Genital infestations Flashcards
What is the incubation for scabies?
1-2 days
Symptoms and signs of pubic 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
• There may be either no symptoms or there may be itch due to
hypersensitivity to feeding lice
• Blue macules (maculae caeruleae) may be visible at feeding sites
How do you diagnose pubic lice?
Finding adult lice and/or eggs
Examination under light microscopy can confirm the morphology if
necessary
What should patients with pubic lice be advised?
- Avoid close body contact until they and their partner have completed treatment and follow-up
- Patients should be given a detailed explanation of their condition, and clear and accurate written information on applying the treatment
Which products for pubic lice are more effective?
Lotions are likely to be more effective than shampoos, and should be applied to all body hair including the beard and moustache if necessary
A second application after 3-7 days is advised
What are the recommended treatments for pubic lice?
Malathion 0.5%. Apply to dry hair and wash out after at least 2, and preferably, 12 hours ie overnight
• Permethrin 1% cream rinse. Apply to damp hair and wash out after 10 minutes
• Phenothrin 0.2%. Apply to dry hair and wash out after 2 hours
• Carbaryl 0.5 and 1% (unlicensed indication). Apply to dry hair and wash out 12 hours later
How to treat pubic lice in eyelashes?
Infestation of eyelashes can be treated with permethrin 1% lotion
Keeping the eyes closed during the 10 minute application
Alternatively, an inert ophthalmic ointment with a white or yellow paraffin base such as simple eye ointment BP may be applied to the eyelashes twice daily for 8-10 days
This works by suffocating lice and avoids any risk of eye irritation by topical insecticide.
What is the management of partners of patients with pubic lice?
Current sexual partners should be examined and treated
What is the PN for pubic lice?
Contact tracing of partners from the previous 3 months should be undertaken
Is follow up of pubic lice advised?
YES
Patients should be re-examined for absence of lice after 1 week
What to do if treatment failure of pubic lice?
- Treatment failures should be given an alternative
- It should be explained to patients that dead nits may remain adherent to hairs. This does not imply treatment failure and the nits can be removed with a comb designed specifically for that purpose.
Aetiology of scabies?
Parasitic mite
Female penetrates stratum corneum and lays eggs 1-3 daily
6 legged larvae hatch and then moult to form a 8 legged nymph
What is lifespan of parasitic scabies mite?
4-6 weeks
How do scabies mites feed?
On lymph and lysed tissue
Absorb oxygen through its surface
How long can scabies mite survive outside of its host?
72 hours
Classical scabies- how many mites?
In immunocomptent- 5-10
What is different about norwegian scabies?
Found in immunocompromised or elderly
May be related to failure of sensitisation to mite antigen
Highly contagious
Honeycomb cavities in skin containing thousands of mites
Crusted lesions with hyperkeratosis over elbows, palms, knees and soles
Most likely route of transmission of scabies?
Holding hands
Prolonged skin to skin
Although less likely- can remain viable on objects for 2-5 days
Why itch with scabies?
Intense immunological reaction
Where is usually affected in scabies?
Finger webs Axilla Wrists Genitals Buttocks Extensor surfaces of elbows - usually eczematous, associated with burrows
How to diagnose scabies?
Identify burrows
Stain sites with washable felt tip
After washing, ink in burrow- delineated
Apply tetracycline- wash off excess
Burrows retain it
Shine under woods light where it will fluoresce
Microscopy- extract mites with needle
What to tell patents about scabies treatment?
Wash clothes/bedding >50 degrees Head to toe treatment Minimum 12 hours Repeat 1 week Wash hands- reapply
Permethrin 5%
Malathion 0.5%
Ivmectin- norwegian
Pubic lice- what is life cycle?
The nit- white oval egg attached to hair base
The nymph- resembles pubic louse but smaller
Hatches in 7 days
Migrates back to hair base to suck blood and mature
Adult- 1-2mm in length
3 pairs of claws with claw like appendages
Sensory attune that detect human smell
Almost blind- photophobic
Buries sharp mouthpiece stylets inside pubic hair follicle to get constant blood supply
Female lays 2-3 eggs / day
15-50 eggs over a lifetime
Treatment of pubic lice
Malathion 0.5% Permethrin 1% Aqueous better than alcohol Lotion better than shampoo Repeat 7 days Leave on 12 hours Dead nits- fine tooth comb Wash clothes etc >50 degrees
Incubation period for scabies?
Reinfection incubation is 24-48 h
1st infection incubation is 4-6 weeks due to delayed type 4 hypersensitivity
