Infections and Infestations Flashcards
How is threadworm transmitted?
Transmission occurs through the faeco-oral route. Eggs can be ingested by hand to mouth transfer (after scratching) from the faeces/perianal area of an infected person or by handling contaminated surfaces such as toys, bedding or clothing.
Occasionally, infestation may be acquired from inhaling and then swallowing eggs that have become airborne, for example after shaking contaminated bed linen
Person to person infestation occurs through handling contaminated clothes or bedding or from touching contaminated surfaces such as furniture and carpets. Eggs can survive on such surfaces for up to 2 weeks. Adult threadworms survive for about 6 weeks and fresh eggs need to be ingested by the host for infestation to continue.
Threadworms infest humans. Transmission from animals such as dogs and cats can occur if eggs are present in their fur and humans are exposed through ingestion following patting.
Classic presentation of threadworm
Night time peri anal itching
Confirming diagnosis is usually made through seeing the worms either around the perianal area, most easily seen at night or more rarely on the faeces. Loss of sleep due to itching may lead to tiredness and irritability during the day. Severe cases of infection can cause loss of appetite, diarrhoea, weight loss, insomnia, enuresis and irritability
Secondary bacterial infection may occur as a result of scratching. Other parasitic worm infections, although rare in the UK are possible e.g. roundworm- referral
Threadworm referral
- Pregnant/breastfeeding
- <2 yrs
- Suspected secondary infection
- Perianal eczema
- Recent travel abroad
- Severe abdominal pain
- Repeated attacks
- Diarrhoea
Suspected food poisoning
Threadworm practical advice
- Wash the perianal area first thing in the morning
- Change bed linen and nightwear daily for several days after treatment
- Thoroughly dust and vacuum and clean the bathroom by damp dusting surfaces, washing the cloth frequently in hot water
- Wear close fitting underpants at night
- Shower each morning, including the perianal area, to remove eggs from the skin
- Wash hands thoroughly with soap and warm water after using toilet, changing nappies and before handling food
Cut fingernails regularly, avoid biting nails and scratching around the anus
Threadworm Treatment
- Mebendazole 2+ yrs
- Treat all members of the household
- Mebendazole doesn’t kill eggs- repeat tretament after 14 days
Not necessary to keep children with threadworm off school
headlice transmission
Transmission of head lice required head to head contact
Once transmitted, lice begin to reproduce and the adult louse lives for approx 1 month. The female louse lays her eggs on the hair shaft near the scalp surface. She lays 50-150 eggs during her 30-40 day lifespan. The eggs hatch in seven to ten days and the shells are left empty. Conclusive diagnosis can only be made by finding live lice. An itching scalp is not sufficient to diagnose active infestation. A pruritic rash on the back of the neck and behind the ears is caused by a hypersensitivity reaction to louse faeces and itching can persist for days to weeks after successful eradication.
headlice riskfactors
- <12 yrs
- Female gender
- Children with more siblings
- Families with a lower economic status
Long hair
Headlice referral
- Scalp inflammation
- Outside licensed age for treatment
- Suspected pubic lice
Treatment failure
Wet Combing
Wet detection combing takes 10-15 minutes per head; lice remain motionless when wet10. To perform wet combing:
* wash the hair using an ordinary shampoo
* apply ample hair conditioner (to aid straightening and untangling hair)
* untangle the wet hair further using a wide-toothed comb
* switch to a detection comb once the wide-toothed comb is able to move freely through the hair without dragging
* make sure the teeth of the detection comb slot into the hair at the roots, with the deeply bevelled edge lightly touching the scalp and draw the comb down to the ends of the hair with every stroke
* check the detection comb for lice after each stroke and remove them by wiping or rinsing the comb
* work through the hair in sections so that the whole head of hair is combed through
* rinse out the conditioner
repeat the combing procedure in the wet hair to check for any lice that may have been missed
Dry combing
Dry combing takes 3 to 5 minutes per head. To perform dry combing:
* straighten and untangle the dry hair using an ordinary comb
* once the comb moves freely through the hair without dragging switch to a detection comb
* starting from the base or the side of the scalp comb the hair from the scalp down to the end of the hair
* comb each section of hair 3 to 4 times before moving to an adjacent section
* look for lice as the comb is drawn through the hair
* if a possible louse is seen, trap it against the face of the comb using the thumb as this avoids the risk of the louse being repelled by static electricity when the comb is withdrawn from the hair
continue combing the hair section by section until the whole head of hair is combed through.
Headlice treatment
Dimeticone 4% lotion (Hedrin)
Dimeticone (Hedrin®) 4% lotion acts by a physical process to cover the lice and disrupt their ability to balance water so that treated insects fail to excrete surplus water11. It is suitable for all ages, those with skin conditions, those with asthma and pregnant and breast-feeding women10,11. It cannot be purchased OTC for children younger than six months of age11. It should be applied twice, with seven days between applications5. Dimeticone is left on the hair and scalp for eight hours or overnight and is then washed out using shampoo11. Dimeticone activity is not diminished in insecticide-resistant head lice11
Pubic Lice symptoms
- Pruritus which is worse at night
- Visible lice or nits in any area with coarse body hair
- Blue spots may be seen on the skin where the lice are living, such as on the thighs or lower abdomen
Scatterings of minute dark brown specks on the skin and underwear
Pubic lice treatment
Derbac M lotion
All close contacts over the past 3 months should be examined for pubic lice
Scabies Presentation
Defined as a pruritic skin condition caused by mites. Generalised itching is the most common presenting symptom and is more intense at night, when the person is warm. Classical scabies is transmitted through close/prolonged skin contact with an infected person. Symptoms begin 3-6 weeks after primary infestation, and 1-3 days following reinfestation, probably due to prior sensitisation.
Scabies rash consists of tiny red spots. Scratching the rash may cause crusty sores to develop. Linear burrows appear on the surface of the skin as wavy, thread like whitish-grey lines of 2-10mm in length that may have a small vesicle with a black dot at the end. They are most commonly found on the fingers, wrists and penis. Itching in several family members suggests scabies
Scabies mites can survive outside the human body for 24-36 hrs. the bedding, clothing and towels of those who have scabies should be decontaminated by washing at a high temperature and drying in a hot dryer, or dry cleaning, or by sealing in a plastic bag for atleast 72 hrs.
Treat all contacts
Treatment should be applied twice, one week apart
Scabies Treatment
Permethrin 5% cream (lyclear)
Applied to the body, allowed to dry before dressing and then washed off after 8-12 hrs. larger patients may require up tp 2 30g packs for adequate treatment
Children under 2 require a prescription for permethrin
Malathion 0.5% aqueous liquid
Should remain on the skin for 24 hrs after application before being washed off
