Sexual partner referral and associated factors among patients with sexually transmitted disease in Jabi Tehnan district and Finote Selam town

BACKGROUND

Partner referral (or contact tracing) is an essential approach for preventing sexually transmitted infections. Even though this approach has been used in Ethiopia, there is a scarcity of evidence in Ethiopia particularly in this study area.

METHODS

A cross-sectional study was conducted among 397 patients with curable sexually transmitted diseases. Factors associated to the practice of sexual partner referral were explored where variables having a p-value of <0.05 in multivariable analysis were considered statistically significant.

RESULT

Referrals for sexual partners were found to be 42.4% in this study (95% CI: 35.3, 45.3). Not expecting the end of the relationship among regular partnerships (AOR: 4.8; 95% CI: 1.9, 12.4), perceived risk of reinfection (AOR: 3.0; 95% CI: 1.8, 5.3), perceived self-efficacy (AOR: 3.8; 95% CI: 2.4, 6.3), intention to refer partners (AOR: 3.7; 95% CI: 2.0, 6.4), and knowledge of sexually transmitted infections (AOR: 3.0; 95% CI: 1.8, 5.0) were significantly associated with sexual partner referral.

CONCLUSIONS

This study showed that sexual partner referral was low. Perceived risks of reinfection, perceived self-efficacy, anticipating the end of a relationship, intention to refer partners, and knowledge of sexually transmitted infections were significant predictors of sexual partner referral. Intervention endeavors need to consider factors pointed out in this study to improve sexual partner referral.

HIV-Positive Status Disclosure to Sexual Partner and Associated Factors Among Adult HIV-Positive Patients in Debre Markos Town, 2019

BACKGROUND

Human immunodeficiency virus (HIV) positive status non-disclosure to a sexual partner is a public health problem where a high prevalence of HIV infection is reported in a region with poor partner disclosure status. This study aimed to assess HIV-positive status disclosure to sexual partners and associated factors among adult HIV clients at Debre Markos town, Amhara Regional State Ethiopia, in 2019.

METHODS

A facility-based cross-sectional study was conducted among 406 adult HIV-positive clients in Debre Markos town from September 1 to 30, 2019. Epidata version 3.1 for data entry and SPSS version 25 for data analysis were used. Bivariable and multivariable logistic analyses at (p<0.05) were performed.

RESULTS

From 421 study participants, 406 were participated giving response rate of 96.4%. The proportion of HIV status disclosure to sexual partner was 92.6%. Male sex (AOR = 2.863, 95%, CI = 1.147-7.146), urban residence (AOR = 2.438, 95% CI = 1.032-5.759), knowing sexual partner's HIV status (AOR = 2.749, 95% CI = 1.015-7.441), good anti-retroviral medication adherence status (AOR = 2.445, 95% CI = 1.023-5.845), and being a member of an anti-HIV club (AOR = 3.07, 95% CI = 1.314-7.171) were factors significantly associated with HIV-positive status disclosure at p value <0.05.

CONCLUSIONS AND RECOMMENDATION

The proportion of HIV-positive status disclosure to sexual partners was high. This study recommended that it is better to promote antiretroviral treatment adherence counseling, mutual partner HIV testing, and membership of anti-HIV/acquired immune deficiency syndrome (AIDS) club through extensive health education with particular attention given to females and rural residents.

Role of Knowledge, Sociodemographic, and Behavioral Factors on Lifetime HIV Testing among Adult Population in Nepal: Evidence from a Cross-Sectional National Survey

Human immunodeficiency virus (HIV) testing is important to HIV prevention, treatment, and care. We aimed to assess the role of sociodemographic, behavioral factors and HIV knowledge on HIV testing among people aged 15–49 years in Nepal. The 2011 Nepal Demographic and Health Survey data was used for secondary data analysis. Herein, 9843 women and 3017 men who had experienced coitus were included. The respondents were asked if they underwent HIV testing and received the test results in their lifetime. Chi-square test and multivariate logistic regression analysis were applied at 5% level of significance. Adjusted odds ratios and 95% confidence intervals were computed separately for women and men. Of the total, 18.0% of men and 7.4% of women had been tested for HIV in their lifetime. As compared to the age of 15 to 24 years, males aged 25 to 29 years were more likely to report, whereas females aged 35 to 49 years were less likely to report HIV testing. Lower caste groups had more likelihood of reporting HIV testing than the other caste in both sexes. The odds of being tested for HIV were significantly higher among those who had higher education in both sexes. There was significant positive association between HIV testing and economic status in males whereas this association was reverse among females. The male respondents who spent more than one month away from home in the last 12 months were 1.68 times more likely to have been tested for HIV in their lifetime. Having multiple sexual partners was associated with higher odds of testing for HIV in both sexes. Having comprehensive HIV knowledge was independently associated with the reporting of higher odds of HIV testing in females. Promotion of HIV testing should consider sociodemographic factors, sexual behavior, and imparting comprehensive HIV knowledge.

Sexual behavior and infection with cervical human papillomavirus types 16 and 18

Objective

This study assessed whether sexual behavior, including engaging in early sexual intercourse and having had multiple sexual partners, can predict the risk of infection with cervical human papillomavirus (HPV) types 16 and 18.

Methods

Records were reviewed of women who underwent cervical cancer screening and were found to be infected with high-risk HPV. The genotypes of high-risk HPV were categorized as HPV 16, HPV 18, and other than 16 or 18. Early sexual intercourse was defined as first sexual intercourse at the age of 19 years or younger. Multiple sexual partners was defined as having more than three lifetime sexual partners. Associations between sexual behavior and HPV 16/18 infection were presented as odds ratios (ORs) and 95% confidence intervals (CIs).

Results

Of the 349 women included in the study, 72 (20.6%) and 30 (8.6%) were infected by HPV 16 and 18, respectively. Eighty-two women (26.0%) reported having engaged in early sexual intercourse, and 33 (10.4%) reported having had multiple sexual partners. After adjustment for age, parity, and smoking habits, we found that women who had engaged in early sexual intercourse tended to have a higher risk of HPV 16 (OR 1.74; 95% CI 0.93-3.29), and those who had had multiple sexual partners were found to be at a significantly higher risk for HPV 18 (OR 4.58; 95% CI 1.44-14.58).

Conclusion

Sexual behavior was associated with an increased risk of HPV 16/18 infection. Engaging in early sexual intercourse increased the risk of HPV 16 infection, and having had multiple sexual partners increased that of HPV 18.

Pattern of sexual behavior among people in a rural area of Bihar: A qualitative study on wives of migrant workers

Background:

Population mobility and migration are important processes of human life. It affects broad range of sociocultural parameters. Mobility increases personal interaction and exposure to sexual partners from high-risk group. Although traditional Indian value prohibits premarital or extramarital sexual activities, but this aspect has not been explored in migrant workers.

Methods:

It was a qualitative study based on indepth interview of participants. The participants were wives of migrant workers. Indepth interviews were conducted by two female field interviewers recruited for the study. A total of 24 study subjects were recruited for the study. An indepth interview guide was prepared which mainly focused on sexual behavior, including premarital, marital, and extramarital, quality of marital relationship, gender roles, peer networks, substance abuse, work-related activities, etc., The transcripts were analyzed in NVIVO and themes were generated.

Results:

The premarital sex was more common in boys than girls. It is more common in the same age group and has increased in the recent years. Various reasons were cited in relation to premarital sex in rural areas like love affair, delayed marriage, watching bad movies, bad company, allurement for gifts money, etc., Some women had opinion that males belonging to affluent and powerful families had tendency to enjoy sex with other women within and outside village. The major themes which emerged from the study were the sexual activity, type of sexual partners, reasons for multiple sexual partner, and risky and nonrisky sexual activity.

Conclusion:

The findings of the study provided insights to design and conduct a larger and more representative quantitative study among the wives of migrant workers to understand the dynamic combination of biomedical, behavioral, and sociocultural factors that may influence transmission of infection within marriage.

pylori-infected subjects: Role of gastroesophageal reflux

Background

Helicobacter pylori is transmitted through faecal-oral or oral-oral routes. Whether H. pylori infection is more prevalent in sexual partners of H. pylori-infected subjects is unclear.

Objective

We evaluated 1) the prevalence of H. pylori infection in sexual partners of H. pylori-infected subjects; and 2) whether presence of gastroesophageal reflux in H. pylori-infected subjects was associated with transmission of infection to their sexual partners.

Methods

We evaluated H. pylori infection by 13C Urea Breath Test in sexual partners of 161 consecutive patients with H. pylori-related dyspepsia. The case-control group consisted of 161 dyspeptic subjects undergoing the 13C Urea Breath Test. The prevalence of reflux symptoms was noted through the Leeds scale. The role of gastroesophageal reflux in transmission of H. pylori infection was evaluated by binary logistic regression. A two-tailed p value of 0.05 or less was considered significant.

Results

Prevalence of H. pylori infection in sexual partners of H. pylori-infected subjects is 74.5% whereas prevalence of H. pylori infection in the control group is 32.3%, p<0.05. At the logistic regression analysis, the presence of reflux symptoms in H. pylori-infected subjects is independently associated with concomitant infection in both members of the couple (odds ratio 4.41, 95% confidence interval 1.6-12.3) and with length of cohabitation (odds ratio 2.39, 95% confidence interval 1.0-5.7).

Conclusions

The prevalence of H. pylori infection is significantly higher in sexual partners of H. pylori-infected subjects than in controls. Members of a couple are four times more likely to be both H. pylori infected if one of the couple has reflux symptoms.

Psychometric testing of the consequences of an HIV disclosure instrument in Mandarin: a cross-sectional study of persons living with HIV in Hunan, China

PURPOSE

This study aimed to examine the psychometric properties of a Mandarin-language version of an instrument that assesses the Consequences of HIV Disclosure (CoHD).

PATIENTS AND METHODS

The original CoHD instrument developed by Serovich was translated into Mandarin and administered to a random sample of 184 persons living with HIV (PLWH) using face-to-face and structured interviews. The CoHD instrument required respondents to rate the importance of eight costs (eg, might lose the relationship) and ten rewards (eg, would bring us closer) in their decision about whether to self-disclose their HIV status. The participants were directed to respond with respect to a current (or hypothetical) sexual partner.

RESULTS

Internal consistency was acceptable (Cronbach's α for the overall scale 0.82, costs 0.71, and rewards 0.86), as was stability (test-retest reliability overall 0.74, cost 0.63, and rewards 0.82). The CVI for the scale was 0.83, with items rated by subject experts ranging from 0.80 to 1.0. To determine structural validity, exploratory factor analysis extracted two subscales consistent with the original CoHD subscales. The Mandarin CoHD scores were significantly correlated with disclosure self-efficacy (indicating convergent validity), but they were unrelated to safer sex efficacy (indicating divergent validity). This criterion was tested by comparing the scores of PLWH who disclosed their HIV status (mean±SD 53.57±9.06) with those who did not disclose it (mean±SD 49.63±7.45); however, the difference was not statistically significant.

CONCLUSION

The Mandarin version of the CoHD instrument demonstrates promising psychometric properties when assessing costs and rewards with respect to sexual partner disclosure. This suggests that it might be useful in research on partner notification strategies. In further studies, larger and more diverse samples and an analysis of responses for different disclosure targets are warranted. Moreover, whether the CoHD score is related to the decision of disclosure should be determined.

Contextual Factors and Sexual Risk Behaviors Among Young, Black Men

Young Black men (YBM), aged 13 to 24 years, face a disproportionate burden of sexually transmitted infections (STIs). STI acquisition among YBM is due to incorrect and inconsistent condom use and is exacerbated by multiple sexual partners. Sexual and reproductive health is influenced by a complex interaction of biological, psychological, and social determinants that contribute to increased risk for STI acquisition. However, there are key social determinants of sexual health that play a major role in adolescent sexual risk-taking behaviors: gender norms, environment, peers, and families as well as a desire to impregnate a woman. Associations between contextual factors (risky environmental context, desire to impregnate a woman, and peer norms supportive of unsafe sex) and sexual risk behaviors were examined among a sample of YBM attending adolescent health clinics. This study used baseline data from a randomized controlled trial ( N = 702). Parental monitoring was also examined as an effect modifier of those associations. Sexual risk behaviors were the frequency of condomless vaginal sex, number of sexual partners within the previous 2 months, and lifetime number of sexual partners. Mean age was 19.7. In the adjusted model, peer norms was the only significant predictor for all sexual risk outcomes ( p < .05). Parental monitoring was an effect modifier for the perceived peer norms and lifetime sexual partners association ( p = .053) where the effect of peer norms on lifetime sexual partners was lower for participants with higher levels of perceived parental monitoring.

Who is not using condoms among HIV-positive patients in treatment in the largest city in Brazil?

Data on risky sexual behaviors in people living with HIV/AIDS (PLWHA) is still scarce in some populations around the world. The purpose of this study was to assess the factors associated with the use of condoms in a representative sample of PLWHA in outpatient treatment in the city of São Paulo. Six hundred and sixty-seven HIV-positive patients (383 men and 284 women) who were being treated at eight centers participated in this study. Data were collected using a sociodemographic survey, the Beck depression and anxiety inventories, a survey of alcohol and other drugs use, the Alcohol Use Disorders Identification Test, a sexual behavior survey, and the Sexual Risk Behavior Assessment Schedule. The majority of study participants were sexually active (almost 62% of the sample had at least one sexual partner in the last three months), and at least one-fourth engaged in unsafe sex (25.3% did not use condoms during at least one instance of anal and/or vaginal intercourse in the past three months). Multivariate logistic regression showed that engaging in unprotected sex was more likely among females (p < .001), persons with an HIV-positive partner (p < .001), and people using cannabis before sex (p = .002). These findings should stimulate health-care workers to create specific groups for women, seroconcordant couples, and cannabis users to discuss condom use, as they seem to be vulnerable groups.

Validation of the partner version of the multidimensional vaginal penetration disorder questionnaire: A tool for clinical assessment of lifelong vaginismus in a sample of Iranian population

BACKGROUND

The role of spousal response in woman's experience of pain during the vaginal penetration attempts believed to be an important factor; however, studies are rather limited in this area. The aim of this study was to develop and investigate the psychometric indexes of the partner version of a multidimensional vaginal penetration disorder questionnaire (PV-MVPDQ); hence, the clinical assessment of spousal psychosexual reactions to vaginismus by specialists will be easier.

MATERIALS AND METHODS

A mixed-methods sequential exploratory design was used, through that, the findings from a thematic qualitative research with 20 unconsummated couples, which followed by an extensive literature review used for development of PV-MVPDQ. A consecutive sample of 214 men who their wives' suffered from lifelong vaginismus (LLV) based on Diagnostic and Statistical Manual of Mental Disorders 4(th) version (DSM)-IVTR criteria during a cross-sectional design, completed the questionnaire and additional questions regarding their demographic and sexual history. Validation measures and reliability were conducted by exploratory factor analysis (EFA) and Cronbach's alpha coefficient through SPSS version 16 manufactured by SPSS Inc. (IBM corporation, Armonk, USA).

RESULTS

After conducting EFA PV-MVPDQ emerged as having 40 items and 7 dimensions: Helplessness, sexual information, vicious cycle of penetration, hypervigilance and solicitous, catastrophic cognitions, sexual and marital adjustment and optimism. Subscales of PV-MVPDQ showed a significant reliability (0.71-0.85) and results of test-retest were satisfactory.

CONCLUSION

The present study shows PV-MVPDQ is a multi-dimensional valid and reliable self-report questionnaire for assessment of cognitions, sexual and marital relations related to vaginal penetrations in spouses of women with LLV. It may assist specialists to base on which clinical judgment and appropriate planning for clinical management.

Factors associated with HIV voluntary disclosure of people living with HIV to their steady sexual partner in the Democratic Republic of the Congo: results from a community-based participatory research

Introduction

HIV disclosure to a steady sexual partner (SSP) is important both in preventing HIV transmission and improving the quality of life of people living with HIV (PLHIV). Its determinants have been poorly investigated in the Democratic Republic of the Congo. The study objective was to determine factors independently associated with voluntary disclosure to one's SSP in PLHIV receiving services from a Congolese community-based organization (CBO).

Methods

A community-based participatory research was performed and 300 PLHIV were interviewed by members of the CBO, using a standardized questionnaire. A multivariate logistic regression was used to determine the variables independently associated with disclosure.

Results

In this sample, 79 of the 127 participants (62%) included in the analysis declared having voluntarily disclosed their serostatus to their SSP. Declaring to be in a relationship (Odds Ratio (95% Confidence Interval): 4.2 (1.4-12.6)), having tested for HIV because of symptoms (2.5 (1.0-6.4)), having taken the test on one's own initiative (3.2 (1.3-8.0)), having felt sympathy and indifference from people when disclosing (6.0 (1.4-26.9) and 5.0 (1.1-22.8), respectively) as well as having a higher score of the “regular discussion about daily life with HIV” index (1.7 (1.1-2.5)) were significantly associated with disclosure to one's SSP.

Conclusion

Several individual and contextual factors were associated with voluntary disclosure to SSP in this study, highlighting the complex nature of the disclosure process. Interventions encouraging disclosure should be designed so as to adapt to one's personal life with HIV as well as psychosocial environment.

Serial monogamy and biologic concurrency: measurement of the gaps between sexual partners to inform targeted strategies

Having multiple sexual partners concurrently increases the risk of transmission of a sexually transmitted infection. Even if partnerships do not overlap, transmission potential exists when the gap between partnerships is shorter than the remaining infectious period. In the present article, we quantify the gap between partners to assess transmission potential using data collected by a cross-sectional survey of 2,203 genitourinary medicine clinic patients in England in 2009. Questionnaires asked about patients' 3 most recent partnerships. Gaps were calculated as time (days) between the last sexual encounter with a former partner and the first sexual encounter with the next partner. Among 1,875 patients who reported 1 or more partners in the previous 3 months, 47.6% of men and 27.7% of women reported 2 or more partners. Forty-two percent of the gaps were negative (i.e., partnerships that were concurrent); the median gaps were -7 and -17 days for men and women, respectively (i.e., overlaps were 7 and 17 days for men and women, respectively). Although half of the gaps were positive (serially monogamous partnerships), many were of short duration; the median gaps were 14 and 24 days for men and women, respectively. In over half of the gaps, condoms were used inconsistently with one or both partners, and in one-quarter, condoms were never used with either partner. There is thus a high potential for sexually transmitted infections, as even if partnerships are not behaviorally concurrent, they may be biologically concurrent. These data have important implications for designing and targeting effective health promotion messages.

Predictors of HIV status disclosure to sexual partners among people living with HIV/AIDS in Ethiopia

INTRODUCTION

Disclosure of HIV positive sero-status to sexual partners, friends or relatives is useful for prevention and care. Identifying factors associated with disclosure is a research priority as a high proportion of people living with HIV/AIDS never disclose in Ethiopia. This study was carried out to assess the magnitude and factors associated of HIV seropositive status disclosure to sexual partners among peoples living with HIV/AIDS.

METHODS

A hospital based cross-sectional study was conducted April-June, 2010, among systematically selected 334 HIV patients attending at Woldia hospital, Ethiopia. Data were collected through pre-tested questionnaire, using exit interview. Bivariate and multivariable logistic regression models were fitted to identify associated factors for disclosing their HIV seropostive status to sexual partner.

RESULTS

One hundred nineteen nine (59.6%) was females, 218(65%) was from urban area, 297(85.8%) are on antiretroviral therapy. The study found a significant association between higher educational status of the respondents (AOR:0.4; 95%CI (0.17-0.92)) and sexual partners (AOR: 9.0; 95% CI(2.8-29.3)), knowing HIV status of sexual partner (AOR:8.1; 95%CI(3.4 -19.2)), being on antiretroviral therapy (AOR:7.9; 95%CI(3.42-18.5)), having follow up counseling (AOR:5.26; 95%CI(2.2-12.5)), and being tested for HIV in ante natal care clinic (AOR:0.21; 95%CI(1.14- 6.46)) with disclosure of HIV status to sexual partner.

CONCLUSION

The study concluded the need for giving more emphasis for the patients who are not on antiretroviral therapy and the need for giving emphasis on techniques how to disclose status to sexual partner.

Partner selection among Latino immigrant men who have sex with men

This qualitative study explored partner selection in a sample of immigrant Latino men who have sex with men (MSM). In-depth interviews were conducted with men living in the greater New York metropolitan area who had been born in Brazil (n = 10), Colombia (n = 14), or the Dominican Republic (n = 9). One focus group was conducted with MSM from each of the three countries (9 Brazilian, 11 Colombian, and 5 Dominican participants). A grounded theory approach revealed three main themes relating to partner selection. The first concerned stereotypes of how Latino and Anglo-American men tend to behave in their sexual encounters and relationships. The participants perceived Latinos to be more affectionate and passionate, whereas they saw Anglo-American men as more independent and practical. These cultural discrepancies sometimes resulted in a preference for Latino partners. A second theme concerned stereotypes of the national groups, including expectations that Brazilians would be sexy and sensual and that Dominicans would have large penises. As found in other research on MSM of color, ethnic and national stereotypes were associated with experiences of sexual objectification. The third theme addressed the importance of masculine characteristics in sexual attraction and partner selection. Negative feelings towards effeminate men who did not conform to normative male physical or behavioral presentation reflect a stigma found inside and outside of the gay community. These findings suggest that gender and ethnic stereotypes play an important role in shaping partner choice and have implications for sexual risk and relationship formation.

Characteristics associated with sex after periods of abstinence among sexually experienced young women

CONTEXT

Adolescent pregnancy prevention is difficult because adolescent sex is intermittent. Understanding why sexually experienced adolescents have sex after a period of abstinence will help clinicians to tailor counseling.

METHODS

For up to 4.5 years between 1999 and 2006, a sample of 354 adolescent women recruited at urban primary care clinics were interviewed and tested for STDs every three months, and were asked to complete three months of daily diaries twice a year. Survival analyses were used to estimate associations between intrapersonal, relationship and STD-related characteristics and the risk of ending an abstinence period with sex.

RESULTS

Participants reported 9,236 abstinence periods, which averaged 31 days. The risk that an abstinence period ended with sex increased steeply for periods of fewer than 17 days (short), rose less steeply for 17-39-day (intermediate) periods and was fairly steady for longer periods. For short periods, the risk increased with age, sexual interest, positive mood, partner support, relationship quality and history of STD diagnosis more than three months ago (hazard ratios, 1.02-1.2); it decreased as negative mood increased (0.98) and was reduced among adolescents with a recent STD diagnosis (0.9). For intermediate periods, the association with a recent STD diagnosis became positive (1.4). For long periods, sex was associated only with age, sexual interest and relationship quality.

CONCLUSIONS

To provide targeted and timely sexual health counseling, clinicians may want to ask adolescents not only whether they are sexually active but also when they last had sex.

Prevalence of sexual dysfunction and its associated factors in women aged 40-65 years with 11 years or more of formal education: a population-based household survey

OBJECTIVE

To evaluate the prevalence of sexual dysfunction and its associated factors in middle-aged women with 11 years or more of formal education.

METHODS

A cross-sectional, population-based study was carried out using an anonymous, self-response questionnaire. A total of 315 Brazilian-born women, 40-65 years of age with 11 years or more of schooling, participated in the study. The instrument used in the evaluation was based on the Short Personal Experiences Questionnaire. Sexual dysfunction was calculated from the mean score of sexual responsiveness (pleasure in sexual activities, excitation and orgasm), frequency of sexual activities and libido. Sociodemographic and clinical factors were evaluated. Poisson multiple regression analysis was carried out and the prevalence ratios with respective 95% confidence intervals (95%CI) were calculated.

RESULTS

The prevalence of sexual dysfunction was 35.9% among our study population. Multiple regression analysis showed that sexual dysfunction was positively associated with older age (prevalence ratios=1.04; 95%CI:1.01-1.07) and with the presence of hot flashes (prevalence ratios=1.37; 95%CI:1.04-1.80). Having a sexual partner (PR=0.47; 95%CI:0.34-0.65) and feeling well or excellent (prevalence ratios= 0.68; 95%CI: 0.52-0.88) were factors associated with lower sexual dysfunction scores.

CONCLUSIONS

Sexual dysfunction was present in more than one-third of women that were 40-65 years of age with 11 years or more of formal education. Within that age group, older age and hot flashes were associated with higher sexual dysfunction scores, whereas feeling well and having a sexual partner were associated with better sexuality.

Detection of human papillomavirus type 16 in sexual partners of patients having cervical cancer by polymerase chain reaction

The polymerase chain reaction (PCR) was employed to detect human papillomavirus (HPV) 16 and 18 in cytological samples from the uterine cervix and in urine samples from the male consorts. HPV 16 was detected in 2 (25%) of 8 males whose wives were positive for HPV 16, while it was detected in only one (7%) of 14 consorts whose wives were negative for HPV 16 and 18. This is the first report of the detection of HPV 16 in urine. Viral detection in urine samples by the PCR method is a non-invasive, convenient and useful tool for large-scale epidemiologic studies and investigations of the mechanism of virus transmission.