Parasites & Prions

Parasites & Prions duce     Entamoeba histolytica – Entering the Historical Dig Transmission via fecal-oral transmission, cysts in water Disease includes amebiasis (dysentery, liver abscess with “anchovy paste” exudate with right upper quadrant tenderness, and “flask-shaped” colonic ulcerations,) Diagnosis via trophozoites or cysts in stool (active disease if only trophozoites, asymptomatic carrier if both are present) Treatment via metronidazole; intestinal cysts via paromomycin and iodoquinol     Giardia lamblia – Giardia Jungle Ride Transmission via fecal-oral route, cysts in water – common in campers drinking water from a “clear” mountain stream Disease includes giardiasis (bloating, flatulence, and steatorrhea) Diagnosis via multinucleated “kite-shaped” trophozoites or cysts in stool Treatment via metronidazole; prophylaxis via sanitation      Cryptosporidium – Tales from the Crypts Transmission via oocysts in water – common in municipal water sources and daycare centers Disease includes watery diarrhea in normal hosts and severe, protracted diarrhea in immunocompromised hosts Diagnosis via oocysts on acid fast stain – appear amethyst shape and color with four motile sporozoites Treatment via nitazoxanide in normal hosts and nitazoxanide or paromomycin azithromycin in immunocompromised; prophylaxis via filtration of city water supplies     Cyclospora cayetanesis & Isospora belli Transmission via fecal-oral route – contaminated raspberries. Disease includes severe diarrhea in immunocompromised patients. Diagnosis via stool microscopy and acid-fast positive (shows ruby-gem shaped). Treatment via TMP-SMX.     Trichomonas vaginalis – Tricks for Money Transmission via STI Disease includes foul-smelling, green vaginal discharge, dysuria, pruritis, and increased vaginal secretions in females; males are asymptomatic Diagnosis via highly motile trophozoites on wet mount prep of vaginal discharge or urine, “strawberry cervix” Treatment via metronidazole (concomitantly for both partners)     Naegleria fowleri – Naegleria Falls Transmission via swimming in fresh water lakes, specifically enters through the nasal passage and pierces the cribriform plate into the CSF Disease includes rapidly fatal meningoencephalitis with no corneal infection (only mature amoeba are present, not cysts) Diagnosis via negative gram stain and motile amoeba in CSF under microscopy, CSF has high PMN, low glucose, and high protein (seen via lumbar puncture) Treatment via amphotericin B (lowly effective)     Acanthamoeba Transmission is common in fresh water lakes and pools Disease includes chronic meningoencephalitis and corneal infection that can progress to blindness in immunocompromised hosts Diagnosis via cysts and mature amoeba in brain tissue and CSF and corneal scraping Treatment via multiple anti-fungal drugs and anti-microbial eye drops     Balmuthis mandrillaris Transmission is common in fresh water lakes and pools Disease includes chronic meningoencephalitis in normal and immunocompromised hosts and granulomatous skin lesions Diagnosis via cysts and mature amoeba found in brain tissue and skin biopsy Treatment via fluconazole, azithromycin, and pentamidine     Toxoplasma gondii – OH HI, IZ MAKIN SUM TOXO Transmission via cysts in meat and oocysts in cat feces – TORCHES infection Disease includes… o Congenital toxoplasmosis (chorioretinitis, hydrocephalus, intracranial calcifications, and sensorineural deafness) o Reactivation in AIDS (brain abscesses with ring-enhancing lesions and corneal infection with yellow-white fluffy patches on red retina) Diagnosis via “crescent-shaped” tachyzoite on biopsy Treatment via sulfadiazine and pyrimethamine, prophylaxis CD4+ <100      Trypanosome brucei – Prince Bruce to the Rescue Transmission via Tsetse fly (painful bite) Disease includes… o W. African Sleeping Sickness (gambiense) (slow progressive fevers, cervical and axillary lymphadenopathy, wasting, and late neurological symptoms) o E. African Sleeping Sickness (rhodesiense) (more severe and rapid with death occurring within weeks to months) Diagnosis via trypomastigote (motile-form) in blood smear Treatment via suramin for blood-borne disease and melarsprol for CNS penetration Other comments include intermittent fevers derived from the presence of a single glycoprotein encoded by VSG genes      Plasmodium Transmission via Anopheles mosquito Disease includes malaria (fever, headache, anemia, and splenomegaly)… o Plasmodium vivax and ovale (48-hour cycle of fevers, dormant in the liver) o Plasmodium falciparum (severe, irregular fever pattern, parasitized RBCs occlude capillaries in the brain, kidney, and lungs) o Plasmodum malariae (72-hour cycle of fevers) Diagnosis via trophozoite ring within RBCs, schizont containing merozoites, and red granules throughout RBC cytoplasm (specific to Plasmodium vivax and ovale) Treatment via atovaquone-proguanil, mefloquine, doxycycline, or chloroquine (for sensitive-species) Other comments include prophylaxis via insect repellant     Babesia microti and divergens Transmission via Ixodes tick – predominately in the NE United States Disease includes babesiosis (fever and mild hemolysis) with potential co-infection with Borrelia burgdorferi (Lyme disease) Diagnosis via ring form or “Maltese cross” in blood smear or PCR Treatment via atovaquone + azithromycin      Trypanosoma cruzi Transmission via Reduviid “Kissing” bug feces (painless bite) – reservoir is rodents, opossums, and armadillos; common in Texas, Mexico, and S. and Central America Disease includes Chagas disease (dilated cardiomyopathy, meningoencephalitis, megacolon, megaesophagus, unilateral periorbital swelling or Romana sign of acute stage) Diagnosis via trypomastigote in blood smear Treatment via benznidazole or nifurtimox Other comments include rodent, opossum, and armadillo reservoir; acute phase occurs for 1 month and then remains latent or in intermediate phase for remainder of life)     Leishmania Transmission via Sand fly – reservoir is rodent, dog, and fox reservoir; common in S. and Central America, Africa, and Middle East Disease includes… o Simple cutaneous (oriental sore and site of bite) o Diffuse cutaneous (nodules all over body, predominately nose) o Mucocutaneous (ulcers on mucus membranes of nose and mouth, destruction of these structures if untreated) o Visceral (spiking fevers, hepatosplenomegaly, and pancytopenia) – common in malnourished children (have distended abdomens) Diagnosis via delayed-type hypersensitivity (DTH) on skin test and amastigotes on skin scraping from ulcers Treatment via amphotericin B and sodium stibogluconate      Pneumocystis jiroveci – PCP Ping Pong Transmission via respiratory droplets Disease includes severe interstitial pneumonia (fever, shortness of breath, and non-productive cough, progress to death if untreated) Diagnosis via silver staining or immunofluorescent staining of alveolar lung secretions, “flying saucer-like” (bronchopulmonary lavage) Treatment via pentamidine or TMP-SMX Other comments include P. jiroveci was previously classified as a protozoa, but was re-classified as a fungi her es acquired by bloodsucking arthropods for human transmission. Associated diseases are caused by allergic responses and treatment involves destruction of endosymbiotic Wolbachia bacteria, which leads to the sterility of the worms. Platyhelminths include tematodes (flukes or schistosomes) and cestodes (tapeworms). Tematodes have a water snail intermediate host, meanwhile cestodes live in the human digestive tract and are hermaphrodites – all cestodes are treated with praziquantel or niclosamide.     Enterobius vermicularis (pinworm) Transmission via fecal-oral route, consumption of contaminated eggs Disease includes anal pruritis Diagnosis via eggs on tape test Treatment via pyrantel pamoate or bendazoles    Ascaris lumbricoides (giant round worm) Transmission via fecal-oral route, consumption of contaminated eggs – common to the tropics and mountainous regions of S. United States Disease includes intestinal block, biliary obstruction, intestinal perforation, and migration from nose-mouth Treatment via bendazoles    Trichuris trichiura (whipworm) Transmission via fecal-oral route, consumption of contaminated eggs Disease includes loose stools and anemia Treatment via bendazoles    Nacator americanus (hookworm) Transmission via larval penetration of skin, contact of exposed wound to contaminated soil Disease includes anemia (blood sucking larvae) and rash at the site of infection Treatment via pyrantel pamoate or bendazoles     Stronglyoides stercoralis (threadworm) Transmission via larval penetration of skin, contact of exposed wound to contaminated soil Disease includes vomiting, weight loss, abdominal bloating, diarrhea, and anemia Treatment via ivermectin or bendazoles Other comments include (1) autoinfection, (2) direct infection, or (3) indirect infection refers to how the disease can be transmitted across individuals and self    Trichinella spiralis Transmission via consumption of undercooked pork Disease includes trichinosis (myalgia – invades skeletal muscle, fever, vomiting, and nausea) Treatment via bendazoles     Onchocerca volvulus Transmission via black fly – common in Africa and Central and South America Disease includes formation of fibrous nodules in skin and subcutaneous tissue, pruritis with darkened pigmentation (intraepithelial granulomas), and river blindness Diagnosis via microfilariae in skin biopsies or slit lamp examination (if found in the eye) Treatment via ivermectin    Wuchereria bancrofti & Brugia malay Transmission via female mosquito – Pacific Island & Africa; Malaysia & SE Asia Disease includes elephantiasis (worms invade and block lymph drainage specifically in the genital and inguinal regions) Treatment includes diethylcarbamazine     Schistosomiasis Transmission via fresh water snails (intermediate host); cercariae penetrate skin of humans Disease includes… o Dermatitis – “swimmer’s itch” o Katayama fever (fever, hives, headaches, weight loss and cough, hepatosplenomegaly, and eosinophilia – occurs as adults begin to lay eggs o Chronic fibrosis of organs and blood vessels leading to chronic abdominal pain, hematuria, neurological deficits, and pulmonary artery hypertension Diagnosis via eggs in stool or urine o S. japonicum and mansoni have eggs in feces o S. haematobium have eggs in urine Treatment via praziquantel     Taenia solium Transmission via undercooked pork containing cysticercus or eggs – attachment to intestinal mucosa via hooks Disease includes neurocysticerocosis (seizures, obstructive hydrocephalus, and focal neurological deficits) Diagnosis via eggs or proglottids in fecal samples Treatment via praziquantel or niclosamide     Taenia saginata Transmission via undercooked beef containing larvae Disease includes malnutrition and weight loss Diagnosis via eggs or proglottids in fecal samples Treatment via praziquantel or niclosamide     Diphyllobothrium latum Transmission via undercooked fish containing larvae Disease includes abdominal symptoms and anemia – larvae will absorb vitamin B12 Diagnosis via eggs or proglottids in fecal samples Treatment via praziquantel or niclosamide     Echinococcus granulossus Transmission via fecal-oral route – common in dog feces, will concentrate in liver and contain allergic fluids Disease includes severe hypersensitivity Diagnosis via CAT scan and tissue biopsy Treatment via albendazole and surgical removal – be careful of potential rupture, which will elicit an allergic response   sive ese n Gerstmann-Straussler-Scheinker disease (GSS) Fatal familial insomnia (FFI)