Question 29

what are the clinical signs of babesia divergens?

Answer 29

-pyrexia, anorexia, depression -anaemia, haemoglobinuria, icterus -diarrhoea or constipation -occasionally neurological signs

Question 30

how can you distinguish haemoglobinuria from haematuria?

Answer 30

-RBC settle on standing in haematuria

Question 31

what are the factors affecting epidemiology of bovine babesiosis in the UK?

Answer 31

-restricted to pastures that support high numbers of ticks -disease outbreaks associate with peaks of tick feeding activity -principally a disease of older animals -inverse age resistance- animal up to 6 months old in endemic areas are protected by colostral immunity and innate resistance -infected cattle develop non-sterile immunity -enzootic stability in endemic areas

Question 32

what is enzootic stability?

Answer 32

-a state of host-tick-pathogen interaction in which there is -a high level of challenge of calves by infected ticks -absence of clinical disease in calves despite infection - a high level of immunity in adult cattle -consequently a low incidence of clinical disease

Question 33

what are the risk factors for outbreaks of bovine babesiosis?

Answer 33

-intro to babesia naive adults to tick areas -intro of tick infested cattle to naive herds -fluctuations in tick numbers

Question 34

how are there fluctuations in tick numbers?

Answer 34

-set aside scheme -changes in pasture harvesting -presence of dipped sheep -use of endectocides for helminths -purpurbation of enzootic stability

Question 35

what is the control of bovine babesiosis?

Answer 35

-ensure adequate exposure of young animals to tick challenge -treatment of affected animals -monitor introduced adult cattle for evidence of infection -tick reduction measures e.g. dipping -vaccination

Question 36

what are the treatments for bovine babesiosis?

Answer 36

-imidocarb diproprionate or long acting oxytetracyclin -diminazene aceturate in some countries -supportive therapy

Question 37

what is leishmania?

Answer 37

a parasitic protozoan of animals and man transmitted by the sandfly causes leishmaniasis

Question 38

what are the features of leishmania?

Answer 38

-flagellate protozoan parasite -vertebrate hosts: human, dog, wild animals -mediterranean basin, Africa, Asia, Central and South America -Vector: blood sucking phlebotomine sandfly

Question 39

what is canine leishmaniasis?

Answer 39

-endemic in mediterranean Europe, Africa, Asia, Central and South America -potential problem in UK dogs imported frmo Southern and Eastern Europe -Rescued stray dogs brought into the UK from endemic countries -A recognised problem in dogs in USA -vectors not present in UK -congenital or venereal transmission, or biting -incubation period of months to years

Question 40

what are the clinical signs of canine leishmaniasis?

Answer 40

-skin lesions, ocular abnormalities, epistaxis -frequently: weight loss, lethargy

Question 41

what are the pathologies of canine leishmaniasis?

Answer 41

-anaemia -thrombocytopenia -hyperglobulinemia

Question 42

what is the diagnosis of canine leishmaniasis?

Answer 42

-cytology of giemsa stained lymph node of bone marrow aspirates -PCR -serology

Question 43

what is the treatment of canine leishmaniasis?

Answer 43

-pentavalent antimonials (toxicity) -allopurinol -miltefosine

Question 44

what can treated dogs of canine leishmaniasis?

Answer 44

-can remain carriers -may relapse -may remain infectious to sand flies

Question 45

what is trypanosomiasis?

Answer 45

-tsetse fly vector- glossina sp -nagana- trypanosoma congolense -extracellular flagellate haemoparasites -sleeping sickness-trupanosoma brucei

Question 46

what is the incidence of trypanosomiasis?

Answer 46

-major problem in sub-saharan africa

Question 47

what does trypanosomiasis cause?

Answer 47

anaemia and loss of production in animals

Question 48

what is the antigenic variation in trypanosomes?

Answer 48

-variable surface glycoprotein coat -vast repertoire of VSG genes -antigenic variation evades host immune response