Term
| Nematode - general properties |
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Definition
| Unsegmented round worm; full-length gut, all feeding through mouth since cuticle prevents diffusion through surface. Organs in body cavity unlike flatworms. Dioecious (separate sexes) usually |
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Term
| Intestinal vs tissue nematodes - location of adult form? |
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Definition
| Intestinal: Adult in GI tract, maturing in small intestine/colon. Tissue: Adult in lymph or subcutaneous tissue, releasing larvae |
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Term
| Intestinal vs. tissue nematodes - direct or vector infection? |
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Definition
| Intestinal: Direct, by eggs/larvae. Tissue: Indirect, arthropod vectors needed |
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Term
| Enterobius vermicularis - classification |
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Definition
| Pinworm, Ingestion --> Intestinal infection |
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Term
| E. vermicularis - locations |
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Definition
| Worldwide, but mostly temperate climates |
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Term
| E. vermicularis - transmission, hosts |
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Definition
| Eggs on anal skin; embryonated eggs ingested by HUMANS (definitive host). No intermediate host, direct life cycle. |
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Term
| E. vermicularis - migration in humans |
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Definition
| To small intestine (larvae), to colon (adults) |
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Term
| E. vermicularis - pathology |
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Definition
| Perianal pruritis, female genital tract infection possible, bacterial superinfection possible |
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Term
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Definition
| Scotch tape test to find eggs on perianal skin (Worms sometimes in feces but life cycle is so fast the eggs aren't in feces?) |
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Term
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Definition
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Term
| Trichuris trichuria - classification |
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Definition
| Whipworm, Ingestion --> Intestinal infection |
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Term
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Definition
| Worldwide, but mostly tropical climates |
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Term
| T. trichuria - transmission, hosts |
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Definition
| Embryonated eggs in feces (3wk to become embryonated, much longer than pinworm) ingested by HUMAN (definitive host) |
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Term
| T. trichuria - often coinfected with |
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Definition
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Term
| T. trichuria - migration in humans |
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Definition
| To small intestine (larvae), adults stay in cecum, ascending colon |
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Term
|
Definition
| Main: Rectal prolapse, bloody diarrhea w/ mucus. Other: abdominal pain, growth stunting, tenesmus |
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Term
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Definition
| Eggs in feces (football w/ plugs) |
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Term
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Definition
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Term
| Ascaris lumbricoides - classification |
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Definition
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Term
| A. lumbricoides - locations |
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Definition
| Worldwide, but mostly tropical climates (SE United States) |
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Term
| A. lumbricoides - transmission, hosts |
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Definition
| Eggs in feces (require 2-4wk to become embryonated), ingested by HUMANS (definitive host) |
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Term
| A. lumbricoides - migration in humans |
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Definition
| Larvae leave small intestine --> to liver, heart --> to lung --> up to trachea and get swallowed --> matures into adult form in the small intestine |
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Term
| A. lumbricoides - pathology |
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Definition
| Pneumonitis, liver enlargement, adults may cause intestinal blockage. High IgE and Eosinophils due to long migration. Aberrant migration to bile duct, liver, peritoneal cavity may be a problem. |
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Term
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Definition
| Eggs in feces - round with thick shell; sometimes whole worms found |
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Term
|
Definition
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Term
| Trichinella spiralis - classification |
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Definition
| Trichinosis - ingestion --> tissue |
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Term
|
Definition
| Worldwide, Europe and US, associated with pork consumption but now mostly just wild animals |
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Term
| T. spiralis - transmission, hosts |
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Definition
| Encysted larvae in striated muscle of contaminated meat. HUMANS may get from eating PIG, who gets it from eating RODENTS; rodents keep it alive by cannibalism. All are definitive hosts |
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Term
| T. spiralis - migration in humans |
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Definition
| Adults live in small intestine (short 7d life), depositing larvae in mucosa, which migrate to striated muscle and become encysted |
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Term
| T. spiralis - pathology (different over 1wk, 2wk, 3wk) |
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Definition
| 1wk: GI symptoms (diarrhea, abd pain, vomiting). 2wk: Extraintestinal; muscle/CNS invasion. (Myalgia, weakness, malaise, petechiae, paralysis, coma). 3wk: Larvae encyst. Eosinophilia begins wk 2, peaks wk 3 |
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Term
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Definition
| Clinical Sx, eosinophilia, diet cues (wild animals), muscle biopsy |
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Term
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Definition
| Steroids for severe Sx in infection, then mebendazole + albendazole |
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Term
| Dracunculus medinensis - classification |
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Definition
| Guinea worm, ingestion --> tissue |
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Term
| D. medinensis - locations |
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Definition
| Rural, isolated areas in African countries (mostly eradicated) |
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Term
| D. medinensis - transmission, hosts |
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Definition
| Larvae emerge through blister, ingested by COPEPOD (intermediate host), where they mature, infectious L3 larvae + copepod ingested by HUMANS (definitive host) in contaminated water |
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Term
| D. medinensis - migration in humans |
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Definition
| Larvae penetrate intestine and mature to adult while migrating to skin. Forms blister, releasing larvae |
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Term
| D. medinensis - pathology |
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Definition
| Painful, localized blister as worms emerge ~1yr after infection |
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Term
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Definition
| Clinical presentation (local blister) |
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Term
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Definition
| Local cleansing and antibiotics for bacterial superinfection if necessary; mechanical extraction of worm, no drug-based treatment |
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Term
| Ancylostoma duodenale, Necator americanus - classification |
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Definition
| Hookworm - Contact --> Intestinal |
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Term
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Definition
| Worldwide (moist, warm climate). N. americanus - Americas, Australia; A. duodenale - Middle East, Africa |
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Term
| A.duod/N.am - transmission, hosts |
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Definition
| *Filiform larvae* penetrates skin directly (hair follicle), enters capillaries. Eggs spread in HUMAN (definitive host) feces |
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Term
| A.duod/N.am - migration in humans |
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Definition
| From site of skin penetration to capillaries, lung --> up to trachea, swallowed, adults reside in small intestine (Very similar to Ascaris, once it is inside) |
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Term
| A.duod/N.am - pathology (3 locations; 3 phases) |
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Definition
| Cutaneous: Ground itch at site of infection. Pulmonary: (Larvae bursting out of lung capillaries) local hemmorhage, pneumonitis, eosinophilia, cardiac/GI complications. Intestinal: Adult worms in anterior 1/3 of intestine usually |
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Term
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Definition
| Eggs in feces (Blunty (segmented) ovoid egg, transparent shell; eosinophilia in migratory phase |
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Term
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Definition
| Albendazole, when treated (not often) |
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Term
| Strongiloides stercoralis - classification |
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Definition
| Threadworm; contact --> intestinal |
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Term
| S. stercoralis - locations |
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Definition
| Tropical/subtropical areas, South US, rural areas |
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Term
| S. stercoralis - transmission, hosts |
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Definition
| Acquired by contact with filiform larvae, HUMANS are a host, and there are other reservoirs (dog, monkey). Doesn't need a host to complete cycle, so no definitive host? |
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Term
| S. stercoralis - migration in humans |
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Definition
| Larvae migrate into skin, enters circulation, goes to lung, up pharynx, gets swallowed; *while in intestine, eggs hatch* (key difference), can mature into fiariform and autoinfect, or immature rhabditiform larvae can pass in the stool |
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Term
| S. stercoralis - two forms of larvae |
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Definition
| Rhabditiform (immature, passed in feces), filariform (invades through contact, or penetrates intestine for autoinfection) |
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Term
| S. stercoralis - non-parasitic cycle |
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Definition
| Capable of completing a full cycle outside of a host as a non-parasite |
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Term
| S. stercoralis - pathology |
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Definition
| GI sx, pulmonary sx (eosinophilia), *urticarial rashes on butt/waist, disseminated strongyloidiasis in immunosuppressed*, septicemia generally fatal |
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Term
|
Definition
| Identify rhabditiform larvae in feces; sputum smears if autoinfection, ELISA |
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Term
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Definition
| Ivermectin (alternative to albendazole) |
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Term
| Wuchereria bancrofti - classification |
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Definition
| Lymphatic filariasis/elephantitis, Bite --> Tissue |
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Term
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Definition
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Term
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Definition
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Term
| W. bancrofti - transmission, hosts, migration |
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Definition
| Mosquito (vector) takes meal, L3 larvae enter; adults grow in lymph of HUMANS (definitive host), produce microfilariae that migrate into lymph/blood. Microfilariae can be picked up by mosquito |
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Term
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Definition
| Acute: Adenolymphangitis, episodic attacts of fever/inflammation. *Hydrocele (fluid-filled scrotum)* in males, Chyluria (milky white urine), elephantitis of limbs, scrotum, vulva, breasts, Tropical pulmonary eosinophilia (TPE) |
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Term
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Definition
| Find microfilariae in peripheral blood, OR detect filarial antigen in blood (easiest); urine exam, eosinophilia & high IgE, PCR |
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Term
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Definition
| Ivermectin, Diethylcarbamazine (asymptomatic), Antihistamine, corticosteroids, pain relief, IV antibiotics (inpatient to treat Sx), surgical excision of hydrocele/elephantitis |
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Term
| Onchocerca volvulus - classification |
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Definition
| River blindness, Bite --> Tissue |
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Term
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Definition
| Black fly (Simulium) that lives on rocks with fast moving water |
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Term
|
Definition
| Africa, Central/South America, Middle East |
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Term
| O. volvulus - transmission, hosts, migration |
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Definition
| Black Fly (vector) takes blood meal, L3 larvae enter. Migrates to subcutaneous tissue of HUMANS (definitive host), adults produce microfiliariae, which can be picked up by Black fly |
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Term
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Definition
| Generalized pruritis, itchy eyes --> scarring --> blindness, subcutaneous nodules on skin, onchodermatitis, lympedema, "Leopard skin" (Depigmentation) of shins, "Hanging groin" (drooping of inguinal skin) |
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Term
| O. volvulus - time-course |
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Definition
| Sx begin 9mo-2yr. Adults can live 10-15y in nodules. Microfilariae live 1-2 years then die in skin or eye, causing inflammation |
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Term
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Definition
| Microfilariae in skin biopsy, examination of nodules, DEC patch test (topical application elicits response to dying microfilaria) |
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Term
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Definition
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Term
| Anisakiasis (Anisakis simplex) - classification |
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Definition
| Larvae wander; Ingestion --> Tissue |
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Term
| Anisakiasis - transmission/migration/Sx |
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Definition
| Eating contaminated fish --> larvae penetrate gastric wall --> violent abdominal pain, eosinophilic response in bowel, mimicking Crohn's disease |
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Term
|
Definition
| Gastroscopic exam, biopsy |
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Term
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Definition
| Surgical/endoscopic removal |
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Term
| Toxocara cani/cati - classification |
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Definition
| Wander worm; Contact --> tissue |
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Term
|
Definition
| Dogs/cats definitive; Rabbits intermediate; Humans accidental. In humans, larvae penetrate gut wall |
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Term
|
Definition
| Visceral larva migrans - fever, coughing/wheezing, anemia, eosinophilia, hepatomegaly. Ocular larva migrans uncommon |
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Term
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Definition
| Serology/larvae in biopsy |
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Term
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Definition
| For visceral larva migrans: Albendazole + anti-inflammatory |
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Term
| Ancylostoma caninum/braziliense - classification |
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Definition
| Hookworms (Wander) - Contact --> Tissue Infection (Cutaneous larva migrans) |
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Term
| A. caninum/brazilliense - hosts/replication cycle |
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Definition
| Dogs/cats - definitive hosts. Zoonotic - infects humans, with dogs/cats as reservoir |
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Term
| A. caninum/brazilliense - form that infects humans |
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Definition
| Filariform larvae infect by contact; larvae wander in the tissue aimlessly |
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Term
| A. caninum/brazilliense - Sx/Tx |
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Definition
| Intensely pruritic; ground itch, but self limiting. Tx if severe with albendazole, ivermectin, surgical removal |
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