Pinworms

Question 1

what is enterobiasis

Answer 1

• intestinal infection caused by nematode Enterobius vermicularis (aka pinworm, seatworm, roundworm or threadworm
• humans are only natural host, cats and dogs can hold eggs on thier fur but no evidence that they can act as carriers of infection

Question 2

how is Enterobiasis transmitted

Answer 2

• human-to-human via fecal oral route
• nature eggs are transferred from anus to mouth and ingested
• larvae hatch in small intestine and adults establish in colon
• cycle ~ 1 month and life span of adults is ~2 months
• mature females migrate to anus at night and lay eggs on perianal or perineal skin, eggs become infective in 4-6 hours
• eggs remain infective ~20 days

Question 3

Pinworm infection is most common in what population

Answer 3

5-14 y/o

• uncommon in children < 2
• estimated that 1/3 children globaly wil be infested durign childhood

*most common intestinal parasite in primary care regardless of socioeconomic circumstances

Question 4

where is enterobiasis most prevalent

Answer 4

• in temerate and cold climates bc of less frequent bathing and infrequent changing of underlcothing
• overcrowing in shcools and family gatheirngs and inadequate personal and community hygiene are also factors

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Question 5

what are the usual consequences of infection

Answer 5

loss of sleep, discomfort due to anal itching and embarrassment do to social connotations of having “worms.”

*often entire family is infected

• secondary bacterial infections can occur as complication of excessive scratching
• rarely associated with signifacnt patholgoy like vulvovaginitis, dysuria, enuresis, urinary tract infection, appendicitis, chronic salpingitis, and ulcerative lesions of the small and large intestine.

Question 6

goals of therapy for pinworm treatment

Answer 6

Eliminate the infection

Relieve symptoms such as itchiness

Promote good hygiene

Prevent transmission, reinfection and complications

Question 7

how to assess for pinworms

Answer 7

• most infetions are asymptomatic
• often associated with perianal or perineal itching, esp if high worm burden
• itching is worse at night when females aly eggs that are attached to perianal area by sticky substnace causing pruitus
• itching can cause insomnia and reslessness

*rule out diaper dermatitis, constipation, psoriasis of the anogenital region, and perianal eczema before recommending pinworm treatment

• scratching can cause skin irritation -> if severe skin can break down and allow for secondary bacterial infection, eczematous dermatitis or bleeding

Question 8

what can extnesive pinwro infection cause

Answer 8

abdominal pain, nausea and vomiting -> not typical of uncomplicated infection

* If abdominal pain, severe diarrhea, bloody bowel movements, dysuria, fever, extreme poor appetite, neurotic excoriation (self-inflicted lesions produced by repetitive scratching) or anogenital symptoms associated with sexual abuse

REFER

Question 9

how is pinworm diagnosis confirmed

Answer 9

• visual identification of ova or worm itself
• eggs are only seen on occasion in stool, so stool sample is not a reliable diagnosis

most common diagnostic methods are

• Flashlight test
  
  • can directly observe worms during ovipositon
  • put child to bed w/o underpants and use flashlight to examine anus after child sleeping for 2-3 horus
• Scotch tape test
  
  • performed at gome in morning before defication or washing
  • piece of transpaent adhesive tape pressed on perianal skin, then stuck to slide and examined under microscope
• microscopic analysis of subungual samples
  
  • ova ma be found under fingernails of infected patients, since anla itching is common

Question 10

prevention of pinworms

Answer 10

difficult.

proper hygiene is helpful and includes careful handwashing after going to the toilet, after scratching the perianal area, and before and after eating or preparing food

Question 11

is pinworm self limiting

Answer 11

• if ingestion of eggs and subsequent reinfection can be avoided, the infection can be self limited and eradicate in 4-8 weeks
• difficult to achieve and reinfection and ongoing infestion is common

Question 12

non pharm measures for pinworm

Answer 12

• shower each morning
• avoid co-bathing, reusing or sharing washlcoths during treatment time and 2 weeks after treatment
• handwashing and fingernail cleaning, esp prior to meals or after suing bathroom
• keep fingernails short/clean, avoid nail bting
• discourage children from thumb sucking, pacing hands in mouth of sucking on toys
• encourage all family members to wear cotton underpants washed in hot soappy water, change twice daily
• wash nightclothes, udnerwaer and ahnd towels daily F2W
• change sheets frequently at start of each treatment
• avoid shaking linens or lcothes priot to washing
• wash toilet seat frequently

Question 13

when is pharmacologic therapy used

Answer 13

• confirmed daignosis by health care provider is recommended before pharmacologic treatment is intiiated to minimize unnecessary exposure to potential adverse effects of the anthelmintics

Question 14

non prescription treatment for pinworms

Answer 14

pyrantel pemoate

• dosage
  
  • adults & children >1y: 11mg/kg (base)
  • single dose PO; repease in 2 weeks
  • Maximum base dose = 1g
• adverse effects
  
  • anorexia
  • N/V/D
  • abdominal cramps,
  • HA, dizziness
  • drowsiness
• Drug Interactions
  
  • N/A
• Comments
  
  • dosage often expressed as 1 tab (125mg base)/ 11kg (25 lbs)
  • avodi in pregnancy in favour of alternative therapies due to insufficient avidence
  • caution hepatic impairment

Question 15

prescription treatment for pinworms

Answer 15

mebendazole

• Dosage
  
  • adults and children >2, 100 mg single dose, repeat after 2 and 4 weeks
• adverse effects
  
  • abdominal pain, diarrhea, vomiting in patietns w/ hgih parasite buden
  • less common: dizziness, drowsiness, flatulence, HA, itchiness
  • rare: anemia, agrenulocytosis, glomerulonephritis
• Drug interactions
  
  • may raise risk of Stevens Johnson syndrome or toxic epidermal necrolysis when coadministered w/ metronidazole
• Comments
  
  • can chew or crush tabs and mix w/ food
  • avoid in first trimester of pregnancy due to limited data

Question 16

what treatment is only avialable through Health Canada’s Special Access Program (SAP)

Answer 16

• albendazole
• Dosing
  
  • adults and children >2
    
    • 400 mg single dose PO, repeat in 2 weeks
  • children 1-2
    
    • 200mg single dose, repeat in 2 week
• Adverse Effects
  
  • mild and transient abdominal pain, N/V/D, HA, dizziness insomnia
  • rare: aplastic anemia, bone marrow suppression, agranulocytosis, erythema multiforme & stevens johnson syndrome
  • cation w/ hepatic impairement
• Drug interactions
  
  • grapefurit juice can inc concentrations
• Comments
  
  • food esp high fat content increases bioavailability
  • tablets can be chewed or crushed
  • avoid in frist trimester of preg due to limited data

Question 17

cases of pinworms during pregnancy

Answer 17

• dont self treat -> limited data on available anthelmintics in pregnancy
• asymptomatic pregnant patient with pinworms should eb treated after delivery
• if patient is experiencing symptoms that may negativeley affect pregnancy (weight loss or sleeplessness) treatment may be considered, preferably in third trimester

*Do not use mebensazole - maybe in 2nd or 3rd trimester

pryantel pamoate: insufficient info

albendazole: some reports suggesting not a major human teratogen, shown not of major risk during first trimester

Question 18

pinworm treatment while breastfeeding

Answer 18

• Mebendazole: poorly absorbed with <10% of oral dose reachign systemic cirucletion
• > amount in breast milk is clinicaly insignificant, no adverse rxn in breastfeeding

Pyrantel pamoate: limted into in breastfeeding, but its poorly absorbed orally do considered compatible

Albendazole: metbaolized into active, its minimally transferred itno breast milk and poorly absorbed from GI -> minimal risk from a single oral dose treatment

Question 19

minitoring: perianal itching

Answer 19

• patent/patient: monitor daily

HC provider: day 7

• if itching has not resolved in 7-14 days of starting medication, repeat treatment
• it not resolved within 7 days of second course or signs of bacterial superinfection occur, refer to HC practictioner

Question 20

monioring for N/V/D and abdominal cramps

Answer 20

parent/patient: monitor daily

HC practitioner: day 1 after treatment

• if adverse GI effects interfere w/ functioning or persist for more than 3 days after treatment ends, consult with HC provider

Question 21

monitoring: dizziness and drowsiness

Answer 21

parent/patient: monitor daily

HC practitioner: da 1 after treatment

• caution patient not to drive r use haxardous machinery until effect of drug is known
• if symp interefere w/ function persist more than 24 h after reatment, contact HC provider