Platyhelminthes Flashcards
Tapeworm found in fish
Diphyllobothrium latum
Pathology of Echinococcosis
Hydatid cysts in liver (50-70%) and lungs (20-30%) but also spleen, kidney, bone and CNS
Latent periods up to 20 years
Disease onset when hydatid cysts cause pain or rupture
Cyst rupture can seed new sites by release of protoscolices
Anaphylaxis associated with rupture can be fatal
Transmission of Taenia solium
Intestinal (adult) - Ingest raw pork, Lung (larva) - Ingest free eggs
Location of Echinococcus granulosus
Liver, lungs, etc.
Location of Echinococcus granulosus
Tissues mainly lungs and liver, but also spleen, kidneys, heart, bone, and CNS
Describe the life cycle of* Echinococcus granulosus*
Basic cestode lifestyle; humans as intermediate host only
Requires intimate contact with dogs
Humans are a dead end host
Immunity of Diphyllobothrium latum
No clincally relevant immunity…reinfection is possible
Location of Schistosoma haematobium
Bladder
Katayama syndrome is associated with which pathogen?
Schistosomiasis. intense fever with onset of oviposition
14-84 days (middle onset/1-2 months)
What is a scolex?
The anterior end of adult tapeworms, used to attach to the gut wall of definitive hosts
Which of the Schistosoma species lay the most eggs per day?
Schistosoma japonicum = 1000 eggs/day
(Schistosoma mansoni and Schistosoma haematobium = 100 eggs/day)
Describe transmission of Trematoda
Transmission can be invasive or ingestive
Transmission of Diphyllobothrium latum
Undercooked fish containing plerocercoid
Describe the chronic onset (5-15 years) of Schistosomiasis pathology from S. haematobium
Eggs lodge in tissues in the bladder
Egg secretions lead to eosinic inflammatory response and granulomas
Extensive fibrosis of bladder leads to mucosal thickening & ulceration which leads to l_oss of bladder function_
Bladder cancer
Describe the body of a tapeworm (Cestoda)
Flattened, segmented bodies
Prevention of Echinococcosis
De-worm dogs, proper disposal of livestock internal organs
Good hygiene
Name the 4 species in Cestoda that we need to know
- Taenia saginata*
- Taenia solium*
- Diphyllobothrium latum*
- Echinococcus granulosus*
What is taeniasis and how is it acquired?
Tapeworm in the intestine from eating undercooked pork, ingesting cysticerci (larva)
Describe the chronic onset (5-15 years) of Schistosomiasis pathology from S. mansoni and S. japonicum
Eggs lodge in tissues in the intestine and liver
Egg secretions lead to eosinic inflammatory response and granulomas
Severe liver disease leading to periportal (liver) fibrosis which can lead to portal hypertension / hepatosplenomegally / megaesophogus which can lead to rupture of gastric or esophageal varices
Liver and colon cancer
Epidemiology of Diphylobothrium latum
Found globally in temperate zones where fish is a major part of the diet
Was brought to the New World by European immigrants
Treament of Schistosomiasis
Praziquantel in single or multiple dose
Potentiates active immune system killing of adult worms
Location of Schistosoma mansoni
Intestine (eggs migrate to descending colon)
Describe Trematoda (fluke) digestion
Simple digestive system, a single opening serves as mouth and anus
What is plerocercoid larva?
last larval form found in the second intermediate host of many Cestoda with aquatic life cycles (Diphyllobothrium latum)
Immunity against Schistosomiasis
Adults masked by absorption of host serum proteins
Immunity primarily involved in pathology
Evidence for immunity to reinvasion in endemic areas, immune killing of schistosomula
Intensive effort under way for a vaccine
Greek translation of Platyhelminthes
platy = flat, helminth = worms
What are proglottids?
Segments of the tapeworm bodies
Location of Diphyllobothrium latum
Intestinal
What is cysticercosis and how is it acquired?
Larva in muscle, eyes, brain from eating tapeworm eggs
What is a procercoid larva?
an elongate larval stage of some tapeworms (Diphyllobothrium latum) that usually develops in the body of a freshwater copepod
Intermediate hosts of Diphyllobothrium latum?
copepod that infects fish
What is the immunity against Taenia solium?
Humoral response to adult worms thus reinfection is possible
Tapeworm found in pork
Taenia solium
Diagnosis of Diphyllobothrium latum
Same as beef and pork tapeworm
Easily discriminated from Taenia ssp by egg and proglottid
Pernacious anemia, raw fish diet in endemic areas indicatve
Which Schistosome eggs are isolated from urine?
S. haematobium
Pathology of Diphyllobothrium latum
Like beef tapeworm
Adults absorb 80-100% of dietary B12
B12 deficiency, anemia, occasionally neurological symptoms
Describe the early onset (0-2 weeks) of Schistosomiasis pathology
Most people have no symptoms when first infected
Rash from invading cercaria, many exposures leads to hypersensitivity
Rash subsides: fever, headache, nausea as the schistosomula migrate
Class for flukes
Trematoda
Describe the body of a fluke (Trematoda)
Broad, flattened body
Describe alveolar echinococcosis
Caused by Echinococcus multiocularis
Humans are usually exposed when hunters feed internal organs to domestic dogs
Wild animal cycles: wild canines and game animals in wilderness of North America, Europe, Asia
Tapeworm found in beef
Taenia saginata
How can Taenia solium presence be diagnosed?
Self: active proglottids
Clinical:
- observation of proglottids or eggs in stool (proglottid morphology discriminates from T. saginata & D. latum)
- contrast studies show ribbon-like strucutre from intestine
- Cysticercosis by X-ray, calcified dead larva
- CAT/MRI, viable cysticerci
Diagnosis of Schistosomiasis
Observation of eggs in feces or urine most common
Serology now available
Transmission of Taenia saginata
Ingest raw beef
Definitive host of* Echinococcus granulosus*
Wild & domestic canines
Treatment of Echinococcosis
Percutaneous drainage with instillation of hypertonic saline or alcohol
Surgical removal, avoiding rupture
If inoperable, treat with albendazole (28 day), low cure rate
What are the intermediate hosts of Taenia solium?
Pigs (or humans)
Transmission of Schistosomiasis
Invasive, aquitic free-living cercaria penetrate skin
Which Schistosome eggs are isolated from the stool?
S. mansoni and S. japonicum
Transmission of Echinococcus granulosus
Ingest free eggs
Schistosoma mansoni adult worms travel in which veins?
Inferior mesenteric veins
Class for tapeworms
Cestoda
Location of Taenia solium
Intestinal (adult), Any tissue, i.e. lungs (larva/cysticerci)
Definitive Host of Schistosoma organisms
Humans
Describe Cestoda (tapeworm) digestion
No internal digestive system, nutrients are absorbed across the cuticle
Describe the maturation process of Cestoda (tapeworms)
Segments (proglottids) mature from anterior to posterior, specialized for hermaphroditic reproduction
What are the definitive hosts of Taenia solium?
Humans
How did Echinococcus arise in the US?
It is not endemic in the US, but immigration and transportation increases have caused a rise throughout North America
Intermediate host of* Echinococcus granulosus*
Wild & domestic ungulates (hoofed animals)
Humans
How can eggs of Schistosoma organisms incite chronic inflammation?
The eggs canf low into the portal vein tributaries and become trapped in the terminal portal venules, where they incite chronic inflammation
Describe the pathology of Cysticercosis
1) Muscle may cause lumps but usually no symptoms
2) Brain cause neurocysticercosis - symptoms depend upon where and how many cysticerci there are
Definitive host of Diphyllobothrium latum
Humans
Name the 3 species in Trematoda that we need to know
- Schistosoma mansoni*
- Schistosoma japonicum*
- Schistosoma haematobium*
Prevention of Schistosomiasis
Reduce source (treat infected individuals)
Dispose of waste properly
Control of intermediate hosts: molluscicides environmentally damaging
Avoid contact with infested water: difficult in rural areas
Name the two classes of Platyhelminthes
Cestoda (tapeworms), Trematoda (flukes)
Location of Taenia saginata
Intestinal
Treatment of Taenia solium
Praziquantel, niclosamide, or albendazole, single dose effective for adult worms but prolonged treatment of cysticerci
Dexamethasone used to reduce inflammation during treatment, especially true in the CNS, treatment can induce seizures
Immunity against Echinococcosis
Circulating antibodies to hydatid cyst antigens
Pathology more than protection
Diagnosis of Echinococcosis
Residence in endemic area, animal husbandry/hunting
CAT scan/ultrasound
Often presents as slow growing tumor
Serology is used for confirmation
Transmission of Schistosoma spp.
Cercaria penetrate skin
Location of Schistosoma japonicum
Intestine (eggs migrate to small intestine)
What is Hydatid Disease?
from* Echinococcus granulosus* hydatid cysts in liver, lungs, etc.
Intermediate host of Schistosoma organisms
Snails
Schistosoma japonicum adult worms travel in which veins?
Superior mesenteric veins
Transmission of Echinococcus granulosus
Ingestion of eggs from dogs
Describe the pastoral cycle of Hydatid disease
Domestic grazing livestock (sheet) are in contact with dogs. The dogs must eat internal organs.
Location of Schistosoma spp.
Veins to gut/bladder
Describe the symptoms of Cystericercosis (neurocysticercosis)
Confusion, difficult with balance, brain swelling, excess fluid around the brain (hydrocephalus), seizures, headaches, and mortality
Describe the middle onset (1-2 months) of Schistosomiasis pathology
Symptoms mostly from immune response to eggs
Katayama syndrome (intense fever)
Intestinal schistosomiasis causes abdominal pain, diarrhea, blood in stool
Urogenital schistosomiasis is haematuria (blood in urine)
What are coracidia?
larvae of Diphyllobothrium latum that hatch and get eaten by freshwater crustaceans such as copepod
Epidemiology of Schistosomiasis
240 million infected globally
public or agricultural water supply contaminated with human waste
Presence of appropriate snail intermediate hosts
Peak infection rate in second decade: children playing in water
Pathology proportional to worm burden
Schistosoma haematobium adult worms travel in which veins?
Venous plexus (bladder)
Describe the symptoms/pathology of Taeniasis
Often asymptomatic or causes abdominal discomfort, occasionally nausea, vomiting, diarrhea, weight loss, & obstruction
Treatment of Diphyllobothrium latum
As in Taenia ssp, praziquantel or niclosamide, single dose
Vitamin B12 supplement when deficiency is evident
