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Latest CDC Guidelines on Treating STDs: Ectoparasitic, Protozoan, and Fungal Infections

Latest CDC Guidelines on Treating STDs: Ectoparasitic, Protozoan, and Fungal Infections


Which treatment approaches are effective in a woman who has persistent or refractory vaginal trichomoniasis? Should the male sex partner of a patient who has recurrent vulvovaginal candidiasis be treated? Answers to these and other questions can be found in the recently updated CDC guidelines on managing sexually transmitted diseases (STDs).1

In previous issues of CONSULTANT (June 2002, page 849, and July 2002, page 1032), the CDC's recommendations for treating sexually transmitted bacterial and viral (excluding HIV and hepatitis virus) infections were reviewed. Here the focus is on the management of pediculosis pubis, scabies, trichomoniasis, and vulvovaginal candidiasis.


Treatment. Pruritus and the appearance of lice or nits on the pubic hair usually prompt patients to seek medical care. The recommended regimens are:

  • Permethrin, 1% creme rinse, applied to affected areas and washed off after 10 minutes.
  • Lindane, 1% shampoo, applied to the affected area and thoroughly washed off after 4 minutes. This drug is contraindicated in pregnant or lactating women, children younger than 2 years, and patients with extensive dermatitis.
  • Pyrethrins with piperonyl butoxide applied to the affected area and washed off after 10 minutes.

Permethrin has less potential for toxicity than lindane. Do not apply the recommended agents to the eyes. Treat pediculosis of the eyelashes by applying occlusive ophthalmic ointment to the eyelid margins twice a day for 10 days.

Bedding and clothing should be decontaminated (machine-washed or machine-dried with the heat cycle or dry-cleaned) or removed from body contact for at least 72 hours. Fumigation of living areas is not required. Also treat those who have had sex with the patient during the previous month.

Follow-up. If symptoms persist, examine the patient again after 1 week. A second course of therapy may be required if lice are found or if eggs are observed at the hair-skin junction. If the patient's condition does not respond to therapy, select a different recommended regimen.


Sensitization to Sarcoptes scabiei (Figure 1), which results in pruritus, occurs several weeks after the first infestation. In subsequent infestations, Figure 1


pruritus might develop within 24 hours. Scabies in adults (Figure 2) may be sexually transmitted, although in children it usually is not.


Treatment. The recommended therapy is permethrin cream (5%), which is applied to all areas of the body from the neck down and washed off after 8 to 14 hours. Alternative regimens are:

  • Lindane (1%), 1 oz of lotion or 30 g of cream, applied thinly to all areas of the body from the neck down and thoroughly washed off after 8 hours. Advise patients not to apply lindane after bathing.
  • Ivermectin, in a single oral 200-µg/kg dose, which is repeated 2 weeks later.
Figure 1
Figure 1
Figure 2
Figure 2

Seizures have occurred when lindane was used after bathing or in persons with extensive dermatitis; aplastic anemia has also been reported following lindane use. Resistance to lindane has been reported in some areas of the United States.

As with pediculosis pubis, bedding and clothing should be decontaminated (machine-washed or machine-dried with the heat cycle or dry-cleaned) or removed from body contact for at least 72 hours. Fumigation of living areas is not required. Also examine and treat the patient's sex partners, as well as close personal or household contacts, from within the previous month.

Follow-up. The associated rash and pruritus may persist for up to 2 weeks. Some experts recommend treating again after 1 week if the patient still has symptoms; others advise retreatment only if live mites are observed. For patients whose condition does not respond to permethrin, select one of the alternative agents.


Most men with Trichomonas vaginalis infection have no symptoms, although a few have nongonococcal urethritis. In women, T vaginalis infection typically produces a diffuse, malodorous, yellow-green discharge with vulvar irritation; however, many women have few or no symptoms. During pregnancy, vaginal trichomoniasis may be associated with premature rupture of the membranes, preterm delivery, or low infant birth weight.

Diagnosis. Trichomoniasis is usually diagnosed by microscopic examination of vaginal secretions; however, the sensitivity of this method is only about 60% to 70%. Culture is the most sensitive commercially available method.

Treatment. The recommended regimen is metronidazole, 2 g PO, in a single dose; the alternative is metronidazole, 500 mg bid, for 7 days. Patients who are allergic to metronidazole require desensitization, since no effective alternatives to this drug are available. Neither metronidazole gel nor other topical antimicrobials are recommended because these agents are considerably less effective than oral metronidazole in this setting.

The recommended regimens have cure rates of about 90% to 95%. Treating both patients and their sex partners results in relief of symptoms, microbiologic cure, and reduced transmission. Advise patients to refrain from sexual intercourse until microbiologic testing shows they and their sex partners are cured or, if such testing is not available, until therapy has been completed and they are asymptomatic.

Follow-up. For patients who have no symptoms either initially or after therapy, follow-up is not needed. If either recommended regimen fails, treat the patient again with metronidazole, 500 mg bid, for 7 days. If treatment failure occurs repeatedly, administer a single 2-g dose of metronidazole once daily for 3 to 5 days. Most strains of T vaginalis with diminished susceptibility to metronidazole respond to higher doses.

Consult an expert if the patient has culture-documented infection-not reinfection-that does not respond to the regimens described here. Consultation is available from the CDC.


About 75% of women have at least 1 episode of vulvovaginal candidiasis each year, and 40% to 45% have 2 or more episodes. A small percentage (probably fewer than 5%) have recurrent vulvovaginal candidiasis (ie, 4 or more episodes of symptomatic disease per year).

Evaluation. Pruritus and erythema in the vulvovaginal area suggest Candida vaginitis; a white discharge may also be present. Other symptoms can include vaginal soreness, vulvar burning, dyspareunia, and external dysuria.

In a woman with signs and symptoms of vaginitis, the diagnosis can be confirmed by 1 of the following methods:

  • A wet preparation or a Gram stain of vaginal discharge that demonstrates yeasts or pseudohyphae.
  • A culture or other test that yields a positive result for a yeast species.

In wet preparations, 10% potassium hydroxide improves the visualization of yeast and mycelia by disrupting cellular material that might obscure the yeast or pseudohyphae. Treatment is not needed if Candida is identified in a woman with no symptoms; about 10% to 20% of women usually harbor Candida species and other yeasts in the vagina.

Treatment. The recommended regimens are listed in the Table. Topically applied azole drugs, which produce symptom relief and negative cultures in 80% to 90% of patients who complete therapy, are more effective than nystatin.

The ease of administration of oral therapy is an advantage over topical preparations; however, the greater potential for toxicity with a systemic agent must be kept in mind. Only topical azoles should be used by pregnant women.

Self-medication. Intravaginal preparations of butoconazole, clotrimazole, miconazole, and tioconazole are available over the counter (OTC). Self-medication with an OTC preparation is recommended only for women who have received a previous diagnosis of vulvovaginal candidiasis and in whom the same symptoms recur. Advise patients that if symptoms persist after treatment or if symptoms recur within 2 months, they should seek medical care.

Treating recurrent disease. Obtain vaginal cultures to confirm the diagnosis and to identify unusual species, such as Candida glabrata.

Patients with recurrent vulvovaginal candidiasis require longer therapy than those with uncomplicated disease. Initial therapy consists of a 7- to 14-day topical regimen or a single 150-mg oral dose of fluconazole repeated 3 days later. A 6-month maintenance antifungal regimen is recommended. Options include clotrimazole, ketoconazole, fluconazole, and itraconazole.

Treating sex partners. Although vulvovaginal candidiasis is usually not acquired through sexual intercourse, consider treating the sex partners of women who have recurrent infection. A few men have balanitis, which is characterized by erythematous areas on the glans that are associated with pruritus or irritation. These men might benefit from topical antifungal therapy to relieve symptoms.


1. Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines 2002. MMWR. 2002;51(RR-6):1-79.
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