Abstract

Non–health care–seeking male United States Army recruits were tested for Chlamydia trachomatis (n=2245) and Neisseria gonorrhoeae (n=884), using a urine ligase chain reaction test to determine prevalence and potential risk factors for infection. The prevalence of chlamydial infection was 5.3%. Black race, a new sex partner, a history of trichomonas, and the presence of symptoms were associated with chlamydial infection. The prevalence of N. gonorrhoeae infection was 0.6%. Only a reported history of or positive test for C. trachomatis was associated with gonorrheal infection. Of those testing positive for chlamydia, 14% reported symptoms versus 40% of those with gonorrhea. Younger age was not a predictor of either infection, as has been shown for women. A substantial number of male army recruits are infected with C. trachomatis but few are infected with N. gonorrhoeae. Screening on the basis of symptoms alone would miss the majority of both infections

Chlamydia trachomatis and Neisseria gonorrhoeae are among the most commonly reported diseases in the United States [1]. Up to 80% of women with chlamydial infections and 40%–50% of women with gonorrheal infections of the cervix are asymptomatic [2]. The proportion of men with asymptomatic urogenital infections is less well defined, although several studies suggest it is high [2, 3]. Asymptomatic persons are less likely to seek medical care, are potentially at increased risk for developing complications, and may represent a large reservoir of infection for continued transmission

With the development of urine-based screening, using highly sensitive and specific amplified nucleic acid assays, it has become relatively easy to screen large numbers of women and men in nonclinic settings [4, 5]. The sensitivity (88%–98%), specificity (99%–100%), and positive predictive value (98%) of these assays are excellent for both genital and urine specimens in both symptomatic and asymptomatic persons [6–9]

We conducted a prevalence survey and risk factor analysis for C. trachomatis and N. gonorrhoeae infections among young men beginning US Army basic training. We sought to determine the extent of infection among these mostly asymptomatic non–health care–seeking men from throughout the US and to assess risk factors associated with infection that might be useful in developing effective chlamydia and gonorrhea control programs

Methods

All new male army recruits who were present on Sundays during May and June 1998 and during November 1998 through March 1999 at Fort Jackson, South Carolina, were invited to enroll in the study. Those recruits enrolled during May and June 1998 were offered chlamydia testing. Those enrolled during the second enrollment period also were offered gonorrhea testing. Of the recruits approached, 2273 (76.5%) volunteered to participate. Volunteers received a briefing to explain the study and an educational presentation about chlamydia and gonorrhea by a civilian research nurse. All subjects completed a questionnaire to record demographic information, sexual history, condom use, previously diagnosed sexually transmitted diseases (STDs), and symptoms. Participants were asked to identify themselves as white, black, American Indian, native Alaskan, Asian Pacific, or other. Separately, they were asked whether they considered themselves to be Hispanic. With regard to condom use, participants were simply asked if they used a condom “with every sex act.” Symptoms were defined as a recent fever, abdominal or pelvic discomfort, penile discharge, discomfort during urination, or any physical complaint considered to be relevant by the volunteer. Those who declined to participate were asked to complete the questionnaire anonymously

Urine samples were tested by ligase chain reaction (LCR; Abbott Laboratories) for chlamydial DNA, according to the manufacturer’s directions; a subset (n=884) was tested similarly for N. gonorrhoeae DNA. Infected subjects were referred for medical management at the Troop Medical Clinic at Fort Jackson

The results of the LCR, demographic information, and risk factor information were analyzed as binary variables. Participants with missing age information (n=28) were excluded from further analysis. Separate univariate analyses that compared excluded with included participants were performed for each variable, and no statistically significant differences were found. Persons with missing data for other variables were included in the analysis and were analyzed as if they had given a negative response in an effort to provide the most conservative estimates of statistical association. Persons who did not volunteer for the study but who completed the questionnaire anonymously were compared with those who did volunteer by univariate analysis with respect to each variable. No statistically significant differences were found. Univariate and multivariate logistic regression analyses were performed with Stata statistical software (release 6.0, 1999). All independent variables were entered into a model, and a 2-sided P<.05 was considered to be statistically significant

Results

Among the 2245 men studied, the mean age was 20.6 years (range, 17–35 years); 89% of the participants were <25 years old. Most (59.5%) were white, 27.2% were black, and 13.3% were of other races; 10.8% considered themselves to be Hispanic. A majority (87.4%) reported ever having had vaginal sex, 32.9% reported having had sex with >1 partner in the previous 90 days, and 34.1% reported having had sex with a new partner in the previous 90 days. Twenty percent reported using condoms every time they had sex. Only 2.6% reported having been diagnosed with chlamydia in the past, 2.4% reported a history of gonorrhea, 0.4% had a history of syphilis, and 0.2% reported a history of trichomonas; 95.3% denied ever having had an STD (table 1)

Table 1

Univariate analysis of factors associated with Chlamydia trachomatis infection (n=2245)

Table 1

Univariate analysis of factors associated with Chlamydia trachomatis infection (n=2245)

The overall prevalence of C. trachomatis infection was 5.3%. Although the highest prevalence rates were among men <25 years old (table 1), a χ2 test for trend did not reveal a statistically significant relationship between age and being chlamydia positive (P=.73). Of men who denied ever having had vaginal sex, 1.8% were positive for chlamydia; of those who reported always using condoms, 4.1% were positive. Only 14.4% of the men testing positive for chlamydia reported symptoms of any kind

By univariate analysis, 10 variables were significantly associated with chlamydial infection (table 1). In multivariate analyses, the model most predictive of being chlamydia positive included black race, a new sex partner in the previous 90 days, a history of trichomonal infection, and the presence of symptoms (table 2)

Table 2

Multivariate analysis of factors associated with Chlamydia trachomatis infection (n=2245)

Table 2

Multivariate analysis of factors associated with Chlamydia trachomatis infection (n=2245)

The overall prevalence of gonorrhea was 0.6%. The prevalence of chlamydial infection in this subset was 4.5%, and, of those infected with chlamydia, 7.5% were coinfected with gonorrhea. All 5 men who tested positive for gonorrhea were <25 years old. Of men who tested positive for gonorrhea, only 40.0% reported having symptoms of any kind, and 60.0% were coinfected with chlamydia

Discussion

Among new recruits at the US Army’s largest training facility, we found a 5.3% prevalence of chlamydial infection. The prevalence of chlamydial infection in our volunteers is slightly higher than that reported in another non–health care–seeking US male military population (4.1%) [5] and among Austrian male military recruits (3.8%) by use of the same assay [8]. In a study of teenagers and young adults in a variety of civilian clinic settings in the Seattle area that used the same LCR technique, the prevalence of chlamydia among males was 5.3% [10]. The prevalence of gonorrhea among our recruits was 0.6%. In one study among shipboard navy personnel, Brodine et al. [5] found no gonococcal infections. Low rates of gonorrhea are consistent with the overall declines in gonorrhea in the United States over the past 2 decades

Recruits are not routinely screened for chlamydia or gonorrhea at entry into the US Army. Our finding of a high prevalence of chlamydia among these non–health care–seeking men is of concern and warrants intervention. Since only 14.4% of men infected with chlamydia and 40.0% of men infected with gonorrhea were symptomatic, screening based on symptoms alone would be inadequate. It is not known if persons with asymptomatic infections transmit these infections with the same efficiency as those with symptoms or if they are as likely to develop sequelae if untreated. However, civilian-based chlamydia screening programs have been associated with a decline in the prevalence chlamydial infections and their sequelae [11]. At present, it is prudent to consider asymptomatic infections to be as serious as symptomatic infections

The most consistent predictor of chlamydial infection in sexually active women is young age [2, 4, 10]. Young age also is a risk factor for chlamydial infection in civilian men attending STD clinics [12]. Although no statistically significant association of chlamydial and gonorrheal infection with age was seen in our population, perhaps because of the small numbers of men in older age groups, the prevalence of chlamydial infection was highest among men <25 years old

Risk factors that were independently predictive of chlamydial infection included black race, a history of a new sex partner within the last 90 days, the presence of symptoms, and a reported history of trichomonas. The findings that black race and new or multiple sex partners are associated with infection are consistent with data from similar studies of young men and women in civilian populations [10, 13, 14]. The association with trichomonas has a wide confidence interval and probably is spurious. These results do not identify an acceptable screening strategy, given the need for obtaining a complex sexual history and the unacceptability of screening based on race

Analyses of risk factors associated with gonorrheal infection were of limited value, given the small number of infected recruits in this study. Our finding that 60% of men infected with gonorrhea were coinfected with chlamydia and 7.5% of those infected with chlamydia also had gonorrhea is similar to that observed in a population of military males attending an STD clinic at Fort Bragg [15] and reinforces the importance of testing for both infections

Collection of urine specimens in this study was highly acceptable and easily implemented, enabling us to test >2000 men in a nonclinic setting in a short time. We did not identify variables that might be used to develop an effective screening program. However, military basic training centers represent a point of entry through which many people pass each year. Some do not complete basic training and quickly return to civilian life. Many others complete basic training and then return to their civilian communities within a matter of months as members of the US Army Reserve or National Guard. Considering the 5.3% prevalence of chlamydia infection that we found, it would appear that screening all male army recruits would benefit STD control and prevention programs in both the military and civilian sectors

Acknowledgments

We thank Pam Syffus and Jane Lindner, for help and support during data collection at Fort Jackson; Billie Jo Wood, for technical assistance; and Nina Shah, for help with statistical analyses

References

1
Centers for Disease Control and Prevention
The leading nationally notifiable infectious diseases: United States, 1995
MMWR Morb Mortal Wkly Rep
 , 
1996
, vol. 
45
 (pg. 
883
-
4
)
2
Stamm
WE
Holmes
KK
Sparling
PF
Chlamydia trachomatis infections of the adult
Sexually transmitted diseases
 , 
1999
3d ed
New York
McGraw Hill
(pg. 
407
-
22
)
3
Stamm
WE
Cole
B
Asymptomatic Chlamydia trachomatis urethritis in men
Sex Transm Dis
 , 
1986
, vol. 
13
 (pg. 
163
-
5
)
4
Gaydos
CA
Howell
MR
Pare
B
, et al.  . 
Chlamydia trachomatis infections in female military recruits
N Engl J Med
 , 
1998
, vol. 
339
 (pg. 
739
-
44
)
5
Brodine
SK
Shafer
MA
Shaffer
RA
, et al.  . 
Asymptomatic sexually transmitted disease prevalence in four military populations: application of DNA amplification assays for chlamydia and gonorrhea screening
J Infect Dis
 , 
1998
, vol. 
178
 (pg. 
1202
-
4
)
6
van Doornum
GJ
Buimer
M
Prins
M
, et al.  . 
Detection of Chlamydia trachomatis infection in urine samples from men and women by ligase chain reaction
J Clin Microbiol
 , 
1995
, vol. 
33
 (pg. 
2042
-
7
)
7
Smith
KR
Ching
S
Lee
H
, et al.  . 
Evaluation of ligase chain reaction for use with urine for identification of Neisseria gonorrhoeae in females attending a sexually transmitted disease clinic
J Clin Microbiol
 , 
1995
, vol. 
33
 (pg. 
455
-
7
)
8
Stary
A
Tomazic-Allen
S
Choueiri
B
Burczak
J
Steyrer
K
Comparison of DNA amplification methods for the detection of Chlamydia trachomatis in first-void urine from asymptomatic military recruits
Sex Transm Dis
 , 
1996
, vol. 
23
 (pg. 
97
-
102
)
9
Johnson
RE
Green
TA
Schachter
J
, et al.  . 
Evaluation of nucleic acid amplification tests as reference tests for Chlamydia trachomatis infections in asymptomatic men
J Clin Microbiol
 , 
2000
, vol. 
38
 (pg. 
4382
-
6
)
10
Marrazzo
JM
White
CL
Krekeler
B
, et al.  . 
Community-based urine screening for Chlamydia trachomatis with a ligase chain reaction assay
Ann Intern Med
 , 
1997
, vol. 
127
 (pg. 
796
-
803
)
11
Scholes
D
Stergachis
A
Heidrich
FE
Andrilla
H
Holmes
KK
Prevention of pelvic inflammatory disease by screening for cervical chlamydial infection
N Engl J Med
 , 
1996
, vol. 
334
 (pg. 
1362
-
6
)
12
Marrazzo
JM
Whittington
WL
Celum
CL
, et al.  . 
Urine-based screening for Chlamydia trachomatis in men attending sexually transmitted disease clinics
Sex Transm Dis
 , 
2001
, vol. 
28
 (pg. 
219
-
5
)
13
Hilger
TM
Smith
EM
Ault
K
Predictors of Chlamydia trachomatis infection among women attending rural Midwest family planning clinics
Infect Dis Obstet Gynecol
 , 
2001
, vol. 
9
 (pg. 
3
-
8
)
14
Todd
CS
Haase
C
Stoner
BP
Emergency department screening for asymptomatic sexually transmitted infections
Am J Public Health
 , 
2001
, vol. 
91
 (pg. 
461
-
4
)
15
McKee
KT
Jenkins
PR
Garner
R
, et al.  . 
Features of urethritis in a cohort of male soldiers
Clin Infect Dis
 , 
2000
, vol. 
30
 (pg. 
736
-
41
)
Presented in part: 37th annual meeting of the Infectious Diseases Society of America (IDSA), Philadelphia, November 1999 (abstract 606); 36th annual meeting of the IDSA, Denver, November 1998 (abstract 658)
The study protocol was approved by the Johns Hopkins University Joint Committee for Clinical Investigation and by the institutional review board for Fort Jackson, South Carolina, at Eisenhower Army Medical Center, Fort Gordon, Georgia. Informed consent was obtained from all study participants, and the human experimentation guidelines of the authors’ institutions were followed in the conduct of this clinical research
Financial support: Department of Defense Women’s Health Initiative (DAMD 17-95-1-5064)
The views and opinions expressed here are those of the authors and do not necessarily reflect the official policy positions of the Johns Hopkins University, the US Army, the US Department of Defense, or the Henry M. Jackson Foundation for the Advancement of Military Medicine