Nematodes Flashcards
List the nematodes:
- Trichuris trichiura (whipworm)
- Ascaris lumbricoides
- Toxocara canis/cati
- Enterobius vermicularis (pinworm)
- Strongyloides sterocoralis (threadworm)
- Ancylostoma duodenale / Necator americanus (hookworm)
- Ancylostoma braziliense
- Trichinella spiralis
Yikes.
Life cycle of Trichuris trichiura? (whipworm)
Adult worms attach to human cecum - lay 1000-7000 eggs/day
Pass in feces and embryonate (become infective) in 3-6 weeks
Eaten; larvae hatch in intestine, penetrate villi; develop into adults in 1-3 months
Pathogenesis of Trichuris trichiura?
Asymptomatic if less than 100
Colon damage, abdominal pain, vomiting, diarrhea, BLOOD in stool, prolapsed rectum
NO eosinophilia
Diagnosis / Treatment of Trichuris trichiura?
Demonstrate barrel-shaped egg in feces
Mebendazole/albendazole
Life cycle of Ascaris lumbricoides?
Largest nematode - up to 1 foot long
- Live in small intestine
- Eggs in stool / ingested by humans
- Hatch in duodenum –> mucosa, lymph –> portal circulation (LIVER) –> heart –> lungs (molt)
Migrate to bronchioles, trachea, glottis, esophagus, small intestines (adults)
Why the hell did he write so much.
Pathogenesis of Ascaris lumbricoides?
Heavy infection: larvae migrate to lungs –> hemorrhage –> pneumonia
- Malnutrition from feeding on contents on intestines
- Bolus = intestinal blockage
- Can go to gall bladder, liver, appendix
Diagnosis / Treatment of Ascaris lumbricoides?
Egg in stool / larvae in sputum
Mebendazole / albendazole
Life cycle of Toxocara canis/cati?
Most puppies/kittens infected (like, nearly 100%)
Larvae activated in pregnancy and passes from mom to puppy/kitty - Humans ingest eggs
Pathogenesis of Toxocara canis/cati?
Human infection is visceral larval migrans (VLM)
Random migration
HIGH eosinophilia; lesions in liver
Ocular larval migrans (OLM); trapped in eye tissue
Can be major tissue damage and immune response
Diagnosis / Treatment of Toxocara canis/cati?
ELISA for antigen
Self-limiting, but thiabendazole used sometimes
Life cycle of Enterobius vermicularis? (pinworm)
Humans only host
Live and mate in cecum; female migrate to anus; perianal region to lay eggs
Pathogenesis of Enterobius vermicularis?
Intense anal itch –> scratch –> reinfection hand to mouth with eggs
Clothing and bedding can also hold eggs
Symptomes of Enterobius vermicularis?
Self-limiting
Lack of sleep, poor appetite, nervousness, irritability in children
Adults: “pinworm neurosis” (from associated stigma)
Diagnosis / Treatment of Enterobius vermicularis?
Scotch tape test –> visualize eggs
Pyrantel pamoate OR mebendazole
Life cycle of Strongyloides sterocoralis?
In small intestine, lay eggs; hatch into rhabditiform larvae
- Direct: Develop to free-living filarifrom larva in soil
- Indirect: Free-living male/female worms
- Autoinfection: Filariform larvae in gut and invade mucosa
Filariform penetrate unbroken skin –> blood/heart –> lungs –> trachea –> small intestine
Pathogenesis of Strongyloides sterocoralis?
Mild: Abdominal discomfort, nausea, vomiting, diarrhea
Heavy: Chronic dysentery, bronchitis, damage to intestinal mucosa (can lead to bacterial invasion and enteritis)
Diagnosis / Treatment of Strongyloides sterocoralis?
Larvae/eggs in feces
Invermectin (hyperinfection), thiabendazole
Life cycle of Ancylostoma duodenale / Necator americanus? (hookworm)
Suck blood from mucosa of small intestine (2-5 years)
Eggs in feces –> rhabditifrom larvae –> filarifrom larvae –> penetrate skin (like foot) –> blood to heart –> lungs/coughed up and swallowed –> intestines
Pathogenesis of Ancylostoma duodenale / Necator americanus?
3 stages:
- Cutaneous: papule at site of penetration
- Pulmonary: larvae migrate through lungs (can cause bronchitis)
- Intestinal: suck blood
Anemia, weakness, vomiting, nausea, diarrhea
In infants: retardation
Diagnosis / Treatment of Ancylostoma duodenale / Necator americanus?
Demonstrate hookworm in stool (blood in stool)
Mebendazole / albendazole; iron/vitamins
What is Ancyclostoma braziliense?
Hookworm of dogs/cats (accidental in humans)
- Cutaneous larvae (creeping eruptions)
- Subcutaneous areas (migrate an inch a day)
Diagnosis / Treatment of Ancyclostoma braziliense?
Appearance of lesion on hands, feet, buttocks
Albendazole or Ivermectin
Life cycle of Trichinella spiralis?
Eating larvae in cysts in poorly-cooked pork
Mate in small intestine
Female invade mucosa/lymph nodes
Larvae in bloodstream
Encyst in muscle –> degeneration and calcifying cysts
Pathogenesis of Trichinella spiralis?
Abdominal pain, diarrhea, nausea, vomiting
Migration of larvae causes localized edema (face), fever, eosinophilia, inflammation of heart
Intense muscular pain
Diagnosis / Treatment of Trichinella spiralis?
Demonstrate larvae in muscle
Mebendazole / albendazole; pain relievers
