Cestodia Flashcards
- head region
- deep or shallow, smooth or fimbriated, proteinaceous hooks accompany this
- in GI tract for nutrients/possess organs that allow for attachment
- scolex
- genital pores lateral or medial
- vitellaria scattered throughout segment
- testes are numerous
- uterine pore present
diphyllobothridia characteristics
- made up of many individual proglittids
- growth takes place at anterior end of worm
strobila (strobilization)
Where are the older proglottids located?
the posterior end
are tapeworms considered segmented?
no because the tegument and muscle fibers are continuous
what can the end of a tapeworm do?
detach, disintegrate (apolysis), release eggs via pores
section with organs that allow the organism to attach to the host GI tract
head/scolex region
suckers, grooves, hooks, spines, glands, tentacles
examples of scolex structures
- cup-shaped, ovoid, muscular structures
- 4 in tapeworms
acetabula in tapeworms
- usually 2-6
- shallow pits or long grooves
- lateral or dorsoventral
bothria
- muscular
- usually 4
- project from scolex, +/- mobile
- leaf-like margins
- found in ocean environment
bothridia
- important in its absorptive capacity (no mouth or digestive tract)
- living tissue with high metabolic activity
tegument
- outer finger like projections that cover worm surface and suckers
- large absorptive area
microtriches
- highly ornate
- have four kinds of microtriches existing on the scolex
- filamentous
tegument of marine tapeworms (tetraphyllideans, trypanorhynchs)
- can copulate with self
- others in the strobili (proglottid chain)
- other worms
how proglottids replicate
are tapeworms typically monecious or diecious?
monecious— each segment has male and female reproductive systems (advantageous to reproduction if spread out in ocean)
sperm transferred and oocytes fertilized —> male organs mature first and sperm are stored until ovary matures
- two hosts, sexually mature tapeworms live in intestine
life cycle of tapeworm
- tapeworm affecting dogs
- passed through feces, egg and larval stages
- flea ingested by dog
- egg packets
dipylidium caninum
- people eat undercooked pork containing cysts
- mature in intestine
- passed in stool
taenia solium
- smash with cover slide to observe eggs
- problem = may not be gravid
squash prep
- crustacean first IH
- fish 2nd intermediate host
life cycle of diphylloborthriidea
- crustacean to small fish to predator to human
- from eating undercooked fish
- unembryonated eggs in water
diphyllobothrium latum
- sperm whales
- 30 m long
- each segment has 4 to 14 sets of genetalia
hexagonoporus physeteris
- intestinal parasites of freshwater fish
- fewer than 10cm
- monozoic (no generation of proglottids)
- simple scolex that is never armed, contains loculi
caryophyllidea
- motile anterior end
- one proglottid
- catfish, minnows, and suckers are most common hosts
caryophyllidea
- parasites of marine and freshwater fish
- complete absence of segmentation
- scolex unarmed
- no life cycles known
- linear set of proglottids
spathebothriidea
- tapeworms of birds and mammals
- 4 acetabula
- veterinary importance
- rostellum may or may not posses hooks
- single vitelline gland
- genital pores lateral
- most species small
- development in-utero, non-violated hecacanth embryo
- non-operculate shell
cyclophyllideans
- family containing largest cyclophyllidean tapeworms
- most medically important
- armed rostellum on most species
- larval stages called metaceatodes
Taeniidae
- human definitive host or intermediate host
- larval form cysticercus
- DH by eating undercooked muscle tissue of pig
taenia solium
- harbor in organs (subcutaneous connective tissues most common followed by eye, brain, muscles, etc)
- gets to other locations through bloodstream
- 138 cases in US
cysticercosis
- hooved animals are DH
- large tapeworms (up to 6 meters)
- proglottids more wide than long
- unarmed scolex
anoplocephalidae
- sheep, cattle, goats
- eggs in square shapes/triangles
- eggs posses pyriform apparatus, embryophore with hook/horn-like extensions
- mite intermediate host
monezia
- widespread carnivores
- worldwide distribution
- medioventral position of genital pores
- scolex with four simple suckers, no rostellum
- may undergo asexual reproduction in a definitive host
- undercooked meat
mesocestoides
- can be free-living or parasitic/plants or insects
- bilaterally symmetrical, elongated, tapered at both ends, possess a pseudocoel, mouth anterior anus posterior
nematodes
form of the lumen of pharynx and esophagus
triradiate
- muscles of body wall are 1 layer thick
- arranged in circular layer
- mostly dioecious, some hermaphroditic and some parthenogenetic
- most oviparous (lay eggs), some ovoviviparous (eggs hatch and give rise to larvae)
nematodes
- vary in size (1mm to 10m)
- carbohydrate-rich surface coat over cuticle, may be important in immune evasion
- markings on cuticle can help differentiate
- alae = circular thickenings
nematodes
- musculature, pseudocoel, fluid it contains, and cuticle
- enclosed noncompressible fluid moved by muscles responsible for s shaped movement in nematodes
the hydrostatic skeleton
- wide and shallow muscle cells with contractile portion close to epidermis
- spindle shaped muscle cells that are contractile
platymyarian muscle cells and coelomyarian muscle cells
- mouth (circular opening with max of 6 lips), gut, and anus (buccal cavity in between)
- shedding of cuticle lining
nematode digestive system
which stages are typically in the environment for nematodes and in the host?
1st larval stage passed into environment, 3rd stage infection in the host
blood, tissue cells, fluids, intestinal contents
What can nematodes use as food?
List two important structures required for reproduction in nematodes for males and females
male - copulatory spicule
female - uterus
usually 4 juvenile stages and an adult stage separated by ecdysis or molting (increase in size after final molt)
typical development of a nematode
- parasitic in nearly all organs and tissues
- affects all classes of vertebrate
capillaridae
- parasite of the liver
- predominately rodents (some humans)
- eggs deposited in liver/transmission depends on eggs being released from liver (consumption by predator, decomposition after death)
- eggs cannot embryonate in the liver –> in soil
- loss of liver cells/function, hepatomegaly
calodium hepatica
- intestinal parasite of humans
- epidemic in Luzon
- also reported in Thailand, Iran, Japan, and Egypt
Paracapillaria philippinensis
lung parasite of dogs, cats, and other carnivores
Eucoleus aerophilus
- affects esophagus and crop chickens, turkeys, and other birds
- requires an earthworm IH
eucoleus annnulata
- blood red blunt end nematodes that are large
- found in mammals around the world
- males have bell-shaped bursa
- eggs are lemon shaped
- eggs require 2 weeks to 3 months to embryonate (temperature dependent)
- from fish diet –> raw or undercooked
- can cause loss of kidney function
dioctophyme renale
- small in size
- species alternate between free-living and parasitic generations
- may inhabit soil, decaying matter, decaying fruit
tylenchina suborder of nematode
- both sexes of free-living adults have a rhabditiform esophagus
- parasitic females burrow into small intestine
- eggs hatch as they are passed through the DI tract
- infection by skin penetration
- free living adults can produce successive generations of free-living adults
- may undergo autoinfection, immunocompromised hosts can lead to hyperinfection
- through contact with contaminated water or soil
- lung phase may be mistaken for asthma
- diagnose using baermann or serodiagnosis by ELISA for antigens
strongyloides stercoralis
- nodular worms of livestock
- large intestine of ruminants and non-human primates
- developing juveniles form nodules in walls of intestines
oesophagostomum
- largest nematodes
- female has white ovaries wrapped around her intestine (“barber pole worm”)
- male bursa present
- live in fourth stomach of ruminants
- can cause severe anemia in heavy infections
- single well developed tooth in buccal cavity
haemonchus contortus
- brown stomach worm
- rudimentary, lacks tooth
- life cycle similar to Haemonchus but L4s burrow into mucosa of abdomen to molt
ostertagia
- the smallest abomasal nematodes
- small intestine parasite of ruminants
- colorless, unarmed buccal cavity
- worms burrow and molt in mucosa
- causes damage to intestinal epithelium
trichostrongylus
- diluting population with susceptible worms
refugia
- gapeworm of poultry
- adults live in trachea of bird hosts (gasping and gaping)
- eggs coughed up, swallowed, and passed into environment
- earthworm/arthropod potential paratenic host
syngamus trachea
- adults in bronchi and bronchioles
- eggs hatch in host and are found in feces
- GI tract –> bloodstream –> lungs
- long and slender worms
- use bayermann
dictyocaulus
- discovered in pulmonary arteries and hearts of rats –> humans
- snail/slug IH
- humans accidental hosts –> eosinophilic meningitis
- small, slender worm
angiostrongylus cantonensis
- females swollen and bright red (only ends retain nematode appearance)
- parasites of aquatic birds
- eggs embryonated when laid
- IH crustaceans or insects
- DH water birds, chickens, owls, hawks
tetrameres
- terrestrial counterpart of tetrameres
- glands of insectivorous birds
- swollen females twisted into spiral
- IH crustacean/insect
- little effect on host health
microtetrameres
- upper digestive tract of birds and mammals
- cuticle covered with bosses/scutes
- alae and papillae present
gongylonematidae
- found in ruminants and swine
- IH dung beetle/cockroach
- many human cases of infection
- invade esophagus, causing irritation and bleeding
gongylonema pulchrum
- responsible for esophageal cancer in dogs
- stout worm/bright pink in color
- mouth w/ lips, cylindrical embryonated eggs
- adults found in clusters in GI tract
- IH beetles
- paratenic hosts: birds, reptiles, mammals
spirocerca lupi
- right side of heart and pulmonary artery of dogs and other mammals
- found in humans but do not mature (worms harbor wolbachia)
- transmission through mosquitos
- treated through preventatice heartworm meds
dirofilaria immitis
- respiratory insufficiency
- chronic cough
- vomiting
- exercise intolerance
clinical signs of heartworm in cats
- immunodiagnostics
- detection of microfilariae in the blood (can be confused with other non-pathogenic species)
diagnostics for heartworm
- disease caused by large filaroid worm
- common in Africa and South America
- causes river blindness/skin disease
- adults live under skin
- humans only definitive host
- diagnose with skin snip
onchocerca volvulus
- parasites of arthropods
- elongated, active worms
- emerge from hind ends of hosts when they fall into water
- tangled masses resembling Gordian knot (mating events)
- adults not encountered very often in nature
Nematomorpha/Gordian worms/horsehair worms
which subgroup are most hairworms a part of
gordiida (not nectonematida)
- adults are long, cylindrical, and filamentous
- mature worms pure white to almost black or brown
- calotte = light colored area followed by pigmented ring
- females larger than males
- thick cuticle body wall ornate with areoles
- nervous system = calotte, highly innervated/may be photosensitive
- reduced digestive system with no mouth
- coiling movements
- dioecious
- cannot be reared in a laboratoru/nutrients likely taken up across surfaces as adults do not feed (remain active in cool water)
nematomorpha
- juveniles in arthropods
- transition to adult stage in water (infected insects more likely to go swimming)
- mating occurs upon emergence
- females produce millions of eggs on vegetation –> arise to larvae
- aquatic invertebrates consume
life cycle of nematomorpha
