6/17- Helminths I: Intestinal Nematodes Flashcards Preview

Term 5: Infectious Disease > 6/17- Helminths I: Intestinal Nematodes > Flashcards

Flashcards in 6/17- Helminths I: Intestinal Nematodes Deck (53):
1

What are Neglected Tropical Diseases (NTDs)?

The most common afflictions of the "bottom billion"

2

What are the 3 most common afflictions of people living in poverty? Relative sizes?

(Intestinal Helminth Infections: soil-transmitted)

1. Ascariasis (2 in)

2. Trichuriasis (2 ft, largest)

3. Hookworm (cm, smallest)

3

What are the Millenium Development Goals?

6. Combat HIV/AIDS, malaria, and other diseases

 

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4

Prevalence of "worms" in Guatemalan kids? (chart)

Basically, all kids are infected; kids are disproportionately affected (adults have them too, but not as much)

- Peak just under 10 yo (practically 100%)

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5

What is this a symptom of? 

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Ascaris infection

6

Symptoms of hookworm and other soil-transmitted helminth infections?

- Hookworm leads to __% _____________

- Stunting

- Impaired memory

- Decreased school performance

- Debilitating and limit potential, but typically not fatal

Hookworm leads to 40% reduction in future wage earnings

7

What is this? Characterisics?

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Trichuris trichiura (Whipworm)

- Male on left

- Female on right

Thinner end is anterior (internal existence), while fatter back end is external in gut

- Causes inflammation

8

Structure of Tirchuris trichuria (whipworm) in environment?

Thinner end is anterior (internal existence), while fatter back end is external in gut

- Causes inflammation

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9

What is this? 

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T. trichiura egg

10

Life cycle of Tirchuriasis?

- Eggs ingested

- Larva hatch in small intestine

- Larvae migrate to colon

- Adults mature in colon

- Unembryonated eggs pass out in feces

- Eggs embryonate in soil

- Eggs ingested (May cause prolapsed rectum)

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11

What is this? 

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SEM of T. trichiura with its intracellular and extracellular existence

12

What are the clinical sequelae of Trichuriasis?

- Trichruis dysentery syndrome

- Trichuris colitis

- Rectal prolapse

(because feel like something is in rectum and straining hard)

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13

Life cycle of Ascaris lumbricoides?

- Eggs ingested

- Larvae hatch in small intestine, enter bloodstream, go to liver (then to IVC)

- Larvae migrate to the heart (right side)

- Larvae reach lung capillaries (via pulmonary a.)

- Larvae enter alveolar spaces; will have eosinophils and IgE in the lung (induces asthma)

- Larvae migrate up trachea and are swallowed

- Adults mature in small intestine

- Cause penetration and obstruction in the gut

- Eggs pass out in feces

- Eggs embryonate in soil 

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14

What is this? Characteristics? 

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- Eggs are very hardy

- Sticky: mucopolysaccharide

15

Disease syndromes of Ascariasis?

- Loeffler's syndrome (pneumonitis)

- Impaired nutrition

- Growth retardation

- Acute Intestinal Obstruction

- Biliary Tract Obstruction: pancreatitis, cholangitis, hepatitis

16

What is this? 

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Ascariasis obstruction of gut

17

Treatment for intestinal worms? Exception?

- Mebendazole

- Albendazole

Except Strongyloides

18

What is the life cycle of Toxocariasis?

Toxocara canis and Toxocara cati (Ascaris homolog found in cats and dogs):

- Animals eat embryonated eggs, acquires adults

- Eggs pass in feces and embryonate in soil

- Eggs are ingested by humans

- Larvae hatch in small intestine and penetrate wall

- Larvae migrate to all organs via bloodstream (don't become adult worms in intestine cause kinda in wrong host; migrate elsewhere)

- Causes pathology in eye, CNS, and liver (visceral larva migrans)

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19

What is this? 

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Eggs of Toxocara canis or T. cati

20

Clinical Syndromes of Toxocarisis? Ages affected?

Visceral Larva Migrans (1-3 yo)

- Pneumonitis (wheezing)

- Hepatitis

- Cerebritis

- Eosinophilia

- Hypergammaglobulinemia

Ocular Larva Migrans (>5 yo)

- Strabismus (exotropia)

Covert Toxocariasis

- Environmental cause of asthma- getting eosinophils, wheezing, maybe some cognitive deficits

- Rise of asthma in our inner cities?

21

Toxocariasis in the US

- Seroprevalence (by ethnicity)

- Highest in what region?

- Risk factors

Seroprevalence:

- 21.2% in non-Hispanic blacks

- 12% in Whites

Highest in American South

Risk factors:

- Low household education

- Poverty

- Elevated lead levels

- Toxoplasmosis

22

What are these? What are included in this category? 

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Hookworms:

- Necator americanus (85% of infxn)

- Ancylostoma duodenale

- Ancylostoma ceylanicum

23

Global distribution of human hookworm infection?

What is the prominent species?

Necator americanus

Wherever rural poverty and adequate climate overlap 

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24

Life cycle of Necator americanus?

- Larvae hatch and develop in soil

- Filariform larvae on blades of grass

- Larvae penetrate skin, enter bloodstream, and reach heart (not always through feet, may also spread over skin- cause dermatitis)

- Larvae enter lung capillaries and then alveolar spaces

- Larvae migrate up trachea, and are swallowed

- Adults mature in small intestine

- Eggs pass out in feces

- Larvae hatch and develop in soil 

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25

What is the underlying mechanism/cause of disease from hookworms? Result?

Intestinal blood loss (attach to small intestine)

- 25 worms = 1 mL blood loss = 0.55 mg Fe (a child's daily iron intake)

- Results in iron deficiency anemia and protein malnutrition

26

What is this? 

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Hookworm embedded in intestine

27

What is this? 

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Adult hookworms in situ (1 cm)

28

What can be done to detect hookworms?

Adult hookworm antigens- hemoglobinases

(Ac-MEP-1, hookworm metalloendopeptidase 1) 

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29

Symptoms of hookworm infections?

- Iron deficiency anemia and severe anemia

- Reduced growth, psychomotor development, physical fitness

- Developmental delays, lower IQ

- Reduced school performance and attendance

- Pallor and facial edema

- Anasarca

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30

At risk populations for hookworm disease? Symptoms?

Women and children: low iron stores

Children:

- Physical growth stunting

- Cognitive deficits and intellectual retardation

Women of child-bearing age:

- Puberty

- Menstruation

- Pregnancy (adverse fetal outcomes)

31

Comparison of typical age/intensity relationships of the three main infections?

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32

What can be used to treat these? (hookworms?)

- Benzimidazoles

- Mebendazole

- Albendazole Targeting the blood-feeding in the hookworm gut is in phase I trials in Brazil

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33

What drug fails to treat hookworm?

Mebendazole

34

What is this?

Caused by?

Where is it found?

What at risk populations?

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Cutaneous Larva Migrans, "Creeping Eruption"

- Caused by A. braziliense

- Found in Caribbean, Florida, Gulf Coast

- Travelers from tropical resorts and Military person

35

Distribution of Strongyloidiasis?

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36

How to differentiate hookworm larvae with Strongyloides larva?

Strongyloides have notched tail??? 

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37

Life cycle of Strongyloides stercoralis?

- Reservoir hosts in dogs and monkeys

- Free living soil cycle

- Larvae penetrate unbroken skin

- Larvae enter bloodstream and reach lung capillaries

- Larvae enter alveolar spaces

- Larvae are swallowed

- Adult worms live in small intestine

- Larvae develop to L3 in colon and enter bloodstream

- Larvae pass out in feces

- Free-llving soil cycle

There is a potential for auto-infection from gut into lungs 

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38

What is this?

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Adult S. stercoralis in crypts of small intestine

39

Clinical features of Strongyloidiasis? Caused by what?

Clinical features:

- Enteritis

- Diarrhea

- GI discomfort

Autoinfection:

- Larva currens (creeping infection)

- Eosinophilia present

Caused by Strongyloides stercoralis

40

What is this?

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Lava Currens from Strongyloides

- Larva currens = autoinfection with Strongyloides filariform larvae

41

Clinical features of hyperinfection with Strongyloides?

- Intestinal perforation

- Shock, sepsis, gram-negative meningitis

- Hemorrhagic pneumoina

- Eosinophilia often absent

42

Risk factors for Strongyloides hyperinfection?

Steroids

- Immunosuppressive therapy

- Autoimmune disease, malignancy HTLV-1 infection (not HIV)

Malnutrition (especially children under 10 yo)

43

Diagnosis of Human Strongyloidiasis?

- Hunting in "black gold"- multiple fecal exams looking for larvae

- Blood agar plate looking for larval tracks

- Culture with charcoal to amplify through heterogonic life cycle

- Serologic tests ("not yet ready for prime-time")

44

What is this?

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First stage larvae of Strongyloides (NOT EGGS)

45

Treatment for Strongyloides?

Ivermectin

46

What is this?

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Pinworm, or Enterobiasis

- Enterobius vermicularis

47

Life cycle for Enterobiasis (pinworm)?

Enterobius vermicularis

- Eggs ingested

- Larvae hatch in small intestine

- Larvae migrate to colon

- Adults mature in colon

- Gravid adults migrate out of anus

- Adults lay eggs on perianum

- Eggs embryonate on perianum

- Eggs contaminate fingers

- Eggs are ingested

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48

Epidemiology of Enterobius vermicularis?

- Geography

- Transmission

Geography

- Worldwide prevalence

- Tropical and temperate climates

Transmission:

- Re-infection

- Person-to-person

- Sexual

- Fomite

49

Adult habitat of Enterobius vermicularis?

Cecum and appendix

- Gravid female nocturnally deposits eggs onto perianal skin

- Eggs mature after 4-6 hrs of oxygen exposure

50

Clinical features of hookworm infection (Enterobius vermicularis)?

- Asymptomatic -> pruritus ani (itchy butthole)

- Appendiceal inflammation

- Female urogenital tract infection, granulomas

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51

Diagnosis of pinworm infection (Enterobius vermicularis)?

Unfrosted scotch tape over anus (early morning test) 

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52

Treatment of pinworm infection (Enterobius vermicularis)?

- Albendazole (1 dose)

- Repeat in 2-4 weeks

- Treat entire family

53

What is this? 

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Enterobius vermicularis egg (?)