Parasites Flashcards
What is a definitive and intermediate host?
- Definitive Host (sexual cycle occurs in this host)
- An animal in which the parasite passes its adult existence and/or undergoes a sexual reproductive phase
- Intermediate Host
- The intermediate host is where the parasite spends some time, but generally not as an adult, and with no sexual reproductive phase
What are the types of general parasites?
Helminths- worms, protozoa- malaria Giardia lamblia (intestinalis, duodenalis), arthropods- tick, mites
What are the types of worms- 2 types of platyhelmiths (flat worms) and nematodes
platyhelminths:
cestode (tapeworm) - Taenia solium and saginata, Hymenolepis nana (dwarf tapeworm)
trematodes (flukes)- Schistosoma sps
nematodes are ROUND worms
- Enterobius vermicularis (pinworm/threadworm)
- Trichuris trichiura (whipworm)
- Ancylostoma duodenale/Necator americanus (hookworms)
- Ascaris lumbricoides (large round worm of humans)
- Strongyloides stercoralis
what are the 2 less common sp of schistosoma?
S. mekongi (SE Asia only)
- S. intercalatum (stool only
what are the symptoms of schistosoma (bilharziasis)
how do we diagnose it and what is the treatment?
- May be asymptomatic
- fever, cough, abdominal pain, diarrhoea, hepatosplenomegaly, and eosinophilia
eggs in faeces, Tx – Praziquantel or Oxamniquine
Lifecycle of schistosoma
1. eggs shed from infected human diagnosed in faeces are shistosomas ______, _______, ______, while diagnosed in urine are _____, ______. (diagnostic stage)
2.eggs hatch and release _________
3. _________ penetrate snail tissue
4. _________ develop in snail (successive generations)
5. Free swimming _______ are released from snail to water (infectious stage)
6. _______ penetrate the skin, lose tail through penetrate and become _________. they circulate the body.
7. Migrate to ______ _______ in liver and ___________.
8. paired adult worms of S mansoni, japonicum and mekongi migrate to __________, S haematobium migrate to __________
- s. mansoni, japonicum and mekongi and haematobium. in urine just s mekong and japonicum and hematobium.
- miracidia
- miracidia
- sporocysts
- cercariae
- cercariae, schistosomule
- portal blood, mature
- Mesenteric venules of bowel or rectum that lay eggs that circulates in liver and shed in stool and haematobium migrate to venous plexis of the bladder - eggs shed in urine
What genus are cestodes?
what are the definitive host?
how long does it take to grow into an adult
how can you speciate the cestodes?
what is the treatment?
Taenia sp, - saginata (beef) and solium pork, worldwide distribution. Taenia asiatica (pork) is another sp
- Republic of Korea, China, Taiwan, Indonesia, Thailand
Humans are the only definitive host
- Eggs can survive for days to months in the environment
- Cysticercus can survive for several years in the animal
- 2 months to grow to adult worm
- survive in host for years
- Diagnosis (after 3 months)
- eggs in faeces
- 30-40 μm (circular)
- proglottids in faeces
- Speciation by examination of proglottids or scolex NOT eggs
- Tx – Praziquantel
what is the sage between sporocysts and cercariae in schistosoma?
Rediae
Lifecycle of taenia
1. ______ or _______ in faeces (diagnostic) is passed to the environment
2. _____ and ___ become infected by ingesting ________ contaminated by ____ or______.
3. __________ hatch, penetrate _____ walls and circulate to _______.
4. ________ develop into _________ (infectious) in _____
5. Humans are infected by ingesting ____ or _____ infected meat.
6. _______ attach to intestine (different ones for solium and saginata)- saginata more wide and solium more little
7. Adults in the small intestine
what do the proglottids look like for solim and saginata?
- eggs or gravid proglottis
- cattle or pigs, vegetation, eggs, gravid proglottis
3.oncospheres, intestinal, musculature - onchosphere, cysticerci (infectious) in muscle
- raw or undercooked
solium lines in glottids look fatter and less of them (pig= fattier), saginata more skinny more lines
which taenia sp can cause cycticercosis?
what is different from the development of normal tapeworm?
where can the cysticerci form? which is the most serious?
T. solium
Normal infective cycle is for humans to ingest the cysticerci in pig muscle but it is the Ingestion of embryonated eggs can lead to cysticercosis
can form at - cardiac
- spinal - ocular sites
cerebral (neurocysticercosis)
- seizures
- mental disturbances
- neurologic deficits
- death can occur suddenly
What is Hymenolepis nana known as?
Its a cestode- dwarf tapeworm
Life cycle of dwarf tapeworm
1. Embryonated egg in faeces (diagnostic AND infectious)
2. egg ingested by insect, _________ develops in insect
3 humans and rodents infected when the infected arthropods. or embronated egg ingested by human through hand to mouth, contam food
4. _________ hatches, cysticercoid dev in intestinal villus then grow to a _______ then an adult in the _____ portion of the small intestine
5. eggs can be released through the gential atrium of the ________ and they can also release eggs that are passed through stool by disintegrating
- cysticercoid
- oncosphere, scolex, ileal_
- gravid proglottids
how can autoinfection occur for dwarf tapeworm?
if egg remains in the intestine they then release a hexacanth embryo which penetrates the intestinal villus that continues the cycle
What is the lifecycle of enterobius vermicularis and trichuris trichiura
1. eggs in faeces
2, infective eggs develop in _______
3. the eggs are ingested and they hatch in the _______ where the young worms remain and mature
4. adult worms in the _____
- soil
- intestine
- intestine
what is another name for pin worm?
where do the female worms lay their eggs and when do they become infective?
what are the symptoms and how can it be spread?
what happens after eggs are ingested?
Enterobius vermicularis- a nematode, females lay eggs in perineal folds at night - Eggs become infective in 4 to 6 hours under ideal conditions
Itchiness because of secretion and self infection by hand to mouth also person to person or fomites, eggs also inhaled
larvae hatch in SI and grow to adulthood in COLON (caecum), can have male and female
* The time from ingestion to an adult female laying eggs is 1 month
* The life span of the adults is about two months
