Historical and epidemiological background

History has shown that seafarers have always been vulnerable to STD’s3. During the first voyage of Christopher Columbus to America in 1492, his sailors had sex with Haitian women and they got infected with syphilis, which they later brought to Europe4. In the UK, as early as 1665, Admiralty laws gave a bonus to surgeons for any venereal disease they treated while the patient-seafarer was fined.5 During the third voyage (1776-9) of Captain James Cook, half of his crew got infected with venereal diseases causing concern on their possible spread.6

Early researches have shown similar trends. In 1943, Hutchison found 542 cases (10.1 %) of venereal infections among merchant seamen in the Clyde anchorages in a period of two years.7 In Finland, from 1946-1949, Putkonen8 found that seafarers comprised 10.5% of the total male population with gonorrhoea. The incidence in seafarers increased from 9.7% to 13.3% and was 11 and 16 times greater than the rest of the male population in 1947 and 1948, respectively. 27.8% of the seafarers’ STD’s were contracted abroad compared to 3% among the rest of the male population. Most cases were due to paid sexual intercourse. 7% of females with STD’s had their infection transmitted from seafarers.

In 1948, a study on merchant seamen admitted with primary and secondary syphilis9 showed evidence of the potential global spread of STD’s by a small occupational group of seamen who were possibly exposed in every continent except Australia. A detailed analysis of 80 men showed that they have had sexual intercourse with a total of 615 individuals in 112 different ports in 45 different countries. There was an average of 1.3 contacts per port of call per seaman. In one instance, a seaman reported intercourse with 90 different individuals during the probable period of his infection. Another seaman reported intercourse with individuals in six different ports. The total group of 149 seamen reported having had sexual relations with 1,098 different persons, or an average of 7.3 contacts per seafarer, during the period of possible infectiousness.9

As early as mid-20th century, a high number of venereal diseases were documented in many ports in the UK.10 Syphilis was prevalent in the busy ports of Liverpool and Merseyside, Manchester and district, Hull, Bristol, Tyneside and Southampton and the trade was at its peak during this period. The study reported an incidence of 2,375 males and 1,336 females with syphilis in the ports compared to 1,010 males and 661 females in inland towns attesting to the vulnerability of port populations to STD’s. In 1955 a serological study of 9,140 Norwegian seafarers (8,189 men and 951 women) for syphilis demonstrated positive reactions in 132 men and 24 women.11

An investigation by Schofield in 196510 (later presented by Cross and Harris12) described the vulnerability of seafarers and some of the issues encountered by those who got infected with STD’s:

Over a 3-year period, 429 mariners with symptoms of urethritis attended two port clinics in the northeast of England. Of these, 107 (25%) admitted to prior treatment, 84 having been treated on board ship. It was notable that by the end of the 3-year survey the number of mariners treated at sea had increased, and that 94 had received various doses of anti-treponemal drugs. Another significant finding was that the younger the seafarer the more likely he was to have sought and obtained prior treatment.  

124 of the men got infected within the UK and 71 outside Europe.

The recognition of the vulnerability of seafarers led to many prevention programs and interventions since the very start. For example, there has been an international agreement in terms of STD control measures in ports. In Denmark, free treatment has been provided since 1802 to seafarers with venereal diseases irrespective of their nationality. An important paper entitled ‘The Frequency of Venereal Disease among Seafarers’ provided a comprehensive picture of the workers’ vulnerability to STD’s. This paper highlighted the rise in their incidence at the global level during and after the First World War. This rise led to the establishment of the Brussels Agreement of 1924 where seafarers got the opportunity to have free examination and treatment of venereal diseases in each principal port.2 In spite of acknowledged difficulties in practice, the ILO has encouraged contact tracing and treatment of infected contacts.13 The special provisions for venereal disorders remained until the ILO Maritime Labour Convention 2006, which now provides for treatment on board and ashore for all disorders irrespective of their character.

Emerging HIV problem in the seafaring industry

Recently published studies of STD’s in seafarers as a mobile population show a high risk to HIV/AIDS3, 14-19 and makes seafaring, already considered a risky profession, even more at risk. A European study in 1991 showed that STD’s (mainly gonorrhoea) were reported to be 5-20 times more frequent among merchant seafarers, deep-sea fishermen and navy staff than among the male population living on land.20 Data reflecting the current situation, however, are limited. General trends show an increased risk among young seafarers starting a maritime career. It has also been shown that there is a gradient according to the position on board with seafarers of lower rank acquiring STD less often than officers and other senior staff. Furthermore, it has been reported that seafarers from developing and less economically favoured countries contract STD rarer than seafarers from countries where they are better paid.20 While this finding may apply to foreign crews employed in vessels from developed countries, the situation in a global context may be quite different with disadvantaged seafarers and fishermen in developing countries at more risk.

The first two identified cases of AIDS in history happened to be seafarers who got infected years prior to the identification of the virus among the gay population in San Francisco in 1978.21 The first was a 25 year-old former naval seaman from Manchester, UK who died in 1959.22, 23 This, however, was contested by Connor24 and Hooper and Hamilton25 who argued that exposure in Africa (which had supposedly the highest rate of AIDS at that time) was unlikely because he only went to the low-prevalence country of Morocco while his ship was docked in Gibraltar.

The second case was a Norwegian seafarer who contracted HIV in Cameroon between 1961-62.26 He visited several ports in Africa where he was diagnosed twice with gonorrhoea. He died in 1976 at the age of 29. His wife and youngest daughter born in 1967 also died. The blood specimen frozen was later identified positive for HIV in 1988 when laboratory tools had become available. Before his death, this seafarer became a truck driver who travelled around Europe. Virus of the subtype he was infected with has been seen around his travel route providing early evidence of mobility as a factor that promotes the spread. It also sheds light on the development of the virus as it passed from one person to another and the impact of the disease on the immediate family.

The current rate of infection in the international maritime population has not been much studied though many countries have documented positive cases of HIV among its seafaring population.

Some early studies already revealed seafarers with HIV/AIDS in Europe.20, 27-29 0.5% of 60-80-year-old Hamburg seafaring outpatients were HIV-positive.20 In 1991, Dhar and Timmins quoted a high prevalence of HIV-positivity among seafarers tested in Valencia (2.4%) and Belgium (5.4%) that far exceeded the prevalence in the background population.29 In 1994, Hansen et al. identified 33 Danish HIV-infected seafarers most of whom were probably infected heterosexually in high-endemic areas early in the AIDS era. He estimated the risk of seafarers as eight times greater than that of the general population.19 Towianska et al. detected 14 HIV-infected Polish seafarers and fishermen (0.05%) in 1996.30 An analysis of the central register of HIV/AIDS from Montenegro indicated that 15% of the overall 68 notified HIV infected persons in Montenegro were seafarers by profession.31

In a study conducted by the Occupational Safety and Health Center in the Philippines in 1998, 59% of seafarer respondents confirmed to have contracted STD.32 A 2005 report of the Department of Health of the Philippines, which supplies the largest number of seafarers of any country globally, analysed 2250 HIV positive cases. 745 were overseas Filipino workers, of which 36% were seafarers. The main mode of transmission was sexual.33 Seafarers in the Philippines contribute approximately 10% of the total HIV seropositive cases in the country.34 There is evidence that the vulnerability of Filipino seafarers may increase consequent to an observed threefold increase in the rate of HIV in the Philippines between 2003 and 2008.35 This rising number of seafarers contracting HIV has alarmed the government of the Philippines. It is believed that underreporting is most likely due to stigma and low reporting by the clinics conducting the annual medical examination of seafarers (before signing a contract). Some manning agencies do not require HIV testing, and HIV-positive seafarers may be undetected until the development of AIDS symptoms.36 Seafarers identified as positive while on board may go home without the authorities knowing. For example, a Filipino seafarer remained undetected for many years until developing respiratory problems while on board. He was eventually diagnosed in the port of Rotterdam with advanced pulmonary tuberculosis and AIDS and died three days later.37

In Pakistan, the first AIDS case was an African seafarer who died in 1986.38 At present, seafarers are surmised to make up a sizeable portion of recognized HIV/AIDS cases in Pakistan.39 In Denmark, seafarers were infected in high-endemic areas and were identified as a risk group carrying the infection into the heterosexual population in non-endemic areas.19 The link between seafarers and HIV was further drawn into international attention when HIV-positive Thai seafarers were reported in various islands of Indonesia in 1992 thus alarming the latter country.40 In South Korea it has been estimated that there is a prevalence of 0.007-0.071% among its seafarers.41

In Mumbai, a doctor reported 25-30 cases of seafarers infected with HIV under his treatment in 2001. In 2000, the city reported at least 10 to 12 new HIV infections among seafarers.42 In Vietnam, a rapid assessment of seafarer vulnerability to HIV/AIDS and drug abuse revealed seropositive individuals in the ports of Hai Phong, Da Nang, Rach Gia and Can Tho.43 Similar findings were seen by others in Vietnam44 and in Thailand.45 An Ethiopian study showed an alarming prevalence of HIV-1 infection among seafarers at 9.6% with the prevalence inverse proportional with increasing level of education. Fourteen percent of the studied Ethiopian sailors reported to use condoms irregularly.46

In the South Pacific island nation of Kiribati fifteen seafarers affected with HIV were documented from 1999-2000. It also noted five wives of seafarers who contracted the virus.47. Croatia has been documenting HIV/AIDS among its seafarers.17 Between 1985-2009, out of 784 Croatians diagnosed with HIV/AIDS, 79 were seafarers (9.4%) making it 0.25% of the seafaring population.48 Seafarers infected with HIV have also been reported from Iran,49 Mauritius,50 Malaysia,51 Myanmar,52 Poland,18 Bangladesh,53 and Spain54 An increasing trend of HIV infection in the fishing sector has been observed in Malaysia with 7.8% of AIDS cases.51    

The issue of HIV/AIDS and seafarers is not confined to international seafaring. Regional or cross-border movement of seafarers is also seen as a problem.55 This was shown by the movement of undocumented workers from Myanmar, of which 80% are seafarers, operating off the coast of Thailand in dirty, dangerous, low-paid jobs. When they are in port, a combination of homesickness, isolation and a lack of AIDS awareness lead to high-risk behaviour. These seafarers frequent the port of Ranong, in which 20% of commercial sex workers (CSW) are HIV-positive. 

Determinants of seafarers’ vulnerability to STD’s

The world’s seafarers have been tagged as a population at risk to the virus since the beginning of the epidemic. Though they do not command the stature of the universally accepted high-risk populations such as CSW’s, men having sex with men and injecting drug users, the seafaring population is of special interest because of their mobility and status as potential major clients of many CSW’s in the world’s ports.56

Giacomo and Rion in 1948 recorded high frequency of sexual intercourse of 80 seafarers with prostitutes – 615 women at 112 ports of 45 countries.9 Based on studies on HIV infection among Filipino seafarers, heterosexual transmission is still the predominant mode.57 In this context, we look at the engagement of seafarers with CSW’s as risk behaviour in itself together with the non-use of condoms during the sexual encounters. This vulnerability is fuelled by spending a long time away from home, providing opportunities for casual sex, often in areas with a known high prevalence of STD’s. In some places condoms may not be available or are of bad quality thus increasing the seafarer’s risk. Evidently, the seafarer is mostly more likely to contract a STD in port away from home because the social structures that constrain sexual behaviour at home may not apply in foreign ports. The limited possibilities for going ashore may be compensated for by inviting sex workers on board the ship while it is moored off the quay.

Working in a risk-taking occupation may extend a culture of risk denial to displays of risk-taking in the social and sexual arena. Marginalization and low status may cause exaggerated masculinity that challenge mainstream norms such as expectation of multiple sexual partners.56 The use of alcohol for coping with the dangers and stress of the occupation may further compound the vulnerability of seafarers.58

The number of CSW’s in various parts of the world and their rate of infection run roughly parallel. The proportion in the population ranges from more than 6% in Africa to less than 0.15% in Central Europe, the Middle East and North Africa. Their HIV prevalence ranges from more than 40% to close to zero59 and their general prevalence of STD’s may well exceed 50%.60

An epidemiological study of sick or injured seamen from all over the world attending the outpatient ward of Hamburg from 1967-1987 indicated 3.1% with a STD.20 Interviews with the seafarers showed a poor knowledge on HIV27 and that most did not use condom protection. The same was seen in a Croatian questionnaire survey in 1989 to 1990 that demonstrated the inadequate knowledge among seafarers about the routes of HIV transmission and the limited use of condoms for protection.17 Thirty percent of Thai fishermen reported a history of STD and of self-treatment in 31% of their last STD.61 The situation was comparable for seafarers.62 In some developing countries, condoms are rarely if ever used, e.g. in Indonesia.63

In Nigeria, the knowledge of HIV was limited and 41% of Nigerian naval staff did not use a condom during the most recent contact with a sex worker.64 Bangladeshi boatmen had even lower knowledge of HIV risk and almost none used condom.65 The situation for a sample of Croatian migrant workers was not much better.66 Reaching these vulnerable groups, e.g. with antiviral therapy for HIV infection, remains a challenge.67 Viewed at the global level, fishermen are regarded among groups most at risk of HIV.58 Findings such as these suggest high exposure and disease rates in many developing countries.

Whether, in fact, there is now less STD among seafarers in global service than previously has not been studied in detail. While several previous studies have dealt with the transmission and prevalence of STD in seafarers2, 12 most current studies tend to rather focus on knowledge, perceptions and attitudes toward STD’s. There are, however, a number of indications that STD’s may be a less severe problem in global maritime transport workers today than in the past. Due to shorter transit time in ports and high work-activity among crews during loading and unloading, there is a reduced option for commercial sex. Many seafarers, nowadays, have better awareness of risk of STD’s and in particular HIV transmission. They show a more cautious behaviour and provide adequate precautions such as the use of condoms or abstinence.

This is supported by a study in Rotterdam where the yearly number of outpatients with STD was reduced from 300 to 110 cases of urethritis and from 51 to 15 cases of gonorrhoea from 1984 – 1995. The number of syphilis patients, however, was largely unaltered (3 and 5, respectively).68 Current data with regard to the prevalence of HIV infection in seafarers are limited, and the frequency of infection with traditionally significant STD’s such as gonorrhoea, syphilis, Chlamydia urethritis, and genital herpes have been even less studied.