Helminths Flashcards
List the general types of Helminth worms and the general lifecycle.
Roundworms
Tapeworms
Hookworms
Flukes
Nematodes
Outline/define Nematodes and give an example.
- Soil-transmitted Helminths
- Areas with poor sanitation
- Faecal/oral transmission
- Human (and animal) faeces contaminated with eggs contaminate…Soil, Food, Water supplies, Rivers - Survive several weeks outside body
- Significant physical and mental impairment in infected children
- Chronic effects: Diarrhoea/abdominal pain, Weakness, Impaired development
Ascaris lumbricoides
Explain the features, lifecycle, symptoms, diagnosis and treatments of Ascaris lumbriciodes.
-
Giant roundworm
- Causes intestinal infection
-
Adults sexually reproduce in the small intestine
- ~200,000 eggs/worm/day
- Do not hatch in same host – pass in feces
- Fertilised eggs mature and become ingested
-
Eggs hatch in small intestine - larvae
- Invade intestinal mucosa
- Migrate to lungs
- Eventually swallowed
- Mature into adults in small intestine
DRAW FROM NOTION
-
Symptoms
- Many are asymptomatic
- Diarrhea
- Stomach cramps
-
In extreme cases
- Malabsorption (children)
- Intestinal obstruction
-
Diagnosis
- Presence of eggs in stool
- Adult worms in stool
- Cough up larvae
-
Treatments
- albendazole
- Mebendazole
- Prevents larval growth/egg production
Explain the features, lifecycle, symptoms, diagnosis and treatments of Necator americanus(hookworm).
-
Hookworm
- Causes intestinal infection
- Adults sexually reproduce in the small intestine
- Do not hatch in same host – pass in faeces
- Fertilised eggs hatch into larvae and develop
- Survive 3-4 weeks outside host
- Larvae penetrates human skin (typically feet)
- Invade blood stream
- Migrate to lungs
- Eventually swallowed
- Mature into adults in small intestine
DRAW FROM NOTION
Discuss helminth therapy.
Name another roundworm and how it’s an exception to most Helminth worms.
Trichinella spiralis
An exception to the rule due to it being an INTRACELLULAR roundworm
Explain the features, lifecycle, symptoms, diagnosis and treatments of Trichinella spiralis(intracellular roundworm).
- Causes intestinal infection
- Followed by muscle tissue
Trichinella cysts found in muscle tissue of many carnivorous animals.
If consumed, cysts releases larva in intestine
- Larva mature into adult (~2 weeks)
- Adults (1.2-2.2 mm) release larva
- Migrate into blood vessels
- Enter muscle cells and encyst
- Dead-end?
1-2 days after ingestion - gastrointestinal
- Nausea
- Diarrhea
- Vomiting
2-8 weeks after ingestion
- Muscle pain
- Fever
- Swelling of the face, particularly the eyes
- Weakness or fatigue
- Headache
- Chills
- Itchy skin or rash
Then symptoms end…
Diagnosis
- Serology – antibody test
- Muscle biopsy
Treatment
- Antiparasitic drugs albendazole or mebendazole
- Only for intestinal stage
- Intracellular stages - little benefit
Define/outline tapeworms generally.
- Long, segmented body
- Intestinal parasite (in humans)
- Indirect lifecycle
Explain the features, lifecycle, symptoms, diagnosis and treatments of Taenia solium(Pork tapeworm).
Life cycle
- Form cysts in pig muscle tissue
- Raw/undercooked pork/beef
ingested
- Cysts develop into adults in small
intestine (~2 months)
- Scolex anchors worm to intestinal epithelium
- Adults can grow several meters in length - taeniasis
- Eggs/gravid past in faeces
If eggs are ingested directly…
- oncospheres hatch, invade intestinal wall
- Enter blood stream
- Invade tissues, including brain
Cysticercosis
Diagnosis
- Taeniasis – presence of eggs/gravids in stool
- Cysticercosis – clinical (symptoms + imaging)
Treatment
- Taeniasis – Niclosamide – easy!
- Cysticercosis – Praziquantel + corticosteroids
- surgery
Any recent developments regarding helminth worms?
