EXAM 1 GI Parasites Flashcards
what is symbiosis?
- The intimate living together of two dissimilar organisms in a mutually beneficial relationship.
- An interaction between individuals of different species (symbionts).
- The term symbiosis is usually restricted to interactions in which both species benefit (see cooperation; mutualism), but it may be used for other close associations, such as commensalism, inquilinism, and parasitism.
what is a parasite?
An organism that lives and feeds on or in an organism of a different species and causes harm to its host; an organism that lives on or in a host organism and gets its food from or at the expense of its host; Organism that gains its nourishment from and lives in or on another organism.
what is a pathogen?
An agent that causes disease, especially a virus, bacterium, or fungus.
what is a host?
Species of animal or plant that harbors a parasite.
what are amoebas?
Not all closely related; Trophozoites move by pseudopodia; Multiply by binary fission; Found in nature; → Most are nonpathogenic
what is an infestation?
Parasitic infections are often referred to as infestations, especially for the macroscopic parasites.
what is eosinophilia?
an increase in the number of eosinophils in the blood, occurring in response to some allergens, drugs, and parasites, and in some types of leukemia.
what is hematology?
the study of the physiology of the blood
what are the 3 types of protozoa?
- Amoebas are not all closely related
- Flagellates are not all closely related
- Sporozoans are apicomplexans
Parasitic protozoa conduct respiration via what process?
facultative anaerobic processes
how do parasitic parasites reproduce?
Reproduce via binary fission (merogony), except sporozoans that include cycles of multiple fission (schizogony) alternating with sexual reproduction (sporogony)
describe platylhelminthes
flatworms (helminths)
– May not be a true phylum
– Class Trematoda (trematodes, flukes)
– Class Cestoda (cestodes, tapeworms)
what are the two types of helminths?
platyhelminths (flatworms) and nematoda (nematodes, roundworms)
what are the 3 general types of parasites?
protozoa, helminths, and arthropoda
describe arthropoda
– Class Hexapoda or Insecta (insects)
– Class Arachnida (including ticks and mites)
describe trophozites
- Motile
- Sensitive to environment (drying and gastric acid)
- Feeding
- Reproductive stage
- Find in diarrheal stools
- For most species, noninfectious
describe cysts
- Nonmotile
- Protected by cyst wall; Resistant to environment
- Nonfeeding
- Non-reproductive stage
- Find in more formed stools
- Infectious
they generally survive because they have a thick cell wall and are not particularly metabolically active
Infection by ___ occurs by ingestion of mature cysts (2) in fecally contaminated food, water, or hands.
Entamoeba histolytica
what is the primary known reservoir of Entamoeba histolytica?
humans
what is the reproductive mechanism of Entamoeba histolytica?
sexual
how can Entamoeba histolytica cysts be spread?
- they survive in the environment for weeks or months, especially under damp conditions
- domestic mammals, nonhuman primates, cockroaches, and flies may spread cysts
what disease is caused by Entamoeba histolytica?
dysentery
bloody diarrhea (trophs)
describe dysentery
disease caused by Entamoeba histolytica
o Lyses host tissue in colon → Ulcers in colon → Troph migrates to liver and brain, sometimes lungs
o If patient has pulmonary abscesses, it can be coughed up in sputum
o About 90% of people infected with E. histolytica are asymptomatically colonized
Entamoeba gingivalis is an ___ pathogen
opportunistic
Entamoeba gingivalis normally lives where?
in the gingival pockets near the base of the teeth in the human mouth
Entamoeba gingivalis may be coughed up in sputum specimens, thus it must be distinguished from ___
E. histolytica
infection by what parasite is characterized by stool that is watery early in illness, and then becomes foul smelling and can float?
Giardia lamblia
where is Giardia lamblia found?
streams, ponds, etc.
areas of poor sanitation or personal hygiene
untreated freshwater, especially in the wilderness
what is the route of transmission of Giardia lamblia?
oral/fecal
beavers appear to be a source of ___
Giardia lamblia
what disease is caused by Giardia lamblia?
giardiasis
describe giardiasis
▪ Diarrheal disorder that affects the small intestine directly
▪ 1 – 14 days incubation (7 days average)
▪ Usually lasts 1 – 3 weeks
▪ Diarrhea, Cramping, Nausea & vomiting, Weight loss if chronic
what parasite is describe by the following?
o Genito-urinary parasite
o Distribution: Worldwide
o Female lower genital tract
o Male urethra and prostate
o Transmission: Sexual
o Most common protozoan pathogen of humans in industrialized countries
Trichomonas vaginalis
what disease is caused by trichomonas vaginalis?
trichomoniasis
describe trichomoniasis
▪ Indicative of pH or other imbalance in the vagina
▪ In women - Vaginitis, purulent discharge, itching, burning, odor; Can have lesions, abdominal pain, urinary problems; Can complicate pregnancy
▪ In men - Often asymptomatic, Can have inflammation of GU system
what parasite causes toxoplasmosis that resembles a mild cold or mononucleosis in adults, is caused by ingesting its cyst which is found in uncooked lamb or pork or cat feces, sexual reproduction occurs in cat intestines, and can cross the placental barrier
Toxoplasma gondii
what parasite is described by the following characteristics:
o Transmission: Contaminated food and water, including recreational water
o Water-borne transmission well documented (~300,000 in Milwaukee in 1993. Recent SLC outbreak in public pools)
o Zoonosis: Spread animal to animal, animal to person, and person to person (by fecal-oral or anal-sexual contact)
o Some reports of transmission in fresh fruits and vegetables
cryptosporidium paryum
who are the risk groups for cryptosporidium paryum?
Veterinarians, animal handlers, those who practice anal sex, and day care participants
cryptosporidium paryum resists ___ and ___ treatment
chlorine and ozone
what disease is caused by cryptosporidium paryum?
cryptosporidiosis
what disease is characterized by the following?
▪ Exposure may result in asymptotic carriage
▪ In otherwise healthy hosts: mild, self-limiting, watery diarrhea without blood
▪ Spontaneous remission in ~10 days
▪ In immune-compromised (HIV): 50 or more stools/day
▪ Tremendous fluid loss; lasts from months to years
▪ Can disseminate to lungs and biliary tract
▪ AIDS patients are encouraged to boil or filter their drinking water
▪ Distribution: World-wide, in mammals, reptiles, and fish
▪ Infective stage: Thick-walled (sporulated) oocyst
▪ Dx stage: Same
cryptosporidiosis
what parasite causes pneumonia in immunocompromised patients and is often fatal
pneumocystis carinii
what parasite is the largest protozoan parasite in humans; it is a ciliated protozoan that can cause nausea, vomiting and bloody stools
balantidium coli
what is the morphology, sex, alimentary tract, and number of intermediate hosts of tapeworms (cestodes)?
- morphology - head with flat, segmented body
- sex - hermaphrodites
- alimentary tract - none
- number of intermediate hosts - one
what is the morphology, sex, alimentary tract, and number of intermediate hosts of roundworms?
morphology - spindle shaped
sex - separate sexes
alimentary tract - tubular
number of intermediate hosts - none (GI spp.) or variable (tissue spp.)
what is the morphology, sex, alimentary tract, and number of intermediate hosts of flukes?
morphology - leaf-shaped with oral and ventral suckers
sex - hermaphrodites (most) and separate sexes (blood flukes)
alimentary tract - blind
number of intermediate hosts - two (most) or one (blood flukes)
___ absorbe nutrients through outer tegments
cestodes (tapeworms)
cestodes (tapeworms) are ___-shaped
ribbon
what are two examples of cestodes?
taneia sagniata (beef) and taneia solium (pork)
what is the name of the infection of humans with the adult tapeworm of Taenia saginata, T. solium or T. asiatica?
taeniasis
___ are the only definitive hosts for Taenia saginata, T. solium and T. asiatica.
humans
what are the symptoms of taeniasis?
development of cysticerci in various sites
what is the greatest concern with taeniasis?
cerebral cysticercosis (neurocysticercosis)
the following manifestations are characteristic of what infection?
Seizures, mental disturbances, focal neurologic deficits, and signs of space-occupying intracerebral lesions, sudden death
taeniasis
what pathogen is described by the following characteristics?
o Leaf-shaped flat worms
o Have a mouth and intestinal track
trematodes (flukes)
trematodes include ___ flukes and ___ flukes
blood and lung
what is the main lung species of trematodes?
● Paragonimus westermani (oriental lung fluke)
what are the three blood species of trematodes?
● Schistosoma japonicum (blood fluke)
● Schistosoma mansoni (Manson’s blood fluke)
● Schistosoma haematobium (bladder fluke)
what pathogens are described by the following?
o Include tissue-dwelling and intestinal worms
o Have a mouth and intestinal track
nematodes (roundworms)
intestinal worms include ___ and ___, and are the ___ common helminthic parasites in humans
- hookworm
- strongyloides stercoralis
- most
what is the definitive host for nematodes?
humans
what is the infective stage of nematodes?
filariform larva
what is the diagnostic stage of nematodes?
egg, rhabditiform larva, filariform larva
what is the transmission of nematodes?
penetration of human skin
what pathogen is described by the following?
● Bilaterally symmetrical
● Tough, stiff cuticle serves as an exoskeleton
● Segmented bodies
● Different groups show various patterns of segment fusion (tagmosis) to form integrated units (heads, abdomens, and so on)
● Paired, usually jointed appendages on some or all of the body segments
● Appendages may be modified in a number of ways to form antennae, mouthparts, and reproductive organs
philum arthropoda
describe the exoskeleton of philum arthropoda
- tough, stiff cuticle
- made of chitin and proteins
- may be stiffened further with CaCO3
in order to grow, arthropods periodically shed their cuticle by a process called ___; this trait is shared with the ___
- ecdysis
- nematodes
philum arthropoda includes what 10 things?
insects, millipedes, centipedes, spiders, ticks and mites, scorpions, crustacea, horseshoe crabs, sea spiders, trilobites
describe the distribution of the philum arthropoda
worldwide: on land, and in water
what pathogen is described by the following characteristics:
- Human head and body louse
- Egg: Called a nit; hatches in ~ one week
- Nymph: Looks like adult, but is ~ the size of a pinhead
- Adult: ~ the size of a sesame seed, has 6 legs (each with claws), and is tan to grayish-white
- Both nymph and adult lice must feed on blood to live
pediculus humanus
what are the human head and body louse species from pediculus humanus?
○ P. humanus capitis (head louse)
○ P. humanus humanus (body louse)
what disease is caused by pediculus humanus?
pediculosis
the majority of head lice infestations are ___
asymptomatic
what are the symptoms of pediculosis?
tickling feeling of something moving in the hair, itching (caused by an allergic reaction to louse saliva) and irritability
in ___, a secondary bacterial infection may occur
pediculosis
body lice can serve as vectors for what 3 conditions?
○ Rickettsia prowazekii (epidemic typhus)
○ Bartonella quintana (trench fever)
○ Borrelia recurrentis (louse-bore relapsing fever)
what pathogen is described by the following characteristics?
● Primary medical importance: Inflammation associated with their bites (due to allergic reactions to components in their saliva)
● Although bed bugs have been found naturally-infected with blood-borne pathogens, they are not effective vectors of disease
cimex lectularius (bed bugs)
