Shistosomiasis and Tapeworms Flashcards
What are flukes?
Schistosomiasis Biharzia
What phylum are flukes classified as?
Platyhelminthes
What class are flukes?
Trematoda
What phylum are tapeworms?
Platyhelminthes
What class are tapeworms?
Cestoda
What is the human portion of schistosomiasis?
Cercaria (free-swimming infective stage)
Cercariae penetrate skin
Tail is lost during penetration
Cercariae migrate via blood circulation to the liver of the host and mature
Adult male + Adult female (Gynecophoral canal)
Adults migrate to blood vessels of intestine or bladder; eggs are laid and appear in faeces or urine
S. haematobium
Eggs
What is the snail portion of schistosomiasis?
Eggs S.mansoni Eggs enter fresh water Miracidium hatches from egg Penetrates into snail tissue Developing cercariae Sporocyst in snail (2 generations) Cercariae penetrate human skin
What happens when a schistosoma mansoni egg is in the liver?
Eggs and granuloma → portal vein hypertension→rupture→death
What is the histopathology of the baldder in histopathology?
Bladder can’t stretch
Causes tumours
Chronic inflammation→ tumour
Where are schistosoma haemotobium also found in females?
Veins of vagina
How many women are affected with urogenital schistosomiasis?
9-13 million women, primary in 53 countries in sub-Saharan Africa and eastern Mediterranean
What do dams and irrigation canals provide for schistosoma haemotobium?
Snail breeding sites
What is the natural resistance to schistosoma haemotobium?
IgE antibody- Th2
What drugs are used to treat schistosoma haemotobium?
Praziquantel
In what form is schistosoma haemotobium?
Highly polymorphic
What can schistosoma haemotobium lead to?
Increased susceptibility to HIV infection
What is the lifecycle of tapeworms?
Eggs or gravid proglotttids in feces and passed into environment
Cattle (T. saginata) and pigs (T. solium) become infected by ingesting vegetation contaminated by eggs or gravid proglottids
Oncospheres hatch, penetrate intestinal wall, and circulate to musculature
a. Oncispheres develop into cysticerci in muscle
Humans infected by ingesting raw or undercooked infected meat
Scolex attaches to intestine
Adults in small intestine
• Cysticerosis- an infection of both humans and pigs with the larval stages of the parasitic cestode, Taenia solium
What is cysticercosis?
An infection of both humans and pigs with the larval stafes of the parasitic cestode, Taenia solium
What is the pig life cycle of Cysticercosis?
Eggs or gravid proglottids in feces and passed into environment
Embryonated eggs and/or gravid proglottids ingested by pigs
Oncospheres hatch, penetrate and intestinal wall and circulate musculature
Oncospheres develop into cysticerci in pig muscle
What is the human life cycle of cysticercosis?
Human infected by ingesting raw or undercooked infected meat
Scolex attaches to intestine
Adults in small intestine
Eggs passed into environment (starts pig cycle)
Embryonated eggs ingested by human host
Oncospheres hatch, penetrate intestinal wall, and circulate to musculature
Cysticerci may develop in any organ being more common in subcutaneous tissue as well
Cysticercosis
What is the life cycle of hydatid disease
- Adult in small intestine
- Embryonated egg in feces
- Oncosphere hatches; penetrates intestinal wall
- Hydatid cyst in liver, lungs etc
- Protoscolex from cyst
- Scolex attaches to intestine
What is Cystic echinoccosis (CE)?
Hydatid disease
Caused by infection with larval stage of Echinococcus granulosus
Harmful, slow growing cysts in the liver
What is Alveolar echinococcosis (AE)?
Infection with larval stage of echinococcus multilocularis
Small rodents intermediate host
Parasitic tumours form in liver, lung, brain and other organs
Fatal if untreated
What is the treatment for hydatid disease?
Surgery
Drugs benzimidazoles
Anaphylaxis
What is the life cycle of the snail in echinococcus granulosa?
S. mansoni, S. japonicum, S. haematobium in feces and in urine
Eggs hatch releasing miracidia
Miracidia penetrate snail tissue
Sporocytes in snail
Cercariae released by snail into water and free-swimming
What is the human cycle in echinococcus granulsoa?
Penetrate skin
Cercariae lose tails during penetration and become schistosomulae
Circulation
Migrate to portal blood in liver and mature into adults
Paired adult worms migrate to mesenteric venules of bowel/rectum
