Sexual abuse in children and adults

C. trachomatis and sexual abuse in children

A definitive diagnosis of genital or rectal C. trachomatis infection in pre-pubertal children is an indication of sexual abuse or assault. However perinatally transmitted C. trachomatis infection of the nasopharynx, urogenital tract, and rectum may persist for >1 year.

Ingram et al., 2001 analysed data obtained between 1988 to 1998 on 3040 children (2414 girls and 626 boys) aged 0 to 12 years who were being evaluated for sexual abuse in Raleigh, N. Carolina. Children were interviewed, examined, and tested by chlamydial and gonococcal culture of oral, rectal, and genital samples. Information from referral sources, accompanying guardians, and the results of recent physical examinations of the child were also recorded. Standard statistical techniques were then used to develop screening criteria to predict children at greatest risk of infection with either gonococci and / or C. trachomatis; or with gonococci alone. Fifty-eight infected children were identified by culture techniques, 37 with gonococcal infection, 25 with C. trachomatis infection; and 4 children who were infected with both organisms. The authors describe an algorithm for C. trachomatis or gonococcal infections which was capable of identifying all children with these infections, while avoiding testing 56% of uninfected children. Using genital cultures only, the proposed algorithm would have identified 100% of gonococcal or chlamydial infected cases with 85% fewer cultures than would have been necessary to test all children with oral, rectal, and genital cultures. [MEW comment: This is a major and interesting study. However it is relatively easy to design discriminatory algorithms from the retrospective analysis of data. The real test is whether such algorithms are found to be clinically useful and predictive in other clinical and social settings].

Diagnosis

A diagnosis of rectal or genital C. trachomatis infection in a child may lead to prosecution of a suspect for sexual abuse and is likely to be subject to detailed cross examination by the defence. Under these circumstances, only the positive isolation and identification of C. trachomatis by tissue culture procedures is unambiguously acceptable. Even when culture is used, there is significant variation in performance from laboratory to laboratory [Pate & Hook, 1995]. The diagnostic laboratory concerned can expect to have to demonstrate in a court of law if necessary that there are good standard operating procedures and laboratory practice in place. This is to ensure beyond reasonable doubt that the specimen from the child has been neither misidentified nor contaminated with another specimen.

Clearly the collection of vaginal and rectal swabs from victims of sexual assault is an invasive procedure which is likely to add to the victim's trauma [Hammerschlag 2001]. Nucleic acid based amplification tests have the capability to use non-invasive specimens e.g. urine, minimising the trauma to the victim. For C. trachomatis these tests are licensed for use on genital tract and urine (but not rectal or pharyngeal) specimens, but there is little data on their use in pre-pubertal children and that which there is [Embree et al., 1996; Mathews-Greer et al., 1999] was considered unsatisfactory by Hammerschlag, 2001. While it is probably reasonable to extrapolate data from trials on adults to trials on adolescents, one may not be able to do so for younger girls. Moreover the prevalence of C. trachomatis and N. gonorrhoeae in girls evaluated for sexual abuse is often of the order of 1 to 2% [Everett et al., 1998], whereas most diagnostic tests have been evaluated on populations with much higher prevalence of these infections. A test of 97% sensitivity and 99% specificity applied to a population with disease prevalence of 2% would have a positive predictive value of 66% [Hammerschlag 2001], which is barely adequate. However culture, with even lower sensitivity, probably has a poorer positive predictive value. Currently use of nucleic acid based amplification tests for C. trachomatis in sexual abuse cases has been insufficiently tested in the courts to know whether it is legally acceptable. Hammerschlag 2001, reviewing the evidence, considered that, in the absence of adequate studies, it would be premature to recommend the use of nucleic acid amplification based tests for C. trachomatis in sexual abuse cases involving children. None of these tests is approved or recommended by the manufacturers for rectal specimens from adults let alone children. The legal implications of the diagnosis of a sexually transmitted disease in a child mean that, in any laboratory test, specificity is paramount and much more important than sensitivity. What may be appropriate for screening a sexually active adult in an STD clinic may well not be appropriate for evaluating a child victim of suspected sexual abuse. The ramifications of a false-positive test for a sexually transmitted infection, which would lead to erroneous reports of sexual abuse and possible incarceration, do not presently justify the use of nucleic acid amplification based tests [Hammerschlag 2003]. In the case of N. gonorrhoeae, nucleic acid based tests are not dramatically better than culture [Hammerschlag 2001] and for the same reasons are best avoided in sexual abuse cases.

The practical dilemma is that ever fewer laboratories do routine diagnostic culture of C. trachomatis. Thus there may be no choice but to rely on the results of nucleic acid amplification based tests even though such evidence may be legally inadmissible. In this situation it is important that the results of one such leading test should be confirmed by a different amplification-based test targeting a different chlamydial gene, preferably using a different amplification method. This too is problematic as many of the confirmatory tests are not FDA approved and many laboratories use only one test. The situation is somewhat easier when testing urine based samples, as, given good practice, the most likely problem with urine based tests is false negatives rather than false positives [Hammerschlag 2001].

Tests based on monoclonal or polyclonal antibody, e.g. an EIA or immunofluorescence test, should not be used because of the possibility of false-positive test results. On pharyngeal specimens, there is a risk of cross-reactions with C. pneumoniae. On genital and anal specimens, there is the possibility of cross-reaction with faecal or other flora.

Treatment

The CDC STI treatment guidelines 2002 recommend the following for the treatment of chlamydial infection in children:

Sexual assault in adults

[There is almost nothing in the literature on male victims of rape, but presumably the same considerations below apply].

An important issue is whether antibiotic prophylaxis against sexually transmitted infections should be offered to adult victims of sexual assault. Gibb et al., 2003 assessed the acceptability of prophylaxis, follow up attendance rates, and the prevalence of sexually transmitted infections among female survivors of rape or sexual assault attending a London clinic. Women age greater than 16 years who were attending the clinic within two weeks of assault and who had experienced vaginal and/or anal penetration were selected for the study and were offered antibiotic prophylaxis and diagnostic tests for sexually transmitted diseases. They were invited to attend for test results at two weeks and offered a further diagnostic screen at three months post assault. Bacterial vaginosis was present in 32% of the women screened, C. trachomatis was identified in 8%, and none tested positive for Neisseria gonorrhoeae [note that there was no control group]. Antibiotic prophylaxis was generally acceptable to these women but follow-up rates for test results were low. Similarly, Worm et al., 2002 considered that adult female victims of rape should be screened for and offered prophylactic treatment for Chlamydia. They recommended screening for gonorrhoea initially and at follow-up, with treatment only given if gonococcal infection is definitely established. Furthermore, all victims should be screened for hepatitis B initially and again after three months and vaccination offered if any information indicates that the assailant has an increased risk of hepatitis B. Victims should also be screened for HIV initially and again one and three months later and offered anti HIV prophylaxis if necessary.

Actual practice seems to be far from these ideals. A survey of US hospital emergency departments found that none of 160 cases of sexual assault from 137,822 emergency department visits had received the full regimen of antibiotics for sexually transmitted infections recommended by the US Centers for Disease Control and Prevention. Antibiotics for gonococcal and chlamydial infection were provided for only 24.8% of adults and adolescents. No antibiotics were ordered in 62.5% of all cases or in 51.3% of cases of patients 12 years and older. Only twenty-one percent of those eligible received emergency contraception. Human immunodeficiency virus prophylaxis was almost never prescribed. It was calculated that more than 60,000 victims of sexual assault who visit US emergency departments annually may not be offered antibiotic treatment for the prevention of sexually transmitted infections [an appalling indictment of medical practice in this area]. It was concluded that the US, at least, a comprehensive national standard of care is needed for the medical treatment of victims of sexual assault together with appropriate training for health care providers [Rovi & Shimoni, 2002]. Sexually abused women are likely to need psychological as well as medical treatment [Champion et al., 2002].

[MEW] July 2003

NEXT: Sexually acquired reactive arthritis

References

Champion, J.D., Shain, R. N., Piper, J. & Perdue, S.T. (2002). Psychological distress among abused minority women with sexually transmitted diseases. Journal of the American Academy of Nurse Practitioners 14, 316 - 324.

Embree, J.E., Lindsay, D., Williams, T., Peeling, R.W., Wood, S. & Morris, M. (1996). Acceptability and usefulness of vaginal washes in premenarcheal girls as a diagnostic procedure for sexually transmitted diseases. The Child Protection Centre at the Winnipeg Children's Hospital. Pediatric Infectious Disease Journal 15, 662 - 667.

Everett, V.D., Ingram, D.L., Flick, L.A.R. et al., (1998). A comparison of sexually transmitted diseases (STDs) found in a total of 696 boys and 2973 girls evaluated for sexual abuse. Pediatric Research 43, 91A.

Gibb A.M., McManus T., Forster G.E. (2003). Should we offer antibiotic prophylaxis post sexual assault? International Journal of STD and AIDS 14, 99 - 102.

Hammerschlag, M.R. (2001). Use of nucleic acid amplification tests in investigating child sexual abuse . Sexually Transmitted Infections 77, 153 - 154.

Hammerschlag, M.R. (2003). Special article: Appropriate use of nonculture tests for the detection of sexually transmitted diseases in children and adolescents. Seminars in Pediatric Infectious Diseases 14, 54 - 59. [Useful review]

Ingram, D.M., Miller, W.C., Schoenbach, V.J., Everett, V.D. & Ingram, D.L. (2001). Risk assessment for gonococcal and chlamydial infections in young children undergoing evaluation for sexual abuse. Pediatrics 107, E73. Full article

Matthews-Greer, J., Sloop, G., Springer, A., McRae, K., La Haye, E. & Jamison, R. (1999). Comparison of detection methods for Chlamydia trachomatis in specimens obtained from paediatric victims of suspected sexual abuse. Pediatric Infectious Disease Journal 18 ,165 - 167.

Pate, M.S. & Hook, E.W. 3rd. (1995). Laboratory to laboratory variation in Chlamydia trachomatis culture practices.Sexually Transmitted Disease 22, 322 - 326.

Rovi, S. & Shimoni, N. (2002). Prophylaxis provided to sexual assault victims seen at US emergency departments. Journal of the American Medical Womens Association 57, 204 - 207.

Worm, A.M., Sidenius, K. & Hilden, M. (2002). Sexually transmitted infections and sexual violence against women. Guidelines for examination, prophylactic treatment and follow-up. Ugeskr Laeger. 164, 4768 - 4773. [In Danish].