Parasitology - Lecture 6 Flashcards
What are the general features of Order Oxyurida?
- normally small (>10mm)
- oesophagus has posterior bulb
- F have long, pointed tail (pin worms)
- M much smaller than F, have single spicule
- eggs often asymmetrical
- direct lifecycles
- infect large intestine of humans, horses, rabbits, rodents
- generally have reduced pathogenicity
What species and where does Oxyuris equi infect?
large intestine of horses
what is the morphology of Oxyuris equi?
size: M up to 1.2cm, F up to 15cm
anterior end: hexagonal mouth with 6 lips. 3 teeth in females
posterior end (F): pointed (pinworm)
posterior end (M): truncate tail, 1 spicule, pin shaped
eggs: thick shelled, asymmetrical, mucoid plug at one end, contain morula
describe the lifecycle of Oxyuris equi?
- female worms migrate to anus and emerge head first
- eggs laid in perianal region embedded in a viscous substance that adheres to surface. yellow/ grey crust when dry.
- host scratches and spreads eggs in environment
- molt to L3 in 3-5 days
- infection by ingestion of embryonated eggs with food
- L3 hatch in SI, migrate to LI enter crypts of caecum and colon and mature
- L4 feed on mucosa in lumen. moult toadult
- adults move to lumen of LI and feed on intestinal content
PPT = 5 months - M dies after copulation. F lives around 6 months
What species and where does Probstmayria vivipara infect? basic morphology?
large intestine of horse
size: 0.2-3cm, long filamentous tail
What species and where does Passalurus ambiguus infect?
large intestine of rabbits
What species and where does Syphacia obvelata infect?
large intestine of rodents
What species and where does Enterobius vermicularis infect?
large intestine of humans
What are the general features of Superfamily Spiruroidea?
- wide range of shapes
- mouth without lips, or with 2 or 4 lips
- muscular and glandular parts of the oesophagus
- no buccal capsule, but has vestibule
- posterior (M): spirally coiled, 2 uneven spicules
- most species are ovo-viviparous (egg countains L1)
- indirect lifecycles
What superfamilies are within Order Spirurida?
Spiruroidea
filarioidea
What parasites are within the family Habronematidae?
Draschia megastoma
Habronema microstoma
Habronema muscae
What species and where does Draschia megastoma infect?
host: horses
adults: stomach
larvae: skin, conjunctiva, lungs, etc.
What is the morphology of Draschia megastoma?
white worms
- 2 lips separated from body by a groove
- buccal vestibule, thickened funnel shaped, no teeth
- uneven spicules
- eggs contain larvae that hatch quickly
What is the morphology of Habronema muscae?
- mouth made of 2 parts, wider anterior part and a cylindrical part
- 2 spicules
- eggs contain larvae that hatch quickly
describe the lifecycle of Draschia/ Habronema?
IH = muscid flies
- F lay embryonated eggs, passed in poop
- larvae ingested by IH, develop to L3 inside IH
- L3 migrate to mouthparts of IH
- larvae stimulated to leave IH when IH feeds on moist, warm surfaces
- larvae may be deposited around mouth (gastric habronemosis) of host or around wounds, penis, anus, nostrils,etc. (cutaneous/pulmonary habronemosis - severe path)
Describe Gastric Habronemiasis
causes large nodules/ tumours. may block pyloric region or may perforate the stomach, leading to peritonitis
- nodules divided into cavities where the worms live
Describe Cutaneous Habronemiasis
inflammation and hypersensitivity caused by the presence of larvae. larvae do no develop on the skin.
Describe Pulmonary Habronemiasis
multiple abscesses filled with necrotic debris containing parts of nematode larvae in the lungs
What species and where does Spirocerca lupi infect?
host: dog, fox, etc.
adults: wall of oesophagus
immature stages: stomach and dorsal aorta
describe the morphology of Spirocerca lupi
size: M 54mm, F 80mm
- normally pink,coiled in. spiral in nodules
- trilobed lips, short pharynx, unequal spicules
- eggs: parallel side, contain larvae
describe the lifecycle of Spirocerca lupi
IH: dung beetle
- eggs passed in poop, ingested by IH. reach L3 in 2 months
- DH ingests beetles or paratenic hosts
- larvae release in stomach, penetrate wall, reach aorta, migrate to oesophagus
PPT = 5-6 months
What species and where does Ascarops strongylina infect? What is the basic morphology?
- stomach of pigs
- pharynx strengthened by triple or quadruple spirals
What species and where does Physocephalus sexalatus infect? what is the basic morphology?
- stomach of pigs
- pharynx strengthened by annular rings
describe the lifecycle of Ascarops/ Physocephalus
IH: coprophagous beetles
- F lay embryonated eggs, ingested by IH, larvae reach L3, pigs ingest beetles.
PPT= 1-2 months
