Studydroid is shutting down on January 1st, 2019

by mtoom

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What parasitic infections might you get from a food vendor (3)?
  • Enterobius histolytica
  • Giardia lamblia
  • Ascaris lumbricoides
What parasitic infections might you get from swimming (1)?
What parasitic infections might you get from walking barefoot (1)?
Hookworm (Necator americanus)
What parasitic infections might you get from an insect bite (1)?
What are the 4 types of protozoa?
  • Amoeba
  • Flagellates
  • Ciliates
  • Sporozoa
What is the purpose of parasite cysts (3)?
  • Survive harsh conditions
  • Allow parasitic species to survive outside the host
  • Allow transmission from one host to another
Describe the trophozoite form (2)?
  • Metabolic state
  • Actively feeding form
On the topic of protozoa, give an example of 1 amoeba, 1 flagellate, and 1 sporozoa.
  • Amoeba: e.g. Entamoeba histolytica
  • Flagellates: e.g. Giardia lamblia
  • Sporozoa: e.g. Plasmodium
What worms are segmented and non-segmented? Describe the components of a segmented worm.
  • Non-Segmented: Nematode/Roundworms
  • Segmented: Cestodes/Tapeworms

A segmented worm has a Scolex and Proglottids.

Scolex: Attachment organ with 4 suckers.
Proglottid: A segment of the worm full of embyronated eggs.
What are the 4 worms of the Nematode/Roundworms?
  • Ascaris lumbricoides
  • Enterobius vermicularis (Pinworm)
  • Strongyloides stercoralis
  • Necator americanus (Hookworm)
What are the 2 Cestodes/Tapeworms?
  • Taenia solium (Pork tapeworm)
  • Diphylobothrium latum (Fish tapeworm)
Name 1 genus of Trematodes/Flukes?
Schistosoma spp.

What are the symptoms (2) of Giardia Lamblia?
  • Diarrhea
  • Fat malabsorption - Greasy floating stools
Describe the lifecycle of Giardia lamblia? (simple explanation)
  • Cysts/trophozoites (intestine)
  • Contaminate water/fruit
What is the vector for Plasmodium spp?
Anopheles mosquito
What does P. falciparum develop on RBCs? What do these cause?
Sticky Knobs

Cause adherence of RBCs to endothelial cells in blood vessels, preventing clearance in spleen.
What is the sequelae of sticky knobs?
Brain hypoxia, because RBCs don't reach the brain in sufficient numbers (they are sticking to endothelial cells).

Leads to neurological problems, coma, impaired conciousness, etc.
What are symptoms of Plasmodium infection (i.e. malaria)?
  • Headache, fever, muscle & back pain
  • Sweating, chills, dry cough
  • Naseua, vomiting
  • Enlargement of spleen
What is an infection due to Entamoeba histolytica called? What does it cause?
It is called Amebiasis

It causes Amebic dysentery
How does Amebiasis present?
Typically asymptomatic
  • Bloody diarrhea
  • Liver cysts
  • Chronic disease (mimicks IBD) 
How do you diagnose Amebiasis (3)?
  • Stool O&P
  • Serology (IgG)
  • Enzyme immunoassay (on stool) 
What is the common name for Nematodes? Describe the basic characteristics.
Roundworms (Nematodes)
  • Non-segmented
  • Bilateral symmetry
  • Fully-functional digestive tract
Name 4 species of Nematodes
  • Ascaris lumbricoides (roundworm)
  • Enterobius vermicularis (pinworm)
  • Necator americanus (hookworm)
  • Strongyloides stercoralis (stongyloidiasis)

  • Ancyclostoma duodenale
  • Trichuris trichiuria
Describe Ascaris lumbriocoides infection
  • Asymptomatic
  • Large, 15-35cm worms
Describe Enterobius vermicularis infection
  • Worms on perianal area, spread by fecal-oral route
  • Visible to eyes, cause itchy anus, common in kids
Describe Strongyloides stercoralis infection
  • Microscopic worms
  • Acquired from skin penetration in tropics
  • Lasts for lifetime because can replicate within human body
Describe Necator americanus infection
  • Microscopic worm
  • Acquired from skin penetration in the tropics
  • Causes anemia, poor growth, lethargy
Common name for Cestodes? What are the Cestodes (2)?

Common name: Tapeworms (Segmented)

  • Taenia solium
  • Diphylobothrium latum
What is a proglottid?
A segment of a Cestode. Each one is hermaphroditic, when mature they are full of eggs.
What is a scolex?
Attachment organ with 4 ventral suckers sometimes with hooks
What is the main medical issue associated with Tapeworms?
Cysticercosis: Development of cysticerci in various sites (brain, skeletal muscle). Neurocysticercosis is most common cause of seizure in developing world.
Describe a Taenia solium infection

Pork Tapeworm
  • Intermediate host is pigs
  • Definitive host is humans
  • Pigs infected by ingesting mature proglottids shed by human carrier
  • Humans infected by eating undercooked pork
Describe a Diphylobothrium infection
Fish tapeworm
  • Causes B12 deficiency
  • Get it from sashimi
Name the 2 Trematodes/Flukes
  • Fasciola hepatica
  • Schistosoma spp
Describe Trematode/Flukes
  • Intestinal parasites
  • Required snail as intermediate host
  • Hermaphroditic
Describe Fasciola hepatic infection
  • Causes disease called fascioliasis in humans
  • Infects sheep/cattle
  • Feeds on liver cells/blood, causing anemia
Describe Schistosomiasis infection. Name the 2 types
  • Get it by swimming in bad fresh water
  • Causes by organisms of genus Schistosoma spp
  • S. mansoni - Affects GI mesentery
  • S. hematobium - Affects bladder
  • Symptoms: Anemia, malnutrition, sores, fatigue, fever, hepatosplenomegaly
What infections can cause anemia of the parasites discussed?
  • Necator americanus
  • Schistosomiasis
  • Fasciola hepatica
What tick transmits Lyme?
Deer tick

Lyme: Borrlelia burgdorferi bacteria
What tick transmits Rickettsia?
Dermacentor tick
Name 4 ectoparasites
  • Scabies - Sarcoptes scabiei
  • Head/body lice - Pediculus humanus
  • Genital crabsPthirus pubis
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