Genital Infestations Flashcards
What is phthirus pubis
Pubic lice
How is phthiriasis diagnosed?
Pubic lice - Can be seen by the naked eye
Nits (eggs) - seen with naked eye - adhere to hairs
Examination under light microscopy can confirm morphology if necessary
Treatment of phthiriasis
Malathion lotion or permethrin cream.
All body hair should be treated.
All bedding should be washed at high temperatures.
Sexual partners need treatment.
Transmission of phthirus
public lice transmitted by close body contact
incubation period for phthirus (lice)
incubation period usually 5 days to several weeks
Symptoms / signs of phthirus (lice)
itching
can be asymptomatic
visible lice or nits (eggs)
Blue macules (maculae caeruleae) may be visible at feeding sites
What areas can be affected by phthirus (lice)
Adult lice infest coarse hairs of the pubic area, body hair and, rarely, eyebrows and eyelashes
Eggs (nits) are laid which adhere to the hairs
Management of phthirus pubis (lice)
Lotions more effective than shampoos
apply to all body hair including beard + moustache
A second application after 3-7 days
- Malathion 0.5%. Apply to dry hair- wash out 2 - 12hrs
- Permethrin 1% cream - Apply to damp hair- wash out 10min
- Phenothrin 0.2% - apply to dry hair - wash out 2hr
- Carbaryl 0.5 and 1% - Apply to dry hair - wash out 12 hr
avoid close body contact until they + partner(s) completed treatment + follow-up
full STI screen
Treatment of pubic lice infestation of eyelashes
permethrin 1% lotion - keep eyes closed - 10 minute application
OR
inert ophthalmic ointment with white / yellow paraffin base applied to the eyelashes BD for 8-10 days - works by suffocating lice - avoids risk of eye irritation
treatment of phthirus pubis (lice) in pregnancy or breastfeeding
Permethrin is safe
Permethrin 1% cream - Apply to damp hair- wash out 10min
Advice for sexual partners of patients with phthirus pubis (lice)
Examine and treat current sexual partners should be examined and treated
Contact tracing - partners in last 3 months
follow up for patients treated for phthirus pubis (lice)
Review at 1 week - re-examine for absence of lice
Treatment failure should be given an alternative
Dead nits may remain adherent to hairs - does not imply treatment failure - nits can be removed with a nit comb
What is scabies
Sarcoptes scabiei var hominis
human itch mite
Lifecycle of scabies mite
lifecycle of sarcoptes = 4-6 weeks Mites burrow into skin + lay eggs eggs hatch ~10% grow into adults in 10 - 15 days female lays ~25 eggs and dies
Transmission of scabies
close skin contact
frequently sexually acquired
mites can live off a host for 24-36 hours
Fomite transmission is uncommon but can occur
Why is format transmission more common in crusted scabies
greater number of mites present
and mites can survive longer - up to 7 days
Symptoms of classical scabies infection
intense generalised itching
worse at night
due to delayed type-IV hypersensitivity reaction to mites, and mite faeces + eggs
How long after primary infestation do symptoms of scabies occur
Symptoms begin 3-6 weeks after primary infestation
earlier ( 1-3 days) in a re- infested person
Scabies is infectious before the rash develops
signs of scabies infestation
most common = erythematous papules excoriation characteristic distribution pathognomonic lesion= burrow -linear intra-epidermal tunnel = short wavy greyish/ white threadlike elevations of 2-10mm length Nodular lesions
Anatomical sites commonly affected by scabies
interdigital webspaces / sides of fingers / under finger nails
flexor aspects of wrists / extensor aspects of elbows
anterior + posterior axillary folds
around nipples / penis + scrotum / umbilicus
upper medial thighs / buttocks / sides + back of feet
Spares face + scalp
what is Norwegian scabies
Crusted scabies / Scabies crustosa / Norwegian scabies) occur in immunocompromised states
When does crusted scabies occur
occur in immunocompromised states
e.g. in AIDS, leprosy, lymphoma, systemic or potent topical steroids, organ transplant recipients, elderly
what proportion of patents with crusted scabies have no identifiable risk factor (e.g. no immunocompromised)
40%
suggests possible genetic susceptibility
Symptoms / signs of crusted scabies
Erythematous scaly crusted lesions can be malodorous associated with fissuring can affect any part of the body including the face and scalp itching may be mild or absent