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

6/17- Helminths I: Intestinal Nematodes Flashcards

(53 cards)

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1
Q

What are Neglected Tropical Diseases (NTDs)?

A

The most common afflictions of the “bottom billion”

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2
Q

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

A

(Intestinal Helminth Infections: soil-transmitted)

1. Ascariasis (2 in)

2. Trichuriasis (2 ft, largest)

3. Hookworm (cm, smallest)

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3
Q

What are the Millenium Development Goals?

A
  1. Combat HIV/AIDS, malaria, and other diseases
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4
Q

Prevalence of “worms” in Guatemalan kids? (chart)

A

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
Q

What is this a symptom of?

A

Ascaris infection

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6
Q

Symptoms of hookworm and other soil-transmitted helminth infections?

  • Hookworm leads to __% _____________
A
  • Stunting
  • Impaired memory
  • Decreased school performance
  • Debilitating and limit potential, but typically not fatal

Hookworm leads to 40% reduction in future wage earnings

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7
Q

What is this? Characterisics?

A

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
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8
Q

Structure of Tirchuris trichuria (whipworm) in environment?

A

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

  • Causes inflammation
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9
Q

What is this?

A

T. trichiura egg

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10
Q

Life cycle of Tirchuriasis?

A
  • 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
Q

What is this?

A

SEM of T. trichiura with its intracellular and extracellular existence

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12
Q

What are the clinical sequelae of Trichuriasis?

A
  • Trichruis dysentery syndrome
  • Trichuris colitis
  • Rectal prolapse

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

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13
Q

Life cycle of Ascaris lumbricoides?

A
  • 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
Q

What is this? Characteristics?

A
  • Eggs are very hardy
  • Sticky: mucopolysaccharide
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15
Q

Disease syndromes of Ascariasis?

A
  • Loeffler’s syndrome (pneumonitis)
  • Impaired nutrition
  • Growth retardation
  • Acute Intestinal Obstruction
  • Biliary Tract Obstruction: pancreatitis, cholangitis, hepatitis
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16
Q

What is this?

A

Ascariasis obstruction of gut

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17
Q

Treatment for intestinal worms? Exception?

A
  • Mebendazole
  • Albendazole

Except Strongyloides

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18
Q

What is the life cycle of Toxocariasis?

A

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
Q

What is this?

A

Eggs of Toxocara canis or T. cati

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20
Q

Clinical Syndromes of Toxocarisis? Ages affected?

A

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?
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21
Q

Toxocariasis in the US

  • Seroprevalence (by ethnicity)
  • Highest in what region?
  • Risk factors
A

Seroprevalence:

  • 21.2% in non-Hispanic blacks
  • 12% in Whites

Highest in American South

Risk factors:

  • Low household education
  • Poverty
  • Elevated lead levels
  • Toxoplasmosis
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22
Q

What are these? What are included in this category?

Study These Flashcards
A

Hookworms:

- Necator americanus (85% of infxn)

  • Ancylostoma duodenale
  • Ancylostoma ceylanicum
23
Q

Global distribution of human hookworm infection?

What is the prominent species?

Study These Flashcards
A

Necator americanus

Wherever rural poverty and adequate climate overlap

24
Q

Life cycle of Necator americanus?

Study These Flashcards
A
  • 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
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?
Hookworm embedded in intestine
27
What is this?
Adult hookworms in situ (1 cm)
28
What can be done to detect hookworms?
**Adult hookworm antigens- hemoglobinases** (Ac-MEP-1, hookworm metalloendopeptidase 1)
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
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?
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
33
What drug fails to treat hookworm?
Mebendazole
34
What is this? Caused by? Where is it found? What at risk populations?
**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?
36
How to differentiate hookworm larvae with Strongyloides larva?
Strongyloides have notched tail???
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
38
What is this?
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?
**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?
First stage larvae of Strongyloides (NOT EGGS)
45
Treatment for Strongyloides?
Ivermectin
46
What is this?
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
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
51
Diagnosis of pinworm infection (Enterobius vermicularis)?
Unfrosted scotch tape over anus (early morning test)
52
Treatment of pinworm infection (Enterobius vermicularis)?
- **Albendazole** (1 dose) - Repeat in 2-4 weeks - Treat entire family
53
What is this?
Enterobius vermicularis egg (?)

Term 5: Infectious Disease (18 decks)

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