Prevalence of genital chlamydial infection among a community sample of young international backpackers in Sydney,Australia

Abstract

We conducted a chlamydia prevalence study from January to June 2009 among a community sample of young international backpackers by recruiting at hostels in Sydney, Australia. Participants completed a questionnaire; men provided a urine sample and women provided a self-collected vaginal swab, which were tested for Chlamydia trachomatis DNA by strand displacement amplification. We recruited 225 men (median age 24 years) and 207 women (median age 23 years). Most (87%) of the travellers came from Europe. A new sexual partner during travel was reported by 67%, and 51% had more than one new sexual partner. Of those reporting a new sexual partner, 40% always used condoms. Prevalence of chlamydia was 3.5% (3.1% in men, 3.9% in women). Previous testing for chlamydia was reported by 40%. Drinking alcohol at hazardous levels was reported by 58% of men and 29% of women. Despite the reporting of new sexual partners and inconsistent condom use, the prevalence of chlamydia in these backpackers was not higher than that found in more general populations, and may relate to good health-care seeking behaviour. Young travellers need education about sexual risks and promotion of condom use prior to travel, and access to public sexual health services.

Keywords

sexually transmitted infections chlamydia travel alcohol backpackers

INTRODUCTION

Travel can facilitate the spread of sexually transmissible infections (STIs).¹ In the UK, a significant proportion of heterosexually transmitted HIV infection is acquired through sex while abroad.² Many STIs are more common in young people who travel abroad frequently.³ The social phenomenon of ‘backpacker’ has emerged to describe the young traveller who stays in low-cost accommodation (often labelled ‘backpacker hostels’) where similar travellers congregate and participate in holiday activities together, and travels for lengthy periods of time.

Approximately 10% of people in general population samples report a new sexual partner while travelling,^4–6 with variable condom use. Young travellers are more likely to report a new sexual partner, with 11–56% of short-term travellers^7–10 compared with 45–60% of longer-term backpackers^11–13 reporting a new sexual partner. Alcohol and other drug use are associated with casual sex while travelling.^10,13

There are few data on specific STIs among travellers. Chlamydia is the most common bacterial STI in many developed nations, including USA,¹⁴ Britain¹⁵ and Australia,¹⁶ and notification rates are increasing. Young age is a risk factor for infection. While chlamydia was no more common among travellers compared with non-travellers in a UK clinic-based study,⁷ in a recent retrospective clinic study in Sydney chlamydial prevalence among 5698 young international backpackers was 7%, significantly higher compared with 5% among local residents.¹⁷ International travellers are more likely to report previous chlamydial infection than local clinic patients.^8,17 In Queensland, Australia, an outreach project tested 65 backpackers for chlamydia and reported a prevalence of 7.7%.¹⁸ Apart from this, there are no reported studies of STIs among a community-based sample of young travellers.

Australia is a popular destination for backpackers. In 2009, backpackers comprised 11% of the 5,174,744 international visitors to Australia, with 60% coming from Europe, and Sydney is the most frequented city.³ Their stay in Australia is an average of 76 nights. We sought to determine the prevalence of genital chlamydial infection among a community sample of young international backpackers in Sydney.

METHODS

Participants

A sexual health promotion campaign was conducted over six months in 2004–2005 targeting backpacker accommodation hostels in central and beachside locations of Sydney (areas popular with young travellers).¹⁹ This campaign had promoted awareness of STIs and safe sex among backpackers and included provision of condoms and condom vending machines, messages on posters in hostels and on drink coasters in local pubs, and targeted special events. We used a list of hostels from this campaign, and approached the managers of some of these hostels with information about our study, seeking permission to recruit their clients on site. We chose hostels in four areas popular with young international travellers to provide sufficient recruitment, for geographical spread and for convenience reasons. These areas were: Manly and Bondi, which are two beachside Sydney suburbs, and Kings Cross and central Sydney, which is known for nightlife and proximity to the attractions of Sydney. We approached six sites in Manly (five agreed to participate); eight sites in Kings Cross (four agreed), two sites in central Sydney (both agreed) and one site at Bondi Beach (agreed). Sites were visited repeatedly until the target recruitment was reached, but subjects could only participate once. We visited hostels to recruit during business hours, during the evenings and on weekends. For an expected prevalence of 5%, 456 subjects would be required to provide a 95% confidence interval (95% CI) of ±2%. A sample size of 203 for each gender would be required for a 95% CI of ±3%. Our target recruitment number was a minimum of 205 for each gender.

We defined the study population as self-identified international travellers, staying in backpacker hostels and aged 18–30 years. For most of the last five years, they have lived in a country other than Australia and been in Australia ≤ 2 years. There were no exclusion criteria apart from age and this definition of international backpacking travellers.

Backpackers were invited to participate individually. We provided verbal and written information about the study (including information about chlamydia in several European languages). Condoms and a small chocolate were offered as a reward for participation. We asked for and noted the main reason for declining participation. A notice to advertise the study was occasionally displayed on foyer notice boards. Rarely, the on-site manager announced our presence over an intercom system.

Participants provided written informed consent and then completed a questionnaire on sociodemographic characteristics, alcohol consumption and questions specific for the sexual behaviour of the participant while travelling on this particular trip. These questions asked about numbers of sexual partners while travelling en-route to Australia and while in Australia, condom use, and whether sexual partners were locals or fellow travellers. This questionnaire was pilot-tested with young people and travellers prior to the study.

Specimen collection

Male participants provided a sample of first-void urine into a sterile jar; women provided a self-collected vaginal sample using the test kit's swab. Participants were provided with verbal and written instructions in specimen collection. All specimens were self-collected in the bathrooms of the hostels.

Laboratory methods

The specimens were refrigerated within three hours of collection and transferred to the laboratory within 24 hours. They were processed according to the manufacturer's instructions and tested for the presence of Chlamydia trachomatis DNA by the BD Viper™ strand displacement amplification assay (Becton Dickinson and Company, Sparks, MD, USA).

Results were available within one week of collection and were provided by email or by phone according to the participant's preference; if positive, free treatment was arranged at the closest public sexual health service.

Data management and statistical analysis

Data were entered into Excel and analysed by Statistical Package for Social Sciences version 17. Frequencies for independent variables and prevalence of chlamydia were calculated. Proportions were calculated with exact binomial 95% CI. Independent variables were investigated for associations with chlamydia using the Pearson chi-squared test or Fisher's exact test for categorical variables and the Mann-Whitney test or Kruskal–Wallis test for continuous variables.

Ethics approval was granted by the Human Research Ethics Committee of Northern Sydney Central Coast Area Health Service.

RESULTS

We recruited over five months from January to June 2009. We conducted 17% of our recruitment visits in the evenings and 10% on weekends. We recruited 226 men from 450 who were invited (50.2%) and 207 women from 453 who were invited (45.7%). Results were available for all except one man (inhibitors in urine); analysis excludes this subject. One woman provided a urine sample rather than a vaginal swab (included in analysis). The sites in Manly contributed 54% of the participants; Kings Cross sites provided 26%, central Sydney 14% and the Bondi site 5.3%. Pre-visit advertising (by a foyer notice board or intercom announcement) occurred in <5% of recruitment visits and for <5% of participant recruitment.

The most common reason given for not participating (given by 42% of men and 41% of women) was ‘had a test recently’. Other commonly stated reasons were: ‘don't need a test’ in 14% and 21%, respectively, ‘don't want a test’ in 30% and 19%, respectively, ‘never had sex’ in 3% and 4%, respectively, and 5% responded with disinterest. Nine people could not participate due to language difficulties.

The median age of participants was 24 years for men (range 18–30 years) and 23 years for women (range 18–30 years); 19% and 27%, respectively, were aged 18–20 years and 54% and 53%, respectively, were aged 21–25 years.

Most of the participants were usually domiciled in Europe: 41% came from the UK, 11% from Scandinavia, 9.3% from Ireland, 8.1% from Germany, 8.1% from France and 9.7% from elsewhere in Europe. Non-Europeans made up 13% of participants: 7.4% came from North America (mostly Canadian), 2.5% came from South America and 1.4% came from Asia.

At the time of recruitment, the backpackers had been travelling for a median of four months (men and women), and had been in Australia for a median of three months (men) or two months (women). Their main purpose in Australia was travel for 83%, work for 13% and study for 4%. Of the 425 participants with available data, 246 (57.9%) had travelled directly to Australia without any stay in another country en route. An additional six men had travelled in their own countries prior to departure to Australia, and four men had come directly to Australia from their home country, and then travelled to other tourist destinations before returning for more travel in Australia.

Sexual behaviour

Table 1 lists characteristics of reported sexual behaviour. Overall, 67% had sex with a new partner on this trip and 51% had more than one new sexual partner. Of those reporting a new sexual partner, this was a fellow traveller for 87%, and 127 of the total 432 (29.4%) had sex with a local Australian person. Overall, 115/286 (40.2%) reported always using condoms with a new partner. Of the 10 men who reported paying for sex (eight in South-East Asia, one in Brazil and one in Africa), six of eight reported consistent condom use.

Table 1

Sexual behaviour in a community sample of international young backpackers in Sydney

Characteristic	Men		Women
	n/total	%	n/total	%
Heterosexual (exclusively)	215/223	96.4	195/206	94.7
Travelling with a regular partner	27/221	12.2	35/207	16.9
Number of new sex partners*
None	64	28.4	78	37.7
One	31	13.8	40	19.3
Two	42	18.7	38	18.4
Three or more	88	39.1	51	24.6
Condom use with any new sex partner
Never	14/159	8.8	7/127	5.5
Sometimes/often	80/159	50.3	70/127	55.1
Always	65/159	40.9	50/127	39.4
New sex partner en route to Australia ^†	63/101	62.4	40/88	45.5
While travelling in Asia^‡	31/61	50.8	25/ 39	64.1
A local person(s)^‡	41/63	65.1	13/40	32.5
Always used condoms	23/38	60.5	8/13	61.5
Paid for sex with local person	10/38	26.3	Nil
A fellow traveller(s)^‡	38/63	60.3	34/39	87.2
Always used condoms	22/37	59.5	22/34	64.7
New sex partner in Australia	143/225	63.6	109/207	52.7
A local ‘Australian’ person(s)^§**	77/143	53.8	50/109	45.9
Always used condoms	38/76	50.0	21/49	42.9
A fellow traveller(s)^§	129/143	90.2	95/109	87.2
Always used condoms	57/128	44.5	42/94	44.7

*New sex partner = a new vaginal or anal sexual partner while travelling

^† n = 189 (179 who did not come directly to Australia from their home country, plus 6 men who travelled in their own home country immediately prior to travelling to Australia, and 4 men who came directly to Australia from their home country, and then visited another country before returning for more travel in Australia)

^‡Of those who had a new sexual partner en route to Australia

^§Of those who had a new sexual partner in Australia

^**Includes 7 who had a sexual partner in Australia who was neither a fellow traveller nor a local Australian

Alcohol consumption

In our questionnaire, a standard unit of alcohol was 10 g, approximately equivalent to 100 mL of wine, 280 mL of full-strength (5%) beer or 30 mL (one standard nip) of a spirit. Reported alcohol consumption for the men was three (median) standard drinks of alcohol per day; 58% of the men drank more than two standard drinks of alcohol per day, and 33% drank more than four. Reported alcohol consumption for the women was one (median) standard drink of alcohol per day; 29% of the women drank more than two standard drinks of alcohol per day and 12% drank more than four.

Prevalence of C. trachomatis

Fifteen cases of chlamydia were detected among the 432 participants for an overall prevalence of 3.5% (95% CI 2.0–5.7). Seven cases of chlamydia were detected in the 225 men (3.1%, 95% CI 1.3–6.3) and eight in the 207 women (3.9%, 95% CI 1.7–7.5). In the men aged ≤25 years, prevalence was 3.6%; in the women aged ≤25 years, prevalence was 3.0%. All specimens testing positive produced high signal scores; there were no weakly reactive positive results.

Past infection with C. trachomatis

A previous test for chlamydia was reported by 40% of the men and 43% of the women (16% and 23% tested within the previous 12 months, respectively). Previous genital infection with chlamydia was reported by 17 (7.6%) of the men and 21 (10.1%) of the women. None of those reporting previous chlamydial infection had a positive test for chlamydia in the study.

All cases of chlamydia were contacted within one week and treated. Contact tracing was initiated in all cases but results of partner notification or treatment are not available.

We investigated all the independent variables obtained from the questionnaire for associations with chlamydial infection. These included sociodemographic variables, sexual behaviour (Table 1), alcohol consumption and past testing for, and infection with, chlamydia. We found no statistically significant associations. Only two independent variables had significance at P < 0.1. These were: travelling for at least four months (odds ratio [OR] 2.63, 95% CI 0.83–8.40, P = 0.09), and staying at a beachside backpacker hostel (in Manly or Bondi) compared with central Sydney or Kings Cross (OR 3.19, 95% CI 0.88–11.6, P = 0.08).

Chlamydia prevalence was 4.5% among those who travelled in another country en route to Australia compared with 2.8% among those who came direct to Australia (OR 1.6, P = 0.37). Only two chlamydial infections were detected among those who had sex with local partners in these en route countries. No chlamydial infections were detected among the men who paid for sex in countries en-route to Australia.

DISCUSSION

In this community-based prospective study of chlamydia among 432 young backpacking travellers, prevalence was 3.5% (3.1% of 225 men and 3.9% of 207 women). Despite the reported numbers of sexual partners by our study population, this prevalence is similar to that found among general population surveys. For example, prevalence of chlamydia was 3.7% of sexually active women aged 18–24 years in Australia;²⁰ 2.7% in men and 3.0% in women aged 18–24 years in the UK;²¹ 2.5% in men and 3.2% in women aged 18–29 years in France;²² 5.8 and 7.1% among 21–23 year old men and women, respectively, in Denmark;²³ and 3.0% among young adults in Baltimore, USA.²⁴ Our study found lower prevalence compared with 5.7% of 2519 female college students in London,²⁵ and the current proportion testing positive for chlamydia in the National Chlamydia Screening Programme in the UK is 6.2% of women and 5.0% of men aged 16–24 years.¹⁵ Prevalence in northern Sweden in an Internet-based home sampling screening project was 6.0% among men and 4.6% among women,²⁶ and community-based screening in Stockholm was 8% in 2007.²⁷

Approximately 40% of our study population (and a similar proportion of those who declined participation) reported a recent past test for genital chlamydia. This may suggest good health-care seeking behaviour. There are few data on proportions of populations who have had STI testing. In Australia, less than 9% of young people aged <25 years have had a chlamydia test.²⁸ In the UK screening programme, it is estimated that approximately 22% of 15–24 year olds have had a test for chlamydia.¹⁵ In our study, previous chlamydial infection was reported by 8.8%, which provides an ever-infected proportion of 11% of the men, and 14% of the women. Unusually, we detected no incident infections among those participants who reported a past chlamydial infection. This finding is difficult to explain as previous infection with chlamydia is a strong predictor for incident infection. Perhaps the interval for re-infection after treatment was too short, or the young travellers were not mixing in their usual sexual networks when travelling.

In our study 67% of the backpackers reported at least one new sexual partner met while travelling, and 51% had two or more partners. These figures are consistent with other recent studies. Among single British backpackers in Australia, 69% had a new sexual partner, and 46% had multiple partners while travelling.¹³ Egan found that 53% of 559 international backpackers surveyed in Australia reported sex with a new person met on their trip, and 48% reported sex with a local resident,¹² and in her study of international backpackers in Canada, 45% had sex with a new partner met during travel.¹¹ A new sexual partner was reported by 11% of UK university students on short-term travel abroad¹⁰ and by 30% of spring break university students in the USA.²⁹ The context and destination of travel also influences the likelihood of casual sex; 56% of young travellers on short-term holiday to Ibiza, popular because of nightlife, reported a new sexual partner.⁹

Consistent (100%) condom use was 40% overall in our study, a figure similar to reported condom use with a new partner in large general population surveys in Australia³⁰ and in Britain,³¹ and again similar to condom use reported by some studies of travellers. Returning travellers at two genitourinary clinics reported consistent condom use between 40% and 45%,^32,33 and was 62% of single tourists to Ibiza.⁹ This contrasts with the UK general practice patients where 71% reported inconsistent condom use.⁴ In the two sexual behavioural surveys of international backpackers in Australia, 41% of British backpackers reported inconsistent condom use¹³ and 37% of international backpackers did not use a condom (on the last occasion of sex).¹² Though the numbers were small, 61% of the backpackers in our study who had sex with a local person in a country en route to Australia always used condoms. This may suggest that young backpackers are selective in their attitude to safe sex, and may perceive a sexual partner chosen from fellow travellers or local Australians to be at lower risk of STIs than local people from countries where HIV at least is known to be more common.¹³

Current Australian guidelines advise men and women to have no more than two standard drinks of alcohol per day, and no more than four drinks per single occasion of drinking, to reduce significant lifetime risk of alcohol-related disease or injury.³⁴ More than half the men in this study exceeded, and a third drank at least double, the amount recommended by this guideline, and 29% of the women exceeded the guideline. While our study did not investigate the effect of alcohol on sexual behaviour, there are many reports of this influence. Young travellers commonly drink hazardous amounts of alcohol,^{4,5,10,11,13,17,29} exceeding their usual drinking behaviour when at home.³⁵ Increased alcohol consumption is associated with engaging in casual sex,^4,5,10,13,29 and the study by Hughes et al. ¹³ found a dose-ranging influence of alcohol on rates of sexual partner change.

Our study has some limitations. The study population was a convenience sample of backpackers who may not be representative of young travellers in Sydney. There was disproportionate recruitment from hostels in Manly for convenience reasons. We avoided hostels patronized predominately by backpackers from countries where English is less understood (for example Korea, China and Japan). Nevertheless, the proportional representation of nationalities in our study is in accord with Australian statistics of young backpackers.³ Language was the main reason for non-participation in only nine travellers. Recall bias could be present in answers regarding number of sexual partners, condom use and alcohol consumption. In our study, 36% of the men had passed urine within an hour of providing the sample used for chlamydia testing, but we do not expect that this would underestimate prevalence.³⁶ The sample size in this study was not large enough to find associations with chlamydial infection, given the prevalence of chlamydia was 3.5%.

While peers were the most common new sexual partners of participants in our study, over a third reported inconsistent condom use with sexual partners from countries with probable high STI prevalence, including HIV, placing themselves at considerable risk of infection. Those who engage in casual sex while travelling abroad also tend to have multiple partners at home.^{4–6,9,13,29} Therefore, they can be identified by sexual risk assessment prior to travel, provided with information about high STI/HIV prevalence countries, safe sex promoted, warned about the influence of alcohol and the travel social environment on sexual behaviour, and advised about screening for STIs on return. We believe that the travel industry and the public health sector have responsibilities to implement such activities.

Young international backpackers in Australia suffer financial penalties for sexual health care because they usually cannot access Australia's health insurance system and travel insurance commonly excludes an STI from reimbursement of health-care costs.³⁷ They are unfamiliar with local medical services. Therefore, they need ready access to public sexual health clinics. Such clinics could consider outreach screening of backpackers at hostels.

Footnotes

ACKNOWLEDGEMENTS

We thank the following: Glyde in Sydney, Australia, for providing condoms; Becton Dickinson and Company provided the test kits; Prof Basil Donovan of Sydney Sexual Health Centre for methodological advice; Evert Rauwendaal, Lynda Hart, Fiona King, Kate Mason, Cate Latham, Christine Mangioni, Marika Burgess and Helen Jennings of Northern Sydney Sexual Health Service for recruitment; Dr George Kotsiou, Head of the Department of Microbiology in PaLMS for laboratory support and approvals; Stacey Dowman, Leonie Chan and Grace Perez of the Department of Microbiology in PaLMS for processing of specimens; Anna Nikolov of Manly Council for communication and negotiation with backpacker hostels; and the managers and reception staff of the hostels. We are grateful to the young travellers who participated. Apart from the free provision of chlamydia test kits and condoms, this study was not funded by an external source.

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