Parasitology: Nematodes

Question 1

Answer 1

hookworm

• Necator americanus
• Ancylostoma duodenale (ancylos=Greek for anchor)
• Transmission:
  
  • by skin penetration
  • fecal-larval-skin penetration (L3 infective)
• Sx:
  
  • Pneumonitis (larval migration to lungs)
  • anemia hypochronic microcytic (larvae migrate up resp. tract, coughed up, swallowed, small intestine)
  • edema
  • myalgia
  • pallor
  • breathlessness
• Dx: eggs in faeces (female highly fecund) id by salt flotation
• Rx: Albendazole, iron therapy, HWA

Question 2

Answer 2

Ascaris lumbricoides

• Epi: global
• Transmission: by ingestion of L2 larva in egg
• Sx:
  
  • Larvae: Loeffler’s syndrome: fever, cough, wheeze, eosinophilia - rapidly changing x-ray picture
  • Adult worm: mechanical obstruction, jaundice, appendicitis, asphyxia. mild bouts of colic, appearance of worms in bouts of diarrhoea and body orifices
• Rx: Albendazole/Ivermectin

Question 3

Answer 3

Enterobius vermicularis (Pinworm)

• Transmission: direct by ingestion of eggs containing L3 larvae
  
  • No hepatic-tracheal migration
  • adult worms in caecum
• Sx: itchy anus - especially at night
• Dx: adult worms & eggs
• Rx: Albendazole

Question 4

Answer 4

Trichuris trichiura (whip worm)

• Epi: global
• Transmission: by ingestion of eggs, no migration, adult worms in caecum
• Features: thin head end
• Sx: bloody diarrhoea, ab pain, prolapse of rectum from diarrhoea, anemia, impaired growth, reduced cognitive fx
• Dx: salt flotation
• Rx: Albendazole

Question 5

Answer 5

Strongyloides

• Epi: global
• Hosts: humans and dogs
• Features: larvae undergo hepatic tracheal migration
  
  • only few larvae produced
  • L3 are free-living adults
  • Infection by L3 skin penetration
• Sx:
  
  • Early: itchy eruption at site of penetration, cough and wheeze, upper ab pain & diarrhea, wt. loss, established autoinfection -> larva currens appearing as wiggly line on skin
  • Established strongyloidiasis: intestinal sx, flattening of microvili, malabsorption, smelly yellow stool, long lasting diarrhoea, anemia in severe cases
• Dx: stool microscopy, stool culture, ELISA (indirect)
• Rx: Thiabendazole/ivermectin

Question 6

Toxocara canis

Answer 6

• Epi: poverty, dog ownership
• Definitive hosts: puppies
• Sx:
  
  • Ocular Larva Migrans (OLM): usually unilocular blindness
  • Visceral Larva Migrans (VLM): sydroe primarily of young children, inflammation of internal organs and sometimes CNS
  • Covert toxocariosis
  • Neurotoxocariosis
• Dx: Hx, serology, US,
  
  • DDx: retinoblastoma; check serology
• Rx: Albendazole, corticosteroids

Question 7

Answer 7

Mansonella ozzarrdi

Question 8

Ancylostoma caninum

Answer 8

• Sx:
  
  • Cutaneous Larva Migrans (CLM)
  • Eosinophilic Enteritis

Question 9

A. braziliense

Answer 9

• Sx:
  
  • Cutaneous Larva Migrans (CLM)
  • Eosinophilic Enteritis
• Rx: Ivermectin/Albendazole/topical thiabendazole

Question 10

Answer 10

Mansonella perstans