Parasites--Worms Flashcards
Main divisions of worm parasites
- Cestodes and Trematodes (Flatworms and Flukes)
2. Nematodes (roundworms)
List: Cestodes
Tapeworms.
- Teniae solium (pork tapeworm)
- Diphyllobothrium latum (fish tapeworm)
- Echinococcus granulosus (Hydatid disease, dog tapeworm)
List: Trematodes
Flukes
1. schistosoma (blood fluke)
not in lecture:
- Clonorchis sinensis (Chinese liver fluke)
- Paragonimus westermani (lung fluke)
List: Intestinal Nematodes
- Enterobius (pinworm)
- Ascaris lumbricoides (giant roundworm)
- Strongyloides stercoralis
- Necator americanus/Ancylostoma duodenale (hookworm)
- Trichuris trichiuria (whipworm, trichoniasis)
List: Tissue Nematodes
- Trichonella spiralis (pork roundworm, trichinosis)
- Toxocara canis (Dog roundworm)
not in lecture:
- Dracunculus medinensis (guinea worm)
- Onchocerca volvulus (river blindness)
- Wuchereria bancrofti (elephantiasis)
- Loa Loa (eyeworm)
Trichuriasis, Trichomoniasis, Trichinosis–difference?
Trichuriasis–whipworm, nematode
Trichomoniasis–STD nematode
Trichinosis–pork roundworm
definitive vs intermediate host
Definite: sexual cycle occurs here
Intermediate: asexual cycle
incidental host
Host that is not original part of the natural parasite life cycle (ex: humans and toxoplasma)
vector
animal that transmits parasite to human
reservoir
animal host that maintains the natural cycle in the wild, typically not harmed by the parasite it carries. (eg toxoplasma and mice)
Cestodes:
- body morphology
- digestive system?
- transmission forms
Tapeworms.
- flattened bodies with segments called proglottids, which allow hermaphroditic repro. Anterior end has a scolex that attaches to gut wall of host.
- no internal GI system, so absorption
- ingestion of eggs or cysticerci larvae
Trematodes:
- body morphology
- digestive system?
- hosts
- transmission forms
Flukes.
- flat bodies
- yes, internal GI
- snail is intermediate host
- Ingestion, or Skin penetration.
Taenia saginata
Beef tapeworm
Taenia solium
- transmission
- disease/symptoms
- diagnosis
- immunity
- prevention
Pork tapeworm
- transmission: eat undercooked pork.
1. ingest eggs (taeniasis)
2. ingest cysticerci larvae. (cysticercosis) - symptoms:
1. taeniasis: abdominal discomfort
2. cysticercosis: danger of neurocysticercosis–severe encephalitis - diagnosis:
1. proglottids/eggs in stool
2. cysticercosis by Xray/CT/MRI of calcified dead larva - immunity: reinfection is possible
- prevention: fully cook pork or freeze it
Diphyllobothrium latum
- transmission
- disease/symptoms
- diagnosis
fish tapeworm
- ingestion of larvae in undercooked fish
- lack of vitamin B12 absorbed in gut (pernicious anemia)
- eggs/proglottids in stool
Echinococcus
- transmission
- disease/symptoms
- diagnosis
Dog tapeworm/Hydatid disease
- ingest eggs from dog feces (dogs eat cysts from infected hooved animals.) Humans are accidental host.
- Hydatid disease: Cysts form in liver/lungs, may rupture with fatal anaphylaxis reaction.
- imagining of cysts
Schistosoma
- transmission
- disease/symptoms
- diagnosis
- immunity
-skin penetration, go to intestinal/bladder veins
- symptoms:
1. Early–few or no symptoms
2. Middle–Katayma syndome: cytokine storm response to eggs several weeks after infection. bloody stool/urine
3. Chronic (5-40 yrs): Eggs lodged in intestine and liver (portal HTN) in japonicum and mansoni. Eggs lodged in bladder causes fibrosis and cancer in haematobium - eggs in feces/urine
- no vaccine
Schistosoma types (3):
- where do adults live
- how to eggs leave body
- egg morphology
- mansoni:
- inferior mesenteric veins, stool, lateral spike - japonicum:
- SMV, stool, no spike - haematobium:
- Bladder veins, urine, terminal spike
Egyptians: What to remember about parasites?
- Middle aged Egyptians have high rates of Schistosomiasis (because of snails from Aswan dam construction) and Hep C (infected needles).
- Chronic inflammation from Schistosomiasis worsens Hep C.
List all nematodes (from lecture) and categories they fit in
- Intestinal nematodes
- Enterobius (pinworm)
- Ascaris (giant roundworm)
- Strongyloides
- Necator americanus/ancylostoma (hookworm)
- Trichuris trichiuria (whipworm) - Tissue nematodes
- Trichonella spiralis (pork roundworm)
- Toxocara canis
Enterobius vermicularis
- transmission
- disease/symptoms
- diagnosis
Pinworm
- ingest eggs, possible direct person-person! Adults in colon lay eggs in perianal area.
- perianal pruritis
- visual observation of eggs, scotch tape test
Trichuris trichiuria
- transmission
- disease/symptoms
- diagnosis
Whipworm
- ingest eggs, adults migrate to colon.
- mild to severe. Bloody stool, anemia
- eggs in stool
Ascaris lumbricoides
- transmission
- disease/symptoms
- diagnosis
Giant roundworm
- ingest eggs from soil. Larvae travel from intestine to lung, coughed up back to GI tract.
- mild to severe. malnutrition, intestinal obstruction, lung inflammation
- eggs in stool
Necator americanus Ancylostoma duodenale -transmission -disease/symptoms -diagnosis
Hookworms
- skin penetration, travel to lung, coughed into GI tract. Eggs in feces
- anemia b/c hookworms suck blood in GI tract, bronchitis
- anemia, eggs in stool
Which intestinal nematodes have no eggs in stool?
- Strongyloides- eggs hatch in intestine
- Trichinella spiralis– they don’t make eggs
Strongyloides
- transmission
- disease/symptoms
- diagnosis
- Skin penetration, travel to lung, coughed into GI tract, larva autoinfect or released in feces (autoinfection, direct, indirect pathways)
- GI malabsorption, dystentery, hyperinfection by autoinfection (in immunosupprssed pts) can be fatal
- larvae in stool/sputum (no eggs!)
Vitamin B12 deficiency? What parasite
Fish tapeworm (diphyllobothrium latum)
Which intestinal nematodes stay only in intestine, which travel to lungs?
Lungs:
- Strongyloides
- Ascaris (giant roundworm)
- Necator/Ancylostoma (hookworms)
Only intestine:
- Enterobius
- Trichuris trichiuria
Which parasite can autoinfect in humans, causing a hyperinfection?
Strongyloides. Autoinfection can occur when pt is immunosuppressed (eg using steroids). Parasite does not need another animal host anymore. Hyperinfection can be fatal.
Trichinella spiralis
- transmission
- disease/symptoms
- diagnosis
Pork roundworm
- undercooked pork with encysted larvae. Larvae mature in GI tract and release larvae that encyst in muscle
- muscle pain, inflammation
- eosinophilia, serological tests
Toxocara canis
- transmission
- disease/symptoms
- diagnosis
Dog roundworm
- Ingest eggs from dog feces. Larvae can infect any tissue!
- mild to severe: blindness, necrosis in any organ
- no eggs in stool b/c infection does not progress to adults. ELISA for larval antigens.
