018 Parasite Infections of GI tract Flashcards
What are cysts/ova?
Resistance structures that can exist in the outside world. This releases the next stage during environmental triggers.
What is Giardiasis?
Protozoa causing girada
Symptoms of giardiasis
Ranges from immunosuppressed to immunocompetent; bulky diarrhoea; sulphurous smell diarrhea; fat globules present
Why is the smell of giardiasis so distinct?
Giardia is an anaerobic organism, so its respiratory chain uses sulphur-containing compounds.
How does giardiasis work?
Deconjugates bile salts to gain fatty acids, presence of fat in intestine alter osmotic balance causing water drawn into the gut; binds strongly to the surface of the mucosa blocking absorption.
What is the incidence of giardasis?
Protective immunity; 20% prevalence in endemic areas
What is ameobiasis ?
Protozoa causing entamoeba infection
What is the pathogenesis of ameobiasis?
Actively invades mucosa and can disseminate to other organisms through passage of hepatic portal vein
What are the symptoms of ameobiasis?
Range of symptoms; asymptomatic, colic frequent bowel movements; dysentery due to disruption of gut wall, meningitis due to disseminated disease
How is giardiasis transmitted?
Although there is developed immunity, cysts still form to cause contamination through the diarrhoea.
Which protozoa is a flagellate protozoa?
Giardiasis
Which protozoa is from the apicomplexan parasite family?
Cryptosporidium paryum
What is a apicomplexan parasite?
It means the front end of the parasite has series of organelles that can invade host cells.
Which animal hosts the reservoir of cryptosporidium parvum?
Cattle
Describe the life cycle of the cryptosporidium parvum
oocyst invades the intestinal mucosa, there is division of the protozoa but no cysts are formed so it is not transmitted
Which type of helminth is able to transmit through direct invasion?
Hookworm
What is the life cycle of Ascaris lumbricoides?
Females shed 200,000 eggs per day. They remain infective for long periods of time. Eggs then hatch in the gut and the larval stages occur around the body and undergoes pulmonary migration.
What are the symptoms of Ascaris lumbricoides?
Asthma - like presentation, malnutrition, B12 deficiency
What is cutaneous larval migration?
When worm has left but has left a trail of immune response against the worm
What is the life cycle of hookworm?
They have a larval stage that is in the warm, moist environment. It invades the skin, enter through lymph nodes and then go through tracheo-oesophageal migration.
Symptoms of the Amylostoma duodenale and Necator amencacus
Clinical manifestations include itchy papules in the skin, migration through lungs and iron & protein loss.
Describe the life cycle and symptoms of of trichuris trichuria
Found in warm, humid climates. This is usually only symptomatic in children (due to protective immunity). Clinical manifestations include bloody diarrhoea (with no fever), rectal prolapse (due to agitation), anaemia, wasting and eosioniphilia.
Which type of helminth results in reinnoculation?
Strongyloides stercoralis
Describe the significance of Enterobius vermicularis
This is a pinworm found in the caecum and perianal region. It can cause severe scratching. Diagnosed by scotch tape test.
