Parasites Flashcards
Giardia lamblia (Giardiasis)
Features: “* Most commonly seen parasite in US
Reservoir: “*Fecal oral
* Contaminated water
*Beavers (reservoir hosts)
*Camping, daycare, IgA deficiency, HIV CD4 < 100”
Transmission: “ingested cyst –> trophozoite in upper sm intestine
Trophozoites: motile, feeding stage (2 nuclei, 1 flagella); large ventral sucking disk that attaches to sm intestine
* Cyst: inactive, environment”
Diseases: “Chronic fatty diarrhea, bloating
Jejunal atrophy –> malabsorption especially in children”
Diagnosis: “Stool O&P (multinucleated trophozoites or cysts)
* Stool antigen (EIA, more sensitive)”
Treatment: “*Metronidzole
*Boil/filter water (chlorine may not be effective)”
Protozoa of Intestinal Tract
Entamoeba histolytica (Amebiasis)
Features:
Reservoir:
Transmission:
Diseases:
Diagnosis:
Treatment:
Protozoa of Intestinal Tract
Entamoeba histolytica (Amebiasis)
Features:
Reservoir: “*Fecal oral
* Tropical areas w poor sanitation”
Transmission: “ingested cyst –> trophozoite –> passes to colon & invades
Trophozoites: motile, feeding stage (nucleus w karyosome, ingests RBCs)
* Cyst: inactive, environment”
Diseases: “Infectious colitis w bloody diarrhea, abdominal pain (flask shaped ulcers on mucosa)
*Liver abscess w RUQ pain “
Diagnosis: “Colitis
*Stool O&P (cysts)
*Stool antigen
Liver abscess
* CT or US
*Serum Ab
Aspiration (ag detection or PCR)”
Treatment: “Metronidzole
*Luminal agent (paromycin)”
Protozoa of Intestinal Tract
Cryptosporidium
Features: “*Low infectious dose
* Long survival in moist environments
Protracted communicability
* Extreme chlorine tolerance”
Reservoir: “Fecal-oral route: ingestion of oocysts from contaminated drinking water or lakes/water parks, infected animals, raw oysters
OI: HIV w CD4 < 100”
Transmission:
Diseases: “ Watery diarrhea within 2 wk of travel that is self-limited
AIDS: prolonged non-bloody diarrhea, abdominal symptoms, poor oral intake, fever, wasting/malabsorption”
Diagnosis: “Acid fast stain of stool (oocysts)
* Biopsy of sm intestine: cysts on brushborder
ELISA, PCR”
Treatment: “Supportive
* Nitazoxanide in immunocompetent hosts (inconsistent evidence, but ART should help)
* Resistant to chlorination
*No PPX for HIV pts”
Protozoa of Intestinal Tract
Cystoisoporia (Isospora belli)
Features: * Larger than cryptosporidium
Reservoir: “*Fecal-oral route: ingestion of oocysts
* Tropical/subtropical areas
* OI: HIV w CD4 < 100”
Transmission:
Diseases: AIDS: prolonged non-bloody diarrhea, abdominal symptoms, poor oral intake, fever, wasting/malabsorption
Diagnosis: “Acid fast stain w stool (oocysts)
ELISA, PCR
* Biopsy of sm intestine”
Treatment: “ TMP-SMX
*No PPX for HIV pts”
Protozoa of Intestinal Tract
Cyclospora
Features:
Reservoir: “* Ingestion of imported berries, produce & related to migrating birds
Seen in outbreaks with contaminated food, returning travelers or HIV infected pts”
Transmission:
Diseases: “Non-bloody, watery diarrhea in healthy adults without significant fever
* Does NOT cause systemic or severe disease”
Diagnosis: *Acid fast stain w stool: spherical bodies or oocyst (8-10 um in diameter)
Treatment: TMP-SMX
Protozoa of Intestinal Tract
Microsporidia
Features: “* Many species with many presentations
* Smallest one”
Reservoir: “*Fecal-oral route: ingestion of spores
* OI: HIV w CD4 < 100”
Transmission:
Diseases: “Can be systemic or involve eyes, muscles, intestine, biliary tree; chronic diarrhea in immunocompromised (esp AIDS)
AIDS: prolonged non-bloody diarrhea, abdominal symptoms, poor oral intake, fever, wasting/malabsorption”
Diagnosis: “Modified trichrome stain
Acid fast stain w stool: oocytes/spores in stool
* ELISA, PCR
* Biopsy of sm intestine”
Treatment: “benzimidazole
*No PPX for HIV pts”
Protozoa of Intestinal Tract
Toxoplasmosis (Toxoplasma gondii)
Features:
Reservoir: “* ingestion of cat oocyst from feces, cysts in meat, crosses placenta (greatest risk during 3rd trimester, but most symptoms if contracted during first semester), blood transfusion/ transplant
* OI: HIV w CD4 < 100”
Transmission:
Diseases: “* Immunocompetent: flu like symptoms, self limited
* Immunocompromised: reactivation of infection –> brain abscesses that cause HA, altered mental status, seizures, personality changes, focal neuro deficits
Congenital:
* Chorioretinitis (unlikely w CMV), hydrocephalus (Not seen w CMV, enlarged ventricles), intracranial calcifications (more diffuse than CMV which is along ventricles)
* Petechiae, lymphadenopathy, jaundice, muscular-papular rash, small for gest age, microcephaly”
Diagnosis: “* Brain biopsy (cysts in tissue)
* CSF (tachyzoite)
*PCR
* Brain CT/MRI: multiple ring-enhancing lesions
*Serology (IgM/IgG)
Congenital:
During pregnancy: US (growth delay, hydrocephalus, calcifications, ascites)
* 18 wk: Fetal blood sample, amniotic fluid sample for PCR
* Newborn: IgM screening”
Treatment: “Pyrimethamine + Sulfadiazine + Leucovorin (mitigates bone marrow suppressive effects of pyrimethamine)
* Clindamycin (against only tachyzoites, not cysts)
- HIV PPX: TMP-SMX (CD4 = 50-100)
Congenital:
* Spiramycin: reduces transmission by 50%; does NOT tx infected fetus
* Pyrimethamine & Sulfadiazine: 1 yr for infected NB (stops active disease and restores normal functioning)”
Protozoa of CNS
Naegleria fowleri
Features: * Warm freshwater in Southern states
Reservoir:
Transmission: Enters nose during water activity (freshwater, pools, tapwater) & invades CSF through cribiform plate
Diseases: Primary Amebic Meningoencephalitis (PAM): seizures, hallucinations, vomiting, stiff neck, lack of coordination
Diagnosis: “*CSF (trophozoites & occassionally flagellates)
*Brain biopsy”
Treatment: *Amphotericin B effective in few survivors
Protozoa of CNS
Trypanosoma cruzi (Chagas)
Features: Mexico/southern countries
Reservoir: “Reduviid bug bites & defecates w trypomastigote
* Rats, racoons (reservoir)
*Thatched roof hut, poor areas”
Transmission:
Diseases: “Chagas Disease
*Early: asymptomatic or chagoma, fever, GI symptoms, Romana’s sign (if bite is near eye)
Late (years): cardiomyopathy, megacolon, megaesophagus”
Diagnosis: “Blood smear: early trypomastigote w C or U shaped hemoflagellates
*2 different serological tests
Heart tissues on autopsy with late stage amastigotes”
Treatment: “Benznidazole
*Nifurtimox”
Protozoa of Blood
Trypanosoma brucei (African Sleeping Sickness)
Features:
Reservoir: “Tsete fly carrying trypomastigote
* Rhodesiense: E Africa, dry areas, animals = host; acute (death in mo)
* Gambisense: Central/W Africa, wet areas, humans = host; chronic (slow)”
Transmission:
Diseases: “African Sleeping Sickness:
* Early phase: posterior cervical lymphadenopathy (winterbottom’s sign), chancre, headache, night sweats, anemia, recurring fever
* CNS phase: somnolence, coma, death
* Rhodesiense/Acute: CNS involvement in weeks (meningoencephalitis)
* Gambisense/Chronic: personality changes, daytime sleepiness, progressive confusion “
Diagnosis: “Card Agglutination Test (CATT)
*Lymphatic aspiration (if CATT is +)
- Blood smear: Flagellated trypomastigote; also in CSF”
Treatment: “Rhodesiense: - Early: Suramin (blood borne)
- Late: Melarsoprol (CNS)
Gambiense:
* Early: Pentamidine
*Late: Nifurtimox-eflornithine”
Protozoa of Blood
Babesia microti
Features:
Reservoir: “* Ixodes tick (Lyme disease)
White foot mouse (reservoir)
NE US”
Transmission:
Diseases: “ General malaise, fever, HA, chills, weakness
* Severe disease (asplenia or immunocompromise)
* Hemolytic anemia w hemoglobinuria & jaundice, transaminitis, thrombocytopenia”
Diagnosis: “ General malaise, fever, HA, chills, weakness
* Severe disease (asplenia or immunocompromise)
* Hemolytic anemia w hemoglobinuria & jaundice, transaminitis, thrombocytopenia”
Treatment: “* Atovaquone & Azithromycin
*Exchange transfusion w high parasite load > 10%”
Protozoa of Blood
Plasmodium species
Features:
Reservoir: * Anopheles mosquito (at night)
Transmission: “*Sporozoites enter blood -> Liver -> Schizonts -> Rupture releasing merozoites (causes symptoms) -> infect RBCs -> immature trophozoite ->
- Erythrocytic Cycle: Mature trophozoite -> Schizont -> Merozoite -> infects RBC (repeat)
*Sexual Phase: Gametocytes form that are ingested by mosquito when it feeds - Hypnozoites: dormant liver forms that may not progress to merozoites for months (NOT sensitive to chloroquine, only P. vivax/ovale)”
Diseases: “Uncomplicated Malaria (<5% parasitemia): Non-specific symptoms (fever, sweats, headaches, nausea/vomiting, body aches, abdominal pain), can take oral meds
Severe Malaria: Hyperparasitemia (> 5%), severe anemia, hypoglycemia, organ failure (AKI, ARDS, shock), cerebral malaria (clogs capillaries –> confusion, seizures, abnormal behavior); death can occur within hrs; usually P. falciparum; cannot take oral drugs”
Diagnosis: “Light Microscopy: Gold standard
* Thick Smear: (Giemsa) Lysed RBCs with parasites outside RBCs; more conc and sensitive
*Thin Smear: (oil immersion) determine species & degree of parasitemia
Rapid Antigen Test (RDT): Immunochromatography to detect presence (NOT type or degree)”
Treatment: “* Chloroquine: RBC stage (NOT liver); pregnant; falciparum in susceptible areas
*Primaquine: liver stage
*Quinidine: severe falciparum or chloroquine-resistant P. vivax
*Atovaquone-Proguanil: ALL stages of falciparum & ppx
* Aretmether-lumefantrine: MOST active (against ring-forms & schizonts of P vivax & falci); reduces gametocyte carriage
PPX: before, during and after travel
*Atovaquone-Proguanil ($$$, shortest)
* Mefloquine (safe in pregnancy)
* Doxycycline (long, but cheapest)
*Chloroquine (only in sensitive areas)”
Protozoa of Blood
Plasmodium falciparum
Features: “*Most common
*Tropical/subtropical areas
* NO liver stage
Infects RBCs at any stage”
Reservoir: * Anopheles mosquito (at night)
Transmission: “Sporozoites enter blood -> Liver -> Schizonts -> Rupture releasing merozoites (causes symptoms) -> infect RBCs -> immature trophozoite ->
- Erythrocytic Cycle: Mature trophozoite -> Schizont -> Merozoite -> infects RBC (repeat)
*Sexual Phase: Gametocytes form that are ingested by mosquito when it feeds - Hypnozoites: dormant liver forms that may not progress to merozoites for months (NOT sensitive to chloroquine, only P. vivax/ovale)”
Diseases: “*Shorter, severe disease course; fatal if not treated - Quotidian fevers (sporadic)
*infected RBCs adhere to endothelium in peripheral cap –> sludging
Multiple can infect 1 RBC”
Diagnosis: “ Ring form trophozoites
Crescent/banana gametocytes”
Treatment: “ Chloroquine: only in susceptible areas - Atovaquone-Proguanil: ALL stages
- Aretmether-lumefantrine: MOST active (active against small ring-forms & maturing schizonts of P vivax & falciparum); reduces gametocyte carriage”
Protozoa of Blood
P. vivax
Features: “*Widest geographic distribution
Liver stage (can relapse)”
Reservoir: * Anopheles mosquito (at night)
Transmission: “Sporozoites enter blood -> Liver -> Schizonts -> Rupture releasing merozoites (causes symptoms) -> infect RBCs -> immature trophozoite ->
- Erythrocytic Cycle: Mature trophozoite -> Schizont -> Merozoite -> infects RBC (repeat)
*Sexual Phase: Gametocytes form that are ingested by mosquito when it feeds - Hypnozoites: dormant liver forms that may not progress to merozoites for months (NOT sensitive to chloroquine, only P. vivax/ovale)”
Diseases: “* Less pathogenic than falciparum, but can be as severe
*Splenomegaly
Tertian fevers (q48h)”
Diagnosis: “Schuffner’s Dots: small granulations in RBCs/gametocytes - Ring form trophozoites”
Treatment: “* Chloroquine (does not kill liver forms) AND primaquine (kills liver forms) - Quinidine: chloroquine-resistant P. vivax
- Aretmether-lumefantrine: MOST active (active against small ring-forms & maturing schizonts of P vivax & falciparum); reduces gametocyte carriage”
Protozoa of Blood
P. ovale
Features: “*Tropical areas, less widespread
Liver stage (can relapse)”
Reservoir: * Anopheles mosquito (at night)
Transmission: “Sporozoites enter blood -> Liver -> Schizonts -> Rupture releasing merozoites (causes symptoms) -> infect RBCs -> immature trophozoite ->
- Erythrocytic Cycle: Mature trophozoite -> Schizont -> Merozoite -> infects RBC (repeat)
*Sexual Phase: Gametocytes form that are ingested by mosquito when it feeds - Hypnozoites: dormant liver forms that may not progress to merozoites for months (NOT sensitive to chloroquine, only P. vivax/ovale)”
Diseases: “* Benign (similar to P. vivax) - Tertian fevers (q48h)”
Diagnosis: “*Schuffner’s Dots: small granulations in RBCs/gametocytes - Ring form trophozoites”
Treatment: “* Chloroquine (does not kill liver forms) AND primaquine (kills liver forms) - Quinidine: chloroquine-resistant P. vivax
- Aretmether-lumefantrine: MOST active (active against small ring-forms & maturing schizonts of P vivax & falciparum); reduces gametocyte carriage”
Protozoa of Blood
P. malariae
Features: P. malariae
Reservoir: * Anopheles mosquito (at night)
Transmission: “*Sporozoites enter blood -> Liver -> Schizonts -> Rupture releasing merozoites (causes symptoms) -> infect RBCs -> immature trophozoite ->
- Erythrocytic Cycle: Mature trophozoite -> Schizont -> Merozoite -> infects RBC (repeat)
*Sexual Phase: Gametocytes form that are ingested by mosquito when it feeds - Hypnozoites: dormant liver forms that may not progress to merozoites for months (NOT sensitive to chloroquine, only P. vivax/ovale)”
Diseases: “* Low pathogenicity
*Nephrotic syndrome
*Quartan fevers (q72h)
Persistent low levels can cause recurrence of symptoms”
Diagnosis: “Band or basket form trophozoite
*Rosette schizont”
Treatment: * Chloroquine
Protozoa of Blood
P. knowlesi
Features: *Southeast Asia
NO liver stage
Reservoir: * Anopheles mosquito (at night)
Transmission: “Sporozoites enter blood -> Liver -> Schizonts -> Rupture releasing merozoites (causes symptoms) -> infect RBCs -> immature trophozoite ->
- Erythrocytic Cycle: Mature trophozoite -> Schizont -> Merozoite -> infects RBC (repeat)
*Sexual Phase: Gametocytes form that are ingested by mosquito when it feeds - Hypnozoites: dormant liver forms that may not progress to merozoites for months (NOT sensitive to chloroquine, only P. vivax/ovale)”
Diseases: “*Can cause severe disease: Quotidian fevers, rigors, HA, abd pain, resp distress, hepatorenal failure - Multiple can infect 1 RBC”
Diagnosis: “*Can cause severe disease: Quotidian fevers, rigors, HA, abd pain, resp distress, hepatorenal failure - Multiple can infect 1 RBC”
Treatment:
Protozoa of Blood
Features:
Reservoir: * Anopheles mosquito (at night)
Transmission:
Diseases:
Diagnosis:
Treatment:
Protozoa of Blood
Acanthamoeba
Features: Acanthamoeba
Reservoir: “*Inhalation of cysts through resp tract
Direct skin innoculation (use of non-sterile contact lens soln)”
Transmission: “Inhalation of cysts through resp tract
Direct skin innoculation (use of non-sterile contact lens soln)”
Diseases: “ Immunocompromised: Altered mental status, granulomatous amebic encephalitis
*Immunocompetent: keratinitis in contact wearers, corneal ulcer
*Disseminated infection to lungs, sinuses or skin”
Diagnosis: *CSF or corneal scrapings (trophozoites and wrinkled cysts)
Treatment:
Protozoa - Other Tissues
Ascaris lumbricoides
Features: “* Most common parasitic infection worldwide
Intestinal/macroscopic worm”
Reservoir: Fecal oral: Ingestion of ova in soil
Transmission: Eggs in soil are ingested –> larvae that invade GI mucosa –> blood –> lungs & are swallowed again –> adult worms that live in intestine
Diseases: “Vague abd pain, nausea, anorexia, intestinal obstruction w heavy infection
Loeffler Syndrome: Inflammatory response to larvae as they migrate through lungs –> pneumonitis cough/wheezing (similar to asthma attack) during acute infection”
Diagnosis: “Stool (eggs with mammilations along walls)
Treatment: “ Albendazole
Helminths - Nematodes
Acylostoma duodenale & Necator americanus (Hookworms)
Features:
Reservoir: “*Larvae in soil penetrate skin
*Beaches/soil, fertilizer”
Transmission: Larvae penetrate skin & become dormant in tissues OR enter circulation –> lungs –> coughed up & swallowed –> Adults in sm intestine
Diseases: “ Intestine infection causing iron-deficiency anemia & protein deficiency
*Cutaneous larva migrans (itchy, dormant in tissues)”
Diagnosis: *Stool (thin shelled ova/eggs)
Treatment: * Albendazole (mebendazole)
Helminths - Nematodes
Trichuris trichiura (Whipworm)
Features: “* Tropical/subtropical areas
*S US”
Reservoir: Fecal oral: ingestion of eggs in soil
Transmission: Eggs ingested –> adults live in lg intestine –> excreted in feces
Diseases: “Dysentery, abd pain, bloody diarrhea, weight loss
*Cause rectal prolapse”
Diagnosis: “Stool (eggs w plugged ends = tea tray)
Treatment: *Albendazole
Helminths - Nematodes
Stromyloides stecoralis (roundworms)
Features: “* Topical/subtropical areas
Appalachian area of US”
Reservoir: Skin penetration by larvae in soil
Transmission: “ Eggs hatch forming adults in intestine –> larvae that are shed in stool
* Autoinfection: larvae penetrate GI mucosa or perianal skin & migrate to other organs causing infection (persists for many decades)
* Hyperinfection: disseminated when larvae penetrate bowel in setting of immunosuppression”
Diseases: “Epigastric pain (adult worms live in sm intestine), NON-bloody diarrhea, eosinophilia
Hyperinfection: larvae confined to lungs/GI tract –> bacteremia, pneumonia, high mortality rate
* Disseminated –> GN meningitis”
Diagnosis: “Epigastric pain (adult worms live in sm intestine), NON-bloody diarrhea, eosinophilia
*Hyperinfection: larvae confined to lungs/GI tract –> bacteremia, pneumonia, high mortality rate
* Disseminated –> GN meningitis”
Treatment: *Ivermectin
Helminths - Nematodes
Enterobius vermicularis (Pinworm)
Features: “*Most common helminth in US
“
Reservoir: “Children & caretakers
* Eggs survive in environment for 1-2 wk”
Transmission: Pinworm eggs ingested –> adult worms live in cecum –> females exit & lay eggs at night on anus
Diseases: Significant perianal pruritis
Diagnosis: * Scotch tape test
Treatment: “ Albendazole
*Laundering (hot water/dryer)”
Helminths - Nematodes
“Angiostrongylus catonensis
(Rat Lungworm)”
Features: “Rat lungworm
* SE Asia & tropical Pacific islands”
Reservoir: “Rat –> snails, slugs, freshwater crabs (IM hosts)
Ingestion of larvae in freshwater shrimp or crabs”
Transmission:Humans consume entering GI tract –> blood -> meninges where larvae die -> immune response
Diseases:“Eosinophilic meningoencephalitis (> 10 eosinophils/CSF)
* Larvae die in brain causing eosinophil driven immune response
* Most cases are self-limited sometimes with neurologic sequelae”
Diagnosis:“*No commercial tests
*DOH labs (PCR on CSF)
*CSF (eosinophilic pleocytosis, elevated protein, low/normal glucose)
* Stool NOT HELPFUL (not passed in stool, larvae die in brain)”
Treatment:None (steroids to decrease headache)
Helminths - Nematodes
Baylisascaris procyonis (Racoon roundworm)
Features: “* Racoon roundworm
* Canada & US (NE mostly)”
Reservoir: “* Racoons & rarely dogs
Ingestion of infective eggs”
Transmission: Humans ingest eggs –> Larvae encyst in hosts in different sites
Diseases: “ Symptoms depend on where larvae encyst
* Visceral: skin infection, rash, abd pain, pneumonitis
Ocular: photophobia, retinitis, unilateral blindness
* Neural: eosinophilic menigoencaphalitis, incoordination, ataxia, weakness, altered mental status, stupor, seizure, coma”
Diagnosis: “ Lab findings: peripheral eosinophilia, CSF eosinophilic pleocytosis
* CDC: serologic testing of CSF/serum
*Ocular exam (migrating larva, larval tracts, lesions)”
Treatment: * Albendazole + steroids
Helminths - Nematodes
Trichinella spiralis
Features: *Europe & US
Reservoir: Ingestion of undercooked meat
Transmission:Ingested larvae –> adults in sm intestine that release larvae that invade GI tract –> blood –> muscles
Diseases:Fever, eosinophilia, myalgia, periorbital edema
Diagnosis:“Serum ab
Muscle biopsy (high risk of sampling error, encysted larvae in muscle)”
Treatment:Albendazole + steroids if severe
Tissue Nematodes
Toxocara canis/catis
Features:
Reservoir: “*Ingestion of undercooked meat
Definitive host = puppies & cats”
Transmission:Ingestion of eggs –> larvae in gut to blood to tissues where larvae cannot develop further, but cause local inflammatory rxn & mechanical damage instead
Diseases:“Visceral larvae migrans: fever, rash, coughing, pneumonitis, hepatomegaly, eosinophilia
*ocular larvae migrans: uveitis, retinitis, blindness
neuro larvae migrans: eosinophilic meningitis, rare”
Diagnosis:“ELISA Ab test
Muscle biopsy”
Treatment:Albendazole
Tissue Nematodes
Loa Loa (African eye worm)
Features: * W & Central Africa
Reservoir: “*Chrysops fly bite
* Only infects humans”
Transmission: Fly bites releasing larvae –> develop into adults in human –> adult worms migrate throughout tissues AND live in them between layesr of CT releasing microfilariae in bood during day
Diseases: Adult worm migration through eye & subcutaneous tissues causes calabar swelling
Diagnosis: “ After removal from eye
*Blood smear collected during day (adults release microfilaria during the day)”
Treatment: *Diethycarbamazine (DEC): heavy infection with tx risks brain inflammation; kills both adult & microfilariae forms
Blood Nematodes - Filiaria
Onchocerca volvulus (River Blindness)
Features: “* Rivers
Africa, Central/S America”
Reservoir: * Black fly (lives near rivers)
Transmission: Larvae enters bite & mature into adult worms that live in nodules in skin & release microfilariae
Diseases: “ Release of microfilaria in skin causes itching
* Microfilariae in eye causes inflammation & scarring –> blindness”
Diagnosis: “* Release of microfilaria in skin causes itching
* Microfilariae in eye causes inflammation & scarring –> blindness”
Treatment: “*Surgical (nodule removal)
*Ivermectin - kills microfilariae & sterilizes female worms
* Doxycyline - kills microfilariae”
Blood Nematodes - Filiaria
Wuchereria bancrofti & Brugia malayi
Features: 90% cases are caused by Wuchereria
Reservoir: * Mosquito
Transmission:Larvae enters bite & mature into adults worms that produce microfilaria –> lymph & blood at night –> adults live in lymphatics & damage it
Diseases: Elephatiasis: lymphedema from adults living in lymphatics mostly in legs –> hardening/thickening of skin (can also live in male scrotum)
Diagnosis:“*Blood smear at night (microfilaria)
*antifilarial ab test”
Treatment:Diethycarbazamine, Ivermectin, Albendazole
Blood Nematodes - Filiaria
Diphyllobtrum latum (Fish tapeworm)
Features: “Fish tapeworm
* Infection can last up to 25 yrs”
Reservoir: “Cold bodies of water
* Undercooked fish”
Transmission:Consume larvae-containing fish –> Uses scolex to attach to intestine & grows into adult –> proglottids release eggs into feces
Diseases:”* Most often asymptomatic
GI side effects
* megaloblastic anemia (consumed by worm)”
Diagnosis:” Most often asymptomatic
GI side effects
* megaloblastic anemia (consumed by worm)”
Treatment:Praziquantel
Helminths - Trematodes & Cestodes (tapeworm)
Taenia solium
Features: “Pig Tapeworm
* Scolex: head of worm contains hooks”
Reservoir: * Contaminated pork
Transmission:Consume infected muscle in meat –> adult tapeworm attaches to intestinal wall –> proglottids filled with eggs pass in feces
Diseases: “Consume larvae –> Mild abd symptoms
* Consume eggs –>Neurocysticercosis: Eggs -> larvae that travel to brain & other tissues forming cystic lesions with small hyperintense dot on some; seizures”
Diagnosis:“*Stool (eggs)
Brain CT/MRI: ring-enhancing cystic lesion with scolex in center (small opaque dot); calcifications (dead)
* Serum Ab”
Treatment: “ Albendazole (kills cysts) + corticosteroids (minimize inflammation)
* Anti-epileptics may be needed if only dead calcified lesions are present”
Helminths - Trematodes & Cestodes (tapeworm)
Echinococcus granulosus
Features: * Hydatid cyst disease
Reservoir: “* Sheep-raising areas
* Ingestion of eggs in dog feces (dogs = def host, produces infective eggs)
* Humans are incidental hosts (cannot pass to other humans)”
Transmission:Ingest eggs that migrate from GI –> blood –> liver or lungs & become larger hydatid cyst
Diseases:”* Enlargement of cyst causes symptoms
* Liver: RUQ pain, nausea, vomiting, jaundice
*Lung: cough, SOB, hemoptysis
Cyst rupture –> anaphylaxis”
Diagnosis:“US/CT (hydatid cyst in liver or lungs)
Ab: serology is supportive, but NOT diagnostic”
Treatment:“Resection of cyst
*Albendazole”
Helminths - Trematodes & Cestodes (tapeworm)
Schistosoma (Schistosomoasis)
Features:
Reservoir: “* Skin penetration in freshwater
Snails (IM host) release cercariae which contact human skin in freshwater”
Transmission:Adult worms coat themselves w host antigens (antigenic mimicry) to evade host immune system
Diseases:“Acute Diseases
Cercarial Dermatitis (Swimmer’s itch): uritcarial plaques or pruritic papules in exposed areas (not under bathing suit)
* Katayama Fever: in previously unexposed pts at onset of egg laying (3-8wk) with fever, myalgia, abd pain, diarrhea, HA, eosinophilia, elevated LFTs
Chronic Disease: re-exposure in endemic areas
* Bowel: ulceration, inflammation, blood loss, scarring (see below)”
Diagnosis:” Stool O&P (negative w Katayama fever since eggs are just forming)
*Serology
Eosinophilia”
Treatment: Praziquantel
Flukes in Blood
Schistosoma haematobium
Features: “*Africa & Middle East
Terminal spine (end) on egg”
Reservoir: “ Skin penetration in freshwater
Snails (IM host) release cercariae which contact human skin in freshwater”
Transmission: * Adult worms live in braches of venous plexus (liver) –> migrate into bladder
Diseases:” Bladder disease due to chronic deposition of eggs in bladder wall –> hematuria, fibrosis/calcification of bladder, granulomatous inflammation
Long-term consequences:
pseudopolyps, urinary tract obstruction –> renal failure & inflammation
* Squamous cell carcinoma of bladder can occur without tx
* Infertility due to infection of genital tract”
Diagnosis:URINE O&P (eggs)
Treatment:* Praziquantel
Flukes in Blood
Schistosoma japonicum
Features: “* East Asia
* Nubby spine (round egg)”
Reservoir:
“* Skin penetration in freshwater
Snails (IM host) release cercariae which contact human skin in freshwater”
Transmission:Adult worms live in branches of mesenteric veins & migrate into portal venous system/liver to mature
Diseases:“*Liver disease
* Peri-portal fibrosis due to egg deposition in portal venous system
*Portal HTN: Blocks portal bloodflow -> hepatosplenomegaly, ascites, esophageal varices, cirrhosis”
Diagnosis:
*Stool O&P (eggs)
Treatment:
* Praziquantel
Flukes in Blood
Schistosoma mansoni
Features: “* Africa & S America
* Lateral spine on egg”
Reservoir:
“* Skin penetration in freshwater
Snails (IM host) release cercariae which contact human skin in freshwater”
Transmission:Adult worms live in branches of mesenteric veins & migrate into portal venous system/liver to mature
Diseases:“*Liver disease
* Peri-portal fibrosis due to egg deposition in portal venous system
*Portal HTN: Blocks portal bloodflow -> hepatosplenomegaly, ascites, esophageal varices, cirrhosis”
Diagnosis:
*Stool O&P (eggs)
Treatment:
* Praziquantel
Flukes in Blood
Clonorchis sinensis (liver fluke)
Features: * East Asia (Chinese Liver Fluke)
Reservoir: Undercooked freshwater fish
Transmission:Eggs ingested by snails are released & infect fish –> encysts in duodenum of human –> adult form that travels through biliary duct & lays eggs –> eggs pass in feces
Diseases:“*Acute: fever, abd pain, anorexia, urticaria 10-26 days post-consumption
Chronic: biliary obstruction; associated w cholangiocarcinoma”
Diagnosis:” Stool (eggs 4 wk after)
* Eosinophilia”
Treatment:Praziquantel
Flukes in Liver
Fasciola hepatica
Features:
Reservoir: “* Fecal-oral
* Raw watercress or contaminated plants”
Transmission:Mature in biliary duct & eggs are excreted in feces
Diseases:RUQ pain, fever, eosinophilia
Diagnosis:“Stool (eggs, not seen during migratory phase)
* adult flukes in biliary tree
* Eggs are indistinguishable from Faciolopsis buski”
Treatment:Triclabendazole
Flukes in Liver
Fasciolopsis buski (Fascioliasis)
Features: “* Largest intestinal fluke
* Asia & India”
Reservoir: * Pigs and freshwater plant consumption
Transmission:
Diseases:Asymptomatic to diarrhea, abd pain, fever, ascistes, asasarca & intestinal obstruction
Diagnosis:“*Serology
Feces/Vomit (eggs - scanty & intermittent production)
* Eggs are indistinguishable from Fasciola hepatica”
Treatment:Praziquantel
Flukes in Intestine
Paragonimus
Features: “* P westermani - SE Asia & Japan
P kellicotti - N America”
Reservoir: Consumption of raw/undercooked crab or crayfish
Transmission:Ex-cyst into duodenum & mature –> adults lay eggs that enter lung & are excreted in sputum OR can be swallowed & pass through stool
Diseases:“Early: (2 mo) fever, diarrhea, abd pain, urticaria
* Larvae penetrate diaphragm into pleural cavity –> chest pain, cough, malaise
Late: inflammation, fibrosis, hemoptysis”
Diagnosis: Sputum/Bronchoalveolar lavage (eggs)
Treatment:“*Praziquantel
* Triclabendazole”
Flukes in Lung
