Worms and Hygiene (Tom Gray)

Question 1

What is the main problem associated with helminthic infestations?

Answer 1

Leads to growth deficiency

Question 2

What is the incidence of roundworm (nematode), flukes (trematode), tapeworms (cestodes)?

Answer 2

Unusual in the UK, almost entirely found in foreign travellers and immigrant populations

Question 3

How can worm infestations be avoided / eradicated?

Answer 3

High standards of personal, food and environmental hygiene

Pharmacy role in counseling and providing advice

Question 4

What are the benefits of worms?

Answer 4

Treatment and prevention of allergies and a number of autoimmune disorder

Question 5

What is the pinworm or threadworm causative micro-organism?

Answer 5

Enterobius vermicularis

Question 6

What is the incidence of nematode infection / Enterobius vermicularis?

Answer 6

Most common nematode infestation in the UK
Only found in humans and transmitted faeccal-orally
Incidence highest in winter, declines in summer

Question 7

How does self-infestation of Enterobius vermicularis occur?

Answer 7

Poor hygiene, linen contamination, retro infestation

Question 8

What are the symptoms of Enterobius vermicularis?

Answer 8

Intense itching (usually at night) - female lays eggs in an irritant mucus, stools only contain 5% eggs but in heavy infections, worms can be seen around the anus.

Scratching can lead to excoriation of the skin and secondary infection.

Question 9

What complications can arise from Enterobius vermicularis?

Answer 9

Secondary infection of excoriated skin in perianal region

Worms transferred to vagina or vulva; severe pelvic inflammatory disease

Question 10

How can Enterobius vermicularis be treated?

Answer 10

Scrupulous hygiene and mebendazole chewable tablet or piperazine family treatment.

Question 11

What can happen if Enterobius vermicularis is long term and untreated?

Answer 11

Loss of appetite, weight loss, insomnia, irritability and may cause bed-wetting in children.

Question 12

What non-drug treatments can be used to treat Enterobius vermicularis?

Answer 12

High standards of hygiene (personal, bedding washed 60ºC, vacuuming, damp dusting surfaces)
Children taught to wash their hands in soap and water after using toilet and before meals.
Wearing tight fitting underpants at night will help to prevent scratching. Bathing every morning immediately after rising will help to reduce reinfection rates. Child being treated and observing strict hygiene measures can go to school.

Question 13

How can mebendazole be used to treat Enterobius vermicularis?

Answer 13

In children > 2years
Given as a single dose but as reinfection is common a second dose may be given 2 weeks later.
Does not kill eggs so must be used alongside hygiene measures
Senna may also be given to evacuate worms

Question 14

What is Strongyloides stercoralis?

Answer 14

Also known as threadworm

Less prevalence in the UK, picked up from travel abroad and prevalent through sub-Saharan Africa, S America and S Asia.

Question 15

What kind of areas does Stronglycoides stercoralis occur in?

Answer 15

Places with poor hygiene that use human excrement as fertiliser
The worms exist in soil as a free living worm or as parasitic filariform larvae; these larvae are picked up by walking barefoot in contaminated soil.

Question 16

What are the symptoms of Stronglycoides stercoralis?

Answer 16

Larvae burrow into skin causing pruritus - ‘ground itch’.
Larvae can migrate via venous circulation to the lungs where they can cause a pneumonitis (Löffler’s syndrome) before being expectorated into the pharynx, swallowed then excreted via the colon.

Question 17

What are the consequences of Stronglycoides stercoralis?

Answer 17

Usually infection does not cause problems.
Can cause a variety of cutaneous, gastrointestinal and pulmonary symptoms
Including a rare and potentially fatal hyperinfestation syndrome - widespread dissemination of larvae leading to systemic organ failure

Question 18

What are the non drug treatments for Stronglycoides stercoralis?

Answer 18

Wear shoes, avoid walking in insanitary areas e.g. open sewers or where raw human sewage has been used as fertiliser.

Question 19

How can Stronglycoides stercoralis be treated?

Answer 19

Ivermectin - available via special order
Two doses (200mcg/kg), administered two weeks apart 

Albendazole 400mg/day 7 days when Ivermectin is not tolerated or contra-indicated

Question 20

How can Hyperinfestation Syndrome be treated?

Answer 20

Combination therapy of daily ivermectin for up to 2 wekks, antibiotics for gram (-) bacterial infection and intensive care support for multiple organ failure.

Question 21

What is Taenia saginata?

Answer 21

Beef tapeworm

Question 22

What is Taenia soliuum?

Answer 22

Pig tapeworm

Question 23

What is the prevelance of Taenia sp?

Answer 23

Common worldwide
Beef and dwarf tapeworms most common in UK
Usually comes from contaminated meat

Question 24

Why is pig tapeworm (T. soliuum) most dangerous?

Answer 24

Larvae hatch in intestines and can migrate to form cysts in muscle, lungs, liver or brain
Cysticerci

Question 25

What are the symptoms associated with Taeniasis?

Answer 25

Usually asymptomatic but can cause abdominal discomfort, diarrhoea, loss of appetite and emaciation.
Anal pruritus as proglottids excreted, can rarely cause intestinal obstruction.

Question 26

How can Taeniases be prevented?

Answer 26

Avoid raw meat, especially abroad, ensure meat is well cooked and comes form a safe source.

Question 27

How can an adult tapeworm (Taenia spp) be treated?

Answer 27

Broad spectrum anti-helminthic
Praziquantel 10-20mg/kg or Niclosamide 2g as single dose
Available as special orders only
Co-prescribed a laxative

Question 28

What is the hypothesis linked to ‘A little bit of dirt’?

Answer 28

David Strachan 1989
Hygiene Hypothesis
Lower incidence of asthma, hay fever, eczema in larger families, with older siblings and environments such as farms.
Protective effect

Question 29

What is the hypothesis linked to ‘Old friends’?

Answer 29

Graham Rook
Immune stimulation from micro-organisms are thought to affect evolution and cause more protection that chicken pox/measles.
Gut flora is also a key factor in priming and regulating the immune system in pregnancy.

Question 30

What lead to the measles epidemic in Wales of 1998?

Answer 30

MMR vaccine scare following publication of fraudulent research

Question 31

What are the disadvantages to modern hygiene practices?

Answer 31

Lost the beneficial symbiotic relationship with viruses and parasites (particularly in childhood resulting in an increase in allergy, autoimmune and immunologically mediated disease).

Question 32

How have moderate hookworm infections shown clinical use?

Answer 32

Demonstrated to have beneficial effects on hosts suffering from diseases of overactive immune system such as asthma, allergy.
Potential benefits hypothesised for MS, Crohn’s disease and type 1 diabetes.

Question 33

How can personal hygiene reduce the incidence of parasite infestation?

Answer 33

Reducing oral-fecal transmission; hands washed with soap and water before and after handling / preparing food, before eating and after using the toilet.
Pet hygiene is equally important - dogs (especially sheepdogs should be regularly de-wormed and avoid feeding with raw meat or offal.

Question 34

How can environmental hygiene reduce the incidence of parasite infestation?

Answer 34

UK - regulations govern how human and animal sewage should be treated and where it can be disposed of. This prevents contamination of rivers/freshwater pools. As well as protecting humans, this also reduces the likelihood of animals such as cows or sheep coming into contact with contaminated pasture.

Question 35

How can food hygiene reduce the incidence of parasite infestation?

Answer 35

Inspection system at all stages of meat preparation
Cooking pork/beef/fish will kill eggs and larvae
Freezing fish and meat below -10ºC for >48h will kill eggs and larvae.
‘Cook it, Boil it, Peel it or Forget it’ - travel advice.

Question 36

How are hygienic standards maintained?

Answer 36

Food Standards Agency - compliance with EU Food Hygiene Regulations; slaughterhouse to plate rules.