C1. Common Nematode Infections Flashcards
What are the common nematode infections common seen in pharmacy ?
Pins, threads, whip, giant
What is the meaning of nematode ?
A worm of the large phylum Nematoda, such as a round work or threadworm
What is the scientific name for Pin worms (classification)?
Enterobius vermicularis
What is the scientific name for threadworm (classification)?
Trichuris trichiura
What is the scientific name for giant worm (classification) ?
Ascaris lumbricoides
Describe three visual features of flatworms (platyhelminths)
- Flat body plan
- No alimentary canal
- Suckers present
- Hermaphrodites (mostly)
Describe three Visual features of tape worms (cestodes)
- Tape like, segmented
- No alimentary canal
- Hermaphrodites
- Head has hooks and suckers
Describe three visual features of roundworms (Nematoda)
- Rounded
- Complete alimentary canal
- No suckers
- Sexually differentiated
What is the definition of geohelminths?
Soil transmitted helminths
Where does development usually take place in intestinal nematodes?
Outside of the body
How does infection occur in intestinal nematodes ?
Through contact with parasite eggs or infective larvae in contaminated soil or food
True or false. Geohelminths are the least common chronic infection of humans
False, most common
When should the term infestation be used?
When talking about infestation of ticks, fleas and other ectoparasites
What is enterobius vermicularis?
Pinworm or thread worm
What is it called when someone is infected with pinworm/threadworm?
Enterobiasis or oxyuriasis
Where are pinworms/threadworm often located when someone has been infected ?
Cecum: First part of colon (large intestine) after leaving the small intestine
What its the average length that pinworms can grow up to?
2-13mm
What is the most common type of infection in the UK and what age group does it usually affect ?
Pinworm/threadworm
children
What are the hosts for pinworm/threadworm?
Humans are the only host
Do threadworms multiply in the body?
No, Mating takes place in the body but reproduction and egg laying takes place externally
Give a brief preview of the lifecycle of enterobius vermicularis
- Embryonated egg ingested by human
- Larvae hatch inside small intestine
- Adults found in the cecum.
- Mating takes place in cecum
- Female migrated to perianal folds to lay eggs
- Eggs mature within 4-5 hours
What are the modes of transmutation of enterobius vermicularis ?
- Direct transmission from anal region to mouth by hands and fingernail contamination
- indirect transmission form visible eggs on surfaces such as bedsheets and clothes
- contamination via airborne eggs entering nose/mouth from contaminated dust
- Reinfection: larvae hatch from eggs on anal mucosa and larvae migrate up bowel
What are the key symptoms of entrobiasis
- Pruritus ani
- Vulvitis, worms entring vulva
- Insomnia and restlessness, loss of appetite
Is entrobiasis detectable through blood samples?
No, this is because it does not cause anaemia not eosinophilia therefore undetectable though blood sampling
Worms fo not feed off of blood, just deriving nutrient from the intestine
How could you diagnose entrobiasis ?
Perianal scrapings/swabs from under the nails
frequently sellotape is used on perianal region because eggs adhere to the sticky tape
How can you prevent the symptoms of entrobiasis ?
Trim fingernails
wear cotton cloths and gloves during sleep
frequently washing of sheets and hands
What is the drug of choice to treat entrobiasis ?
Mebendazole (drug of choice fro children over 6 months)
- Single dose
- Second dose for severe infections after 2 weeks
- Not sold OTC in pregnant women. must see GP
Albendaole
- Not licenced in the UK
What is Trichuris trichiura commonly known as ?
Whipworm
Where is Trichuris trichiura most prevalent in?
Tropical and humid climates where there is poor sanitation
Not in arid/dry areas
What is it called when you are infected with Trichuris trichiura?
Trichuriasis
Where is whipeworm located in infected patients ?
Cecum
Do whipworms migrate outside the body to lay eggs?
No
What is the average size of whipworms ?
3-5cm
Why do they not leave the body?
They burrow to the epithelium of the epithelial cells lining the colon/cecum
Briefly deceive the lifecycle of whipworms ?
- Embryonated eggs are ingested
- Larvae hatch in small intestine
- adults form in the cecum
- Unembryonated eggs pass in faeces
- 2-cell stage
- Advanced cleavage
How long can whipworms live?
Up to 1 year
What are the symptoms of trichuria?
Light infection: Generally no symptoms
Heavy Infections:
- Abdominal pain, stool containing mucus, water and blood
- Rectal prolapsed (rare but can occur in children)
Chronic anemia, growth retardation and impaired cognitive development (can occur in children)
Howe would you diagnose trichuriasis ?
- Stool Examination using microscopy Kate-katz technique
- Egg count reflects severity of infection
- FLOTAC allowing detection of eggs
What is the pathology of trichuriasis ?
- Strongly linked to work load, fewer worms less damage
- Trichuris dysentery syndrome (TDS)
- Mucosal damage caused by white worm and can promote infection with other parasites
What is are the treatments for trichurasis?
Mebendazole and albendazole
What is ascaris lumbricoides?
Giant roundworm
What is the average size for giant round worm?
15-35cm
What is the most common helminthic infection globally ?
Giant round worm
Where do adults of giant round worms reside?
Lumen of the small intestine
Larvae can also migrate to the lungs via circulation
How many eggs do females Giant ring worms lay
200,000 eggs per year
How long is the egg developmental phase of Giant round worms?
20 days with a temp of 25 degrees
Briefly describe the lifecycle of ascaris lumbricodides
.
What are the symptoms of ascariasis ?
Generally no symptoms
Heavy infections
similar to asthma or pneumonia due to migration
- wheezing, shortness of breath, persistent cough
- severe abdominal pain, fatigue, weight loss,
worms in vomit or stools
What is Lofflers syndrome ?
Lung damage due to migration of larvae
Eosinophils accumulate in the lungs (white blood cell)
What is the treatment for giant roundworms ?
Mabendazole
Albendazole
Levamisole
