Emerging Protozoa Flashcards
Cutaneous Leishmaniasis
L. tropica and mexicana
- central and south america
- various mammal hosts
- US: rats, oppossums, armadillos, cats, humans
Visceral leishmaniasis
L. infantum
- US: no acquired human cases, established in US foxhounds
Leishmania vector
Sand fly
- new and old world
Leishmania life cycle in the sand fly
Sand fly ingests amastigotes during blood meal –> amastigotes become promastigotes –> metacyclic promastigotes migrate to proboscis –> enter vertebrae
Leishmania life cycle in the vertebrate host
Host bitten by sand fly –> promastigotes are injected –> phagocytized by macrophages –> amastigotes -> divide via binary fission inside macrophages –> lyse macrophage –> invade new cells
Leishmania is _______ in mononuclear phagocytes
Systemic
- skin, bone marrow, visceral organs
- transplacental
Leishmania infantum
Distribution: Europe, Asia, South and Central America, North America
- host outside US: dog, cat, jackal, fox, horse
- host in US: dog
L. infantum insect vector
- outside US: sand fly
- inside US: none but identified positive for L. infantum
L. infanum reservoir host
Dogs
L. infantum transmission
Direct vertical and horizontal transmission routes
- dog to dog via biting
- reused needles, venerelly, transfusions, tattoos
Canine leishmaniasis
Asymptomatic or clinical
- facial alopecia, nodular skin lesions
- weight loss, progressive wasting disease
- lymphadenopathy
- conjunctivitis
- swollen limbs
- renal failure
- relapse possible
Canine leishmaniasis - diagnostics
Serology: IFA, ELISA
Staining: look for amastigotes
- bone marrow, lymph node aspirates, blood
Canine leishmaniasis - control method
Dog to dog transmission
- euthanize
Eliminate sand fly via insecticides
Eliminate asymptomatic host
Infected human population
- immigrants from endemic regions
- military population
- travelers
3 forms of human leishmania infection
- cutaneous
- visceral
- mucocutaneous
Trypanosoma cruzi - vector
Triatomine insect (kissing bug)
Trypanosoma cruzi - host
Domestic dogs, wildlife, captive animals
Trypanosoma cruzi - morphology
- single large mitochondria (kinetoplast)
- undulating membrane
- single nucleus
- either elongate with single flagellum, or rounded with short nonprotruding flagellum
Trypanosoma cruzi - life stages
Trypomastigote - vertebrate/insect, infectious stage
Epimastigote - insect only
Amastigote - vertebrate, seen in cardiac muscle
T. cruzi - life cycle in vector
Trypomastigotes ingested by triatomine vector during blood meal –> develop into epimastigotes in the gut –> multiply –> metacyclic trypomastigotes –> exit via feces of triatomine insect
T. cruzi - life cycle in host
Trypomastigotes enter vertebrate host cell (macrophages, etc) –> amastigotes –> replicate via binary fission –> differentiate into trypomsatigotes –> circulate and invade new cells or lie dormant as amastigotes
T. cruzi - route of infection for triatomine insect
Ingest trypomastigotes from blood meal from infected vertebrate host
T cruzi - route of infection for vertebrate host
Trypomastigotes in triatomine feces enter wound/mucosal membrane
- or host ingests infected triatomine insect
- transplacental
- blood
T. cruzi distribution
Found in south and central america, mexico
- US: southern states
T. cruzi in the US
Common near shacks, sheds, houses near woods
- behavior differs vs endemic regions: defecate 20 min after feeding (often not on host at that time)
T. cruzi - most common vertebrate host
- confirmed: dog, oppossums, rat, armadillos, raccoons, mice, squirrels, fox
- seropositive: cat, moles, bat, feral hog, bobcat, badger, coyotes, mice
T cruzi - reservoir hosts
Dog
- asymptomatic
- infected directly by insect, ingestion of infected bug or infected animal
Chagas disease
Usually asymptomatic, clincal chagas in dogs:
- incubation period of 3 days PI
- lasts 10-30 days with fever, anorexia, diarrhea, lymphadenopathy, hepatomegaly, splenomegaly, cardiac dysfunction
- chronic: CHF
- latent: asymptomatic
- rare in cats in US
T. cruzi - diagnosis in animal host
Blood smear - typomastigotes Biopsy/histology - amastigotes Culture organisms from blood Serology
T. cruzi - treatment and control
Benznidazole - not available in US
- severe side effects
T. brucei
African sleeping sickness
