micro exam 4

parasite

organism that lives on, or in, another organism

vector

organism that transmits parasite

definitive host

sexual reproduction/adult stage

intermediate host

asexual reproduction/larval stage

amoebae characteristics

move by pseudopods, trophozoite and cyst stages, asexual reproduction

trophozoite stage characteristics

what is motile, is sensitive to environmental factors, dies when outside of the body

cyst stage characteristics

resistant to environmental stress; often what lives outside the body

amebic dysentery is caused by

entamoeba histolytica

amebic dysentery presentation

blood diarrhea with mucus, can cause abscesses in liver and other organs

entamoeba histolytica transmission

ingestion of cysts in fecally contaminated food or water

primary amoebic meningoencephalitis is caused by

naegleria fowleri

primary amoebic meningoencephalitis characteristics

amoeba travels up the olfactory nerve to the brain

naegleria fowleri transmission

water containing amoeba is forced or snorted up nose

entamoeba gingivalis disease association

poor oral hygiene

entamoeba gingivalis transmission

commensal in the mouth

flagellates characteristics

move by flagella, spindle- or pear-shaped rt

trichomoniasis caused by

trichomonas vaginalis

trichomoniasis presentation

asymptomatic in males, smelly yellow discharge in women

trichomonas vaginalis transmission

intimate contact

trichomonas tenax disease association

poor oral hygiene

trichomonas tenax transmission

commensal in the mouth

giardiasis caused by

giardia lamblia

giardiasis presentation

loose, fatty stools, flatulence, malodorous gas and stool, weight loss

giardia lamblia transmission

ingestion of cysts in fecally contaminated food/water

ciliates characteristics

cilia for motility, typically transmitted by ingestion of cysts

balantidiasis is caused by

balantidium coli

balantidiasis presentation

intestinal ulcers

balantidium coli

largest protozoan and only ciliate to cause pathology in huamns

balantidium coli transmission

fecal-oral route via cysts; pigs are primary reservoir

apicomplexans characteristics

complex life cycles, alternative between sexual and asexual reproduction; often have intermediate hosts

malaria is caused by

plasmodium species

malaria presentation

shaking, chills, high cyclic fever, spleen enlargement, anemia, joint pain, tissue anoxia, brain damage

malaria transmission

bite from infected anopheles mosquito

sporozoite stage characteristics

infectious stage; lives in definitive host, mosquito

meroziote stage characteristics

asexuals stage; infects liver cells and later RBCs in human

trophozoite stage characteristics

asexual stage; infects RBCs of blood stream

gametocyte stage characteristics

sexual stage; male and female gametocyte reproduce in mosquito to make sporozoite

oocyst stage characteristics

sexual and infectious stage; lives in definitive host, felines

tachyzoite stage characteristics

rapid growth, asexual stage; infects intermediate hosts, vertebrates like humans

bradyzoites stage characteristics

slow growth, asexual stage; replicates slowly in tissue cysts

toxoplasma gondii transmission

definitive host in felines to sexual phase in intestinal tract of cats to release of infective oocytes → intermediate host in vertebrate to tachyzoite stage in tissue/tissue fluids, later forms cysts containign bradyzoites in tissue

toxoplasma gondii routes of infection

ingestion of oocysts, ingestion of bradyzoites in undercooked or rare meat, tachyzoites cross placenta during pregnancy

disease associated with toxoplasma gondii

toxoplasmosis

toxoplasmosis in immunocompetent

usually asymptomatic or mononucleosis-like syndrome

toxoplasmosis in immunocompromised

encephalitis with severe tissue damage in brain, lesions on heart and lungs

toxoplasmosis in developing fetus

stillbirth, hydrocephalus, chorioretinitis, liver damage, deafness, intellectual disabilities

symptoms of cryptosporidium parvum

watery diarrhea, fever, cramps, anorexia, nausea for 10-14 days, life threatening in immunocompromised

cryptosporidium parvum life cycle

entirely occurs in single host

cryptosporidium parvum transmission

ingestion of oocysts

pneumocystis jiroveci

a fungus that causes pneumonia in severely immunocompromised individuals

helminths categories

flatworms and roundworms

flatworm examples

trematodes and cestodes

roundworm examples

nematodes

trematodes / fluke characteristics

flat, leaf- or lancet-shaped, nonsegmented; ventral and oral sucker; obtain food from absorption through cuticle

hermaphroditic fluke transmission

humans acquire infections by ingesting larva in contaminated food, usually fish

hermaphroditic fluke examples

paragonimus westermani (lung fluke from crabs)

clonorchis sinensis (liver fluke from fish)

non-hermaphroditic flukes example

schistosomes (blood flukes)

schistosome transmission

infection acquired when larva contaminated water penetrate skin

S. mansoni and japonicum

mesenteric vein

S. haemotobium

venous plexus of bladder

response to schistosome eggs

granulosa formation

cestodes / tapeworm characteristics

flat, segmented; hermaphroditic; scolex and proglottids

scolex

holdfast organ

proglottids

segments

taenia solium

pork tapeworm

taenia saginata

beef tapeworm

diphyllobothrium latum

fish tapeworm

tapeworm infection presentation

mild abdominal pain, nausea, diarrhea, fatigue, weight loss

pork tapeworms infection can lead to

brain infection

nematodes / roundworms presentation

complete digestive system, separate males and females, infective stage is egg or larvae

enterobius vermicularis

pinworm

ascaris lumbricoides

roundworm

necator Americans or ancylostoma duodenale

hookworms

strongyloides stercoralis

threadworm

nematode transmission

ingestion of eggs or larvae

prominent Ig in secretions

IgA

prominent Ig in serum

IgG

bramble receptor (FcRB)

receptor on endothelial cells to translocate IgG

structure of IgA

usually monomeric, sometimes dimeric

dimeric IgA components

4 heavy chains, 4 light chains, 4 Fab sites, 1 J chain, valence of 4, sometimes secretory component

roles of IgA in protection

block adherence or neutralize toxins and viruses, pumps out antigen, fixes complement poorly

difference between IgA 1 and 2

1 is susceptible to proteases, 2 is resistant

how does IgA transport into secretions

IgA binds to polymeric immunoglobulin receptors (pIgR) on mucosal cells, complex endocytosed and transported across the epithelial cell, complex is expressed on luminal surface, complex is cleaved by proteolytic enzymes

selective IgA deficiency presentation

increased frequency of enteric and respiratory infections, compensatory high concentration of IgM in secretions

polymeric IgM transport into secretions

via pIgR

inductive sites

generate responses

effector sites

express responses

Peter’s patches

aggregates of lymphoid follicles in the ileum

M cells

portals to the Peters patch; presenting antigens t

MALT effector sites

lamina propria and intraepithelial lymphocytes

lamina propria cellular immunity

IgA secreting plasma cells, T cells (More CD4), macrophages

intraepithelial lymphocytes

more CD8+, can kill intracellular pathogens and produce Th1/Th2 cytokines, NK-like surveillance, rapid cytotoxicity

innate lymphoid cells

cells with lymphocyte morphology particularly active in the lungs and GI tract

Waldeyer’s ring

lymphoid tissue of the pharynx that acts as a filter and protects the body against infecting organisms that enter from the nose or mouth

which poliovirus vaccine induces IgA response

sabin, the attenuated PV given orally

which poliovirus vaccine induces IgG response

Salk, the inactivated PV given parenterally

GI tract bacterial diseases

caused by pre-formed toxins (Intoxication), non-invasive disease caused by bacteria that adhere, invasive / toxigenic caused by bacteria that invade or produce cytotoxin

site of non-inflammatory watery diarrhea

small intestines

pathogenesis of non-inflammatory watery diarrhea

enterotoxin or adherence

symptoms of non-inflammatory watery diarrhea

intestinal fluid loss (N+V, fever)