Parasites

Parasites: Protozoa and Helminths MALARIA Microbiological Features Vector/Transmission Disease Features Diagnosis Treatment At Risk Groups Notes Plasmodium falciparum vivax and ovale Trophozoites have multiple signet rings; high parisitemia, banana gametocytes; sequestration of mature forms Anopheles mosquito Hypnozoite stage, no sequestration (1)Giemsa blood film (2)Immunochromatography, Incubation period: 5-6 days in looks at 2 epitopes: histidine the liver; Fever (quotidian), rich protein II (long lasting) and splenomegaly, anemia glycolytic enzymes (short term) Fever (tertian), splenomegaly, anemia Longest incubation; Fever (quartian), splenomegaly, anemia, can produce long lasting infection that could go on for years, even a lifetime. IV Quinidine/Quinine + Doxycycline; if organism is resistant, Malarone is drug of choice Chloroquine or quinine + doxycycline + Primaquine (kills hypnozoite) Travelers; Expatriots; This is a medical emergency Foreigners who requiring immediate return home treatment. People who have Duffy antigens Duffy antigens are for vivax only. Anopheles mosquito Giemsa blood film examination malariae No sequestration Anopheles mosquito Giemsa blood film examination Chloroquine or quinine + doxycycline; Malarone if resistant OTHER PROTOZOA Microbiological Features Vector/Transmission Disease caused Features Diagnosis Treatment Giardia lamblia Horseshoe crab shaped, many Person to person; flagella, binucleate Water borne Round, intracellular, poking out into the lumen of the bowel. Person to person; Also water borne Fecal/oral; contamination Diarrhea Watery, flatulent diarrhea Stool O&P; Specific antigen test flagyl difficult to treat; Stool O&P; Acid fast stain! nitazoxanide Stoool O; Sensitivity ~50% At Risk Groups/ Notes Kids in daycare; Travelers, campers; Farms with well water Common in daycare; AIDS at risk for severe illness Travelers; gay men; immigrants Cryptosporidium Diarrhea Entamoeba histolytica Leishmania Trophozoite Amebic dysentery Watery diarrhea, no fever Bloody diarrhea; GI ulceration; Liver abscess; Rarely: brain, lung, pericardial abscess Incubates 2 weeks to several years; Causes a non healing ulcer flagyl major & tropica Amastigote and promastigote Sand fly; needles Cutaneous leishmaniasis pentamidine braziliensis Amastigote and promastigote Sand fly Incubates 2 weeks to several years; Infects nose, oral cavity, pharynx, and larynx and destroys Cutaneous and mucocutaneous architecture Biopsy Incubates 3-8 months; fever, weight loss, weakness; hepatosplenomegaly, kala-azar Encephalitis, brain lesions, chorioretinitis, myocarditis, pneumonitis Giemsa or DFA; Culture; PCR Serology (IgM=acute; IgG resolved); Biopsy (particularly for brain lesions pentamidine donovani Amastigote and promastigote Sand fly Ingestion; Undercooked meat, cat feces Systemic leishmaniasis pentamidine Pregnant women (primary); Immune compromised (reactivation) Toxoplasma gondii Toxoplasmosis fansidar? Trichomonas vaginalis Trophozoite; looks a bit like Giardia Sexual transmission; can survive for up to 45 minutes outside Vaginitis; PID; Epidydymitis; host Prostatitis 50-75% asymptomatic; wide ranges of disease in males and females Can clearly see the organism in vaginal secretions Flagyl HELMINTHIC INFECTIONS Nematodes: Roundworms Microbiological Features Vector/Transmission Incubation, infectivity Features Diagnosis Treatment At Risk Groups/ Notes Ancyclostoma Hookworm Nematode; imbeds in the GI tract mucosa Human reservoir; Larva enters skin Consumes blood; major feature is anemia; Can gt asthma and bronchitis when the larva migrate 8 weeks; larva are infective for through the lungs. The worms 2 weeks make a unique anticoagulant. Eggs in stool Normally asymptomatic, can get bowel obstruction, stunted growth, vitamin A deficiency Normally asymptomatic, can get 2-3 months; worm produces 3- GI problems in heavy infections; 20,000 eggs per day rectal prolapse 2-3 months 1 month; shed rhabitoform larva; rhabitoform larva either become infective or they become free living adults that make more larva pyrantel pamoate, mebendazole pyrantel pamoate, mebendazole The anemia is particularly bad for children, causes CNS problems Ascaris Ascariasis Nematode Human reservoir; Ingestion of eggs Human reservoir; Ingestion of eggs Human, canine, primate reservoirs; enter skin, travel to lungs, coughed into GI tract Human reservoir; Ingestion of eggs Eggs in stool, worm in person Eggs in stool, worm in person pulmonary eosinophilia Trichuris Whipworm Nematode mebendazole Stronglyoides Enterobius Strongliodiasis Pinworm Nematode Nematode Skin rash; Local GI damage: diarrhea, enteropathy; eosinophilia and hyperinfection in immune suppressed; larva Adults and larva in stool; currens serology Eggs in stool; Scotch tape method 1 month; autoinfection possible Perianal pruritis thiabendazole pyrantel pamoate; mebendazole Immunosuppressed patitents get hyperinfection Loa loa Filariasis Nematode; Wolbachia bacteria are obligate eendosymbionts; LPS in wolbachia initiates Adult worms cause problems: inflammatory response to Human reservoir; fly 3-12 months; microfilaria are Calabar swellings from adults, dying worm vector the infective stage, cause fever and adults migrating across eye Nematode; Wolbachia bacteria are obligate eendosymbionts; LPS in wolbachia initiates inflammatory response to Human reservoir; fly 3-12 months; microfilaria are dying worm vector the infective stage, cause fever Nematode; Wolbachia bacteria are obligate eendosymbionts; LPS in wolbachia initiates Human reservoir; inflammatory response to Mosquito and fly dying worm vector Microfilariae cause problems: Dermatitis, nodules, and eye lesions; common cause of river blindness if chronic blood smear; eosinophilia Microfilariae in blood Onchocerca volvulus Filariasis blood smear, eosinophilia doxycycline Microfilariae in eye and skin Brugia malayi; Wucheria bancrofti Filariasis 3-12 months; microfilaria are the infective stage, cause fever Lymphitis, elaphantiasis, chyluria blood smear, eosinophilia doxycycline Microfilariae in blood Trematode: Flukes Microbiological Features Vector/Transmission Incubation, infectivity Schistosoma Trematode flatworms; granulomatous reaction to Schistosomiasis eggs Cercaria from snails penetrate skin 2-16 weeks after infection can experience Katayama fever Features Hepatic fibrosis, portal hypertension, cancer of bladder and colon, ectopic eggs and dysuria Diagnosis Treatment At Risk Groups/ Notes Can develop innate and acquired resistance to infection. eggs in stool and urine Praziquantel Cestode: Tapeworm Microbiological Features Vector/Transmission Incubation, infectivity Reservior is wild game and domestic pigs/cows Features Diagnosis Treatment At Risk Groups/ Notes Taenia Tapeworm Cestode ingestion of cyst or aberrant egg yield different diseases Ingestion of cyst: not much; proglottids in stool; Ingestion of egg: cystercercosis; antibody detection; cysts epilepsy in neurcystercercosis on imaging Praziquantel MYCOSES Microbiological Features Mycosis Offending organism In situ In the lab Mode of Transmission Pathogenesis Organism grows in stratum corneum and leads to hypopigmentation by altering melanocytes. Disease Features 1. Hypopigmentation 2. Folliculitis 3. In neonates, fungemia. Diagnosis Tzank prep; Gram stain; Mother gram (+), buds gram (-) Treatment Topical for small areas; Systemic for large areas At Risk Groups Notes Tinea versicolor Malassezia furfur Yeast, buds, and short hyphae Septate, infrequently branching hyphae breaking into boxcar shaped spores Septate, infrequently branching hyphae breaking into boxcar shaped spores Septate, infrequently branching hyphae breaking into boxcar shaped spores Septate, infrequently branching hyphae breaking into boxcar shaped spores Septate, infrequently branching hyphae breaking into boxcar shaped spores ? Organism is common Reserviors in the soil, animals, and arthropods; Person to person, animal to person Reserviors in the soil, animals, and arthropods; Person to person, animal to person Reserviors in the soil, animals, and arthropods; Person to person, animal to person Reserviors in the soil, animals, and arthropods; Person to person, animal to person Reserviors in the soil, animals, and arthropods; Person to person, animal to person Infants are at risk for fungemia. Tinea capitus Trichophyton Microconidia Virulence factors: Keratinases, Elastases, Host mimicry (similarity to blood group A Dry, non permanent antigens) alopecia; sometimes pus. Virulence factors: Keratinases, Elastases, Host mimicry (similarity to blood group A Anular lesions may be antigens) anywhere on body. Virulence factors: Keratinases, Elastases, Host mimicry (similarity to blood group A Jock itch, usually spares antigens) scrotum Virulence factors: Keratinases, Elastases, Host mimicry (similarity to blood group A Intertriginous; Vesicular; antigens) Moccasin type Virulence factors: Keratinases, Elastases, Host mimicry (similarity to blood group A antigens) Nail infections Red, scalded lesions with punctate satellite lesions; most commonly under breasts, axilla, groin, toe and finger webs Direct examination (KOH + Gram's); culture (3 to 14 days) Topical creams Everyone Direct examination (KOH + Gram's); culture (3 to 14 days) Topical creams Everyone Direct examination (KOH + Gram's); culture (3 to 14 days) Topical creams Everyone Direct examination (KOH + Gram's); culture (3 to 14 Best treated days) systemically Direct examination (KOH + Gram's); culture (3 to 14 days) Griseofulvin Humoral responses do not correlate with immunity; CMI does Dermatophytoses Tinea corporus Microsporum canis Macroconidia Humoral responses do not correlate with immunity; CMI does Tinea cruris Trichophyton Microconidia Humoral responses do not correlate with immunity; CMI does Tinea pedis (many types) Trichophyton Microconidia Everyone Humoral responses do not correlate with immunity; CMI does Tinea unguium Trichophyton Microconidia Everyone Humoral responses do not correlate with immunity; CMI does Primary cutaneous candidiasis Candida albicans Yeast, hyphae, pseudohyphae Yeast only Opportunistic Candida is commensal. However, C. albicans is the most virulent strain. NOT BY CULTURE; Direct examination (KOH + gram stain) CMI defects; steroids; wide spectrum Note that some normal antibiotic use. people can get candidiasis, but it's rare. CMI defects; steroids; wide spectrum antibiotic use. Primary mucosal candidiasis Candida albicans Yeast, hyphae, pseudohyphae Yeast only Opportunistic, except some cases of Candida vaginitis Candida is commensal. However, C. albicans is the most virulent strain. White pseudomembranous plaques on oral, esophageal, GI and vaginal areas NOT BY CULTURE; Direct examination (KOH + gram stain) The capsule is diagnostic; Stains poorly with H&E, would want to use india ink or alcian blue to find the capsule. Fontana Masson Stain can identify melanin Opportunists Cryptococcosis Cryptococcus neoformans Encapsulated yeast; buds with very narrow attachments Pathogenesis: You inhale the yeast, it replicates in the lung, it spreads hematogenously to the brain, and you get meningoencephalitis. Virulence: 1. Heteropolysaccharide capsule; 2. Phenyl oxidase 3. Melanin Opportunistic, inhaled inhibits O2 dependent killing 1. Meningoencephalitis 2. Pulmonary involvement 3. Disseminated 1. Alveolar interstitial pneumonia. Usually no extrapulmonary disease. 2. Fever, nonproductive cough, dyspnea. Indolent. Organ transplant recipients; AIDS; high Granulomatous dose steroids response Pneumocystosis Pneumocystis carinii Yeast, indented ping pong balls Yeast, hyphae, pseudohyphae Yeast in the lab; Anticlassical dimorphic. Opportunistic CMI defects Neutrophil defects; Tremendous disruptions. Invasive candidiasis Candida albicans Opportunistic Aspergillosis Aspergillus fumigatus Septate, angular, dichotomously branching hyphae. Conidia Opportunistic Pathogenesis: Conidia inhaled, reach alveoli; germination, hyphal invasion, angioinvasion, spread; sequelae; Virulence factors: Adherence receptors; Hyrdrolytic enzymes; complement inhibitor; toxins Rhinocerebral zygomycosis; Invasion of orbit and eye; Cranial nerve palsies; blindness; strokes Neutrophil defects; very late stage AIDS (due to neutrophil dysfunction) Same as aspergillus + diabetics with ketoacidosis Zygomycosis Zygomyces Big, ribbonlike, nonseptate hyphae with Sporangia, quick right angle branches growing Opportunistic Goes more to the nose, and invades nerves more. Histoplasmosis Histoplasma capsulatum Usually inside histiocytes; smaller yeast At room temperature and with crappy medium: hyphae. Poop of birds and bats; acquired by breathing in the poop. Spelunking! Inhalation of spores from the environment. The disease is mild in most hosts, but some get a bad disseminated disease (.1% of infections). Pathology is granulomatous Pneumonia; Affects the RES system. Systemic infections involve places where histiocytes frequent. histoplasmin test Histiocytes eat this Normal host; CMI bastard, but they can't defects make it worse. kill it. Blastomycosis ENDEMICS Blastomyces dermatitidis 6 B's: Big, broad based buds of the bad blastomyces At room temperature: hyphae with complex septae. Associated with water; acquired via pulmonary route Inhalation of spores from the environment. The disease is mild in most hosts, but some get a bad disseminated disease (.1% of infections). Pathology Pneumonia, skin ulcers, is granulomatous weight loss, night sweats. Inhalation of spores from the environment. The disease is mild in most hosts, but some get a bad disseminated disease (.1% of infections). Pathology is granulomatous Inhalation of spores from the environment. The disease is mild in most hosts, but some get a bad disseminated disease (.1% of infections). Pathology is granulomatous Inhalation of spores from the environment. The disease is mild in most hosts, but some get a bad disseminated disease (.1% of infections). Pathology is granulomatous Normal host; CMI Worse than the other defects make it worse. endemics. Coccidioidomycosis Coccidioides immitis Classically, spherules in the body. Arthroconidia in the lab. Desert soil; pulmonary route Mild pneumonia; bad for AIDS patients in the Southwest. They should not eat dirt. Coccidioidin test Normal host; CMI defects make it worse. Paracoccidiodomycosis Paracoccidioides brasiliensis At room temperature: hyphal South America (particularly Brazil) Normal host; CMI defects make it worse. Penicilliosis Penicillium At room temperature: hyphal Normal host; CMI defects make it worse. Small pox No crops Head-->extremity-->trunk Painful indented pustules Ugly Chicken pox Crops Trunk first Itchy vesicular rash Not as ugly