Prevalence of chlamydia trachomatis among active duty male soldiers reporting to a troop medical clinic for routine health care.

Objective: To determine the prevalence of chlamydia among young, male soldiers receiving routine healthcare and to measure risk factors associated with sexually transmitted infections (STI).

Materials and Methods: Male soldiers between the ages of 18 to 25 years seeking routine healthcare were screened for chlamydia. Educational information regarding Chlamydia trachomatis was provided before testing. The transcription-mediated amplification (TMA) urine-based test was used as a sensitive and specific screening tool to detect disease. Assessment of risk factors was determined by questionnaire. Subjects who tested positive for chlamydia were treated with azithromycin 1 g in a single dose.

Results: A total of 138 male soldiers were screened for chlamydia. The majority of soldiers screened reported to sick call for evaluation of an injury, 31.9%. The estimated prevalence of chlamydia was 8.0% (95% CI: 0.035-0.125). Soldiers who tested positive for chlamydia were more commonly asymptomatic, 72.7%. Of those who screened positive for chlamydia, 63.6% did not use a condom during their last encounter. No subjects who tested positive for disease had been treated for an STI in the past.

Conclusions: The prevalence of chlamydia in this population of young, male soldiers is high. These results should spur providers to incorporate STI risk assessment and screening into a variety of clinical encounters.

Key Words: Chlamydia trachomatis, asymptomatic, nucleic acid amplification test

**********

It is estimated that there are more than four million cases of chlamydial urogenital infections each year in the United States. Infections caused by Chlamydia trachomatis (CT) have been a subject of interest for the military for many years. In the military, much emphasis has been placed on the female soldier and specific guidelines have been established to screen for infection. (1-3) Complications associated with untreated CT infections in women include pelvic inflammatory disease (PID), which is a precursor for infertility, ectopic pregnancy, and chronic pelvic pain. Due to the high rates of chlamydia in a young population, proactive sexually transmitted infection (STI) screening for military women is an identified priority given the significant morbidity associated with disease. (1,2)

Untreated chlamydia in males may also lead to serious complications. CT has been associated with urethritis, epididymitis, and proctitis. Previous studies have demonstrated high rates of CT among asymptomatic males. Podgore et al reported an 11% rate in 97 U.S. military personnel. (4)

Chlamydia infections in males are also an important cause of morbidity in their sexual partners. CT may be transmitted to female partners causing cervicitis or PID. Because of the concern of infertility related to CT, annual screening of sexually active females less than 26 years of age for infection has been recommended by the Centers for Disease Control and Prevention. (3) However, there is no universal policy to screen males based solely on risk factors. Morbidity caused by STIs may result in significant lost time from training, which may have an impact on work performance and deployable status. (5) The investigators wished to determine the rate of CT disease in male soldiers reporting for healthcare to demonstrate a need for routine assessment for high risk behaviors and targeted screening for STIs.

Materials and Methods

This was a cross-sectional study approved by the appropriate local institutional review board. Volunteers were recruited from a population of young, male soldiers between the ages of 18 to 25 years reporting to sick call for routine healthcare at a troop medical clinic from November 2004 to March 2005. An educational pamphlet concerning CT infection and complications was distributed to all male soldiers in the targeted age group presenting for care of various health concerns. Each soldier who agreed to participate in the study gave informed consent to be tested for CT and Neisseria gonorrhea (GC). Particular emphasis was given to the subjects' clear option to not participate without negative impact. Names and contact information were provided by subjects to track results of testing to ensure proper follow-up and treatment of those who tested positive for infection. Participants then completed a questionnaire to assess risk factors associated with contraction of STIs (Table 1). The principal investigator maintained positive control of the record of all participants.

The participants were asked to provide a urine sample to be analyzed for CT/GC using the transcription-mediated amplification (TMA) nucleic acid amplification test (NAAT). The TMA tests specifically for both CT and GC. The sensitivity and specificity of urine specimens from males when compared with urethral swabs were 97.9% and 98.9%, respectively (Ferrero DV et al). Samples were collected each day and appropriately transported to the Department of Pathology, Immunology Division, Brooke Army Medical Center, colocated on the military installation, for analysis. Participants who tested positive for CT were contacted and treated with azithromycin 1 g p.o. in a single dose. Doxycy-cline 100 mg orally twice daily for 7 days was the alternative treatment if there was a history of hypersensitivity to azithromycin. Subsequently, all positive subjects were screened for other sexually transmitted infections, such as HIV, syphilis, and hepatitis B and C. Positive cases were referred to Preventive Medicine Services for contact counseling and partner notification for treatment.

Statistical Analysis

The sample size was based on the prevalence of Chlamydia trachomatis in female military recruits in prior studies. (1,2) The total number of study subjects was calculated using the Wald Equation. (6) The answers to the questionnaire were consolidated onto a Microsoft Excel spreadsheet. Risk factors were analyzed using the [chi square] test. When fewer than five responses were observed in an arm of the distribution, the Fisher exact test was utilized to determine significance. (7) P < 0.05 was considered to be significant.

Results

Results are summarized in Table 2. A total of 138 male soldiers between the ages of 18 to 25 years were screened for STI using the TMA urine NAAT. Most of the consenting soldiers wanted to be tested after obtaining information regarding the high prevalence of asymptomatic chlamydial disease. Eight percent (n = 11) of the soldiers tested positive for CT (95% CI: 0.035-0.125).

Discussion

It is currently the standard of care to screen for risk-taking behaviors among all youths seeking routine healthcare. (8) Sexual activity during adolescence has been an important concern due to the practices placing individuals at risk and the high prevalence of sexually transmitted infections in this age group. In a self-reported survey, 63.8% of male seniors acknowledged being sexually active currently or in the past. (9) Not obtaining this vital information during clinical encounters or providing the opportunity to be screened for sexually transmitted infections may place the youth and his sexual partners at risk for complications. Because older testing methods are less sensitive in detecting asymptomatic disease, individuals were more likely to be screened for chlamydia only if symptoms were present. However, both females and males with chlamydia are more commonly asymptomatic for infection. Therefore, by only testing and treating those with urethritis or other signs of current infection, the majority with chlamydia will remain untreated. The policy of routine screening for sexually transmitted infections in those who are sexually active has been recommended. (3) Furthermore, annual screening of sexually active women less than 26 years of age for chlamydia has been adopted by the United States Armed Forces. (10) A similar guideline for routine screening of males at risk for contraction of sexually transmitted infections has not yet been developed.

A Department of Defense-wide survey of health-related behaviors among military personnel reported the prevalence of sexually transmitted infections. In the self-reported survey, 17.7% of military personnel admitted having an STI in the past, with 3.8% occurring in the past 12 months. (11) In our observational study, there was a high prevalence of chlamydia in the targeted group of male soldiers. The majority testing positive were asymptomatic. One soldier reporting to the troop medical clinic for evaluation of an acute injury admitted to having burning with urination for over 90 days when completing the risk factor questionnaire. In addition, this same soldier did not use barrier protection during his last sexual encounter. Risk behavior screening and STI education permitted this soldier to be screened and treated for chlamydia at a time when his symptoms may otherwise have gone undetected by a healthcare provider.

The Department of Defense (DoD) 2002 survey reported condom use among unmarried soldiers who were sexually active. Approximately 44% of males and 32% of females (42% total) reported use of condoms during their previous sexual encounter. (12) The majority of soldiers testing positive for chlamydia in this study reported no use of barrier protection during their previous sexual experience. Although there was no direct relationship between this behavior and developing an infection caused by chlamydia, this targeted age group is at highest risk of contracting sexually transmitted infections. (3,9) Therefore, ascertaining high-risk sexual behaviors may justify the need for screening and treatment, and subsequently identify female sex partners who may potentially experience reproductive complications related to non-treatment.

The recent conversion to a more sensitive screening tool has been shown to detect asymptomatic disease at a higher rate (Ferrero DV, et al). In addition, use of the urine-based DNA amplification test for chlamydia screening in sexually active females in the targeted group is cost-effective in terms of reducing pelvic inflammatory disease. (13)

Targeted screening in males may also prove to be beneficial in reducing these rates. One study has shown that universal screening of male military recruits was not cost saving (Shuping EE et al). Therefore, tailoring the testing for chlamydia to individuals at risk, identified by providers during routine clinical encounters, may limit costs of screening and increase detection of disease. This noninvasive screening tool may preclude the reluctance to disclose such sensitive health information due to fears of use of the urethral swab for chlamydia analysis.

Limitations

The result obtained in this study was high compared with prior research on the prevalence of Chlamydia trachomatis in young, male soldiers. (14) The current estimated prevalence may not represent the overall number of cases in a general population of male soldiers. A small sample size was utilized and those who agreed to be tested may have been in a group with high risk sexual behaviors which were not disclosed. Symptoms may have been under-reported. A large proportion of soldiers enrolled in the study had "STD concerns." With use of the urine-based test, physical examination was excluded. Although the TMA is a highly sensitive and specific test, use of this assay does not eliminate the need to perform a physical examination in all cases. When symptoms are present, it will be important to consider other causes of urethritis in males, such as Trichomonas, herpes simplex virus, and other minor sexually transmitted diseases, which would not be detected by nucleic acid testing for chlamydia.

Conclusion

Risk factor assessment for sexually transmitted infections should become part of routine evaluations of adolescent-aged males reporting for healthcare. The newer urine-based screening methods may increase their willingness to be tested for asymptomatic diseases, therefore facilitating the initiation of therapy and partner notification. Following this policy may prevent complications related to delayed treatment, including pelvic inflammatory disease and infertility in female partners.

Acknowledgments

We thank the staff of the McWethy Troop Medical Clinic, especially Dr. Sara Martinez Pastoor and Mr. Raymond Navarro, for their assistance. We also thank the dedicated staff of the Immunology Division at Brooke Army Medical Center for their diligent care and prompt service. We gratefully acknowledge the Department of Clinical Investigations for their technical assistance and support.

References

1. Gaydos CA, Howell MR, Pare B. Chlamydia trachomatis in female military recruits. N Engl J Med 1998;339:739-744.

2. Gaydos CA, Howell MR, Quinn TC, et al. Sustained high prevalence of Chlamydia trachomatis infections in female army recruits. Sex Transm Dis 2003;30:539-544.

3. Centers for Disease Control. Chlamydia trachomatis Screening Recommendations. MMWR 2002;51(RR15):37.

4. Podgore JK, Holmes KK, Alexander ER. Asymptomatic urethral infections due to Chlamydia trachomatis in male US military personnel. J Infect Dis 1982;146:828.

5. Brodine S, Shafer MA. Combating chlamydia in the military: why aren't we winning the war? Sex Transm Dis 2003;30:545-598.

6. Ott L, Mendenhall W. Understanding Statistics. Estimation of pi. 4th edition. pp 255-258. Boston, Duxbury Press, 1985.

7. Armitage P, Berry G. Statistical Methods in Medical research. p 129. Oxford, Blackwell Scientific Publications, 1987.

8. Elster AB, Kuznet NJ. AMA Guidelines for Adolescent Prevention Services (GAPS): Recommendations and Rationale. Chicago, Ill, American Medical Association, 1994.

9. Centers for Disease Control and Prevention. Youth Risk Behavior Surveillance, 2005. Surveillance Summaries, June 9, 2006. MMWR 2006:55 (SS-5).

10. DoD Armed Forces Epidemiological Board 1999. AFEB recommendations regarding Chlamydia screening. AFEB(15-1a)99-1, 25 May 1999.

11. Department of Defense Survey of Health Related Behaviors Among Military Personnel, 2002 (Sexually Transmitted Disease: Lifetime, Q122, Past 12 Months, Q121).

12. Department of Defense Survey of Health Related Behaviors Among Military Personnel, 2002 (Condom Use, Q116 and Q117).

13. Howell MR, Gaydos JC, McKee KT, et al. Control of Chlamydia trachomatis infections in female army recruits: cost-effective screening and treatment in training cohorts to prevent pelvic inflammatory disease. Sex Transm Dis 1999;26:519-526.

14. Cecil JA, Howell MR, Tawes JJ, et al. Features of Chlamydia trachomatis and Neisseria gonorrhoeae infection in male Army recruits. J Infect Dis 2001;184:1216-1219.

Jeffery P. Greene, MD, and Elisabeth Stafford, MD

From the Department of Pediatrics, Fort Sam Houston, TX.

Reprint requests to Dr. Jeffery Greene, 3851 Roger Brooke Drive, Fort Sam Houston, TX 78234. Email: [e-mail]

All comments and conclusions are those of the authors and do not purport to reflect the current position of the Army Medical Department, Department of the Army, or the Department of Defense.

Accepted October 17, 2006.

RELATED ARTICLE: Key Points

* The prevalence of asymptomatic Chlamydia trachomatis continues to be high.

* Young males who are sexually active should be screened for common sexually transmitted diseases based solely on experience and not on symptomatology.

* Newer, urine-based tests for chlamydia preclude testing concerns related to invasiveness of prior test methods.

Table 1. Questionnaire

Risk assessment

Have you ever been sexually active in the past?
Did you use a condom during your last sexual encounter?
Have you been treated for a sexually transmitted infection in the past?
Do you now have burning with urination?
Do you now have a discharge from the penis?

Subjects affirm or deny.

Table 2. Characteristics of male soldiers tested for chlamydia (n = 138)

                         n    %     + test         P-value

Age, years
  18-19                   58  42.0   3
  20-21                   35  25.4   5
  22-25                   45  32.6   3
Sexually active
  Yes                    136  98.6  11             NA
  No                       2   1.4   0
Prior condom use
  Yes                     59  42.8   4 (36.4) (a)
  No                      79  57.2   7 (63.6) (a)  0.758
Prior STI
  Yes                     17  12.3   0             0.359
  No                     121  87.7  11
Symptoms
  Yes                      4   2.9   3 (27.3) (a)  0.001
  No                     134  97.1   8 (72.7) (a)
Reason for visit to TMC
  URI                     20  14.5   0
  Injury                  44  31.9   4 (36.4) (a)
  Acne                     5   3.6   0
  Headache                 2   1.4   0
  Stomach ache             2   1.4   0
  STD concern             36  26.1   7 (63.6) (a)
  Other                   29  21.0   0

(a) Percentage of positive cases of chlamydia in subgroup; denominator
n = 11 (total number of subjects positive for disease).
STI, sexually transmitted infections; STD, sexually transmitted
diseases; TMC, troop medical clinic; NA, non-applicable; URI, urinary
tract infection.