Intestine Nematodes and Cestodes Flashcards
Intestinal Nematodes ( round worms )
Helminthic parasites, round worms with round cylindrical bodies.
Intestinal Nematodes(Round worms)Stages ?
eggs , larvae and adult worms(male and female)
Intestinal Nematodes(Round worms) transmission ?
obligatory soil phase indirectly faecal -oral
Some have direct person to person spread or autoinfection
Intestinal Nematodes(Round worms) Infection is either by
ingestion or skin penetration
Intestinal nematodes that need soil phase to complete the life cycle are ?
- Trichuris trichiura (whipworm)
- Ancylostoma duodenale (hookworm)
- Ascaris lumbricoides (roundworm)
Intestinal nematodes that do not need soil phase are?
1-Enterobius vermicularis (pinworm)
2-Strongyloides stericoralis (threadworm)
Trichuris trichiura ( whipworm ) (infected organ, reservoir , host , migration)
Nematode of large intestine
No animal reservoir
Man is the defenitive or final host
No lung migration
Trichuris trichiura (whipworm) Infective stage
embryonated eggs
Trichuris trichiura (whipworm) Life cycle ? (6)
- Eggs hatch in small intestine
- releasing larvae that migrate to the caecum
- Larvae mature into adult worms
- The fertilized female worm lays eggs(un-embyronated) in the caecum and ascending colon
- Eggs pass to the soil in faeces and develop in soil into embryonated infectious eggs
- Embryonated eggs are then ingested and the cycle repeated
Trichuris trichiura (whipworm) C/F ?(4)
- Abdominal discomfort
- Bloody diarrhoea(dysentry)
- Rectal prolapse
- Intestinal obstruction might occur
Trichuris trichiura (whipworm)Diagnosis ?
microscopy of faeces show typical eggs
Trichuris trichiura (whipworm)Treatment and control?
Mebendazole
sanitation and personal hygiene
Ascaris lumbricoides ( Roundworms ) (infected organ, reservoir, migration
Nematode of small intestines
No animal reservoir
Lung migration is present
Ascaris lumbricoides Infective stage is
embryonated eggs
Ascaris lumbricoides life cycle ?(4)
- Embryonated eggs are ingested and hatch in the small intestine releasing larvae
- Larvae migrate from the intestine to the lung and back to the small intestine where they mature into adult worms
- The fertilized female worm lays eggs (unembyronated) that pass in faeces into the soil
- The eggs develop in soil into embryonated infectious eggs,ready to be ingested and repeat the cycle
Ascaris lumbricoides C/F
symptoms depend on worm load Light load: asymptomatic Heavy load cause : 1.abdominal discomfort 2.Diarrhoea 3.Malnutrition 4.Intestinal obstruction 5.Larvae in lungs cause allergic reaction with pneumonitis manifested as cough dysnoea and eosinophilia
Ascaris lumbricoides Diagnosis ?
finding the eggs in faeces
Ascaris lumbricoides Treatment and control?
Mebendazole
education,good sanitation,personal hygiene especially in food handlers
Ancylostoma duodenale ( Hookworm ) ( infected organ , migration )
Nematode of small intestine
Lung migration is present in life cycle
Ancylostoma duodenale infective stage ?
larvae
Ancylostoma duodenale Life cycle ?(5)
- Embryonated eggs hatch in the soil releasing the infective larvae
- Larvae penetrate the skin and migrate first by blood circulation to the lungs and then to the small intestines where they mature into adult worms
- Adult worms attach to the mucosa of small intestine.
- Female worm lays eggs which pass in faeces into the soil
- The eggs hatch and mature into larvae which can penetrate the skin and repeat the cycle
Ancylostoma duodenale Pathogenesis
the worms ingest blood from the human small intestinal mucosa (100 ml daily by 500 adult worms)
Ancylostoma duodenale C/F ? (4)
- itch (ground itch) at skin penetration site 2.Migration of larvae to lungs cause pneumonitis with cough and dyspnoea
- Duodenal ulcer
- Iron deficiency anaemia
Ancylostoma duodenale Diagnosis ?
microscopy of faeces show the typical egg containing a developing larva
Ancylostoma duodenale Treatment and control?
Mebendazole
Iron supplements to correct the anaemia education good sanitation personal hygiene treatment of cases
Strongyloides stercoralis (Threadworm) route of infection ,reservoir
directly faecal-skin
direct anal contact (including sexual contact)
by autoinfection
No animal reservoir
Strongyloides stercoralis infective stage ?
the filariform larvae
Strongyloides stercoralis life cycle?(6)
- Filariform larvae in soil penetrate the skin exposed to soil
- Larvae migrate via the blood to the heart,lungs and trachea and are swallowed
- Larvae reach the small intestine and mature into adult worms
- Female adult worm producse eggs
- The eggs hatch in small intestine and release rhabditiform larvae(non infective larvae ) which pass out in the faeces into the soil
- The rhabditiform larvae then undergo any of three phase
The three phase of rhabditiform larvae
1-it develops into free-living adult worms in the soil and produce infective filariform larvae which can penetrate exposed skin
2-it develops into filariform infective larvae in the soil and these can penetrate exposed skin. There is no development of free-living adult worms
3-it develops into infective filariform larvae while passing down the small intestines into the large intestine and these can reinfect host by penetration of intestinal mucosa or perianal skin (autoinfection)
Strongyloides stercoralis C/F ?(6)
- itch (ground itch) at skin penetrating site
- allergic pneumonitis
- abdominal symptoms and diarrhoea
- small bowl obstruction
- Paralytic ileus
- gut ulceration
Strongyloides stercoralis Diagnosis
microscopy of repeated faeces specimens or duodenal aspirate show the filariform larvae. This indicates acute infection
Strongyloides stercoralis Treatment and control?
Thiabendazole
education, good sanitation, personal hygiene and treatment of cases
Enterobius vericularis (pin worm) infected organ, host , migration , route of infection ,
Nematode of large intestine
Man is the definitive or final host
No lung migration
Spread is person-to-person by direct contact or fomites or autoinfection
Enterobius vericularis Infective stage
embryonated eggs
Enterobius vericularis life cycle?(4)
- Eggs hatch in small intestine and release larvae which mature to adult worms
- The worms ,male and female, migrate to the caecum
- Fertilised female worm migrate to perianal skin region at night to lay eggs and then die
- Eggs are deposited on perianal skin,on under-clothes,bedding or under scratching finger-nails and ingested (autoinfection) to repeat the cycle
Enterobius vericularis C/F ?
perianal itching (pruritis ani)
Enterobius vericularis Diagnosis
- adult worms may be seen on perianal skin
2. eggs can be seen microscopically on cellophane tape pressed to the anus.
Enterobius vericularis treatment and control?
Mebendazole( to the whole family)
hand and nail hygiene,washing of beddings and case treatment
Cestodes ( Tapeworms)
segmented tape-like worms (tape worms)
Cestodes ( Tapeworms)(4)?
- Taenia saginata
- Taenia solium
- Ecchinococcus granulosus (hydatid worm)
- Hymenolepsis nana(dwarf worm)
Humans can be infected in two ways
1-As definitive or final host
2As intermediate host
As definitive or final host
the adult worm in the gut after ingesting encysted larvae in incompletely cooked meat. This produces intestinal disease e.g. infection by Taenia saginata
As intermediate host
larvae in tissues after ingesting eggs in faecally contaminated food or water. This produces tissue disease from encysted larvae e.g.as in infection by Echinococcus granulosus
