Indian Journal of Medical Microbiology Medknow Publications on behalf of Indian Association of Medical Microbiology ISSN: 0255-0857 EISSN: 1998-3646 Vol. 26, Num. 1, 2008, pp. 34-39

Indian Journal of Medical Microbiology, Vol. 26, No. 1, January-March, 2008, pp. 34-39

Original Article

Community-based study on seroprevalence of herpes simplex virus type 2 infection in New Delhi

Chawla R, Bhalla P, Bhalla K, Singh MMeghachandra, Garg S

Department of Microbiology, Maulana Azad Medical College, BSZ Marg, New Delhi - 110 002
Correspondence Address:Department of Microbiology, Maulana Azad Medical College, BSZ Marg, New Delhi - 110 002, rohitchawla_75@hotmail.com

Date of Submission: 09-Jan-2007
Date of Acceptance: 12-Aug-2007

Code Number: mb08007

Abstract

Keywords: Herpes simplex virus type 2, seroprevalence, urban community

Herpes simplex virus type 2 (HSV-2), the primary cause of genital herpes, is one of the most common causes of genital ulcer disease worldwide. ^[1] HSV-2 is transmitted primarily through sexual contact. Genital herpes is considered to be a relatively benign infection, but the chronic, recurrent nature of this infection can cause considerable morbidity in the form of psychosocial impairment. ^[2] Neonatal herpes can manifest as a generalized systemic infection, encephalitis or localized central nervous system infection, causing permanent neurological damage despite appropriate antiviral therapy. ^[3] Furthermore, studies have demonstrated an important role of HSV-2 infection in the spread of HIV infection. ^[4],[5]

HSV-1 and HSV-2 are closely related antigenically and both viruses cause lifelong infections with intermittent reactivation; therefore, definitive tests for HSV-2 antibodies must be based on type-specific antigens. This has been made possible with the advent of glycoprotein G-based enzyme immunoassays, which are able to detect type-specific antibodies to HSV. These immunoassays have been found to be more useful for diagnosis of HSV-2 infection in asymptomatic patients, pregnant women and for epidemiological studies than in symptomatic patients, where virological methods such as culture and antigen detection are more important. ^[3]

Most studies of HSV-2 seroprevalence have been limited to select populations attending specialized clinics such as antenatal, family planning and sexually transmitted disease clinics. Such studies have found a wide range of seroprevalence of HSV-2, which varies according to the populations studied, from 11.3% in women attending antenatal clinics to over 70% in commercial sex workers. ^[6],[7],[8] Various population-based studies conducted in developed and developing countries have reported HSV-2 seroprevalence in the range of 5.6-42.2%. ^{[9],[10],[11],[12]} However, very few population-based studies on the seroprevalence of HSV-2 have been carried out in India. ^[13] The present study was carried out to determine the seroprevalence of HSV-2 in two urban communities in Delhi and to correlate the presence of HSV-2 seroprevalence with sociodemographic profile, risk factors and presence of other reproductive tract infections (RTIs).

Materials and Methods

The communities studied were randomly selected and included one urban slum (Census enumeration block: Lal Bag, Charge No.: 77) and one urban middle class colony (Census enumeration block: Tilak Vihar, Charge No.: 49). Initial house-to-house survey was carried out in 100 households in each area; these households were selected by systematic random sampling method. The number of eligible women (15-49 years of age) enumerated was 137 in Lal Bag and 132 in Tilak Vihar, while the number of eligible men (15-49 years of age) enumerated was 142 and 147 in Lal Bag and Tilak Vihar, respectively. The target men and women to be studied were 65 each in both areas and were selected out of the eligible men and women enumerated in each area by systematic random sampling. Camps were held in the health centres located in these areas. During the camps, demographic, risk factor and clinical data were collected using a structured questionnaire. Relevant specimens (genital specimens, blood and urine) were collected for laboratory diagnosis of various RTIs after obtaining informed consent from all participants. The subjects who had taken antibiotics in the preceding 2 weeks and women who were menstruating or pregnant were excluded from the study. Blood samples were collected from the enrolled subjects. Serum was separated and stored at -20 °C until tested.

Serum specimens were screened for HSV-2 infection by detecting IgG class antibodies against HSV-2 specific glycoprotein G-2 by enzyme-linked immunosorbent assay (ELISA) kit (Euroimmun AG, Seekamp, Germany). All positive samples were confirmed by Western Blot (Anti-HSV-2 gG-2 Euroline-WB, Euroimmun AG, Seekamp, Germany).

For diagnosis of syphilis, serum samples were screened by Venereal Disease Research Laboratory (VDRL) test using antigen from serologist to the Government of India, Kolkata. All sera positive by VDRL were confirmed by Treponema pallidum haemagglutination (TPHA) test using Immunotrep TPHA (Omega Diagnostics Limited, Scotland, UK) kit.

Serodiagnosis of HIV infection was performed according to NACO strategy II. Initial screening for HIV infection was performed by detection of specific antibodies by ELISA (HIVASE 1+2, General Biologicals Corporation, Taiwan) and positive results were confirmed by a second rapid and simple test (Capillus HIV1/HIV2, Trinity Biotech PLC, Ireland).

First-void urine specimens were collected from males and females for diagnosis of Neisseria gonorrhoeae and Chlamydia trachomatis infection by using a commercially available multiplex polymerase chain reaction kit (Amplicor CT/NG test, Roche Molecular Systems, Branchburg, NJ, USA). The urine specimens were transported, stored and tested as per kit literature.

Two vaginal swabs were collected from each woman; one was used for preparation of saline and potassium hydroxide (KOH) wet mount and smear for gram staining. The second swab was used for culture of Trichomonas vaginalis and Candida spp. A urethral swab was collected from males for preparation of saline mount and culture of Trichomonas vaginalis . Culture for T. vaginalis was performed by inoculation of Kupferberg medium followed by incubation at 37 °C; wet mounts were prepared and examined after 2, 4 and 7 days of incubation. For culture of Candida spp, inoculated Sabouraud dextrose agar tube was incubated at 37 °C and examined for growth after 72 hours of incubation. Diagnosis of trichomoniasis and candidiasis was made on the basis of positivity in direct microscopy and/or culture. For diagnosis of bacterial vaginosis, gram stained vaginal smear was examined under oil immersion objective (1000x magnification) and graded as per standardized, quantitative, morphological classification developed by Nugent. ^[14]

Statistical analysis was conducted using SPSS V9.0 and Epi Info version 3.2.2 for correlation of HSV-2 seroprevalence with sociodemographic profile, risk factors and presence of other laboratory-confirmed RTIs.

Results

Out of the total of 130 males invited to participate, 90 (69.2%) enrolled for the study. Forty-six (51.2%) belonged to urban slum, while 44 (48.8%) belonged to urban middle class community. The majority of men were 30-34 years of age (21.3%), married (86.6%), Hindus (88.8%) and educated till primary level (32.2%).

Out of the total of 130 females invited to participate, 120 (92.3%) enrolled for the study. Half belonged to urban slum, while the other half belonged to urban middle class community. The majority of women were 30-34 years of age (28.3%), married (93.3%), Hindus (80.8%) and illiterate (53.3%).

The average monthly income of the urban slum and urban middle class community was Rs 2137.7 and Rs 2663.5, respectively, and this difference was found to be statistically significant ( P = 0.01).

Out of the 90 males enrolled for the study, blood, urine and urethral swabs were collected from 85, 90 and 83 subjects, respectively. Out of the 120 women enrolled for the study, blood, urine and vaginal swabs were collected from 116, 120 and 113 women, respectively. The prevalence of various laboratory-confirmed RTIs in males and females is presented in [Table - 1].

All 16 serum specimens that were positive for specific IgG antibodies to HSV-2 by ELISA were also found to be positive by Western Blot.

[Table - 2],[Table - 3] show the correlation between HSV-2 seropositivity and various sociodemographic and risk factors of males and females, respectively. HSV-2 seropositivity was found to be significantly associated with older age in men ( P = 0.03) as well as women ( P = 0.02) and women residing in urban middle class community ( P = 0.01).

No statistically significant correlation was found between HSV-2 seropositivity and other laboratory-confirmed RTIs in males and females [Table - 4].

Discussion

In the present study, HSV-2 seropositivity was found in a higher proportion of women (8.6%) as compared to men (7%); however, this difference was not found to be statistically significant ( P = 0.68). Various other studies have demonstrated a higher HSV-2 seroprevalence in women as compared to men. ^[11],[15] This disparity in infection rates between genders may reflect anatomic differences in susceptibility to infection and greater efficiency of transmission from men to women than from women to men, as has been noted for many other sexually transmitted infections.

The HSV-2 seroprevalence in our study is similar to the prevalence reported in a population-based study conducted in Bangladesh. ^[9] In contrast to the present study, a much higher HSV-2 seroprevalence has been reported from various urban and rural populations from Africa, South America and North America. ^{[10],[11],[16]} This could be because of a higher prevalence of promiscuous sexual behaviour, larger number of lifetime sexual partners or a higher prevalence of other sexually transmitted infections in these communities.

Similar to other studies, our study also found significant association between HSV-2 seropositivity and older age in both men and women. ^[11],[15] This can be explained by the fact that herpes virus infections persist for life; therefore, the prevalence increases with age through the sexually active years.

Surprisingly, HSV-2 seroprevalence was found to be more common in the urban middle class community with higher average monthly income (12.6%) as compared to urban slum with lower average monthly income (3.1%). The difference was found to be statistically significant ( P = 0.01). However, other studies have reported significant association between HSV-2 seropositivity and lower income. ^[17]
Other studies have also reported significant association between HSV-2 seroprevalence and lower level of education; however, in the present study, no such association could be demonstrated. ^[18]

HSV-2 seropositivity was exclusively found in married men (8.1%) and women (9.3%), with no infection being found in unmarried subjects. The number of unmarried subjects enrolled, however, was very few to arrive at a statistically significant conclusion. Nonetheless, we can presume that premarital sex may not be very common in the communities that were studied.

A higher proportion of men (28.6%) and women (10.5%) with past history suggestive of sexually transmitted infections were found to be seropositive for HSV-2. Unlike other studies, however, this difference was not found to be statistically significant. ^[17]

Contrary to other studies, no significant association was seen between reported genital ulcer and HSV-2 seropositivity. ^[12] Although serological evidence of HSV-2 prior infection was high (7.96%), the reported genital lesions consistent with genital herpes were relatively rare (0.5%). This apparent disparity suggests a high level of subclinical infection, unrecognized signs and symptoms, or barriers to accessing health care.

A number of studies in the recent past have demonstrated a strong association between HSV-2 seropositivity and positive HIV and syphilis serology. ^{[11],[12],[15]} However, no such association was found in the present study. This could be because of smaller sample size and relatively low prevalence of various sexually transmitted infections observed in our study.

As with any population-based study of prevalence at a particular time, caution should be exercised in basing broad conclusions on the present findings. Nonetheless, such studies give some indication of the likely burden of disease in the population studied and highlight associated risk factors. The findings of our study indicate a relatively low prevalence of HSV-2 seropositivity and other sexually transmitted infections in the two communities that were studied.

Acknowledgement

References

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