Infectious Disease -- Parasite Packet #3 Flashcards by Bryan Edwards

Five kinds of Helminths

Schistomiasis
Trichinella
Cistercicosis
Filariasis
Oncocerciasis

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Death from Schistomiasis is usually caused by…

Hepatic granulomas and fibrosis

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Unique symptom of Schistomiasis haematobium

hematuria and obstruction of the bladder

Predisposition to Squamous cell carcinoma of the bladder

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Life cycle of Schistomiasis

Sporocysts in fresh water snails give rise to cercaria
Infection of humans by penetrating skin
Schistosomes migrate in peripheral vasculature
Arrive in portal and pelvic venous system and grow up
Eggs shed in feces, return to the river

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Tissue reactions of Schistomiasis eggs?

Granulomas and Fibrosis

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Cause of hepatic damage in Schistomiasis?

IL3, 4, 5 result in IgE synthesis, mastocytosis, eosinophilia
Eggs induce lymphocytes to secrete fibrinogenic factors, which leads to fibroblast prolif and portal fibrosis

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Hepatic hallmark of Schistomiasis infection?

Hepatic fibrosis out of proportion to parasite injury

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Describe the granulomas surrounding Schistosoma eggs

Calcified, pinhead granulomas

Macrophages, lymphocytes, neutrophils, eosinophils

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How is Schistomiasis liver fibrosis described? It’s significance?

Pipestem potral fibrosis

Portal hypertension, Splenomegaly, Esophageal varices, ascites

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How are people infected with Liver flukes?

Eating undercooked fish

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Symptoms of infection with liver flukes?

Usually asymptomatic

Can cause biliary hyperplasia, fibrosis, portal cirrhosis

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Two types of trematodes

Schistosomiasis

Liver Flukes

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Other word used for cestodes

Tapeworms

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Three main types of cestodes?

Taenia saginata - Beef
Taenia solium - Pork
Echinococcus - Dog

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T. saginata or T. solium – who causes cysticercosus?

Solium

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What is happening during cysticercosus?

When solium eggs are ingested, larvae hatch and penetrate gut wall. Hematogenous dissemination results in CNS cysts.

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CNS symptoms of cysticercosus?

Convulsions, High Intercranial Pressure, Mental disturbances

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What type of cysts are especially problematic in cysticercosus?

Degenerating cysts – cause local inflamm and focal scating, calcifications.
Intact cysts usually don’t evoke much of a reaction.

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Echinococcus cysts tend to form in…

liver and lungs

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Symptoms of Echinococcus?

Usually asymptomatic and chronic
Can cause liver disease
Cyst rupture can lead to anaphylaxis

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Treatment for Echinococcus?

Mabendazole

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Four most common types of nematodes (worms) in the US

Pinworms
Whipworms
Hookworms
Strongyloides

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Pinworms – whats the official name

Enterobius vermicularis

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Most common parasite in US

Pinworms

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Life cycle of Pinworms?

Small worms of the intestine Spread by oral ingestion of eggs extruded from the anus Lifespan -- 2 months

Most common symptoms of Pinworms

Anal pruritis

Reservoir of Pinworms?

ONLY HUMANS

Focus of Pinworm treatment?

Preventing Re-infection

The official name for whipworms?

Trichuris trichura

How big are whipworms?

about a half inch

Where do people tend to get whipworms?

Tropics | Warm, Moist Parts of the Southern US

Symptoms of whipworms?

Local hyperemia | Lesions of colonic mucosa

Official names of hookworms?

Necator amricanus | Ancylostoma duodenale

Hookworm infection is common in the "hookworm belt" | Where is the hookworm belt?

The southern US

What do hookworms do in the host?

Attach to upper levels of the SI

How are hookworms transmitted?

``` Infectious larvae (not eggs) Larvae penetrate between the toes ```

How to ascaris, hookworms, and strongyloides disseminate?

``` Ingest eggs/Penetrate host Bloodstream, Lungs Invasion by filariform larvae Esophagus Infective form --> Intestine ```

Symptoms of hookworms?

Small, itchy papule at penetration site Mild pneumonitis from traveling through lungs Blood loss + Anemia

Strongyloides is important because...

it can cause fatal disseminated disease in an IC host

Strongyloides is endemic where?

Appalachia+SE

Important reservoirs for Strongyloides?

Cats and Dogs

Symptoms of Strongyloides in an IC host?

Severe pneumonitis + Duodenitis

Scond most common parasite of humans

Ascaris lumbricoides

How big are Ascaris lumbricoides?

35 cm

Where do Ascaris lumbricoides live in the host?

They live unattached in the SI

Symptoms of Ascaris lumbricoides infection?

Eosinophilic pneumonitis - dyspnea, dry cough, fever, eosinophilia. Colicky epigastric or periumbical pain Malnutrition

Greatest danger of Ascaris lumbricoides infection?

abnormal migration in the body Blockage of biliary ducts Obstruction of SI

How to diagnose Ascaris lumbricoides?

Eggs in feces

Common SI parasites?

Hookworm, Ascaris, Strongyloides, Giardia

Trichanella spiralis is acquired by...

Ingestion of improperly cooked pork

What happens in the host in a Trichanella spiralis infection?

Larvae penetrate tissues Disseminate hematogenously Encyst in muscle cells

Symptoms of Trichanella spiralis infection?

Eosinophilia Fever, Myalgia Periorbital edema Cardiac Failure

Relationship of Trichanella spiralis to the host heart?

Patchy interstitial myocarditis with eosinophila+ giant cells eventually cause scarring

Relationship of Trichanella spiralis and the lungs

Allergic eosinophilic infiltrate

Muscles especially influenced by Trichanella spiralis?

Diaphragm, Extraoccular, Laryngeal | Deltoid, Gastroc, Intercostal

Three types of Larval migrans syndromes

Cutaneous Visceral Neural

Cause of Cutaneous larval migrans

Ancylostoma

What occurs in cutaneous larval migrans

Larvae can't mature in humans, but survive in SubQ for a long time. Causes intense pruritis skin lesions

Who gets cutaneous larval migrans?

Plumbers, Construction workers, Duck hunters

What gives you visceral larval migrans?

Toxocara canis | T. cati

What happens in visceral larval migrans

Infection from pet | Hepatomegaly, hypereosinophillia, hypergammaglobulinemia, history of geophagia

What gives you neural larval migrans?

Balisascaris

Who gets Balisascaris?

Children with poor hygiene and geophagia

Symptoms to watch for in Balisascaris?

Eosinophilic meningioencephalitis

How is Balisascaris typically diagnosed?

Post mortem

Treatment for visceral larval migrans?

Steroids and anti-histamines

Filariasisis caused by

Wucheria bancrofti

Filariasisis symptoms

Larvae develop in lymphatic channels and damage them via granuloma formation. Causes lymphedema called elephantitis in the lover limb. Also influences scrotum, penus, vulva, leg, arm

How is Filariasisis transmitted?

Mosquito

How if Onchocerciasis transmitted?

Blackflies

Significance of Onchocerciasis?

Major cause of blindness in equatorial Africa

Symptoms of Onchocerciasis

Chronis pruritic dermatitis Subcutaneous dermal nodules (onchocercoma) Punctate keratitis Damage to retina

Cause of retinal damage in Onchocerciasis?

Cross reaction between parasite and retinal pigment epithelial cell antigens

Three arthropods of significance as parasites

Scabies Lice Chiggers