IPAP Microbiology Block 5

disruption, evasion, and inactivation of host defenses

-the parasite must be able to evade the host's immune defense system for the disease process to be maintained -parasites elicit humoral and cell-mediated immune responses -parasites are particularly adept at interfering with or avoiding these defense mechanisms

h. nana

epi: worldwide, most common tapeworm in N. America. contaminated grain and flour. children @ daycare centers are esp. high risk cause: poor hygiene, auto-reinfection symptoms: few worms-none. heavy infections-duarrhea, ab pain, headache, anorexia, other vague complaints Dx: stool exam with _________ egg with six-hooked embryo and polar filaments Rx: praziquantel, alternative is niclosamide prevention: improve sanitation, proper hygiene

d. latum

epi: worldwide, most prevalent in cool lake regions where raw/pickled fish is popular cause: insufficient cooking over campfires and tasting/seasoning gefilte fish account for many infections symptoms: asymptomatic; occasionally epigastric pain, ab cramps, nausea, vomiting, weight loss, 40% have low vitamin B12 Dx: stool exam Rx: niclosamide, praziquantel, paromomycin. B12 supplement may be encessay prevention: cook meat properly, sanitation

incidental parasite

establishes itself in a host in which it does not normally live (dog flea bites a human)

ancylostoma duodenale and necator americanus (hookworms)

filariform larva penetrates intact skin -larva enters circulation, goes to lungs, coughed up, swallowed, develops into adult in small intestine -egg laying 4-8 weeks after exposure, goes on 5 years -once in soil, noninfective larvae released from eggs, develop into filariform larvae, then penetrates exposed skin

diphyllobothrium latum

fish tapeworm (thin, wide segments) larvae: freshwater crustaceans and fish adults: humans, dogs, cats, bears large (20-30ft long) complex life cycle with two intermediate hosts eggs have operculum and a knob on bottom fo shell in 2-4 weeks, coracidium exits the operculum and is eaten by crustaceans, develops into procercoid larval form. crustacean then eaten by fish, the plerocercoid develop in musculature of the fish

helminth physiology and replicaiton

food uptake: ingest host tissue/fluids, causing tissue destruction or absorption of nutrinets from surrounding fluids and intestinal contents energy conversion: respiration in ___________ is primarily anaerobic, although larval forms may require oxygen survival: -the major protective barrier for most _______ is the tough external layer (cuticle or tegument) -worms may also secrete enzymes that destroy host cells and neutralize immunologic and cellular defense mechanisms -some evade host immune response by incorporating host antigens into their external cuticular layer. worm can sometimes survive in host for decased reproduction: most lay eggs, somebear live young

trichinella spiralis

may cause trichinosis adult lives in gut of flesh0eating mammals (most common in pigs) larvae die in muscle -meat contain encysted larvae is eaten, larvae develop into adult worms, larvae move from intest mucosa into blood, various muscle sites -found in extraocular muscles of eye, tongue, delt, pec, intercostals, diaphragm, gastroc -encysted larvae viable for years

arthropoda

may directly cause disease or act as intermediate hosts and vectors. four major categories of _________ of interest are -myriapoda (centipedes and millipedes) -crustaceans - several are intermediate hosts in life cycels of various intestinal or blood and tissue helminths -chelicerata - mites, ticks, spiders, and scorpions -hexapoda - flies, midges, fleas, lice, bugs, wasps, and ants

trematodes (flukes)

members of platyhelminthes -most are hermaphroditic ---schistosomes are exception: cylindric bodies and separate male/female worms exist. don't have operculum -require mollusks (snails and clams) as first intermediate hosts for completion of life cycles -some require snails plus something else before reaching adulthood

facultative parasite

normally free living organism, but may become an opportunistic parasite

damage caused by parasites

obstruction -host reactions -lost nutrients -loss of fluids/dehydration

route of infection ingestion

oral (nasopharyngeal) in food, water, aerosols -remains in GI tract -internal migration to other host organs or systems -migrations through other host systems and return to gastrointestinal sites

endoparasite

parasite living inside the host

ectoparasite

parasite living on the external surface of the host

pinworm prep- scotch tape prep

pinworm eggs (enterobius vermicularis) are deposited around the perianal region -this method gives best recovery of eggs if used befroe defecation, bathing or dressing in the morning -firmly press scotch tape to skin around folds of anus -do not use cloudy tape

taenia solium

pork tapeworm, cysticercosis larvae: hogs, humans; adults: humans

life cycle

process of a parasite's growth, development, and reproduction, which proceeds in one or more different host depending on the species of parasites

diplydium caninum

pumpkin seed tapeworm larvae: fleas adults: dogs, cats primarily parasite of dogs and cats life cycle involves development of larval worms in dog and cat fleas egg packets enclosed in thin membrane

trichuris trichiura (whipworm)

resembles handle/lash of whip -ingest eggs, hatch into larvae in small intest, migrate to cecum, penetrate mucosa, mature to adults -after 3 months, fertilized female worm lays eggs, 3,000-10,000 per day, female worms live 8 years -eggs go to soil, mature, infectious in 3 weeks -distinctive eggs, dark bile staining, barrel shape, presence of polar plugs in egg shell

animalia (metazoa)

whithin opisthokonta, the parasites of human interest fall under the metazoa in the animalia clade. the animalia clade includes all eukaryotic organisms that are not protozoa, stramenopila, or fungi -helminths (worms) -arthropods (carbs, insects, ticks, and others)

eosinophils

-1-3% in peripheral blood -bilobed nucleus (spectacle shaped) -cytoplasmic granules (bright pink in color, small in size) -killing strategy ---go to battlefield (chemotaxis) ---recognize target (via Fc receptors) ---eat (phagocytosis) ---chemical attack (release toxic contents of granules)

eosiniphilia

-________________ tend to be elevated during most parasitic infections -elevated elvels do not reveal the specific parasite if it is present -can be caused by other inflammatory conditions such as cancer

form of parasite

-adult -larva -egg/ova -trophozoite (found in diarrheal stool) -cysts (found in formed stool)

other types of clinical specimens

-blood - for plasmodium sp. (thick and thin smears) -sputum, pleural effusions, etc (for parasites in the lungs) -urethral and vaginal exudates (for parasites of the urogential tract) -urine sediment (for parasites of the urogenital tract) -csf -skin srapings -biopsy -serum -bone marrow

helminths

-complex multicellular organisms that are elongated and bilaterally symmetric -often helminths possess elaborate attachment structures (hooks, suckers, theeth, or plates) -helminths of human interests are separated into two groups: nematoda and platyhelminthes

platyhelminthes

-consists of flatworms, which have flattened bodies that are leaflike or resemble ribbon segments -can be further divided into trematodes and cestodes

cestode morphology

-flat, ribbon shaped -scolex (head) for attachment -individual segments called proglottids -a chain of proglottids is called a strobili -all are hermaphrodites -no digestive system -___________ found in human intestine have complex lifecycle with intermediate host -humans can serve as intermediate host (cysticescosis, echinococcosis, sparganosis)

factors associated with parasitic pathogenicity

-infective dose and exposure -penetration of anatomic barriers -attachment -replication -cell and tissue damage -disruption, evasion, and inactivation of host defenses

techniques of stool examination

-macroscopic examination -saline and iodine direct wet mounts (fresh stools) ---detect motile trophozoites, larvae, leukocytes, and red blood cells -concentration ---separates protozoan cysts and helminth eggs -permanently stained slides

why study parasitology in the US

-medical parisitology is the study of invertebrate animals capable of causing disease in humans and other animals -parasitic diseases are usually considered tropical -millions of deaths attributed to parasitic infections annually -those at risk: ---tourists ---missionaries ---peace corps volunteers ---refugees ---immunosuppressed ---soldiers

adherence and replication

-most infections start with attachment followed by replication to establish colonization -the parasitic life cycle is species dependent -attachment can be: ---relatively nonspecific ---mediated by mechanical/biting mouthparts ---ihe interaction parasite adhesin and specific receptors found on specific cell types

cell and tissue damage

-most organisms initate the disease process by invading normally sterile tissue, with subsequent replication and destruciton -parasitic protozoa and helminths are generally not known to product potent -however, parasitic disease can be established by the elaboration of toxic products, mechanical tissue damage, and immunopathologic reactions

enterobius vermicularis (pinworm)

-small white worm that parents find in perianal folds/vagina of infected child begins by eating embryonated eggs -larvae hatch in small intestine, migrate to large, mature into adults 2-6 weeks -asymmetric eggs -20,000 eggs in perianal skin, eggs rapidly mature, infectious w/in hours

control of parastiic infections

-surveillance: monitoring of incidence, prevalence, distribution and severity of disease -innteruption of parasitic life cycle ---proper disposal of human/animal wastes -----best mehtohd of controlling parasitic life cycle -----applicaiton of latrines -----avoid spreading of raw fecal waste on soil ---purification of breathing water -----treatment with chlorine or iodine -----prevention of contamination of ground water sources from leaking latrines and flooding -----replace inadequate water filtration systems ---processing and treatment of food -----cooking/heating: 1 hour at 55 degrees C -----freezing: 20 days at -10 C ---improvement of housing quality -----locatin of house, houseing construction ---elimination of intermediate hosts/vectors -proteciton ---prophylaxis when entering endemic areas ---immunization against parasite infective forms -thearpeutic measures ---protection from infective persons ---curative therapy (antiparasitic drugs) -----antimalarial chloroquine phosphate (aralen) -----antihelminthic praziquantel (biltricide) -----antiprotozoal metronidazole (flagyl) -hand washing -education of exposed populations

enterotest - string test

-used to detect parasites, protozoa, and helminths, in upper part of small intestine -do no eat 12 hour prior to testing -end of string is attached to cheek/neck -capsue containing remainer of skin is swallowed -capsule will dissolve and move into stomach where the string will unravel -usually patient relaxes for 4 hours -string gathers materials from stomach and upper intestines -string is pulled back up thorugh throat, placed in coantiner, sent to lab 0remove mucous from string and examine by wet mount technique

pathogenesis of protozoans and helminths

-variable (organism dependent) -the organisms are often not highly virulent or cannot replicate within the host (or both) -the severity of illness is often related to the infecting dose and degree of reinfeciton (repeated exposures result in an ever-increasing parastiic burden) -parasitic infections are often chronic, lasting months to years -a strong immune response causes an immunopathologic contribution to the disease manifestations

specimen recovery

1. proper collection and handlign of specimens is essential 2. improper specimens give inaccurate results 3. some medications may interfere with examination of specimen -antacids -antidiarrheal compounds -mineral oil -antibiotics 4. administration of barium sulfate to patients undergoing radiological exams will make stoll samples difficult to examine for 1-2 weeks. crystals interfere with detection of organisms 5. all specimens should be properly labeled

eggs

a. taenia eggs spheric, 30-40 um, three pairs of internal hooklets b. diphyllobothrium latm egg, operculated. 45x90um c. hymenolepis nana 30-45um, thin shell, six hooked embryo d. h diminuta 70-85um, six hooked embryo surrounded by membrane 3. dipylidium caninum. egg packets 8-15 six-hooked oncospheres inside thin membrane

infective stage

a stage when a parasite can invade a human body and live in it

vector

a carrier (usually an arthropod) which transmits an infective form of the parasite from host to another

paratenic host

a host that serves as a transport host in which the parasitic forms undergo no development, but passes on to the final host

reservoir host

a host which replaces man in the life cycle of the parasite

autoinfection

a reinfection in which the host is its own source of infection from a source already present in the body

echinocuccus multilocularis

alveolar hydatid cyst larvae: herbivores, humans adults: foxes, wolves, dogs, cats primarily in foxes and wolves, although farm dogs and cats harbor them in rural environments intermediate hosts are rodents humans get infecteed with cyst stage due to contact w/ fo, dog, cat feces trappers and workers w/ fur pelts may inhale fecal dust and get infected eggs hatch and penetrate intestinal tract, become oncospheres which enter circulation and go to liver, lungs, brain

host

any living organism, animal, or plant that harbors or nourishes another organism

toxocara and baylisascaris T. canis (dogs), T. cati (cats), B. procyonis (raccoons)

ascarid intestinal parasites accident human infect, makes visceral larva migrans, neural larva migrans, ocular larva migrans humans injest, eggs hatch, penetrate human gut, go to blood, migrate as larvae around body T. most common cause of visceral+ocular B. increased recog as fatal casue of neural LM T. don't go pase larvae, B. grow to large size inside humans

taenia saginata

beef tapeworm larvae: cattle adults: humans epi: worldwide, incl US cause: eating undercooked beef/limit exposure to human waste symptoms: asymptomatic r may complain of vague abdominal pain, chronic indigestion, hunger pains Dx: stool exam Rx: praziquantel or niclosamide Prevention: cook meat properly, sanitation

s. haematobium

blood fluke develops in liver, migrate to uterine plexus, large eggs with shapr terminal spine depositied in wall of bladder epi: nile valley and africa, leading cause of bladder cancer in egypt and other parts of africa cause: needs suitable snail host symptoms: bateruria chronic, squamous cell carcinomas in bladder, can go to lungs, can cause dyspnea, cough, and hemoptysis Dx: large terminally spined eggs, bladder biopsy helpful Rx: praziquantel Prevention: education, irrigation projects must have snail control

obligate parasite

cannot survive in a free living state

katayama syndorme

caused by pen of cercariae through skin from schistosomes -fever, chills, urticaria, lymhadenopathy, splenomegaly, etc 1-2 months after promary exposure results from massive release of parasitic agents, subsequent immune complex fomration. leukocytosis, eosinophilia, and ployclonal gammopathy

clonorchis senensis

chinese liver fluke intermediate: snail, freshwater fish vector: uncooked fish reservoir: dogs, cats, humans two intermediate hosts can survive in biliary tract for 50 years eggs pass inf eces, eaten by snails, cycle continues eggs become adults in bile duct of liver

fecal specimens

do not contaminate with water -water can destroy trophozoites several examinations are necessary befroe parasitic infection can be ruled out -report of no parasites seen based on exam of single specimen should be accepted with caution liquid/diarrhea should be examined within 30 minutes there are preservatives store at 4 degrees C, do not freeze

hymenolepis nana

dwarf tapeworm (2-4cm) larvae: insects adults: rodents, humans simple life, does not require intermediate host eggs hatch in intestine, develop to cysticercoid larva, grow to adult worms and leave host. leads to hyperinfection with heavy worm burdens, severe clinical symptoms

hymenolepis diminuta

dwarf tapeworm (20-60cm) larvae: insects adults: rodents, humans primarily rats and mice scolex lacks hooklets, egg is large and bile stained, no polar filaments life cycle more complex than h. nana

c. senensis

epi: 15 million, asian refugees cause: consumption of raw, pickled, smoked, dry freshwater fish symptoms: biliary obstruction can result in adenocarcinoma of bile ducts, liver abscesses Dx: duodenal aspirates may be necessary Rx: praziquantel prevention: don't eat undercooked fish, sanitize properly

p. westermani

epi: asia, africa, latin america cause: consume undercooked freshwater crabs and crayfish symptoms: various lung shit, larval worms can invade spinal cord and brain, creating neurologic disease Dx: sputum and feces brown operculated eggs, examine pleural effusions for eggs Rx praziquantel prevent: don't eat undercooked crabs. pickling/wine saking of crabs does not kill infective metacercarial stage, proper sanitation

d. caninum

epi: worldwide, esp in children enar dogs/cats cause: pet chews flea, licks childs mouth symptoms: light-asymptomatic. heavier-ab discomfort, anal pruritus, diarrhea, anal pruritis due to active migration of motle proglottids Dx: egg packets, visible proglottids in feces Rx: noclosamids prevention: deworm dogs and cats, no allow licking kid mouths, pets should be treated to eradicate fleas

e multilocularis

epi: canada, ussr, n. japan, central europe, alaska, montana, N+S dakota, minnesota, iowa cause: humans become infected with cyst stage due to contact w/ fox, dog, cat feces contaminated with eggs symptoms: maybe years. in liver, cysts eventually mimic a carcinoma, liver enlargement and obstruction of biliary and portal pathways. may metastasize to lungs and brain. malnutrition, ascites, and portal hypertension mimin hepatic cirrhosis. untreated mortality app. 70% Dx: no protoscolices, pathologists can mistake for carcinoma. radiology helpful Rx: surgical removal of cyst. mebendazole and albendazole can be used prevention: education, proper hygiene, deworming of farm dogs and cats. treat animals that have contact w/ kids

hookworms

epi: egg containing shit deposit in good dirt cause: direct contact with contaiminated soil (barefoot) symptoms: rash at entry sote, pneumonitis and eosinophilia from migrating larvae. adult worms: nausea, vomiting, dairrhea. blood lost from feeding worms, causes microcytic hypochromic anemia. severe: emaciation, mental and physical retardation Dx: characteristic eggs. adult worms rarely seen b/c remain in intestinal mucosa. larva not in stool unless specimen left out for a day. eggs cannot be distinguished Rx: albendazloe or mebendazole, iron therapy may be indicated to raise hemoglobin levels to normal, maybe blood transfusion Prevent: education, improved sanitation, controlled disposal of human shit, wear shoes

toxocara and baylisascaris

epi: eggs from infect dogs, cats, raccoons, are threat to humans esp. kids cause: shit exposure symptoms: depends on where they are. bleeding, eosiniphilic granulomas, necrosis. Dx: presence of eosinophilia, known exposure to animal, serology, stool exam (should not see adult worms) Rx: treat symptoms. no antiparasitic, corticosteroid may save life if patient has pulm, mrocardial, CNS involvement b/c infection is imflammatory response to worm Prevent: kill pet worms, clean up pet shit, keep raccoons out

echinococcus granulosus (hydatid cyst)

epi: global, correlated with raising sheep cause: human infection follows ingestion of contaminated water or vegetation, as well as hand-to-mouth transmission of canine feces carrying infective eggs symptoms: slow growing (5-20 years) pressure from cyst often first sign, location dependent Dx: imaging. aspiration may confirm diagnosis, high risk of anaphylaxis, dissemination. serology, esp for hepatic cysts Rx: surgical resection, if possible, sometimes aspirate cyst, add formalin. if surgery not psosible, albendazole, mebendazole, or praziquantel Prevention: education regarding transmission and role of canines in life cycle

s. stercoralis

epi: low prev, broader geo distro, sexual transmission occurs, can be animal reservoir cause: contaminated soil symptoms: pneumonitis. intest infect asymptomatic. heavy burden effects biliary/pancreatic ducts, small bowel, colon, causing inflammation/ulceration --> epigastric pain, tenderness, vomiting, diarrhea, malabsorption. mimics peptic ulcer disease, peripheral eosinophila... think ___________. autoinfect-->longterm infect, fatal hyperinfection if host-parasite balance distrubed by immunocmpromising drug/illness Dx: difficult. concen. stool sediment reveals larval worms, eggs not seen, shit once a day for 3 days Rx: ivermectin prevent: educate, sanitate, treat

f buski

epi: needs snail host. china, vietnam, thailand, indonesia, malaysia, india, pigs, dogs, rabbits serve as reservoir hosts in endemic areas cause: humans ingest metacercaria symptoms: malapsorption syndrome similar to giardiasis, marked eosinophilia is present Dx: large golden bile stained eggs, operculum on top Rx: praziquantel prevention: education of safe consumption of infective aquatic vegetation, sanitation, control o fhuman feces, kill snails with molluscicides

a. lumbricoides

epi: poor sani+human feces as fertilizer. eggs survive months in sewage, most ocmmon helminth infect worldwide, 1bil infected. no animal reservoir, A. suum found in pigs cause: ingestion of eggs symptoms: -few worms: none; migrate to bile duct and liver, perforate intestine, peritonitis/2nd infect -heavy: pneumonitis (asthma attakk), eosinophilia, oxygen debt, ab tenderness, fever, distention, vomiting Dx: dintinct eggs in stool, adults can pass in feces, pulm:find larvae+eosinophils in sputum Rx: albendazole or mebendazole ***mixed infect, treat ascaris first Prevent: education, improve sani, avoid human shit as fertilizer

a. braziliense

epi: subtropical+tropical regions cause: children play in soil/sandboxes w/ animal shit symptoms: migrating larvae cause erythematous/vesicular reaction, pruritis/scratching causes 2nd infect, half patients Loffler syndrome, pulmonary migration Dx: larvae in skin biopsy, clinical appearance of tunnels, larvae rarely in sputum Rx: albendazole, ivermectin, thiabendazole, antihistamines for pruritis prevent: educate pet owners treat animals for worms, pick up pet shit, wear shoes

h. diminuta

epi: worldiwde. larval insects feed on infected rat feces and humans eat contaminated grain cause: rodent contamination/mealworms in uncooked grain symptoms: mild burden, no symptoms. heavier: nausea, ab discomfort, anorexia, diarrhea Dx: bile-stained egg that lacks polar filaments Rx: niclosamide, w praziquantel an alternative prevention: rodent control where grain is stored

t. trichiura

epi: worldwide cause: shit symptoms: few: asymptomatic. many: ab distention, bloody iarrhea, weakness, weight loss, appendicitis, prolapsed rectum in kids, anemia and eosinophilia in severe infect Dx: bile-stained eggs with polar light manifestitions, may find eggs in stool Rx: albendazole or mebendazole, combined chemo highest efficacy prevent: education, good hygient, sanitaiton, avoid human shit as fertilizer

f. hepatica

epi: worldwide in sheep raising areas cause: human consumption of contaminated watercress symptoms: migration to liver irritates tissue, causes hepatomegaly, worms in bile ducts lead to hepatitis, some worms produce necrotic foci called liver rot Dx: oeprculated eggs in bile ducts Rx: triclabendazole prevention: avoid uncooked aquatic vegetation

e. vermicularis

epi: worldwide, crowded conditions (daycare), most common helminth infect in NA. dientamoeba fragilis correlates well w/this cause: ingestion of eggs, larval worm free to develop in intestines. no known animal reservoir symptoms: many carriers asymptomatic, if allergic loss of sleep and fatigue. scratching causes 2ndary bacterial infection Dx: clinical manifest, detect eggs on anal mucosa. scotch tape prep. eosinophilia rarely seen Rx: albendazole or mebendazole Prevention: hygiene, be aware when dusting an infected house

protozaon physiology and replication

food uptake: pinocytosis of soluble or particulate, ngestion through cytosome, some use diffusion energy conversion: respiration in most parasitic protozoa is accomplished by facultatively anaerobic processes survival: -many parasitic protozoa develop into a cyst form that is less metabolically active -parasites that cannot form cysts must rely on direct transmission from host to host or require an arthropod vector to complete their life cycles -many protozoan have immunoevasive mechanisms that allow them to respond to attack by the host immune system by continusously changing their surface antigens ensuring continued survival within the host reproduction: simple binary fission (morogony), some by multiple fission (schizogony) alternating with sexual (sporogony or gametogony)

cystocercosis

getting the cyst in body tissue epi: where you contact human feces cause: eating t. solium eggs symptoms: cyst location dependent Dx: imaging of calcified cysticersi, visualise after excision, CT/MRI, serology Rx: praziquantel, albendazole, possibly steroids prevention: sanitation

T. solium infection

getting the tapeworm epi: Africa, India, SE Asia, China, Mexico, Latin America, Slavic countries cause: eating undercooked pork symptoms: indigestion, diarrhea Dx: stool sample Rx: niclosamide, (praziquantel, paromomycin, quinacrine are alternatives) Prevention: cook pork till grey

fasciolopsis buski

giant intestinal fluke intermediate host: snail biologic vector: water plants (water chestnuts) reservoir host: pigs, dogs, rabbits, humans humans ingest metacercaria, develops into immature flukes in duodenum

definitive host

host that harbors the adult or sexually reproducing stages of a parasite

infective mode

how the parasite invades the human body

nematodes (roundworms)

in US, primarily intestinal -intestinal parasites easily recognized by large size, cylindric, unsegmented bodies -live in intestinal tract and ID eggs in feces -ID by egg shape, size, thicknesss, structures inside Filariae infections of blood and tissues cause devastating disease -long, slender parasites of blood, lymph, subcutaneous, and CTs -transmitted by mosquitoes or biting flies -most produce larval worms called microfilariae that demonstrate in blood specimens in subcutaneous tissues and skin snips

ascaris lumbricoides

large pink worms (20-35cm) more complex than pinworms -ingest egg, larval worm penetrates duodenum, enters blood, goes to liver+heart, then pulmonary circulation -larvae goes to alveoli of lungs, where they grow and molt. 3 weeks later, larvae get coughed up, swallowed, returned to small intestine. -as M+F worms mature in jejunum, fertilizaiton starts egg prod, which is 200,000 eggs daily for a year -females can make unfertilized eggs w/out males. eggs in feces 60-75 days, fertilized eggs infectious after soil for 2 weeks

sparganosis

larval forms of several tapeworms closely related to D. latum epi: most prevalent Asia, cold water lakes cause: drinking pond or ditch water that contains crustaceans (copepods) that carry a larval tapeworm, eating raw tadpoles, frog, snakes symptoms: subcutaneous sites, painful inflammatory tissue reactions. In eye: painful w/ periorbital edema, poss corneal ulcers, ocular involvement Dx: surgical removal and sample looks like tapeworm Rx: surgical removal is customary approach prevention: don't drink pond/ditch water with crustaceans that harbor larval worms. ingestion of raw frog/snake flesh or their use as poultices over worms should also be avoided

strongyloides stercoralis

like hookworm, except -eggs hatch in larvae in intestine -larvae can become filariforms in intestine, cause autoinfection -free-living, nonparasitic cycle can be established outside human host skin penetrating larvae enters, follows pulmonary course, coughed up and swallowed, adults dev in small intest. rhabditiform larvae passed in stoll fevelop into living worms autoinfect: intestinal larvae dev into filariform, penetrate intest mucosa, go through circulation, coughed up, repeat cycle

paragonimus westermani

lung fluke intermediate: snail, freshwater crabs, crayfish vector: uncooked crabs, crayfish reservoir: pigs, monkeys, humans eat infected meat, larval worms make their way to pleural cavity, eggs apear in sputum or feces

schistosomes

s. mansoni, s. japonicum, s. haematobium causes schistosomiases (bilharziasis or snail fever) -male/female, no operculum, obligate intracellular parasite (not found in cavities, ducts, other tissues) -skin penetrating free-swimming cercariae -develop in intrahepatic portal circulation or in vesical prostatic rectal and uterine plexuses/veins coat themselves in host substances to have infections last 20-30 years develop in portal vein, pair up and migrate to final location 300-3000 eggs a day for 4-35 years man+japon: feces haema: urine eggs hatch in freshwater after leaving body to release miracidia, invades snail host, makes cercariae, released into water, infectious to humans

cercarial dermatitis

several nonhuman schistosomes have cercariae that penetrate human skin, making swimmers itch, cant dev into adult worms -natural hosts: birds and shorefeeders from freshwater lakes -Tx: trimeprazine and topical palliatives -control hard, bird migration and transfer of live snail. molluscicides most be used, don't move boat from lake to lake, dry your skin immediately

fasciola hepatica

sheep liver fluke intermediate: snail biologic vector: water plants (water chestnuts) reservoir: sheep, cattle, humans larval flukes migrate to live, become adult worms in bile ducts operculated eggs identical to buski

protists (protozoa)

simple microorganisms that range in size from 2 to 100 micrometers -reproduction: usually binary fission -facultative anaerobes four supergroups that contain human parasites -opisthokonta (__________ as well as fungi and animals) -amoebozoa -excavata -SAR (stramenopiles, alveolates, rhizaria)

s. mansoni

small branches of inferior mesenteric vein near lower colon eggs sharp lateral spine, 115-175umx45-70um epi: most widespread schistosome, africa, saudi arabia, madagascar, disease of economic progress (irrigation brings snails) cause: needs suitable snail host symptoms: itch, rash, cough, hepatitis -chronic: hepatosplenomegaly, ascites, white tubercles on lives, eggs in spinal cord lungs and other sites, fibrous tissue surrounding portal vein can be fatal Dx: characteristic eggs Rx: praziquantel (resistance) or oxamniquine. adding artemether (antimalarial) improves. antihistamines + corticosteroids can help w/ schistosomal dermatitis and katayama syndrome prevention: education on worm lifecycles, molluscicide control of snails, improved sanitation

s. japonicum

small, circular eggs with tiny spine, lives in branches of sup. mesenteric vein around small intestine makes the most eggs out of S's, an much more infections makes granulomas in brain, neurologic sympt(lethargy, speech, visual defects, seizures epi: china, philippines, indonesia, braod range of reservoir hosts (dogs, cats, cattle, horses, pigs) cause: needs suitable snail host symptoms: similar to s. mansoni. katayama more common in this b/c more eggs = more immune response. granulomas = seizures, neuro shit Dx: stool exam with smal golden eggs with tiny spines Rx: praziquantel prevention: education, know many work in rice patties and irrigations, vaccine maybe someday

ancylostoma braziliense

species of hookworms, naturally parasitic in intest of dogs and cats, accidentally human infect makes cutaneous larva migrans(aka ground itch and creeping eruption) filariform larvae of hookworm penetrate intact skin but develops no further in humans larvae remain trapped in skin of wrong host for weeks or months, wander through subcutaneous tissue and creating serpentine tunnels

epidemiology

study of distro and determinants of health-related states or events in specified populations, and applicaiton of this study to control of health problems

parasitism

symbiotic relationship in which one organism (the parasite) is metabolically dependant on the other organism (host) and gains all the benefit. Host adversely affected

commensalism

symbiotic relationship in which one organism is benefitted, and the other is neither benefitted nor harmed

mutualism

symtiobic relationship in which both orhanisms are benefitted

cestodes

tapeworms don't eat ham, but bothrium'll atum taenia diplidium echinococcus hymenolepis diphyllobothrium latum

intermediate host

that hose which harbors the immature, larval, or asexually reproducing forms of a parasite

infective route

the entrance which the parasite invades the human body

route of infection injection

though host tissues by vector or agent -arthropod borne: by mouth parts,salivary glands, or waste products -transfusion: present in donor blood at time of transfusion

route of infection active penetration

through host tissues,skin or mucous membranes -remains on.within epidermis or subcutaneous tissues -penetrates to other host organs or tissues cercarial dermatitis (swimmer's itch) -parasites released from infected snails into fresh and salt water where they can burrow into the skin causing allergic reactions

route of infection congenital

transmission of parasites across the placental barrier from mother to fetus

symbiosis

two organisms of different species living together

echinococcus granulosus

unilocular hydatid cyst larvae: herbivores, humans adults: canines resides in bowel eggs passed in feces eggs ingested by intermediate hosts and release oncospheres that migrate to various organs hydatis cysts form, produce protoscolices and daughter cysts these are ingested, causing infection. the protoscolices evaginate, creating protoscoleces scolexes attach to intestine of definite host, develop into adults in 32-80 days