Parasitology blood and tissue flagellates

Question 1

Order Kinetoplastida

Answer 1

Important parasites of man and animals
Canine American Trypanosomiasis
Canine leishmaniasis

Question 2

Kinetoplast

Answer 2

another name for kinetoplastida

Question 3

Promastigotes

Answer 3

stages transmitted by the vector (sandfly; only Leishmania)

Question 4

Epimastigotes

Answer 4

stages in the insect vector (T. cruzi only)

Question 5

Amastigotes

Answer 5

in host cells and tissue (both T. cruzi and L. infantum)

Question 6

Trypomastigotes

Answer 6

in blood of host and in insect vector (T. cruzi only)

Question 7

Insect vectors

Answer 7

Insects become infected when they feed on blood or tissue fluids
Anterior station (salivary) develop in anterior portion of insect digestive tract (Leishmania)
Posterior station (stercoraria) develop in the posterior portion of the insect digestive tract (Trypanosome)(think dogs eat the bugs to get the parasite)

Question 8

American trypanasomiasis

Answer 8

Trypanosoma cruzi
Chagas’ disease
Triatomid bugs are vectors, present in VA
Major cause of chronic heart disease in some Latin American countries

Question 9

Trypanosoma cruzi, life cycle

Answer 9

Possible that feces from bug containing trypomastigotes are rubbed into the bite wound, dogs eat the bug
Trypomastigotes enter cells (heart, brain, esophagus, colon) and multiply as amastigotes, cell ruptures and releases trypomastigotes
trypomastigotes ingested in blood meal by bugs and become epimastigotes then trypomastigotes in vector

Question 10

Trypanosoma cruzi in the US

Answer 10

Found in wildlife- raccoons and opossums
Dogs- mostly Texas, some in other Gulf Coast states
Dogs eat the insect vector and become infected- cardiac disease typified by arrythmias or myocarditis (acute and chronic)

Question 11

Pathology of Trypanosoma cruzi

Answer 11

Infected cell ruptures and releases amastigotes and trypomastigotes
Trypomastigotes invade additional cells or circulate in blood
Trypomastigotes don’t divide in blood
Lesions in tissue are due to amastigotes causing cell damage

Question 12

Diagnosis of Trypanosoma cruzi

Answer 12

Any dog that’s been in an endemic area (like Texas)
Trypomastigotes in blood smear (acute infection)
IFA, ELISA (potential cross reactivity to Leishmania and T. cruzi)
Dipstick “Trypanosoma DetectTM”

Question 13

Treatment of Trypanosoma cruzi

Answer 13

Benznidazole and nifurtimox, but not available in the US and both are toxic
So, supportive care for heart problems

Question 14

Leishmaniasis

Answer 14

Is an important zoonotic parasitic disease in many areas of the world
Several clinical forms of the disease exist: visceral, cutaneous, and mucocutaneous
Dogs are a major reservoir host for visceral leishmaniasis

Question 15

Leishmania in US

Answer 15

In 2000, canine leishmaniasis was observed in foxhounds from 21 states and Ontario
Blood transfusion induced infections reported in not foxhounds (amastigotes)
Many dogs are asymptomatic
Relapse is common in treated dogs
Recognized as endemic in foxhounds in the US, maintained by maternal transmission

Question 16

Leishmaniasis, stages found in hosts and sand fly

Answer 16

Amastigotes in mammalian retichuloendothelial cells and lymphoid cells (macrophages)
Promastigotes found in sand fly pharynx and are inoculated when fly bites

Question 17

Leishmania infantum

Answer 17

The agent isolated from US dogs
Causes visceral leishmaniasis in dogs and humans
Normally asymptomatic in adults but problem in children

Question 18

Clinical signs of leishmaniasis

Answer 18

Lympadenopathy, skin lesions, weight loss
Ocular lesions, nose bleed, lameness
Anemia, renal failure (b/c of antibody-antigen complex deposition), diarrhea

Question 19

Leishmania diagnosis

Answer 19

IFA test
Amastigotes in lymphnode or bone marrow
rK39 dip stick test

Question 20

Leishmaniasis control/treatment options

Answer 20

Relapses are common in dogs
Dog control may help prevent infections in humans (mandated by law in Brazil)
Allopurinol (once off of this they tend to relapse, second choice drug)
Pentavalent antimonial drugs- glucantime (meglutamine antimonate)
Pentostam (sodium stibgluconate) in US, top choice