Parasitology, Zoonoses, and Diagnostics Flashcards
Why is parasitology important ?
global health- malaria (200mil+), US- pinworm, giardia, Immune suppressed- toxoplasmosis, strongyloidiasis, travelers- malaria, schistosomiasis
What are the various types of microbes?
virus, bacteria, fungi, and parasites: protozoan (unicellular), worm or helminth (multicellular), and ectoparasite (on skin or burrowing)
What are the two categories of protozoa?
unicellular, eukaryote, intracellular- often needs a vector, i.e. malaria, extracellular- often fecal-oral transmission, i.e. giardia (2 forms trophozoite- disease in humans and dormant cyst- adapted for passing)
What are the different kinds of helminthes?
round (hookworms causes anemia), flat- cestodes (taenia solium causes seizures), and Flukes- trematodes (schistoma mansoni causes cirrhosis)
What are the differences between protozoa and helminthes?
P: unicellular, vector or fecal oral, no eosinophilia; H- multicellular, also penetrate skin, eosinophilia common
What are the protozoa in the blood?
Plasmodium vivax, Plasmodium falciparum, plasmodium ovale, plasmodium malariae, plasmodium knowlesi, and Babesia microti
What are the key features of the disease Malaria?
Protozoan- plasmodium, intracellular in the blood, human reservoir, vector- female anopheles, red cell lysis, fever, chills
What are all the ways malaria is spread?
female anopheles mosquito (rare in US), rare- needle sharing, transfusion, perinatal
What are the vectors of malaria?
distribution affects disease distribution, strategy: no stagnant water, no mosquito breeding then no malaria, virus replicates inside mosquito increasing viral load with bite
What things affect P. falciparum progression into disease?
less in sickle trait, still need prophylaxis, prophylaxis designed for this strain
What host genetic features affect P vivax?
absent in duffy neg. (W. African trait)
What host genetic features affect P ovale?
fills in Duffy negative niche
What is the incubation period of malaria?
usually 8-30 days after bite, P. vivax and ovale- hypnozoites persist in liver,get attacks months to years later, P. Malariae- older cells, chronic infection
What is the sequence of malaria in humans? Anopheles?
female anopheles bite, drool, saliva in wound, to liver, mature, released as merozoites to RBC, cycles of RBC merozoite release, may form gametes; female ingests gametocytes, combines, invades gut, migrates to salivary gland
How is malaria diagnosed?
thick smear: multiple blood droplets, look for lysed RBC, sensitive for parasitemia; thin smear: see red cell, parasite morphology, can make species diagnosis
What are the features of P. Falciparum disease?
attacks RBC, heaviest parasitemia, deadliest, balanced polymorphism (less severe w/ Hgb AS or SS, “malignant tertian”, cerebral, renal malaria, chloroquine-resistant, gametocyte
What prophylaxis is used with P. Flaciparum that is chloroquine-resistant? Treatment?
mefloquine, atovaquone-proguanil (Malarone), doxycycline; quinine/quinidine or artemisinin, immediate treatment needed
What age RBC and is the cycle length of the species of malaria?
Falciparum- all ages, 48hrs, vivax and ovale- young, 48hrs, Malariae- old, 72 hrs
what is the key histological feature for plasmodium vivax?
schuffner’s dots
what is the key histological feature for plasmodium ovale?
resembles vivax, oval crenated
what is the key histological feature for plasmodium malariae?
“band” form, big dark band
what are the key features of plasmodium knowlesi?
emerging infectious disease, not common in US travelers, known in macaques, SE asia, morphology like P. Malariae, daily fevers, usually not fatal
what is the extra-erythrocyte stage of malaria? Treatment?
persistence with P. vivax/olvale, need drug effective in liver, primaquine usual choice, causes hemolysis with G6PD deficiency
what does the P. falciparum prophylaxis regimen look like?
start 2wk b4 arrival (1-2days for doxycycline or atovaquone-proguanil) drug levels tolerable, Q wk (daily for doxy or atov-pro), continue 4wk after departure (7 days for atov-pro), not 100% effective
what are the drawbacks of doxycycline?
photosensitivity in some, yeast, risk of esophagitis and perforation, take with full glass of water, remain upright 30 min
What are the drawbacks of mefloquine?
disturbing dreams, under controversy about long-lasting psychologic illness
What besides prophylaxis is recommended to prevent malaria?
mosquito avoidance- sleep screened or netting, indoors evening and nights (aedes dengue/yellow fever day time biting), DEET repellent, also lemon oil or eucalyptus, picaridin, permethrin on clothing (knock down), long clothing
What are the features of babesi microti?
often in cape cod and Martha’s vineyard, tetrad in cell, like malaria- protozoan, intracellular, vector, blood, fever and chills, unlike malaria- tick sread, mild in spleen, clindamycin, quinine if severe
What are the various protozoa in tissue?
toxoplasmosis, pneumocystis jiroveci, leishmaniasis, trypanosoma cruzi, Trypanosoma brucei (rhodensiense and trypomastigote) naegleria-acanthoamoeba
What are the features of toxoplasmosis?
toxoplasma gondii, intracellular protozoan, variety of syndromes- mononucleosis, retinitis, congenital infection, brain (AIDS), other immune gap, oocytes from cat feces and inadequately cooked meat
What are the features of pneumocystis jiroveci?
classic AIDS opportunist, protozoan (fungus now), theory- infects nearly everyone but host defenses control it, defect in cell immunity, prevent & treat- trimethoprim-sulfamethoxazole
What are the features of leishmaniasis?
protozoa in tissue, spread by phlebotomine sandflies, manifests as cutaneous non-healing ulcer or visceral (kala azar- fever, wt. loss, anemia, leukopenia
What are the features of Trypanosoma cruzi?
chagas disease, protozoan in tissue, latin America, Rub reduviid bug feces w/ T. cruzi into wound, esophageal dysmotility, heart disease, kinetoplast in front of cycle shaped nucleus with flagella
What are the features of Trypanosoma brucei?
African sleeping sickness, protozoan, tissue, Tsetse fly salivary glands, bite, ultimately encephalitis, treatment difficult and limited; rhodesiense and trypomasigote
What are the features of naegleria?
other free-living ameba, acanthoameoeba, wear contact lenses, get eye infection, swim in fresh water, get meningoencephalitis, occurs in US
What are the protozoa infections in the intestine?
E histolytica, Zoonoses- giardia, cryptosporidium, cyclospora
What are the protozoa infections in the vagina?
trichomonas vaginalis
What are the features of entamoeba histolytica?
ameba, asymptomatic human carriers pass cysts, diarrhea pt pass labile trophozoites, fecal-oral, bloody diarrhea, liver abscess, hard to distinguish from non-pathogenic amoebae (normal flora), white cells in stool, only decolonize in outbreaks, treatment of invasive disease- metronidazole and luminal agent
What are the features of giardia lamblia?
blocks portion of bowel, preventing absorption of fluids and nutrients, chronic diarrhea, fecal oral: day care, oral-anal sex, streams contaminated by beavers, St Petersburg Russia, stool, duodenal aspirate for tophozoites, treat w/ metronidazole
What are the features of cryptosporidium?
initially- zoonotic diarrhea in calf handlers, AIDS, Milwaukee system users; Acid fast stool, self limited in immune-intact, treat- nitaoxanide
What are the features of cyclospora cayentanensis?
“big crypto”, resembles large version of cryptosporidium, causes diarrhea, raspberries from central America (contaminated food and water), treat with trimethoprim-sufamethoxazole
What are the features of isospora belli?
watery diarrhea in AIDS, responds to trimethoprim-sulfamethoxazole
What are the features of microsporidia?
enterocytozoon-bieneusi, transient diarrhea in normal, chronic in AIDS, treat with albendazole
What are the features of trichomonas vaginalis?
15% of women, only occasionally causes vaginitis, sexual transmission, men asymptomatic usually, frothy cream discharge, pH> 4.5, treat- metronidazole
What are the features of intestinal helminths?
nematodes (roundworms)- ingested: acaris, enterobius, Trichuris, penetrate skin- hookworms, strongyloides; cestodes (tapeworms)- pork, beef, fish
What are the intestinal roundworm helminths?
ascaris lumbricoides, enterobius (pinworm), trichuris trichiuria (whipworm), strongyloides, hookworms (necator americanus, ancyclostoma duodenale)
What are the features of ascaris lumbricoides (human roundworm)?
ingest eggs, hatch in small bowel, larvae to lymphatics and lungs, up to trachea, swallowed, mature to worms in intestine, females release eggs in stool, symptoms- depend on worm burden, pneumonia, worm ball bowel obstruction, treat-albendazole or mebendazole, visceral larva migrans (dead end animal round worm infection)
What are the features of enterobius (pinworm)?
fecal-oral, ingest eggs, hatch duodenum, jejunum, larvae to ileum, gravid female migrate to perianal skin to lay eggs at night (scotch tape on paddle between butt cheeks) albendazole or mebendazole, treat family, bed and clothes
What are the features of trichuris trichiura (whipworm)?
fecal-oral, ingest eggs, hatch in small bowel, larvae migrate to colon (adults mature), eggs pass out in feces, mature in soil, diarrhea, rectal prolapse due to tenesmus (defecation sensation), treat- mebendazole or albendazole
What are the features of strongyloides?
filariform larvae in stool, larvae penetrate skin, to lymphatics, lung, coughed, swallowed to duodenum and jejunum
What are the features of the strongyloides illness?
cough, wheezing, fever, pain, vomiting, diarrhea (large worm burden), sepsis (larvae cross abdominal wall), immunosuppressed self-hyper-infection (reinfect themselves) chronic symptoms WWII POWs
How is strongyloides diagnose and treated?
eosinophilia, hard to see larvae in stool, consider duodenal exam, ivermectin