GUM - Parasites/ Infestations Flashcards
What is trichomonas vaginalis?
Trichomonas vaginalis is a highly motile, flagellated protozoan parasite that mainly affects women of African or Asian origin.
What are the features of trichomonas vaginalis?
vaginal discharge: offensive, yellow/green, frothy
vulvovaginitis
strawberry cervix
pH > 4.5
in men is usually asymptomatic but may cause urethritis
Discharge tends to be localised around the posterior fornices.
How is TV investigated?
Microscopy of a wet mount shows motile trophozoites
How is TV managed?
Oral metronidazole for 5-7 days, although the BNF also supports the use of a one-off dose of 2g metronidazole
What is pubic lice?
Pediculosis pubis is a crab shaped pubic louse infestation. It is common in young adults and transmitted by close or sexual contact. Pubic lice infection in children can be a sign of sexual abuse but most children acquire pubic lice innocently.
How do pubic lice present?
Incubation period is usually between 5 days and several weeks.
Diagnosis is based on finding adult lice or eggs. All parts of the body should be examined.
Itchy red papules are the most common presentation. Itching is worse at night and commonly occurs 1-3 weeks after infestation.
What differentials should be considered in pubic lice?
Nits - scratched dermatitis, seborrhoeic scales, hair muffs (all of these can be brushed off, but nits are firmly adherent to the hair follicle)
Body lice
Scabies
How are pubic lice treated?
Consider whether the pubic lice are sexual or non sexual. If acquired via sexual contact refer to GUM for screening of other STIs and contact tracing.
Treat the individual with a topical insecticide: two applications of malathion 0.5% aqueous lotion or permethrin 5% dermal cream, seven days apart. All surfaces of the body should be treated, including the scalp, neck and face (paying particular attention to the eyebrows and other facial hair). Advise the individual to avoid close body contact until they and any current sexual partner have been treated.
Any close contacts over the previous three months should be examined for pubic lice.
If pubic lice infestation is unresponsive to initial insecticide treatment, repeat the previous treatment with the correct technique (rather than switching to a different treatment). If insecticide resistance is suspected, switch to the alternative insecticide (malathion or permethrin).
When re-infestation occurs, repeat the previous treatment; assess all close contacts for pubic lice and treat all positive cases simultaneously.
What is scabies?
Scabies is caused by the mite Sarcoptes scabiei and is spread by prolonged skin contact. It typically affects children and young adults.
The scabies mite burrows into the skin, laying its eggs in the stratum corneum. The intense pruritus associated with scabies is due to a delayed type IV hypersensitivity reaction to mites/eggs which occurs about 30 days after the initial infection.
What are the clinical features of scabies?
widespread pruritus
linear burrows on the side of fingers, interdigital webs and flexor aspects of the wrist
in infants the face and scalp may also be affected
secondary features are seen due to scratching: excoriation, infection
How is scabies managed?
permethrin 5% is first-line
malathion 0.5% is second-line
give appropriate guidance on use (see below)
pruritus persists for up to 4-6 weeks post eradication
What advice should patients being treated for scabies be given?
avoid close physical contact with others until treatment is complete
all household and close physical contacts should be treated at the same time, even if asymptomatic
launder, iron or tumble dry clothing, bedding, towels, etc., on the first day of treatment to kill off mites.
