Prevalence of Hepatitis C Virus Antibody in Patients With Sexually Transmitted Diseases Attending a Harrisburg, PA, STD Clinic

Objective: The prevalence of hepatitis B and hepatitis C in a sexually transmitted disease (STD) clinic population was studied, along with the prevalence of various STD agents, in an attempt to identify possible STD markers for the hepatitis C virus and help delineate the role of hepatitis C as an STD. The hepatitis C antibody rates found in the STD clinic were also compared with those found among patients attending a local OB/GYN clinic and those enrolled in a blood donor program, all from the same geographical area. Methods: A total of 150 women attending an STD clinc were examined for each of the following agents: Chlamyadia trachomatis, Neisseria gonorrhoeae, syphilis, hepatitis B surface antigen, hepatitis B core antibody, hepatitis B surface antibody, and hepatitis C virus antibody. Additionally, several patients who signed informed consent to be evaluated for human immunodeficiency virus (HIV) antibody were tested by an enzyme immunoassay (EIA) screen method. The prevalence of each agent was then compared with the other agents. Results: The overall prevalence rates detected were as follows: hepatitis B 16%, hepatitis C 4%, chlamydia 18.7%, gonorrhea 7.4%, syphilis 0.7%, and HIV 0%. Hepatitis C antibody was detected in 4% of patients in the STD clinic, 0.76% of volunteer blood donors from central Pennsylvania, and 0% of patiants studied from the Harrisburg Hospital (Harrisburg, PA) prentatal population. Conclusions: This screening study reveals an association between attending a Harrisburg, PA, area STD clinic and having an increased prevalence of hepatitis C antibody, but larger matched control studies will be needed to help clarify sexual transmission as a mode of transmission for the hepatitis C virus.

titis has now been attributed to non-A, non-B hepatitis worldwide. 1,2 However, this type of transmission was recently estimated to account for as low as only 10-15% of patients with non-A, non-B hepatitis. 3 Recently, the isolation and cloning of a piece of DNA from non-A, non-B hepatitis virus and development of an assay for the antibody to hepatitis C virus (HCV) made possible the detection of many patients with a non-A, non-B hepatitis and the examination of transmission routes. 4'5 Recently, a 2nd-generation test for the detection of antibody vs. HCV was licensed. 6 This 2nd-generation test offers the advantage of increased sensitivity and specificity for the determination of HCV antibody. s' 6 Results have suggested that HCV is the major cause of transfusion-related non-A, non-B hepatitis, 7 especially in those cases that develop chronicity. 8 Additionally, HCV appears to be the major cause of a number of community-acquired non-A, non-B hepatitis for which no history of percutaneous exposure has been identified. 1,2,9 Studies investigating the possible sources of infection for non-A, non-B hepatitis or I-ICV without a history of percutaneous exposure have been contradictory to date. Several small case reports have been published recognizing possible transmission due to perinatal and conjugal relationships that follow patterns similar to transmission of hepatitis B, human immunodeficiency virus (HIV), and human T-lymphotropic virus type I (HTLV 1). 10,11 In addition, other papers including studies relating HCV to patients with sexually transmitted diseases (STDs) 6'12 and to heterosexual activity with more than partner have been published. 13 Contrary to these findings, other investigations have suggested only rare sexual transmission of HCV among homosexuals 3 and among sexual contacts of high-risk intravenous (IV)-drug abusers. 2 To further delineate the possible method of spread for HCV, we studied the prevalence of hepatitis B infection and hepatitis C infection in an STD clinic population and correlated other known STDs as possible markers for patients at high risk for hepatitis B and hepatitis C.

Subjects
Women attending a Harrisburg area STD clinic were included in the study if they signed informed fection with C. trachomatis. In addition, the culture transport fluid was analyzed by direct immunofluorescence (DFA) for the presence of C. trachomatis antigen as previously described. 14 A specimen was considered positive for C. trachomatis if the culture was positive or if 2 of the 3 direct antigen tests were positive. All chlamydial procedures were performed according to the manufacturers' specifications.

Hepatitis C Testing
The presence of serum HCV (anti-HCV; Abbott Laboratories) antibody was measured according to the manufacturer's specifications. Both st-and 2nd-generation tests for the detection of antibody vs. HCV were used. Each reactive result was confirmed in duplicate and sent for confirmatory testing. The confirmatory test performed was the Chiron HCV recombinant immunoblot assay (RIBA; Chiron Corporation, Berkeley, CA).
Bacterial Culture and Syphilis Serology Gonococcal cultures were performed on Martin Lewis agar medium in a 5% carbon dioxide atmosphere. Standard bacteriologic techniques were used to identify the isolates. 15 Syphilis serology utilized 16 a standard Rapid Plasma Reagin (RPR) assay.

Statistical Analysis
The goal of our analyses was to determine whether there was a significant association between the STDs, i.e., whether presence of STD increased the chance of having another. Thus, every pair of STDs was tested for association using the Fisher-Irwin exact test (Table 2). 17 To determine whether the observed associations would hold up after con- trolling for STD risk status, we classified the women into high-risk and low-risk strata, then carried out a stratified analysis using the Cochran-Mantel-Haenszel (CMH) test. 18 We determined risk status by questionnaire and chart review (Table  3). Using these criteria, we called subjects "low risk" if they had no known behavioral or medical risk factors and classified those subjects with any risk factors as "high risk." Most computations were executed in the S-Plus language on a Sun SPARCstation workstation. 19 Exact tests were computed with StatXact, version 2.0 (Cytel, Cambridge, MA).

RESULTS
Demographic information on patients seen at the Harrisburg area STD clinic is presented in Table  3. Subjects ranged in age from 13 to 54 years. The most frequent risk factors are presented as percentages in Table 3 and by prevalence in Table 2. The most prevalent risk factor was multiple sexual part-ners26 (17%), followed by sex with an IV-drug abuser--15 (10%). Thirty-five patients admitted to having had a chlamydial infection at some time in the past. There were 53 "low-risk" and 97 "highrisk" subjects as defined in the previous section. Prevalence rates of 6 STDs are presented in Table   4. When the 1-sided Fisher-Irwin test was performed, associations between chlamydia and gonorrhea (P 0.034) and between hepatitis B and hepatitis C (P 0.052) were found. After stratification using the CMH test, the chlamydia/ gonorrhea test (P 0.052) and the hepatitis B/hepatitis C test (P 0.086) approach significant positive associations. These results support conclusions reached using the Fisher-Irwin test mentioned earlier. The only statistically significant association following stratification was found between hepatitis C and syphilis (P 0.044). However, the association between these 2 diseases was negative.
Seven patients were found to be repeatedly reactive by the HCV EIA procedure. Six of the 7 (85.7%) reactive EIA specimens were found to be positive for antibody to HCV by the 2nd-generation HCV (EIA) procedure and by the RIBA. Of these 6 patients, 3 were also positive for hepatitis B core antibody. Of the subjects who were confirmed positive for HCV antibody, only (16%) had no risk factor as defined earlier. Three or 50% of the HCV-positive subjects had multiple risk factors with the most common risk factors being previous blood transfusion (50%), IV-drug abuse (33%), and multiple sexual partners (33%). No statistically significant associations were found for HCV-positive subjects and their risk factors. Other STDs were detected in those patients positive for HCV; however, no statistically significant association was determined. The overall prevalence of hepatitis C in 3 populations (STD, prenatal, and blood donor)

DISCUSSION
HCV has been shown to be the causative agent of the majority of cases of post-transfusion hepatitis, 1,20,). especially high-risk transfusion patients such as hemophiliacs, 22-24 chronic renal patients, and those patients with recent cardiac surgery. 24 In addition, the agent has been found in U.S. veterans, 2s and implicated in maternal transmission, 11,26 sexual transmission, 12,13,27 and IV-drug abuse. 28'29 The purpose of the present study was to explore the relationships between STDs and current or prior HCV infection and thus identify known STDs as possible markers for HCV. To discriminate the prevalence of HCV in the high-risk groups from that in the normal population, we studied the prevalence of I--ICV in 2 low-risk patient populations in the Harrisburg area.
Positive associations between STDs were found in the 150 STD patients studied. As expected, pa-tients positive for C. trachomatis were likely to be infected with N. gonorrhoeae. We also found hepatitis B virus (HBV) and HCV to be associated with one another. The presence of hepatitis B markers (anti-HBc, anti-HBe, HBeAg) has been related to the presence of I-ICV in blood donors and chronic HCV carriers. 3'31 However, significant debate continues on the reliability of surrogate markers in blood donor populations for predicting the presence of HCV. [32][33][34] HBV and HCV seem to be transmitted concomitantly in the United States and most of Europe, while Japan and selected countries in Europe show little or no association between transmission of I--IBV and I-ICV. Differences in these associations could possibly be due to some unknown risk factors that are found in certain geographical locales and not in others. It has been suggested that several classes of HCV exist, with varying subtypes more prevalent in different countries. Geographical and/or genetic differences have yet to be explored as a method for interpreting transmission routes and prevalence rates. Studies have also suggested that heterosexual promiscuity and/or homosexual promiscuity with evidence of numerous prior STDs constitute significant risk factors for the transmission of both HBV and HCV. 12'13'27 Considerable debate over the role sexual practices have on the transmission of HCV can be found in the current literature. 3'9 In the present study, antibody to HCV was detected in 4% of patients attending a Harrisburg area STD clinic, in 0.76% of volunteer blood donors from central Pennsylvania, and in none of the patients studied from Harrisburg Hospital's prenatal population. Hess et al. 9 found similar results with 4.7 % and 0.51% positive anti-HCV results from STD and blood donor patients, respectively.
Additional studies in the current literature have shown that the positive rates for I--ICV in blood donors range between 0.5 and 1.5 % 1,21,34,35 Positive rates for sexual transmission of non-A, non-B hepatitis in heterosexual and homosexual populations have ranged between 4.7 and 50%. 9'12'13'27 '35 Additional risk factors have included race, nationality, sex of the patient, multiple sexual partners, IV-drug abuse, preyious or concurrent positive tests for HBV and HIV, and evidence of multiple STDs.
Our data differ slightly from a recently published review by Lynch-Salamon and Combs. 35 The incidence reported in their review of the literature agrees with our data for blood donors and for those patients attending an STD clinic. However, the incidence of HCV positivity by risk groups in our study is lower than that previously reported. 35 This is undoubtedly due to the small number of HCVpositive patients found in the Harrisburg area STD clinic. The present study shows that attending a Harrisburg area STD clinic is associated with an increased prevalence of I--ICV compared with 2 other low-risk populations in the same geographical area. However, we were unable to identify any specific disease among the known STDs that correlated statistically with the presence of HCV for use as a marker for HCV infection. Additional larger studies involving matched controls would be helpful in order to help clarify the mode of transmission of HCV.

ACKNOWLEDGMENTS
We thank the Harrisburg Hospital laboratory staff in the Department of Microbiology and Blood Bank as well as the staff of Planned Parenthood of the Capital Region for their technical assistance. This work was supported by a George Lafferty Foundation grant. Supplies for hepatitis screening were provided by Abbott Laboratories (Abbott Park, IL).
Additionally, we dedicate this paper to the late Dr. Frederick D. Curcio III, whose intellect, guidance, friendship, and compassion will be remembered by all those individuals who have benefited from knowing this extremely caring individual.