Parasitology - Lecture 2 Flashcards
What are the two types of vectors?
mechanical and biological
What is a paratenic/transport host?
host where the parasite does not undergo any development, but in which it remains alive and infective another host
What are some examples of ways that a parasite can infect a host?
ingestion, burrow into skin, injected into skin/blood, transplacental, through milk, autoinfection
What is the size range for the average nematode?
1mm to 1m
describe the body shape of nematodes
cylindrical, elongated, tapered at both ends and bilaterally symmetrical
describe the structure of the. body wall of a nematode
consists of a cuticle, hypodermis, and body wall musculature
List some cuticular structures
ridges, striations, alae, spines, setae, etc.
What are the Orders of Subclass Secernentea
- Rhabditida 2. Strongylida 3. Ascarida 4. Oxyurida 5. Spirurida
What are the general features of order Rhabditida?
- small, transparent - oesophagus composed of corpus, isthmus and bulb - species make transition from free-living to parasitic
What two families are under Order Rhabditida?
- Family Rhabditidae 2. Family Strongyloididae
What are the hosts of Rhabditis strongyloides?
dogs, ox, sheep
What is the host location of Rhabditis strongyloides?
skin
Describe the lifecycle type of Rhabditis strongyloides?
normally freeliving, but become parasitic when animals are housed in wet/ soiled bedding
What is the common name of genus Strongyloides (Family Strongyloididae)?
thread worms
What family is the genus strongyloides?
Family Strongyloididae
What are the hosts of genus strongyloides?
sheep, cattle, pigs, dogs, horses, humans, etc.
What is the location in the host of genus strongyloides?
small intestine. occasionally in the respiratory, pancreatic or biliary system
What is the host and location of Strongyloides papillosus?
ruminants, small intestine
What is the host and location of Strongyloides vituli?
cattle, small intestine
What is the host and location of Strongyloides ransomi?
pigs, small intestine
What is the host and location of Strongyloides westeri?
horses, small intestine
What is the host and location of Strongyloides stercoralis?
dogs, cats and humans. small intestine
What is the host and location of Strongyloides felis?
cats. small intestine
What is the host and location of Strongyloides fuelleborni?
primates, small intestine
What is the host and location of Strongyloides avium?
poultry, caeca
Explain the general morphology of parasitic females of the genus Strongyloides.
Size: up to 9mm Body shape: filiform Oesophagus: fillariform. long and may occupy 1/3 of body length Feeding: blood
Explain the morphology of the eggs of parasites of the genus Strongyloides.
40-60microns long, thin shelled, embryonated when laid
What genus does this egg belong to?
Strongyloides
Describe the first stage larva (L1) of the genus Strongyloides
Size: 220-250microns
Oesophagus: Rhabditiform, long (extends over 1/3 of body length)
Other: no granules in intestine, tail is short and pointed
Describe the thrid stage larva (L3) of genus Strongyloides
Size: 400-700microns
Oesophagus: fillariform, extends over 40-50% of body length
other: tail is notched (tripartite)
Describe the lifecycle of parasites of the genus Strongyloides.
- parasitic females live in SI and lay embryonated eggs
- eggs/ larvae passed in faeces and hatch in environment
- larvae then develop through direct or indirect lifecycles.
- L3 infect host through skin or orally.
- after skin penetration, larvae may migrate (lungs, trachea, phrynx, then swallowed and mature in SI) or they may reach other tissue (muscle, fat, mammaries, etc. and arrest (can then reactivate and migrate to SI or pass through milk)
- after oral infection, L3 mature in gut without migrating
What factors might influence the development of larvae?
condition of the host: disease, imunity, etc.
environmental factors: pH, temp, hummidity, food availability
What conditions promote heterogonic development?
adverse conditions within the host and good conditions outside
What conditions promote homogonic development?
good coniditions in the host, bad conditions outside
How are hosts infected with the genus Strongyloides?
- L3 from environment; orally or through skin
- L3 from milk
- autoinfection
- maybe trnsplacentally
What superfamilies are included in Order Strongylida?
- Trichostrongyloidea
- Strongyloidea
- Ancylostomatoidea
- Metastrongyloidea
What are the general features of parasites within Order Strongylida?
Common name: ‘strongyles’ or “bursate nematodes’
anterior end: corona radiata or 3-6 lips
posterior end (Male): copulatory bursa
Eggs: thin shelles, contain many cells (morula stage)
What is a Bursa?
bell shaped structure with 3 lobes (2 lateral, 1 dorsal) supported by rays or papillae
What Bursa features are important for ID of a species?
- shape of bursa
- development of the lobes
- arrangment of the rays
What are the general features of superfamily Trichostrongyloidea?
- slender worms, small mouth
- lips absent, or 3-6 lips
- bursa well developed
- direct lifecycle
- most species in GIT (except Dictyocaulus)
- most important worms of ruminants
What are the genuses within the superfamily Trichostrongyloidea?
- Trichostrongylus
- Haemonchus
- Ostertgia
- Teladorsagia
- Cooperia
- Hyostrongylus
Name the hosts and the location in the host of Trichostrongylus axei
ruminants, horses ad pigs. abomasum and stomach
Name the hosts and the location in the host of Trichostrongylus colubriformis
sheep and goats, duodenum
Name the hosts and the location in the host of Haemonchus contortus
sheep ad goats. abomasum
Name the hosts and the location in the host of Haemonchus placei
cattle. abomasum
Name the hosts and the location in the host of Ostertagia ostertagi
cattle. abomasum
Name the hosts and the location in the host of Teladorsagia circumcincta
sheep and goats. Abomasum
Name the hosts and the location in the host of Cooperia curticei
ruminants. SI
Name the hosts and the location in the host of Cooperia punctata
ruminants. SI
What parasite family are an important cause of production loss in ruminants worldwide?
trichostrongyle parasites
Explain the general lifecyle of the superfamily trichostrongyloidea?
- females lay eggs, passed in poop
- larvae develop in poop
- L1 hatch and feed on bacteria and detritus
- 2 moults to L3 (L3 retain cuticle)
- L3 moves onto grassto be ingested (depends on temp, humidity and light)
- L3 exsheath after ingestion and arrive at infection site and attach to mucosa
- molt to L4 after 1-4 days, then adults
- PPT = 3-4 weeks
How can temperature and moisture affect the development of larvae?
- speed of development
- resistance of larvae on pasture
- success rate, etc
In order, list the most susceptible to temp, from least able to handle cold, to most.
- unembryonated egg
- L2
- L1
- embryonated eggs
- L3
What factors are involved in the induction of hypobiosis?
- environmental conditions
- host immune response
- size of population of worms in the host
- genetoc factors
What is the significance of hypobiosis?
- non-pathogenic
- not affected by the host immune response
- less susceptible to treatment
When may parsites resume development after a period of hypobiosis?
- when enviro conditions are favourable
- when adult population has been removed by treatment
- in ewes, during parturition and lactation
What is the evolutionary benefit of hypobiosis?
- protection of larvae against hostile host environment
- mintenace of an adult nematode population by replacing from a pool of inhibited larvae
what are some common names for worms within the genus Trichostongylus?
hair worms, bankrupt worms, black scour worms
describe the morphology of worms within the genus Trichostrongylus
Size: <8mm
- no buccal cavity or cervical papillae
- Excretory pore in conspicuous ventral notch
- Male bursa has long lateral lobes and dorsal lobe not well defined
- spicules are short, brown, stout, ridgid
Eggs: 80-120microns, thin shelled with many cells inside (strongyle type), uneven poles (one more rounded than the other)
What species are within the genus Trichostrongylus?
- T. axei
- T. colubriformis
- T. vitrinus
- T. rugatus
Descibe the lifecycle of parsites from the genus Trichostrongylus (the differences from the general lifecycle)
eggs/ day: 100-200
optimal temp: 25C
PPT: 15-21 days
What is a common name for worms that fall under the genus haemonchus?
barber’s pole
What species are under the genus Haemonchus?
H. contortus
H. placei
Descibe the morphology of Haemonchus contortus
Size: M up to 22mm, F up to 34mm (longest trichostrongyloid in ruminants)
- Females look like barber’s pole (blood in GIT wrapped around uterus)
Anterior end: pointed, small mouth with a tooth, cervicle papillae prominent and spin like
Posterior end (M): large lateral lobes and a small asymmetrical dorsal lobe. dorsal lobe is ‘Y’ shaped. spicules are barbed and end with a button
Posterior end (F): vulva on posterior part of body, often covered with a tongue shaped flap. tip of posterior end is slender and pointed
Eggs: 65-90microns, long, thin shelled, many cells inside (strongyle type), rounded, equal poles
Describe the lifecycle of H. contortus (explain the differences from the general lifecycle of parasites)
eggs/ day: 5k-10k
optimal temp: 25-35C
temp range: 10-35C
larvae have low resistance to dehydration and low temp
PPT: 17-21 days
Describe the general morphology of parsites from the genus Ostertgia/ teladorsagia
Size: 5-12mm
colour: reddish brown, threadlike worms
Anterior end: cuticle may be slightly inflated and transversally striated. small mouth, cervical papille present but small
posterior end (F): vulva may be covered by a flap
posterior end (M): 2 lateral lobes and a smaller dorsal one (has 2 main braches which each gives off 1 or 2 more branches. features of spicules are used to ID, are relatively short and divided distally into 2 or 3 processes)
Eggs: 75-105microns, thin shelled, many cells inside, poles symmetrical and relatively narrow
What species are within the genus Ostertgia/ Teldorsagia?
- O. ostertagi
- T. circumcincta
- T. trifurcata
What are species from the genus Ostertgia known for?
their ability to arrest as ‘early L4’
describe the lifecycle of worms within the genus Ostertagia/ Teldorsagia (differences from the general lifecycle of Trichostrongyloides)
eggs/day: 100-200
optimal temp: 16-25C
temp range: 5-35C
- reaches L3 in 1-2 weeks (depending on temp)
- ingested L3 enters glands in the abomasum where they elicit nodules and swellings. L4 then either emerge into lumen and continue development, or arrest.
PPT: 21 days
Explain Type 1 Ostertagiosis
- due to direct development of large numbers of adultsover a reltively short period of time
- seen in animals on pasture, 3-4 weeks after the availabilty o lrge numbers of L3
Explain Type 2 Ostertagiosis
- due to synchronous maturation nd emergence of large numbers of hypobiotic larvae from the mucosa
- may occurr when larvae intake is low
- nodules in intestine
Describe the morphology of genus Cooperia
small worms, reddish when fresh
size: 6-12mm long
- curled like a comma in C. curticei
- M look like tiny pieces of thread in other species
- Anterior end: cuticle forms small cephlic sweling/vesicle that is transversally striated and divided into a wide and narrow region
- cuticle of remainder of body has 14-16 longitudinal ridges that are transversally striated
- Posterior end (M): bursa is large. dorsal ray is divided into two branches which may be parallel or curved. spicules are short, brown and end in a point, usually hve a ridgid winglike expansion in the middle
- Posterior end (F): vulva behind middle of body, may have flap. long tapered tail
- Eggs: 60-95microns, thin shelled, many cells inside. poles equal and narrow. lateral marg
Explain the lifecycle of Species Cooperia
similar to other Trichostrongyloidea species.
PPT = 2 weeks
What is a common name for the Genus Nematodirus?
threadneck worms
What is the host and loction in the host of genus nematodirus?
small intestine of ruminants
describe the general morphology of the genus Nematodirus
size: 8-22mm
- filiform anterior part (anterior is thinner than posterior)
- cuticle of anterior end is inflaed and forms a cephlic vesicle that is striated
- posterior end (M): bursa has elongated lateral lobes and dorsal lobe is split into 2, each half attached to a lateral lobe. spicules long and slender, united by a membrane either throughout or only at their tips
- posterior end (F): short tail with terminal apendage (looks like stick from olive or apple)
- eggs: large, 160-260microns. big blastomeres (reduced number, 4-8), space between them and the shell
What species does Nematodirus battus infect?
sheep
What species does Nematodirus spatiger infect?
ruminants
What species does Nematodirus filicollis infect?
ruminants`
What species doe Nematododirus helvetianus infect?
cattle and sheep
describe the lifecycle of the genus Nematodirus
- develop to L3 inside the egg
- N. battus requires period of prolonged chill followed by temp increase to hatch egg. causes simultneous appearance of large numbers on pasture
- host ingests larvae with pasture
- eggs can survive on psture
- PPT = 2 weeks
where does genus Dictyocaulus locate in the host?
bronchi and trachea
explain the morphology of Dictyocaulus filaria
filiform, whitish
M= 25-80mm
F= up to 112mm
- mouth surrounded by 4 small lips
- posterior end (M): bursa is short, spicules are brown and bent, foot shaped
eggs: 112-135 x 52-67microns, elipsoidal and embryonated when laid
Describe the morpholgy of Dictyocaulus viviparous
M: 17-50mm
F: 23-80mm
bursa is small, spicules brown
Eggs: 82-88microns, embryonated when laid
Describe the lifecycle of genus Dictyocaulus
- embryonated eggs laid. L1 pass in feces
- L2 and L3 develop in environment within a week at 25C. freeliving larvae do not feed
- L3 ingested with forage. exsheath in abomasum and penetrate intestine. migrate to mesenteric lymph nodes. molt after one week via thoracic duct and reach heart via cranial vena cava, then lungs. move to bronchi via alveoli
- mature in bronchi
- PPT = 3-4 weeks
What special method of dispersion in the environment do D. viviparous have?
they are very inctive, so stay in feces until washed out by rain. can disperse via the capsule (sporangium) of the fungus Pilobolus
What species of the superfamily Trichosrongyloidea infect horses ?
stomach: Trichostrongylus axei
Lungs: Dictyocaulus arnfieldi
What species of the superfamily Trichostrongyloidea infects pigs?
- Hyostrongylus rubidus
- Ollulanus tricuspis
- Trichostrongylus axei
describe the morphology and lifecycle of Hyostrongylus rubidus
- reddish when fresh
- up to 10mm long
- small cephalic vesicle
- bursa with small dorsal lobe and well developed lateral lobes
- eggs: 85x45microns, ovoid, thin shelled,morula
- Lifecycle: direct, ingestion of L3
What species of the superfamily Trichostrongyloidea infect birds?
Amidostomum anseri
Describe the location in host, lifecycle and morphology of Amidostomum anseris
location: gizzard, under horny layer
lifecycle: direct, L3 infect via ingestion
- slender, reddish worms, short and wide buccal capsule with 3 sharp teeth
