Table 1 summarizes the trend in key indicators of sexual behaviors and STI/HIV prevalence among tuckers in India during 1990-2011. Studies conducted during early 1990s reported that about 63% to 87% of the truckers reported a history of multiple sex partners including FSWs [23] -[27] , and consistent condom use was poor (0% to 11%) in such relationships [23] -[25] . Similar results in terms of history of multiple sex partners including FSWs (80% - 95%) [28] -[30] and consistent condom use (2% - 14%) [28] [30] were observed in studies undertaken towards the end of 1990s. During this period, studies focusing on sexual behaviors attempted to explore mainly the history of multiple sex partners which is a measure of cumulative risk, and did not stress much on measuring sexual behaviors in recent past [23] [24] [27] -[29] . An exception was a large-scale survey among truckers in 2000 which concluded that nearly one-third of the truckers had sex with FSWs in the past one year preceding the survey [31] .

FSWs: Female Sex Workers; HIV: Human immunodeficiency virus; STI: Sexually transmitted infections.

Truckers’ life-time exposure to FSWs and other non-regular sex partners continued to be high in studies conducted after 2000 although it started showing a sign of declining trend. Studies conducted during 2000-2005 found that about 57% - 67% of the truckers ever had sex with FSWs [15] [19] [32] . The consistent condom use with FSWs as observed in these studies showed a wide range from less than 20% [15] [19] to about 58% [32] . More recent studies conducted during 2006-2011 suggest that about half of the truckers ever had sex with FSWs [20] [33] [34] and nearly one-third to two-fifth visited FSWs in the past one year preceding the study period [16] [17] [20] [35] [36] . Recent studies show that consistent condom use by truckers with FSWs ranged from 53% [34] to nearly 75% [16] [17] [33] [36] . Only few studies investigated about places of sex with FSWs and the most common places were reported to be dhaba (road side eateries) (13% - 53%), bushes/in the field (39% - 84%), and at the trucks’ halt-points (15% - 75%) [33] [36] [37] .

Only recent studies conducted after 2005 collected information on sexual behaviors with non-paid female partners who are defined as females whom truckers were not married and did not pay in cash for sex [16] [17] [36] [37] . These studies report that about one-fifth of the truckers have sexual relationships with non-paid female partners [16] [17] [33] [36] [37] . The consistent condom use in such sexual encounters was found to have increased from about 18% in 2006 to about 39% in 2009-10 [16] [17] [36] . Very few studies collected information on truckers’ sexual relationships with men/transgender. Studies during early 1990s found that about 5% to 15% of the truckers ever had sex with men/transgender [25] [27] whereas this percentage was found to be about 4% - 8% in recent two rounds of large-scale surveys among truck drivers [33] . Although, relatively fewer (1% - 2%) truckers reported having sex with men/transgender within past 12 months preceding the study period [16] [18] [19] , recent studies have found that about 10% of the truckers reported having anal sex with individuals without specifying the gender of the sexual partner [33] [36] . Truckers commonly indicated that “lack of availability of females for sex” or “high-risk of HIV from sex with women” motivated them to have sex with men and transgender [38] [39] .

Compared to studies to explore sexual behaviors of truckers, fewer studies captured information STI/HIV prevalence among truckers in India [16] -[19] [26] [27] [29] [40] -[43] . A study conducted in 1992 in Delhi found that HIV prevalence among truckers was about 1% [27] . This was followed by studies conducted during mid of 1990s in many parts of the country which found high HIV prevalence ranging from about 5% to 8% among truckers [40] -[42] . Studies conducted after 2000 found the HIV prevalence in the range of 2% to 5% among truckers [16] -[18] [33] [43] . Few studies in which truckers were recruited from clinics established to treat STIs found much higher prevalence of HIV ranging from 16% - 57% [19] [29] [44] [45] . Studies during early 2000 found high prevalence of syphilis (6.3%) and Hepatitis B (4% to 6%) among truckers [32] [43] . Recent studies conducted towards the end of 2000 found relatively lower prevalence of syphilis ranging from 1.7% - 2.7% [16] [17] . The prevalence of Neisseria gonorrhea and genital clamydial infections has been found low ranging from 1% - 2% in studies conducted during early 2000 [43] or even lesser in more recent research among truckers in India [16] [17] .

Efforts to curb the HIV among truckers started in early 1990s in the forms of stand-alone intervention programs primarily in southern and eastern parts of the country with different intervention strategies [46] . Some of the initial efforts during early 1990s were more concentrated on raising awareness through Information, Communication, and Education (IEC) activities and condom promotion [27] [46] -[50] . The communication strategies included group discussion, and distribution of pamphlets [27] , using posters, street theatres and puppetry [47] [48] [50] , and airing local songs having integrated messages on condom use and road safety [49] . The condom promotion activities included distribution of condoms [48] -[50] , providing objects like key chains to keep and carry the condom [49] , and advocacy with tea shop owners at trucks’ stops to keep condoms [48] [49] . Some interventions used one-to-one and one-to-group education sessions through peers, and counselling to raise awareness about HIV and provided treatment of STIs by setting up clinics with trained medical doctor and supporting staff at selected locations [51] -[54] . Some of these interventions also included FSWs who operate along the highways as participating populations in the intervention [51] [52] [54] . Several strategies such as opening free tea parlors at the STI clinics, and involving people working at places where truckers spend considerable amount of time such as petrol pumps, and Dhaba were also used to increase the outreach activities and motivate truckers for safe sex practices and STI treatment [52] [53] [55] [56] .

The HIV prevention efforts among truckers were strengthened towards the end of 1990s. This was the time when a large-scale HIV prevention program among truckers, named as Healthy Highway was initiated [57] . The project was implemented at major halt points where at least 50 trucks were parked at any time of the day or night such as transshipment locations, Dhaba, and check-posts. The Program offered a wide variety of services and activities including STI care and counseling, condom promotion and distribution, dissemination of educational materials, and face-to-face behavioral change communication [57] -[59] . The project trained individuals who come into close contact with truckers, such as petrol attendants, tobacco retailers and tea-shop owners as peer educators to motivate truckers for safe sex practices [58] [59] . The intervention also involved transport companies through advocacy meetings and sensitization efforts for behavioral change among truckers [60] . Operationally, it involved intervention through a network of project partners, including over 30 non-govern- mental organizations, and 18 transport companies for providing abovementioned project services [58] -[60] . After few years of the start the Healthy Highway program, specific efforts for HIV prevention among truckers were started in 1998 under the second phase of National AIDS Control Program. It established a decentralized mechanism to implement and manage the HIV prevention programs by establishing State AIDS Control Societies in each state for adopting strategies which are most relevant and effective for the local setting [21] . The interventions for truckers under the National AIDS Control Program were largely based on the strategies of the Healthy Highways program which was handed over to the government in 2000. Although the Health Highway program was envisaged and operated as consolidated national program, it lost its unified national character after being handed over to the government largely because, the central management team of the Healthy Highway program was replaced by independent State AIDS Control Societies [61] .

By the end of the 1990s, the key lessons learnt from the various programs for truckers in India were the need to adopt an integrated national approach for programming and management to maintain effectiveness of interventions, selection of intervention sites, and inclusion of transport companies and other stakeholders such as brokers and transport associations [61] [62] . The main challenge realized by the HIV prevention programs among truckers was the unorganized structure of the Indian trucking industry which is fragmented with a vast majority working for small transport operators [63] , and lack of coordination among several stand-alone programs being implemented by various State AIDS Control Societies and non-government organizations [61] . The absence of a well-defined and regulated industry architecture limited options for HIV prevention programs for truckers. The road transport sector is regulated by the Motor Vehicles Act 1998 which specifies regulations for truck operators in terms of hours of work of truckers, condition of vehicles, facilities and amenities provided to truckers, etc. [64] . However, enforcement of provisions of the Act is limited to units employing five or more truckers due to which a vast majority of fleet operators do not fall within the ambit of this Act. This makes structural and policy interventions to promote preventive behavior (e.g., requiring that truckers carry condoms, undertake routine health checkups and STI treatment) impractical. Also, the unorganized structure of the industry also implied that workplace interventions were not feasible [61] . Language barriers and absence of a standard network of services also reportedly reduce the efficacy of standalone projects for reaching out to the truckers traveling across the states which often have different languages [61] [65] .

Considering these facts about the structure of the industry and learning from previous efforts under HIV prevention programs for truckers, a large-scale HIV prevention program named as Kavach (meaning “shield” in Hindi) among truckers was initiated in 2004 [61] . In addition to working with truckers, this intervention also worked with high-risk groups such as FSWs and their clients, men who have sex with men/transgender and injecting drug users in several Indian states that have high HIV prevalence [65] . The Kavach intervention was initiated at 36 transshipment locations in India covering major national highways along the six routes, namely, North-East, North-West, North-South, West-South, South-East and West-East. The program monitoring data in first 18 months of the project revealed low service utilization by truckers and hence the program was redesigned in 2006 by selecting 17 out of 36 sites through research [61] . The selected intervention sites were the major transshipment locations and check-posts in the country where large number of truckers halt and wait for their consignments for considerable period of time. The redesigned program aimed to provide maximum coverage to truckers by working with high intensity by ensuring more contacts by peer educators, greater program visibility and greater service utilization of project-run clinics. The project-run clinics were named as Khushi, meaning “happiness” in Hindi and Urdu. The redesigned strategy of the intervention was largely influenced by the business franchise model of McDonald. As in McDonald’s business model, the look and service of outlets do not differ across any location [66] ; the Khushi clinics were branded with uniform appearance and services across all intervention sites to facilitate greater acceptance and easy recognition by truckers.

The Kavach intervention had three components: mid-media events; one-to-group discussions by trained peer educators, and one-to-one counseling and STI care at Khushi clinics by professionals and qualified medical doctors. Mid-media events included street plays, health games, film shows, truckers’ festival and the distribution of audio cassettes/compact discs. Films shows were organized to attract truckers and messages on the availability of Khushi clinics were imparted during the movie. Truckers’ festivals were large-scale events conducted annually to create an interest among brokers, transporters and truckers and about the program. Audio cassettes/ compact discs with catchy local songs interspersed with spoofs on popular film actors delivering HIV prevention messages and endorsing services at Khushi clinics were distributed to truckers to reinforce positive messages on HIV when they were on the move along the highways. At each intervention site, static and mobile Khushi clinics were established at strategically chosen locations that were accessible to the truckers from that intervention site. These mobile clinics operated either at brokers’ premises or in a mobile van. Social marketing of condoms was promoted in partnership with condom marketing organizations by opening non-traditional outlets such as tea stalls, and installing condom vending machines at strategically chosen places at the intervention sites. More details of the Kavach intervention are available elsewhere [61] [65] . The project was handed over to the National AIDS Control Program in March 2012.

Another large-scale intervention which included truckers as one of the targeted populations was implemented during 2002-2006 at 12 port cities in nine states of the country. The project was named as “Operation Lighthouse” and it targeted adult men including truckers, port laborers, and fishermen at selected intervention sites [67] . The heart of this program was the integrated behavior change communications which delivered focused messages around a single behavior change theme across all communication channels for three months at a time. The communication channels were interpersonal communication sessions (one-to-one and one-to-group by trained peer educators), street performances by trained professionals, group games and printed materials. The themes for integrated behavioral change communications were identified through research taking into consideration the exposure, attitudes and behaviors of the targeted populations based on data which were collected each quarter. The intervention established 13 mobile or conveniently-located clinics to provide high-quality voluntary HIV/AIDS counselling and testing services. More information about the intervention could found elsewhere [67] [68] .

Besides the large-scale interventions, few attempts have been made to explore new approaches for HIV prevention among truckers. An Information-Motivation-Behavioral (IMB) model-based HIV prevention program was implemented among truckers in 2003 in Chennai, Tamil Nadu [69] . The IMB model asserts that HIV prevention information, motivation, and behavioral skills are the fundamental determinants of HIV preventive behavior [30] . HIV prevention information included facts about how HIV is transmitted and prevented, HIV prevention heuristics, and implicit theories of HIV risk, which hold that one can detect and avoid HIV by assessing a partner’s dress, demeanour, and social associations. HIV prevention-motivation included motivation constructs drawn from the Theory of Reasoned Action [70] (e.g., attitudes towards performing specific HIV preventive acts, perceptions of social support for performing HIV preventive acts, and behavioral intentions to engage in HIV preventive acts). The behavioral skills component of the model was composed of an individual’s objective ability and perceived self-efficacy for the performance of HIV-preventive behaviors [71] . The IMB intervention consisted of single session of five interactive activities with a group of truckers which took around four hours to complete. These activities were designed to address the specific information, motivation, and behavioral skills deficits that were identified in research previously conducted with truck drivers in India [30] [72] . A total of 9 IMB workshops were implemented with 11 to 16 truckers in each workshop. It was concluded that the IMB interventions had greater effects on condom use with marital partner than its effects on condom use with non-ma- rital partners. More details about the intervention are available elsewhere [69] .

Another study conducted among truckers in Andhra Pradesh assessed the association between hygiene, sexual behavior and HIV infection. Participants were recruited into an integrated HIV and hygiene Information-Moti- vation (IM) program [73] . From 2005 to 2007, a once-a-week workplace intervention was established at a large cargo company’s truck depot in Hyderabad, Andhra Pradesh. The intervention incorporated information and motivation theory components from the IMB skills approach to HIV prevention to provide a uniquely integrative HIV and hygiene behavioral intervention. The information component of the intervention included an introduction to germ theory principles, setting the stage for hygiene and HIV transmission teaching. These were discussed within the infectious disease context of communicable disease prevention through sanitary practices. The motivation component of the intervention included individualized counselling on current HIV risk-taking behaviors, potential HIV preventive practices and exploring mechanisms to improve hygiene behaviors. Based on the results from the evaluation studies, it was concluded that while this modest intervention could improve the personal hygiene habits, like hand-washing, it could not alter HIV risk-taking behaviors. More details about the intervention and evaluation are available [73] . More recently, efforts are being made to examine the acceptability of implementing circumcision and pre-exposure prophylaxis as another possible HIV prevention intervention among truckers in the country [74] . The initial results suggest that truckers exhibited low levels of initial commitment towards pre-exposure prophylaxis and even lower for circumcision [74] [75] .