Nematodes Part Two: Rare

Strongyloides spp. - common name

Intestinal threadworms

Strongyloides spp. - definitive host

Vertebrates

• esp. carnivores and primates

Strongyloides spp. - zoonotic?

Yes

Strongyloides spp. - clinical signs

Often asymptomatic (parasitiasis); may cause severe disease in puppies

• diarrhea

• loss of appetite

• weight loss

• weakness

• dehydration

• death

Strongyloides spp. - life cycle

• facultative parasite

  • alternating parasitic and free-living generations

  • ALL worms in parasitic generation are female

  • free-living generation can be males or females

• adults reproduce in small intestine via parthenogenesis

• ovoviparous female lays larvated, spiruid-type ova

• eggs hatch into L1 larva in small intestine

• L1 larva passed in feces

• host and environment influence whether L1 will enter parasitic or free-living life cycle

• parasitic larva enter a new by skin penetration

• migrate in the body to the small intestine

• possible for L1 to mature to infective L3 within the small intestine: autoinfection

Strongyloides spp. - infective stage

L3 larva

• 3-5 days (embryo → infective)

Strongyloides spp. - prepatent period

8-14 days

Strongyloides spp. - diagnosis

• fecal flotation or centrifugation

  • some flotation solutions will deform the larvae

• direct smear

• Baermann technique

  • concentrates the larvae in feces