17 - Pinworms Flashcards
What are pinworms?
Intestinal infection due to Enterobius vermicularis
Which species are hosts for pinworms?
Only humans (not transmitted through animal feces)
What is the role of animals in pinworm infestation?
Pinworm eggs can get on animal fur, and then a human can pet the animal and if they put their hand to mouth w/o washing it, can ingest the eggs and become infected
What is the pathophysiology of pinworms?
- Human ingests mature pinworm eggs; ova reaches stomach and outer coating is dissolved to release larvae; larvae hatch in duodenum and mature over 1-2 months
- Live and mate throughout large intestine attached to mucosa
- At night, pregnant females exit anus to lay eggs, leaving about 10,000 ova on perianal skin
- After laying eggs, females usually die (but can re-enter the individual)
- Ova become infective w/in 6 hours of being deposited and remain infective for up to 14-20 days
- Ova have sticky outer layer, allowing them to stick to various surfaces
What are the methods of transmission for pinworms?
- Finger to mouth (swallowed)
- Inhalation
- Retroinfection
What are risk factors for pinworms?
- Overcrowded living conditions
- Children 5-10 y/o (uncommon in children under 2 y/o)
- Temperate and cold climates
What are the signs and symptoms of pinworms?
- Can be asymptomatic
- Perianal or perineal itching (worse at night)
- Insomnia, irritability, restlessness
- Major infestations may cause abdominal pain, anorexia, or diarrhea
- Less common = urinary tract and vaginal sx
What are red flags for pinworms?
- Must have diagnosis before treatment (esp. if pregnant, under 12 y/o, and have renal or hepatic dysfunction)
- Abdominal pain
- Severe diarrhea
- Bloody bowel movement or painful urination
- Fever
- Extremely poor appetite
- Self-inflicted lesions from repetitive scratching
- Suspect sexual abuse
What are the 3 ways to diagnose pinworms?
1) Inspection of perianal area – 1 hour after child falls asleep, visually examine anus w/ flashlight to observe worms
2) Scotch-tape test – first thing in the morning, press a piece of tape on perianal skin, then stick to glass slide; may be repeated several times
3) Microscopic evaluation of subungual sample (under fingernails)
What are the goals of treatment for pinworms?
- Eradicate pinworms from px and household
- Eliminate symptoms
- Promote good hygiene
- Prevent reinfection and transmission
How can pinworms be prevented?
- Handwashing after using toilet, after scratching perianal area, and before and after eating/preparing food
- Keep nails short and discourage nail biting
What are some non-pharms to recommend for pinworms?
- Shower every morning
- Wash bed sheets, towels, and underwear in hot water daily for 2 weeks
- Wash hands and clean fingernails frequently
- All family members should wear cotton underwear during day and night and change twice daily (for 1 week after tx)
Who should be treated for pinworms?
Infested individual and all household members/close contacts (unless contraindication for medication)
What is the OTC treatment for pinworms? What schedule is it and why?
- Pyrantel pamoate
- Schedule 2 b/c family members need to be treated after 1 diagnosis has been made
What is the MOA of pyrantel pamoate in patient friendly language?
Paralyzes the pinworms, so they no longer stick to intestinal wall and then are carried out of the patient in the stool
What is the dosing for pyrantel pamoate?
- For adults and children over 1 y/o – single oral dose of 11 mg/kg, repeat in 2 weeks (max. single dose of 1 gram)
- Take any time of day, w/ or w/o food
Why is pyrantel pamoate dosed twice?
Because it doesn’t kill the eggs, so give time for eggs to grow and then dose again
What are common SE of pyrantel pamoate?
- N/V
- Tenesmus (straining when passing a bowel movement)
- Anorexia
- Diarrhea, abdominal cramps
Which drug does pyrantel pamoate interact w/?
Piperazine
What are contraindications for pyrantel pamoate?
- Hypersensitivity to drug or any ingredients
- Avoid in 1st trimester
- Caution in hepatic impairment
What is the Rx treatment for pinworms?
Mebendazole
What is the MOA of mebendazole?
Inhibits glucose uptake by helminths, so inhibits larval development
What is the dose of mebendazole?
For adults and children 2 years and older - single dose of 100 mg, repeated in 2 weeks
What are SE of mebendazole?
- Abdominal pain or diarrhea
- Anorexia
- Flatulence
- Vomiting
- Neutropenia
Which drugs does mebendazole interact w/?
- Metronidazole
- Carbamazepine
- Phenytoin
- Cimetidine
Can pyrantel pamoate and mebendazole be used in breastfeeding?
Yes
What are the monitoring parameters for pinworms?
- Patient monitor daily for perianal itching and adverse effects of medication (N/V, diarrhea, dizziness, drowsiness)
- Pharmacist follow up 1 day after tx regarding SE and 7 days after tx regarding perianal itching
What are some referrals after treatment?
- If not resolved w/in 7 days of second course
- If adverse effects interfere w/ functioning or last for more than 3 days (N/V, diarrhea) or more than 1 day (dizziness, drowsiness)
What are the symptoms of hookworms?
- Mild epigastric pain and tenderness
- Headache
- Fatigue
- Anemia
- Hypoproteinemia
What are the symptoms of roundworms?
- Abdominal discomfort
- Abdominal obstruction
- Vomiting
- Right upper quadrant pain
What is the tx for hookworms?
- Mebendazole 100 mg BID for 3 days
- Pyrantel pamoate 11 mg/kg (max. 1 g) per day for 3 days
What is the tx for roundworms?
Mebendazole 100 mg BID for 3 days
What are the symptoms of tapeworms?
- Range form mild epigastric or abdominal pain to a burning sensation
- General weakness
- Weight loss
- Headache
- Constipation, diarrhea
What is the tx for tapeworms?
Praziquantel
