Parasites of circulatory system Flashcards
Dirofilaria immitis = parasites of the _____
pulmonary arteries
Purpose/function of Wolbachia of Dirofilaria immitis
- symbiotic bacteria that is required for survival and reproduction of the nematode.
- release associated w/ increase in inflammatory cytokines + decr. in host immune response
Caval syndrome
Most severe manifestation of HW dz
- >40 worms migrate into RV, RA and Caudal Vena Cava –> interfere w/ valv. function and/or bloodflow
- acute clincial syndrome = DIC
- if worms not surgergically removed, fatal outome
When worms die during tx, what is a consequence and why dogs must be kept calm/exercise limited?
Thromboembolism
- dead worms worse vascular damage and enhance coagulation
What is the only state where HW is NOT endemic?
Alaska
How is Dirofilaria immits diagnosed?
Detecting microfilaria via direct smear or Knott’s test (a concentration technique- best per AHS)
Knott’s test involves using a centrifuge (a machine that spins the sample very quickly in a small circle) to concentrate the microfilariae
Snap antigen test for Dirofilaria immitis detects antigen from where? What can cause a false negative?
The uterus/adult female repro tract. False negative = male-only infection, low female infection, a PPP infection, production of antigen-antibody complexes in dogs
False negatives for Knott’s Test
How do macrocylic lactones (avermectins, milbemycins) prevent HW dz?
kill immature worm (prevent from developing into adult)
What life cycle stage are macrocyclic lactones approved for?
1 dose will kill L3 and L4 up to 6-8 weeks post infection
most L3 mature into L4 is SC tissue in 1-3 days -> L4 migrate thru tissue and mature into sexually immature/adolescent adults b/w 50-70 days -> sexually immature worms migrate to heart and lungs -> worms develop into sexually mature in pulmonary artery -> microfilariae appear in blood b/w 6-7 months PI = stage where MF are killed
When is a dog considered cleared of HW infection with adulticide tx?
after 2 consecutive NAD (no antigen detected), 6 months apart
What is the most common clinical syndrome observed in cats infected with HW?
Heartworm Associated Respiratory Disease (HARD)
- occlusive medial hypertrophy of small pulmonary arterioles –> disease in cats is due to MIGRATION of the larvae
may be misdiagnosed as asthma or allergic bronchitis
How is feline HW diagnosed?
there is no single test that will detect all HW cases.
only confirms that there are adult nematodes in the pulmonary arteries, does not verify that clincial signs are cuased by larval migrating tin the respiratory tract
HW disease: interpret a positive antigen result in cats
only confirms that there are adult nematodes in the pulmonary arteries, does not verify that clincial signs are caused by larvae migrating around in the respiratory tract!
What transmits Piroplasms
Hard (Ixodid) ticks
Piroplasms = blood parasite
Babesia spp. pathogenesis and clinical signs
Erythrocyte lysis, asspocated with parasite release –> fever, hemoglobinuria, anemia, icterus, splenomegaly
Babesia = type of piroplasm
What causes Texas Cattle fever
Babesia sp. transmitted to cattle via Rhipicephalus (Brown dog) ticks
- One-host ticks (infest animal as larva, remain on same animal thru adult stage)
- a serious livestokc dz -> we eliminated the tick
How is Canine Babesiosis transmitted (2)
- Rhipicephalus sanguineus (tick) transmits the organisms after 24-48 hours of feeding
- Direct transmission (iatrogenic via needles, dog-to-go via FIGHTING [esp. B. gibsoni])
What organism and what tick are involved in Feline Piroplasmosis
Cytauxzoon felis transmitted by Amblyomma americanum (Lone Star Tick), affecting bobcats and cats
Pathogenesis of Cytauxzoon felis
sporozoites in cat enter endothelial møs and multiply (schizogony) –> disease from occlusion of small vessels in lungs, spleen, liver and kidney, + RBC loss
acute fever, resp. signs, depression, icterus, lethargy, anorexia
Bovine theileriosis
Theileria in cattle spread by longhorned Asian tick (Haemaphysalis longicornis) – Asia, Australia and NZ
Trypanosoma cruzi
- type of organism
- species affected
- location
- flagellate, protozoan organism
- infects dogs and wild animals
- Cases mostly in Texas and Gulf Coast region
Life cycle and pathogenesis of Trypanosoma cruzi
KEY: transmitted thru the FECES of the kissing bugs –> enters host bloodstream & multiply in cardiac cells
Clinical signs of Trypanosoma cruzi
- Peracute death from acute myocarditis;
- Chronic: heart failure (months-year; more common)
