Parasites 1 Flashcards
What is the difference between a definitive and intermediated host?
definitive- host in which the sexual stage of a parasite life cycle occurs
intermediate-host in which asexual reproduction or development occurs
What is a reservoir?
animal host that maintain the natural cycle in the wild (often not harmed by the carriage)
List the CDC neglected parasitic infections in the US.
Chugs Cysticercosis Toxocariasis Toxoplasmosis Trichomoniasis
Contrast the immune responses to parasitic and protozoan parasites.
helminth- eosinophils and TH2 response
protozoan: TH1 response
T/F Although parasites vary widely by phylum, they are separated from hosts as prokaryotes.
F. Parasite represent a wide variety of phylums within eukaryotes, which is shared with humans and other mammals
Distinguish the difference between cyst and cysticerci.
cyst is a dormant stage found encysted in hosts (intermediate or definitive) in undercooked meat
cysticerci: encysted chested larval forms in an infected intermediate host (Hydatid is a specialized cysticercal form in Echinoccocccus granulosus)
Contrast the physical characteristics of cestoda and trematoda and examples of each.
cestoda (tapeworms) have flat segmented bodies that they use to absorb nutrients, attaching by scolex and reproduce by hermaphroditic reproduction using proglottids: Tania saginata, solium, Diphyllobothrium datum, Echinoccoccus granulosus
trematoda (flukes) have a simple digestive system and single opening as mouth and anus, intermediate often a snail and transmission can be invasive or ingestive: Schistosoma spp.
How can you contract Taenia infection and how can spread and what infections result from each route of transmission.
infection by ingesting raw or undercooked infected meat that includes cysticerci (tapeworm of the intestine) or when they eat tapeworm eggs from humans (cysticercosis of the muscle, eyes and brain)
both forms can occur in the same person
What are the symptoms of Taeniassis or Cysticercosis?
often asymptomatic or causes abdominal discomfort, occasionally NVD, weight loss and obstruction
cysticercosis: symptoms related to tissue involved: muscle lumps, brain neurocysticercosis (confusion, balance difficulty, brain swelling, excess fluid around the brain, seizures, headaches and mortality
What are the dx. and tx. available for Taenia infection.
self or clinical observation of active prologttids/ proglottids or eggs in the stool; CAT/MRI: ribbon-like structure in the intestine, or calcified dead larva visible often
tx is praziquantel, niclosamide or albendazole, single dose effective for adult worms, prolonged treatment for cysticerci
humoral response, reinfection possible
How is Diphyllobothrium latum infection unique from other tape worm infections?
caused by undercooked fish containing larvae (copepod infects fish)
causes B12 deficiency and anemia with neurological symptoms
additional tx is Vitamin B12 deficiency if evident
How is Echnoccocosis transmitted? What is the resulting infection?
ingestion of eggs from dogs (definitive host) who eat raw intestine (intermediate host is ungulates) and effects primarily the lungs and liver but also the spleen, kidneys, heart, bone and CNS **formation of hydatid cysts (large), onset of disease when cysts cause pain or rupture; anaphylaxis associated with rupture can be fatal
humans serve only as a dead end host
How is echinococcosis dx or tx?
immunology is pathologic, dx. by risk factors of area with serology for confirmation
tx. percutaneous drainage with instillation of hypertonic saline or alcohol of cysts, or surgical removal with care to avoid rupture; DEWORM dogs
Correlate the different species of Schistosomiasis with the location of blood invasion and site of egg migration.
S. mansoni: mesenteric veins- descending colon
S. japonica: superior mesenteric veins- small intestine
S. haematobium: venous plexus- bladder
How is schistosomiasis transmitted?
is an invasive aquatic free-living cercaria that can penetrate skin with snails as an intermediate host, this is most common when public or agricultural water supply is contaminated with human waste
peak infection is in children playing in the water in their second decade; S. mansion and heamatobium mostly in Africa, S. japonicum mostly in Asia
How are schistosome eggs differentiated?
Distinctive spikes determine the eggs (i.e. lateral v. terminal)
What are the symptoms of early, middle and chronic schistosomiasis pathology?
early: many have no symptoms, rash and hypersensitivity to exposure, fever headache and nausea with larval migration
middle: symptoms mostly from immune response to eggs (Katayama syndrome), intestinal causes abdominal pain, diarrhea and blood in stool, urogenital cause hematuria
chronic: eggs lodge in the tissues, esp. intestine/liver, bladder respectively and egg secretion lead to eosinophilic inflammatory response of granuloma formation and cancer, liver disease and portal HTN, or bladder mucosal thickening/cancer
What is the dx/ treatment for schistosomiasis?
dx by observation of eggs in feces or urine
single dose praziquantel in S.m and S.h. or multiple doses in S.j. which potentiates the active immune system killing of adult worms
avoid contact with contaminated water
