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130 Cards in this Set
- Front
- Back
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why parasitology
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global health impact: malaria prevalence 200 million
US common: pinworm, giardia immunosuppressed: toxoplasmosis, strongyloidiasis travelers: malaria, schistosomiasis |
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parasites main issues
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scientific & common names of organism
reservoir locale, time mode of transmission location in body scientific & common names of disease disease, main attibutes treatment |
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microbes include
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viruses: polio (acellular)
bacteria: Staphylococcus: prokaryote fungi: Canida : eukaryote parasites - protozoan: malaria (uni cell) - worm or helminth: Schistosomiasis (multi cell) - ectoparasite: scabies |
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protozoa
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1 cell ; euk
ic - often needs vector - malaria: Anopheles is its vector ec - often fecal-oral - giardia with 2 forms: active trophozoite & dormant cyst |
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helminths
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round: nematodes
- hookworms: anemia flat: cestodes 0 Taenia solium : seizures flukes: trematodes - Schistoma mansoni: cirrhosis |
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protozoa vs helminths
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both parasites
protozoa - unicellular - vector or fecal-oral - no eosinophilia helminths - multicellular - also penetrate skin - eosinophilia common |
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malaria key points
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protozoan
- Plasmodium - ic - blood human reservoir vector - Anopheles - female (mosquito) Red cell lysis - fever & chills plasmodium vivax has ring form cytology |
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malaria transmission
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unusual
non mosquito spread: rare - transfusion, needle sharing - perinatal rare US spread: US Anopheles mosquitos bit infected persons |
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malaria vectors
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distribution affects disease distrubtion
strategy: no stagnant water, no mosquito breeding, no malaria amplify, not a flying syringe in tropics |
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malaria & genetics
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P. falciparum
- less in sickle trait, disease - still need to take prophylaxis P. vivax - basent in duffy neg (west african trait) - P. ovale fills duffy neg niche |
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malaria incubation
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usually 8-30 days after bite BUT
P. vivax & P. ovale - hypnozoites persist in liver - months to years later: attacks P. malariae - older cells, chronic infection |
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malaria sequence in humans
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female Anopheles bites, drools
in saliva, to wound to liver, mature released as merozoites, to RBC cycles of RBC merozoite release may form gametes |
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malaria sequence in anopheles
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female ingests gametocytes
combines invades gut migrates to salivary gland |
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malaria dx
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thick smear
- multiple drops of blood on 1 spot - lyse red cells - sensitive to parasitemia thin smearrr: see red cell, parasite morphology |
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Plasmodium falciparum
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attacks red cells of all ages
- so heaviest parasitemia - so deadliest balanced polymorphism: less severe with Hgb AS or SS X 48 hr? Malignant tertian |
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Plasmodium falciparum disease
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cerebral, renal malaria
chloroquine-resistant - prevent with mefloquine, atovaquone-proquanil (malarone), doxycycline - may need quinine/quinidine or artemisinin Rx immediate treatment needed |
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malaria species, ages of red cells that they attack, theoretical cycle length
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P. falciparum: all ages ; cycle length q 48 hr
- sickle cell ; heavy parasitemia - deadly: prophylaxis - some Hgb AS, SS protection - banana gametocyte - incubation 8-30 days P. vivax, ovale : attacks young ; q 48 hr (benign tertian) - vivax: Schuffner's dots ; large cells - ovale: resembles vivax; oval , crenated malariae attacks old ; q 72 hr (quartan) - Band form |
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plasmodium knowlesi
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"emerging" infectious disease ; not common in US travelers
known in macaques; southeast asia morphology like P. malariae daily fevers ; usually not fatal |
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"extra-erythrocytic" stage
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persistence in liver of P. vivax/ovale
to treat this stage, need drug effective in liver - primaquine is usual choice - BUT it causes hemolsis in those with G6PD def |
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Chloroquine Resistence
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concern mainlly with P. falciparum
not an issue in part of americas - north of panama canal - north of trinidad and tobago |
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P. falciparum prophylaxis
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start 2 wk before arrival : 1-2 days for doxycycline or atovaquone-proquanil
- drug levels, tolerability q wk: daily for doxy or atov-pro continue 4 wk after departure: 7 days for atov-pro ony P. falcip, not 100% effective |
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P. falciparum drug drawbacks
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doxycycline: photosensitivity in some
- yeast - rrisk of esophagitis & perforation ; take with full glass of water ; remain upright 30 min mefloquine: disturbin dreams ; controversy: psychiatric illness atovaquone-proguanil: cost |
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regimen designed for P. falciparum
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deadliest , butt only released from liver 4 wk.
prophylaxis designed for P. falciparum, not P. vivax E. africa: no mefloquine resistance adherence easier for mefloquine some labs inexperienced |
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mosquito avoidance
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sleep screened or netting
indoors evenings & nights: Aedes dengue/ywllow fever day DEET repellent ; also lemon oil of eucalyptus, picaridin permethrin clothing: knockdown long clothing |
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Babesia microti
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resembles malaria
cape cod martha's vineyard ring forms, tetrad fever & RBC abnormalities |
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Babesiosis like malaria
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protozoan
ic vector blood fever, chills |
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Babesiosis unlike malaria
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mild if spleen
tick spread clindamycin, quinine if severe |
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protozoans in blood
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plasmodium & Babesia
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protozoans in tissue
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Toxoplasma
Pneumocystis Leishmania Trypanosoma Naegleria |
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toxoplasmosis
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toxoplasma gondii
protozoan, ic variety of syndromes in tissues - mononucleosis syndrome - retinitis - congenital infection - brain (AIDS), other immune gap oocsts from cat feces & inadequately cooked meat |
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Pnneumocystis jiroveci
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classic AIDS opportunist
protozoan , now fungus fungus formerly classified as tissue invading protozoan therory: infects nearly everryone as child; host defenses control it defect in cell immuity: pneumonia prevent & treat: trimethoprim-sulfamethoxazole, others |
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Leishmania spp
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protozoa, tissue
spread by phlebotomine sandflies manifestations: cutaneous (non-healing ulcer) & visceral (kala azar) |
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Visceral leishmaniasis
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kala azar
soldier, was in southern italy, fever, weight loss, anemia, leukopenia L. donovanii: amastigotes marrow |
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reservoir for Leishmania spp
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dogs
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cutaneous leishmaniasis
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non healing ulcer
no response to usual Ab's for cellulitis service in iraq exposure history critical sandflies: use DEET to avoid cat litter: toxoplasmosis risk man waterborne pathogens many worms with skin contact |
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Trypanosoma cruzi
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Chagas disease
protozoan, tissue latin america rub reduviid bug feces with T. cruzi into wound esophageal dysmotility, heart has flagellum ; nucleus to site & kinetoplast |
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Trypanosoma brucei
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African sleeping sickness
protozoan, tissue africa Tsetse fly salivary glands, bite ultimately envephalitis, treatment difficult |
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Naegleria
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free living ameba
protozoans invading tissue Acanthoamoeba wear contact lenses, get eye infection swim in fresh water, get meningoencephalitis occurs in US |
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tissue protozoa include
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toxoplasmosis
pneumocystis leishmania T. cruzi T. brucei Naegleria, acanthamoeba |
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protozoa of intestinal & vaginal area
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E. histolytica
Zoonoses - Giardia - Cryptosporidium - Cyclospora - other Trichomonas vaginalis |
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Entamoeba histolytica
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ameba
asymptomatic human carriers pass cysts, diarrhea pts pass labile trophozoites fecal-oral bloody diarrhea, liver abscess |
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Entamoeba histolytica challenges
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distinguish from nonpathogenic amoebae, white cells in stool
illustrates contrasting concepts - colonization: org present on surface, not damaging host - infection: in "wrong" place |
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colonization
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humans carry 10x as many procaryotic cells as we have euk cells
generally, no need to decolonize exceptions involve outbreaks, recurrences ex: E. histolytica cyst passers |
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treatment of E. histolytica
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treatment of invasive disease includes both
- Metronidazole - lumenal agent |
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Giardia lamblia
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chronic diarrhea (wks)
fecal-oral: day care, oral anal sex, streams contaminated by beavers, St. petersburg, russia stool, duodenal aspirate for trophozoites metronidazole |
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Cryptosporidium
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initially, zoonotic diarrhea in calf handlers
AIDS, milwaukee water system users acid fast stool for crypto self limited to immune intact therapy: Nitazoxanide |
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Cyclospora cayetanensis
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big crypto: resembles large version of cryptosporidium, causes diarrhea
raspberries from central america: contaminated food & water trimethoprim- sulfamethoxazole |
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other protozoa & diarrhea
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Isospora belli: watery diarrhea in AIDS, responds to trimethoprim-sulfamethoxazole
microsporidia: enterocytozoon bieneusi ; transiet diarrhea in normals, chronic in AIDS ; Albendazole |
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trichomonas vaginalis
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15% of women but only occasionally causes vaginitis
sexual transmission men asymptomatic usually frothy cream discharge, pH > 4.5 metronidazole motile on wet prep yeast buds ; squamous ep cells & PMNs |
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intestinal helminths
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nematodes (roundworms)
- ingested: Ascaris, enterobius, trichuris - penetrate skin: hookworms, strongyloides cestodes (tapeworms) : pork, beef, fish |
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Ascaris lumbricoides
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human roundworm
ingest eggs hatch in small bowel larvae to lymphatics, lungs up trachea, swallowed mature to worms in intestine females release eggs in stool |
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Ascaris lumbricoides syymptoms
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depend on worm burden
maybe pneumonia in lung stage worm ball bowel obstruction see eggs in stool, albendazole or mebendazole visceral larva migrans: dead end animal roundworm infection |
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roundworm infestation
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fecal-oral route: value of hand hygiene to interrupt transmission
example of visceral larva migrans not insect borne |
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Enterobius
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pinworm
fecal-oral ingest eggs hatch duodenum, jejunum larvae to ileum, large bowel gravid female migrate to perianal skin to lay eggs at night - perianal itching from egg laying scotch tape (adhesive out) on paddle b/c buttock cheeks, x100 on microscope albendazole or mebendazole treat fam, bed, clothes |
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Trichuris trichiura
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whipworm
fecal-oral ingest eggs, hatch in small bowel larvae migrate to colon, where adults mature eggs pass out in feces, mature in soil |
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T. trichiura manifestations & treatment
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diarrhea
rectal prolapse due to tenesmus (defecation sensation) mebendazole or albendazole |
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Strongyloides
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filariform larvae in stool
larvae penetrate skin to lymphatics, lung, couged swallowed, to duodenum & jejunum short buccal cavity prominent genital primordium Strongyloides stercoralis rhabditiform larva: threadworm |
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Strongyloides illness
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lungs: cough, wheezing, fever
pain, vomiting, diarrhea if many larvae cross ab wall: sepsis immunosuppressed self-hyper infection chronic symptoms WWII POWs |
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Strongyloides dx, rx
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often eosinophilia
hard to see larvae in stool consider duodenal exam ivermectin |
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hookworms
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necator americanus
ancyclostoma duodenale life cycle like Strongloides BUT - eggs in stool & need to mature outside body - no hyperinfection syndrome - no bowel wall invasion |
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hookworm illness
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chronic anemia, depends on burden
penetrate skin initially "ground itch" dog/cat hookworm: cutaneous larva migrans - migrate on skin |
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hookworm dx, rx
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eggs in stool
albendazole or mebendazole diet supplements to correct anemia |
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nematodes acquired by ingestion
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Ascaris (round): bowel ; eggs
- animal: visceral larva migrans Enterobius (pin) : night itch ; tape Trichura (whip) : prolapse ; eggs |
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nematodes from skin penetration
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Strongyloides (thread) : hyperinfection; larvae
necator (hook) : anemia ; eggs - animal: cutaneous larva migrans |
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Cestodes
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intestinal tapeworm
infected humans with eggs in feces animal eats feces cysticerci develop in animal, migrate to tissues humans eat undercooked tissue parasite hatches in intestine occur where cattle, pigs eat humanfeces usually nausea, vaue discomfort in infected human |
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variants of cestodes
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pork cysticerci to human brain: seizures
fish worm competes for B12 (anemia) |
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beef tapeworm
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Taenia saginata
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other tapeworms
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Taenia solium: pork
diphyllobothrium latum: fish see proglottidis (segments) of big (up to 10 m) worm in stool Praziquantel |
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Diphyllobothrium latum
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cooking & tasting fish, with history of tapeworm, suggests this
cause of vit B12 def leads to macrocytic anemia |
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Tissue, blood helminths : ingested
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Trichinella
T. solium E. granulosus visceral larva migrans guinea worm lung fluke liver fluke |
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tissue, blood helminths: skin
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Schistosomes
cutaneous larva migrans lymphatic filariasis river blindess |
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Trichinella spiralis
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ingest undercooked pork, bear meat
cysts hatch in human bowel, migrate to skeletal, cardiac muscle asymptomatic to fatal, depends on burden |
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Cysticercosis
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tissue invasion of T. solium pork tapeworm after cysticerci ingestion
cyst in brain - seizures & hydrocephalus Albendazole |
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Neurocysticercosis
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in orthodox jews
food prepared by staff carrring T. solium passing eggs in stool, contaminating hands & food eggs ingested, mature to larvae, go to brain, cause seizures |
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Echinococcosis
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hydatid disease of liver
Echinococcus granuulosus egg ingestion from feces of dogs, other carnivores eggs hatch in intestine, penetrate wall, hydatid cysts in various organs concern: spillage in surgery aspirate fluid: inject drug ;systemic albendazole |
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other ingested tissue worms
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visceral larva migrans: dog & cat roundworm migration
guinea worm: pull out of wound with stick lung fluke: paragonimus westermani ; cysts in lung liver fluke: Clonorchis sinensis |
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Etiology of Schistosomiasis
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Schistosomal trematodes
snail intermediate hosts distinct from, but related to, other trematodes (E. asia) - Paragonimiasis : lung - Clonorchiasis: liver |
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egg with large lateral spine
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Schistosoma mansoni
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egg in urine, with large terminal spine
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Schistosoma haematobium
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Schistosoma with very small spine
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S. japonicum
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zoonoses
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life cycle involving humans & other animals
transmitted to humans when skin exposed to fresh water containing cercaria Schistosoma mansoni - both snail & human - invades snail, develops - from snail, released into water (Cercariae) - from water, penetrates human skin, matures & lays eggs - human defecates into water, eggs hatch, & invades snail |
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bird schistosome
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ordinary cycle: birds, snails
penetrates human skin, but cannot mature life cycle not completed dies in skin: swimmer's itch seen in US, resolves spontaneously |
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Schistosomes life cycle
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mate in portal vein
then to site egg release miracidia hatch: water to snails fork tailed cercaria skin, R. heart, lung, gut, portal vein |
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Species & ova of Schistosome
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S. mansoni
- Americas - big spine, lateral - stool - colon, rectum S. haematobium - africa, mid east - big spine, terminal - urine, bladder S. japonicum - east asie - very small, lateral - stool - small bowel, colon |
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Schistosome presentation
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early: skin, itch, fever, headache, ab pain
serum sickness-like : Katayama syndrome (paraplegia) retained eggs, eosinophilic granulomas |
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Schistosome morbidity
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chronic granulomatous inflammation: systemic & local
S. haematobium: bladder & elswehere in urinary tract other species: liver & intestines |
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Schistosome lab dx
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microscopic egg ID
- size & spines serology developing |
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Schistosome treatment
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dermatitis, katayama: anti-inflammatory
worm killing: praziquantel |
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control & prevention of schistosomes
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feces out of fresh water
no vaccine suspect fresh water treat bathing water towel or rubbing alcohol |
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Achistosomiasis
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snails, fresh water
lateral spine: S. mansoni pruritic rash katayama syndrome bladder, bowel, liver, lungs |
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hematuria from S. haematobium
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widespread infection, ladder damage, hematuria
S. mansoni: liver disease P. falciparum: deadliest malarial species P. vivax: common malaria species |
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Filariasis
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black fly bites: onchocerciasis
mosquito bites: elephantiasis subcutaneous larvae mature to adult worms, release microfilariae |
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onchocerciasis
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onchocerca volvulus
subcutaneous spread reach anterior chamber river blindness skin snips treat ivermectin |
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Elaphantiasis
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Wucherreria bancrofti
lymphatic spread; inflame lymphatics obstruction grotesque lymphedema microfililariae in giemsa stained blood smear at 2 am |
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classifying parasites
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protozoa or helminth
site - blood & tissue - intestinal & vaginal route: ingestion, vector, skin and - ectoparasites (skin) scabies |
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general principles of ticks/zoonoses
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vector specificity
limited distribution often ic not from inanimate not person to person |
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tick fauna
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phylum: arthropoda
class: arachnida order: acarina |
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medically important ticks
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soft
hard - Ixodidae important in US - Dermacentor - Amblyomma egs - larva - nymph - adult |
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ticks in general
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arachnids: orrder acarina
hard or soft larva nymph adult humans often dead end (host) mid spring to mid summer |
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tick toxin
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granuloma: rxn to embedded tick part
can cause acute paralysis toxin effect cured by tick removal |
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tick viruses
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colorado tick fever
- high altitude west - biphasic fever - low WBC, platelets flaviviruses, such as tickborne encephalitis |
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Rickettsiae
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many obligate ic
pen ineffective humans often dead end serologic dx limited spotted fever, typhus groups |
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rocky mountain spotted fever
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Rickettsiae rickettsii prototype
fever, headache, rash immunoluorescent biopsy confirms doxycycline, chloramphenicol in eastern states sttarts distally (hands & feets) then proximal can cause vasculitis |
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if you suspect rocky mountain spotted fever
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treat promptly
don't wait for test results generally not cultured; serology takes days pen not regarded as effective ordinarily, no doxycycline if under 8 ; RMSF is an exception |
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Ehrlichiosis & anaplasmosis history
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vet disease
explanation for Rocky mountain spotless fever, in humans with tick exposure - fever, headache BUT - no rash, or RMSF serology |
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Ehrlichiosis & anaplasmosis etiology
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gram - ic
tick vectors often,, men post tick bite early summer subclinical disease: serology study |
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3 tyypes of ehrlichiosis & anaplasmosis
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human monocytic ehrlichiosis ; mulberry leukocyte inclusions within org;
- Ehrlichia chaffeenis - SE, S, central US Human granulo-cytotrophic ehrlichiosis - E. ewingii, E. cani - S. central US Human granulo-cytotrophic anaplasmosis - anaplasma phagocytophilum - NE US, upper midwest, northern California |
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clinical Ehrlichiosis & anaplasmosis
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fever, headache, chills,
rash infrequent transaminases up WBC & platelets down rare leukocyte inclusions: IFA tetracyclines preferred quinolone resistance |
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pathology, dx, & therapy o f Ehrlichiosis & anaplasmosis
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not vasculitis
specialized lab - indirect fluorescent Ab - PCR doxycycline prevention: tick avoidance |
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other tickborne bacteria
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tularemia: Francisella tularensis, ulcer,nodes
- bioterrorism candidate relapsing fever: Borrelia recurrentis, antigenic disguise so relapse lyme disease: rash - joint, neuro, heart, joint, fatigue |
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lyme serology
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may be false positive
overwhelming majority of lyme cses from NE coast or focuse near wisconsin/minnesota skeptical of dx without erythema chronicum migrans |
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yellow fever
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tpe species of Flavivurs : lipid enveloped RNA
from Aedes mosquitos - domestic, day biting - prefer humans multiorgan, includes liver vaccine for travelers |
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mosquito avoidance
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environment
- pyrethrum spray - screeens, bed netting clothes: long, permethrin person: DEET ( or picaridin, lemon oil of eucalyptus) activity: daytime caution |
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Dengue etiology
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a flavivirus: 4 serotypes
Aedes mosquito vectors tropical distribution approximates A. aegypti |
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Dengue features
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usually self limited fever, malaise
musculoskeletal pain (breakbone fever) might reflect marrow involvement |
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Dengue hemorrhagic fever/shock syndrome
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typically occurs if immune to one serotype, but infected with 2nd
vascular permeability, cytokine activation |
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Dengue intervention
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supportive care
no vaccine yet mosquito control, esp Aedes aegypti breeding sites (artifical water container) |
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west nile fever
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<1% fatal
<1% encephalitis 20% west nile fever 80% asymptomatic |
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west nile clinical features
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63% symptomatic at 30 days (possible overestimate) fever
neuroinvasive disease - some with anterior horn cell damage: polio pic - 37% full recovery 1 yr ; still weak, confusion, lightheaded |
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west nile virus
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flavivirus: like yellow fever
Culex mosquitos most infections mild : 1/150 encephalitis also, myelitis, meningitis serum or CSF IgMM no specific treatment |
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solitary angiomatous nodule
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verruga peruana
bartonellosis |
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bartonellosis
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B. bacilliformis, sandflies
andean valleys 2000-8000 ft oroya fever, RBC verruga 16S RNA like B. henselae |
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plague
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yersinia pestis
fleas aandon dying rats (insect vector) painful lymphadenopathy, also pneumonic black plague, few US cases streptomycin doxycycline |
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mycobacterium marinum
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exposure to ssalt water
cellulitis routine cultures negative, routine therapy ineffective need diagnostics & therapy suited for mycobacteria fish is vector |
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virus that's transmitted by rodent vector
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hantavirus pulmonary syndrome
4 corners area sin nombre virus deer mice adult resp distress lassa fever: W africa lymmphocytic choriomeningitis: hamster aseptic leptospirosis: red eye; kidney, liver ;rat urine |
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tularemia vector
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small mammal: rabbits
also ticks |
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what is also transmitted by small mammal
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bartonella henselae
- cat scratch disease - persistent nodes - kitten Anthrax, esp goats - chest, ulcer, GI superior mediastinum prominent (widened) -CSF gram + rods ; large |
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what's transmitted by cattle
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Orf virus
- rancher, vet - maculopapule, often finger (solitary) Brucelllosis: variable, with arthritis, chronic fatigue -hard to dx, treat |
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what's transmitted by mammalian bites
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rat-bite fever
- streptobacillus moniliformis - spirillum minus - fever, arthritis pet: pasteurella multocida - drug choice like E. corrodens - dog bites human bites |
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human bite transmission
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clenched fist injury
eikenella corrodens (human mouth flora) pen, ampicillin ok nafcillin, cephalosporin no amoxicillin-clavulanic acid |
