Sexually Transmitted Infections V

Scabies - mite infestation (sarcoptes scabiei, excellent image from Jens G. Mattsson, MSc. Ph.D.)

The predominant symptom of scabies is pruritus. Sensitization to Sarcoptes scabiei must occur before pruritus begins. The first time a person is infected with S. scabiei, sensitization can take several weeks to develop. However, pruritus can occur within 24 hours after a subsequent reinfestation. Scabies in adults often is sexually acquired, although scabies in children usually is not.

• Causes itching (especially at night), mite burrows into skin.
• Dx
• Grossly or microscopically demonstrate mite, its eggs, larvae, or feces.
• India Ink placed on skin can be used to detect where the organisms burrow in the skin.
• Demonstrate lesion pruritic, erythematous, papular eruptions.
• Typical clinical presentation.

Permethrin cream (5%) applied to all areas of the body from the neck down and washed off after 8--14 hours.

Patients who have pediculosis pubis (i.e., pubic lice) usually seek medical attention because of pruritus or because they notice lice or nits on their pubic hair. Pediculosis pubis is usually transmitted by sexual contact.

• Caused by lice (pediculosis pubis, image 2)
• Dx
• Finding lice or nits attached to genital hairs (definitive Dx)
• Patient with a history of pubic lice presents with pruritic erythematous papules (presumptive Dx)

Treatment

Permethrin 1% creme rinse applied to affected areas and washed off after 10 minutes.
     OR
Lindane 1% shampoo applied for 4 minutes to the affected area and then thoroughly washed off. This regimen is not recommended for pregnant or lactating women or for children aged <2 years.
     OR
Pyrethrins with piperonyl butoxide applied to the affected area and washed off after 10 minutes.

Bedding and clothing should be decontaminated (i.e., machine-washed, machine-dried using the heat cycle, or dry-cleaned) or removed from body contact for at least 72 hours. Fumigation of living areas is not necessary.

Patients with pediculosis pubis should be evaluated for other sexually transmitted diseases.