Sexual Assault, Infectious Disease Prophylaxis

Article Author:
Carolyn Sachs
Article Editor:
Brooke Thomas
Updated:
10/27/2018 12:32:05 PM
PubMed Link:
Sexual Assault, Infectious Disease Prophylaxis

Introduction

Patients presenting for medical treatment after sexual assault may be concerned about the possibility of acquiring an infectious disease. For many types of sexually transmitted infections (STDs) providers should administer appropriate therapy to prevent this transmission. For others, such as genital herpes, no effective prophylaxis can be recommended. 

Recommendations for specific STD treatment and appropriate medications change over time as infectious agents become more or less common. also, some of these STDs become resistant to commonly used antibiotics. New sexually-acquired diseases may appear over time as was the case with HIV in the 1980s. Researchers develop new medications that are effective against certain STDs as was also the case with HIV in the decades after its discovery. Recommendations changed several times over the last decade regarding gonorrhea treatment as that organism became increasingly resistant to current therapies. 

Treatment varies by country and sometimes within a country depending on local resistance and patterns of infections. The following information follows current recommendations made by the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO).

Issues of Concern

Incidence

Transmission of STDs after sexual assault varies widely among populations. They range from high reported rates of 12% for trichomoniasis and 19% for bacterial vaginosis to lower estimates for chlamydia (2%) and gonorrhea (4%). Due to methodological issues, some of these positive cultures may reflect preexisting infections. The literature cannot provide reliable estimate data on the risk for transmission of herpes, hepatitis B, or HIV infection from sexual assault. However, sexual transmission of hepatitis B is common, even in the United States, among non-vaccinated individuals engaging in receptive intercourse with hepatitis B-positive partners and both hepatitis B and HIV transmission after sexual assault have been reported.

Testing

The CDC recommends selective testing for sexually transmitted infections when individuals present for evaluation after sexual assault.  The majority of advanced practitioner sexual assault response team programs in the United States do not routinely perform STD testing on adults and adolescent. STD specimen collection during a sexual assault examination most often does not detect infections transmitted by the perpetrator but merely reflect infections acquired before the assault, and thus, provides no meaningful information for the criminal investigation. Child victims may be an exception if they present with signs or symptoms of an STD. If authorities suspect ongoing child sexual abuse, the discovery of a sexually transmitted infection may provide laboratory proof of the abuse.

For the vast majority of adult and adolescent routine prophylactic antibiotic treatment against Neisseria gonorrhoeae, Chlamydia trachomatis, and incubating syphilis renders testing and discovery of preexisting infections costly as management does not usually differ.

Clinical Significance

Recommended Treatment

Bacterial Infections

Standard recommendations include treatment of gonorrhea and Chlamydia at the time of the initial examination.  Though we use the term "prophylaxis", the antibiotic administration for gonorrhea and chlamydia is more appropriately considered “treatment” that is given so early that the disease has yet to produce clinical symptoms assuming the perpetrator transmitted the bacteria to the victim. Though the CDC recommends routine administration of medication to prevent symptomatic trichomoniasis infection, clinicians may decline to routinely prescribe this treatment due to the significant side effects of the recommended antiprotozoal agents. 

Currently, the CDC recommends ceftriaxone in a 250 mg dose intramuscularly (IM) as the drug of choice in for preventing active infection of gonorrhea after sexual assault. Ceftriaxone in this dose also effectively prevents incubating syphilis from becoming clinical. For chlamydia prophylaxis, give patients either a 1-gm oral dose of azithromycin or a 7-day course of oral doxycycline (100 mg 2 times a day) or oral tetracycline (500 mg 4 times a day). Since tetracyclines are relatively contraindicated in pregnancy, erythromycin may be used as an alternative. Examiners may elect to offer prophylaxis for trichomoniasis with a single 2-gm oral dose of metronidazole or tinidazole as recommended by the CDC. Metronidazole often induces nausea, vomiting, and diarrhea which may prevent absorption of other antibiotic  prophylaxis and emergency contraception. If examiners choose to offer this treatment, it is recommended to give the patient the metronidazole to take at home several hours after the other medications have been taken and absorbed.

CDC Recommended Medications

  • Ceftriaxone 250 mg IM in a single dose PLUS
  • Azithromycin 1 gm orally in a single dose PLUS
  • Metronidazole 2 gm orally in a single dose (delay by 1 to 2 hours after other medications and assure no concurrent ethanol use) OR tinidazole 2 gm orally in a single dose (delay by 1 to 2 hours after other medications and assure no concurrent ethanol use)

Hepatitis B

The CDC recommends serologic testing for hepatitis B if the victim’s vaccination status is unknown. Examiners in some settings may choose to refer patients for HIV and hepatitis B testing rather than at the time of examination as communicating positive test results and facilitating treatment may be impossible. Testing for hepatitis B is recommended as vaccination, and immune globulin treatment may fail to work, and transmission of the virus from the assault may qualify the victims for lifetime coverage of related medical expenses resulting from viral transmission by the by the victims of violent crime compensation fund. Testing may be omitted if the victim is known to be adequately vaccinated with an appropriate antigenic response. Administer vaccination contemporaneous with an examination or within 24 hours of the assault, and schedule the remaining 2 for series completion in victims know to be unvaccinated. When a perpetrator is known to be hepatitis B antigen positive and the victim is known to be unvaccinated and tests hepatitis B antibody negative, the CDC recommends the administration of hepatitis B immune globulin (HBIG) and simultaneous vaccination at a separate site for examinations performed within 14 days of the assault. Complete CDC recommendations for treatment of hepatitis B assault victims can be found at https://www.cdc.gov/std/tg2015/hepatitis.htm#table5 (accessed 2/5/18).

HPV

The CDC recently recommended HPV vaccination for females through age 26 years after the sexual assault. This appears to be more of a public health measure as it follows the recommended childhood vaccination guides rather than a true post-sexual assault specific treatment since not all exposed victims are given this recommendation; although, it might indeed prevent transmission for those over age 26 and for male victims as well. 

Prevention of HIV Infection

There are no published studies on the effectiveness of HIV post-exposure prophylaxis after sexual assault; however, postexposure prophylaxis (PEP) for parenteral occupational exposure to infected body fluids (for example, needlestick) is believed to be effective based on case-control studies.

Although the risk for HIV transmission from one episode of unprotected consensual receptive vaginal intercourse with an infected individual is approximately 1 to 2 in 1000, the violent nature of many sexual assaults and resultant injury may increase the transmission rate. After unprotected receptive anal intercourse, the risk of transmission has been found to be greater at 5 to 32 per 1000.

Almost half of the sexual assault victims express worries about the risk of acquiring HIV after the assault. Examiners must address this concern, provide counseling, and arrange for the option of taking antiretroviral medications (termed post-exposure prophylaxis or PEP) as they may be effective. In the rare case where immediate perpetrator rapid HIV testing can be performed at the same time of the victim’s exam, this information can be used to guide PEP in the same manner used for occupational exposures.  However, this is a highly unlikely scenario. The CDC recommends administering PEP to sexual assault victims within 72 hours of an assault resulting in a substantial risk for transmission with a known HIV positive perpetrator. The 28-day medication course for sexual assault victims is similar to that recommended for occupational exposure. As with occupational exposure, PEP should be initiated as soon as possible post-assault. HIV seroconversion due to failures of PEP following sexual exposure has been reported. In cases where the HIV status of the perpetrator is not known, the CDC advises practitioners to decide with patients on an individual case-by-case basis. Some states in the United States legislate medical examiners to offer HIV PEP to all sexual assault victims, and practitioners must be aware of their state laws. The CDC guidelines provide a useful framework to approach individual decisions in prescribing HIV PEP. Assistance with postexposure prophylaxis decisions can be obtained by calling the National HIV Telephone Consultation Service (800-933-3413 or 888-448-4911) or accessing the National HIV/AIDS Clinician's Consultation Center online.

Other Issues

Post-Examination Follow Up

Though the minority victims complete the recommended follow-up medical care, this should be offered and discussed with the victims verbally and reiterated with explicit written instructions. Most recommend follow-up in 1 to 2 weeks for repeat STD testing if not completely treated during the initial examination, and at 4 to 6 weeks and 3 to 6 months to for HIV, hepatitis B, hepatitis C, and syphilis serology testing.