parasites Flashcards
organism in which the parasite undergoes SEXUAL reproduction
definitive host
the organism in which the LARVAL or ASEXUAL stages of parasite lives
intermediate host
type of lesions that parasites can cause
destructive intraparenchymal lesions
types of mechanisms to escape host immune defenses
- masking
- blocking
- intracellularity
- antigenic variation
- immunosupression
- defense against complement
- defense against non-specific host responses
parasite has host Ig’s that they coat the surface with
masking
antibodies from the host bind to the parasite and prevent the cytotoxic antibodies from binding
blocking
live within the cells so the immune system doesnt catch them
intracellularity
change surface antigens each time there is humoral response or developmental stage
antigenic variation
- stimulate growth of non-specific antibody
- stimulate supressor T cells (inhibiting immune) or supressor factors
- antigen overload
immunosupression
-long surface proteins that bind complement but dont form membrane attack complex OR prevent complement cascade
defense against complement
parasite produces anti-oxidants to combat host attack
defense against non-specific host responses
combat intracellular organisms like protozoa
cell mediated immunity
th-1 subset and interferon gamma
combat parasites like intestinal worms
antibody immunity
th-2 (with Il-4 and Il-6)
primary cytotoxic effector cells
macrophages and eosinophils
antiparasitic immunoglobulin classes
IgM, IgG, IgE
asymptomatic cyst passer, inflammatory pericolonic mass, and liver abscess
amebiasis
most canadian infection acquired through consumption of water contaminated by animal feces
giardiasis
4 species of plasmodia cause
malaria
chloroquine resistance by
plasmodium flaciparum
symptoms include hypoglycemia, cerebral malaria, hypotension, and renal failure
malaria
walking barefoot in contamined soil
hookworm
inhabit rectum, exit at night to lay eggs perianally, causing an itch
pinworm
lower ileum and colon, ingestion of eggs, bloody diarrhea and rectal prolapse
whipworm
acquired by eating undercooked freshwater or contaminated meat
tapeworm
two ectoparasites
- scabies
- pediculosis
the itch mite or “seven year itch”, crowded areas, very contagious
scabies
human lice, sucks on blood causing an itch, close contact
pediculosis
two parasites that inhabit the oropharynx of humans
- entamoeba gingivalis
- trichomonas tenax
permanent niche of e gingivalis
gingival pockets and tonsillar crypts
- found in perio pts
- depends on oral bacteria for nutrients
- phagocytoses RBC in oropharynx
- found in HIV patients
e gingivalis
- natural hosts are man and monkeys
- feeds on microorganisms
- found in necrotic teeth and gums
- sensitive to metronidaxole
- many causes related to the lungs
- found in perio pt
trichomonas tenax
most helminthic infections are
not contagious
what parasite could infect a dentist
pinworm
how does pinworm infect a dentist
- could be injected
- cycle not broken by proper hand washing
what blood borne parasites can be transmitted
malaria and trypanosomes
most likely type of parasitic transmission to occur in dental practice
ectoparasites (scabies and lice)
