CESTODES Flashcards
Taeniasis
Adult form of T. saginata and T. Solium (definitive host)
Treatment against Taeniasis
Praziquantel
Niclosamide
no combination. Just one at a time
Cestodes general characteristics
flat worms (dorso ventrally flattened)
endoparasites
hermaphroditic on each proglottid
segmented bodies (proglottids are broader than long)
Need intermediate host except H. Nana
no alimetary cnal (absorb nutrients thru skin)
Nutrient needed - lipids for reproduction
The two orders of cestodes
cyclophilidae
Pseudophilidae
Order cyclophilidae (xtix)
scolex with suckers (with or without hooks)
lateral genital pores
No uterine pores
Parasites of birds and mammals
5 genuses of cyclophilidae
Taenia spp - T. saginata, solium (cow, pig) Hemenolypsis - H. nana, H. dimunita Dypilidium - D. caninum Echinococcus - E. granulossus (dog) Multiceps - multiceps multiceps
Pseudophillidae (xtix)
Adults: scolex with sucking groove or bothria (no hooklets)
lateral or median genital pore
uterine pores
operculated eggs (special adaptation that enable their adaption in water)
ciliated eggs K.A coracidium
Pseudophilidae genuses
diphyllobothrium spp - d. latum (fish tapeworm)
spirometra - s. mansonii, s. proliferum
How to differentiate T. solium and Saginata using uterine branches
By injecting lactophenol followed by Indian Ink thru the genital pores and counting the uterine branches.
more than 13 - saginata
less - solium
Morphology of larvae of Taenia
It is k.a cysticercus
Fully formed head with the rest of the tissues not developed
Forms into which cysticercus can develop into (4)
Hydatid cyst
coenurus
cysticercoids
strobilocercus
Describe the morphology of cestode eggs
Pseudophilidae: partially embryonated
Cyclophilidae: fully embryonated
Are hatched from oncosphere (hexacanth)
has 3 pairs of hooklets
What infections does taenia spp spread
Taeniasis (t. solium n t. saginata) - caused by adult
Cysticercosis (t. solium) - caused by the larval stage
Identify the smallest cestode
Echinococcus (has 3 segments only)
What kind of host is man in echinococus granulosus?
accidental host
The more serious taenia in causing infection is:
T. solium (egg infects man directly)
2 routes of infection in taeniasis and cysticercosis
In Taenia, humans are which kind of hosts?
Both definitive (adult form) and intermediate (larva stage)
identify the germinative part of taenia
neck
What species of taenia are available and which ones have medical importance?
T. saginata and T. solium (medical importance)
Others: Taenia asciata and taenia multiceps
Differentiuate between T.solium and T. Saginata
The drumlike head with four suckers identifies taenia spp
solium is: shorter, has hooklets, less than 13 uterine branches
Saginata is: longer without hooklets. The uterine branches are more.
Identify the intermediate hosts in Taenia spp
Pig - T. solium
Cattle - T. saginata
Man
Mode of transmission of taeniasis
Eating undercooked meat or pork
Mode of transmission of cysticercosis
- External infection: ingesting eggs from contaminated food, water
- Internal infection: autoinfection by
(i) contaminating your own food/drink and ingesting the eggs thru it
(ii) proglottids carried to stomach thru reverse peristalsis
differences in life cycle between taeniasis and cysticercosis
in Taeniasis, the intermediate host is either the pig or cattle but in cysticercosis the intermediate host is the man instead of the pig.
Describe T. solium lifecycle (Cysticercosis)
- man ingest raw or undercooked pork with cysticerci
- cysts evaginate, attach to the small intestine by their scolex, and mature into adult worms
- Adult tapeworms produce proglottids, which become gravid; they detach from the tapeworm and migrate to the anus.
- Detached proglottids, eggs, or both are passed from man in feces.
- Pigs or humans become infected by ingesting embryonated eggs or gravid proglottids (eg, in fecally contaminated food). Autoinfection may occur in humans if proglottids pass from the intestine to the stomach via reverse peristalsis.
- After eggs are ingested, they hatch in the intestine and release oncospheres, which penetrate the intestinal wall.
- Oncospheres travel through the bloodstream to striated muscles and to the brain, liver, and other organs, where they develop into cysticerci. Cysticercosis can result.
clinical presentation of taeniasis
mild abdominal symptoms passage of proglottids per anum intestinal perforation - peritonitis aspiration of vomited proglottids - reverse peristalsis appendicitis cholangitis
diagnosing taeniasis
Stool microspcopy (eggs) antibody detection (take blood sample)
Cysticercosis clinical presentation
asymptomatic subcutaneous nodules
neurocysticercosis - seizures, mental disturbances, focal neurologic deficits, signs of space-occupying intracerebral lesiuons/intracranial hypertension (intracranial herniation)
extra cerebral cysticercosis: symptoms from ocular, spinal or cardiac lesions.
Diagnosing cysticercosis
Muscle biopsy
imaging
antibody infection
Treatment of cysticercosis
Antihelminthics (albendazole, praziquantel) 4 symptomatic pts with live cysts. NB dont use for intraventricular cysts as you risk precipitating hydrocephalus.
Corticosteroids in neurocysticercoids eg dexamethasone
surgery
anticonvulsants
Genus echonococcus members
E. Granulosus - hydatid dx, cystic echinoccosis
E. Multicularis - alveolar hydatid dx
E. Vogeli - polycystic hydatid dx
Types of cysts in E. granulosus
Primary cyst
secondary cyst
acephalocyst
endogenous daughter cyst
E. granulosus larval form is
hydatid cyst
Morphology of the E. granulosus hydatid cyst
uniocular
subspherical shape
3 layers - (pericyst, ectocyst, endocyst
why the hydatid cyst endocyst layer is vital
secretes hydatid fluid
gives rise to brood capsules with scolices
(hydatid sand formed when brood capsules and protoscolisces break off and become deposited at the bottom as granular deposits)
infective stage of e. granulosus
egg (passed in dog faeces) and infect herbivores animals
What is casoni test used to diagnose
Hydatid dx. (e. granulosus)
which parasite is k.a the fish tapeworm
Diphylobothrium latum
