Textbook of Maritime Medicine

7.6.1 Human Immunodeficiency Virus and Acquired Immunodeficiency Syndrome

Acquired Immunodeficiency Syndrome (AIDS) is caused by Human Immunodeficiency Viruses 1 and 2 (HIV 1/2) which damage the immune system and make affected persons more vulnerable to infections and other diseases.

Epidemiology: AIDS is recognized to be a major public health problem throughout the world. It is now known, that patterns of the epidemic differ between regions (Lancet 2008). In some parts of the world, such as North America, Europe or the Philippines it mainly affects certain risk groups such as i.v. drug users, immigrants or homosexuals but is also a threat to the general population. In other parts of the world, such as Central, Eastern and Southern Africa and some countries of the Caribbean it is primarily seen in heterosexuals. Countries and regions such as Eastern Europe, China or India are facing new public health challenges due to HIV.

Disease Transmission: HIV is present in the majority of body fluids of an infected person. Most infections result from contact with semen and vaginal secretions, blood and blood products of a person infected with the virus. Potential hazards of infection include accidents and injuries, unsafe medical care provided to seafarers in ports of high endemic areas, performance of medical procedures on board, unsafe blood transfusions, tattooing, piercing and unprotected sex. HIV cannot be transmitted through social or workplace contact with an infected person, there are no documented cases of transmission through kissing (WHO: IMGS 3^rd ed.). In the last decade the risk of infections by different sex practices has been studied in detail showing that the often cited value of 0.001 transmissions per 1000 contacts represents a lower bound with a high variability due to transmission cofactors such as circumcision or genital ulcer disease (Lancet Infectious Diseases 9/2009) .

While risk of disease transmission is highest in early stages of infection, treatment of the disease with successful lowering of the viral load is now recognized as a powerful public health tool to reduce the risk of transmission (Lancet Infectious Dis 2009).

Treatment: Cure of HIV infection is not possible, but effective treatment options of HIV infection exist for more than a decade and new are constantly evolving. For most persons to whom this treatment is available, HIV has turned from an acute into a chronic condition. This requires life-long adherence to antiviral medication.

The infected persons usually will be perfectly well for several years after infection. During this time the CD 4 count as a marker of infection will decline slowly over years. However latency time from infection to the point when treatment is needed is highly variable due to genetic factors, exposure to infection and general living conditions.

Generally spoken treatment is begun when damage to the system has reached a potentially dangerous level. Where available, the CD4 test in connection with the viral load is used to determine when a person should start treatment. Other factors are taken into account, such as the presence of opportunistic infections. Treatment guidelines vary between countries and are constantly debated. WHO has issued guidelines for resource-limited settings based upon stages of HIV disease and whether a CD4 test is available or not (WHO 2006)

Strict adherence to therapy and close monitoring of side-effects and immune-status by a specialist are essential for a successful outcome. Of concern is resistance of the virus to the antiviral therapy which necessitates a change of the drug regime. Nowadays a wide choice of treatment options is available. However, advanced laboratory tests, availability of antiviral drug options and access to specialist care are necessary to take full advantage of this development.

Work related risk of HIV/AIDS in seafarers

Very early in the epidemic HIV/AIDS affected the community of seafarers. Later analysis of blood samples taken during the course of disease revealed that as early as the1950´s an English seafarer died of AIDS. This was also the case in the late 1960s with a Norwegian seaman and his family [Hansen et al. 1994].

Hansen et al estimated the risk of HIV infection in seafarers to be eight times higher than in the general Danish population. The authors found that most infections in seafarers were acquired heterosexually. A questionnaire survey from Croatia performed in Rijeka in 1989 to 1990 did demonstrate that seafarers had an inadequate knowledge about the routes of HIV transmission and rarely used condoms for protection against HIV infection [Sesar et al. 1995]. 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 Filipino overseas workers including 36% seafarers. The main mode of transmission was sexual (Department of Health 2005). An analysis of the central register of HIV/AIDS infections from Montenegro in 2007 indicated that 15% of the overall 68 notified HIV infected persons in Montenegro were seafarers by profession. [Jovicevic et al. 2007].

Overall there is lack of comprehensive studies on the prevalence and risks of HIV in seafarers. There is no evidence from the literature that living and working on a ship has a different risk from normal social and work contact. This is also true for First-Aid treatment.

Prevention: Due to the global nature of shipping it seems prudent to advise seafarers to stick to precautionary measures concerning medical care, sexual intercourse or activities such as tattooing in port. Standard precautions taken to reduce the risk of other infections with First-Aid aboard ships are equally effective against HIV infection. Employers and Port Health Authorities are able to contribute to the prevention of HIV/AIDS through programmes tailored to seafarers. These need to involve information on unsafe practices and precautionary measures, availability of safe medical care in ports, the offer of confidential and -if possible anonymous- HIV testing and information on treatment access in a seafarer’s home country.

Employment and HIV/AIDS

The International Labour Organisation has published an “ILO Code of Practice on HIV/AIDS and the World of Work” in 2001 where the organisation advocates for the continuation of employment regardless of HIV status (ILO 2001). However, the ship as a work place has always been seen as a special entity due to the limited access to diagnosis and therapy while on board. In addition, governmental policies to restrict immigration dependent on HIV status, sometimes skewed perceptions on the natural course and the risk of transmission on board and concerns over liability have created a restrictive atmosphere which tends to exclude HIV positive employees from seafaring. The decision on the fitness of a HIV positive person for duty on board is complex and involves in depth knowledge of the natural course of disease, treatment options and living conditions at sea.

Asymptomatic HIV infection will progress slowly to immunodeficiency if treatment is not available. Seafarers who contract HIV are perfectly capable of working normally, subject to periodic medical review. The medical checks should assess the dynamics of CD4 decline and/ or increase in viral load to rule out AIDS and determine the necessity of antiviral treatment.

Seafarers with advanced HIV infection with or without presence of Acquired Immunodeficiency Syndrome (AIDS). This will render the seafarer unfit for work on board. AIDS is signified by persistent infections, general wasting, cancer and others which require constant therapy and access to reliable medical care at any time needed. This can not be guaranteed by employers.

Seafarers treated with antiretroviral substances may or may not be fit for duty. This is a judgement by the HIV specialist treating the seafarers after consideration of the stability of his or her condition. Side-effects, drug interactions, food restrictions, monitoring of drug resistance and adherence need to be discussed between the doctor and the seafarers. Duration of the voyage, access to medical care, type of work on board and the wishes of the seafarer have to be taken into account.

Post-exposure treatment with accidental exposure to blood and other fluids

 Drugs effective against HIV, given as fast as possible after exposure to the virus are believed to lower the risk of HIV infection. For this reason Anti-HIV medication is now recommended by the WHO to be carried as part of the ship’s medical chest (IMGS 3^rd ed.). However, a risk-benefit analysis by a specialized Medical Doctor in a port or through radio-medical advice is necessary before treatment is started. The decision to provide this treatment depends on a number of factors, such as the HIV status of the source individual, the nature of the body fluid involved, the severity of exposure and the period between the exposure and the beginning of treatment. In any case advice should be given on disinfecting the wound immediately. Overall it can be assumed that the occupational exposure risks of HIV infection at sea are slight and limited to the treatment of injuries and procedures undertaken by the health care staff on passenger vessels.

Pre-employment testing for infection with HIV

 In many countries selection for employment based on HIV status is unacceptable or illegal.  Despite this, HIV testing is included in many countries and employers investigation schemes for pre- employment assessment of seafarers. Often seafarers are tested for HIV as part of a panel of tests without being aware of the test being performed. This practice is linked to many practical and legal problems: Seafarers often do not receive pre-test counselling. So they are not informed on possible risks and benefits of being tested. Possible consequences of a positive test are psycho-mental stress and being labelled unfit for work at sea. Often seafarers are not aware about treatment options in their countries and regions.

International guidance prohibits an employer from requiring disclosure of a worker’s HIV (ILO 2001), but uncertainty exits if non-disclosure to the employer will result in non-coverage by insurance schemes in case of acute illness caused by the HIV infection. Such issues should ideally be solved by the implementation of an company HIV/AIDS policy. Even though the WHO advocates against restrictions for entering a country on the grounds of HIV infection some countries still have laws which justify entry restrictions on the basis of a person’s HIV status even though those laws are rarely enforced.

Currently, the International Transport Federation and the International Maritime Health Association in cooperation with the ILO are reshaping the workplace policy for seafarers in the light of the new scientific evidence. These organizations issued a statement in 2008 in which they advocate against selection for employment based on HIV status. The organizations believe that HIV/AIDS should not be considered to be a condition that poses a threat to public heath in relation to shipping because, although infectious, HIV cannot be transmitted by casual contact or the mere presence of a person with HIV [The International Transport Workers’ Federation 2008].

In summary the main concern of the fitness decision in relation to HIV infection is on the increased risk to the individual due to a lack of access to medical diagnosis and care. Risk to other crew members are negligible if standard precautionary measures are observed. The safe operation of a vessel may or may not be an issue with advanced disease but has to be assessed individually. Latent HIV infection is certainly not a reason to declare a person unfit for duty.

7.6.2  Tuberculosis                            

Tuberculosis (tbc) is an infectious disease which damages one ore more organs through a slowly multiplying bacterium. It occurs globally but is a major cause of death and disability in developing countries. Current issues of concern are HIV/tbc Co. infections and the resurgence of multidrug and extensively drug resistant tbc in Eastern Europe, Asia and Southern Africa.

Pulmonary tuberculosis

The infection of the lung is the most frequent infection and also the most important because of its potential for transmission of the disease. Tbc can express many different symptoms, which initially may not be very distinctive. Pulmonary tuberculosis commonly presents with symptoms like cough, expectoration, feeling ill, and a slight temperature rise. Often, the diagnosis of tbc is delayed. Therefore, contact between the patients and their families or other crew members are possible before the patient is being isolated. During this time people are at risk of infection.

Mode of Transmission

The tbc germ Mycobacterium tuberculosis is mainly transmitted via droplets or aerosols which the infected patient spreads while coughing and breathing. This form of transmission occurs when there is “open tuberculosis”, caused by the destruction of normal lung tissue and the development of cavities filled with bacteria. Infectiousness is usually low, on average an untreated patient with “open tbc” infects 10 people within one year with the risk of infection being linked with intimacy and duration of the contact, the ventilation in the shared environment and the degree of contagiousness of the index case. Due to sailors´ close contact to each other an above-average risk of infection has to be presumed and has been demonstrated in case studies: On an US Navy ship with 3338 crew members presence of one patient with open tbc resulted in 21 cases of active tbc and 712 cases of latent tbc as diagnosed by follow-up testing (Bowman et al. 2006).

Latent infection means that the body has demonstrably dealt with the bacterium, but an active disease cannot be diagnosed up to this point of time. There are no specific symptoms. It is assumed that the bacteria encapsulate themselves only to recur on a subsequent date as a reactivated tuberculosis, e.g. due to a weakness caused by another chronic disease. Infection while at sea is unusual [For seamen this way to contract tuberculosis plays a minor part,] (Original unclear - have I got the meaning right?) but it is possible under inappropriate, hard working conditions, and poor board and lodging.

Course of Disease

After diagnosis the patients must be isolated in hospital, especially those with open tuberculosis. The patients will usually be repatriated. Therapy for at least nine month is necessary with initially four anti-tuberculosis drugs which later on can be reduced to two different drugs. In case of a complicated course of disease with resistance against some of the drugs the therapy may be extended. Infectivity is usually best controlled through prompt specific therapy normally leading to disappearance of viable organisms in the sputum in 2-4 weeks and full clearance in 4-8 weeks (Heymann (ed.), 2004). The disease and the therapy cause a major reduction of the patient’s physical fitness and working ability. Furthermore, adverse reactions from the drugs like liver dysfunction must be checked for, with examinations every other week. Even a rapid recovery from the disease leads to a period of limited ability to work for at least 4-5 months. Before getting back to work on board, the X-ray of the lung should show an obliteration of any pulmonary cavities and a significant reduction in the inflammatory changes.

The seaman should feel physically fit and should not suffer from significant adverse reactions from the ongoing medication. Back on board, the patient should be protected from inappropriate working conditions, like working in the cold, poor board and lodging and long working hours, to guarantee further healing.

After tuberculosis has been diagnosed in a seaman, the other crew members have to be examined as well at the time of diagnosis. In the ship’s environment all crew members on cargo ships are to be classified as “close/household” contacts. In passenger ships this is decision to be made by individual assessment.

Control of contacts and the immediate environment

For the management of potentially exposed contacts and source of infection, see the following schema:

1. For some years a special blood test, the interferon gamma release assay (IGRA), has been used to discriminate between an acute infection with mycobacterium tuberculosis and a vaccination-induced immune reaction. This method seems to be the most practicable to use in the maritime environment where passengers and crew do not reside at the place of investigation. The test should be performed not earlier than 8 weeks after exposure has ended because the organism needs this time to induce the specific t-lymphocytes that are measured. The cost of the test is slightly higher than the skin-test but it’s more practical and more specific. Local health authorities initiate the tests in cooperation with the shipping company.

2. An additional X-ray on persons with positive blood test will demonstrate any pulmonary tbc manifestation. A combination of a positive IGRA test and a negative X-ray indicates latent infection that should be treated with Isoniazid for nine months to prohibit a later reactivation of the infection.

3. The diagnostic skin-test is an alternative to IGRA to see whether the tested patient’s immune system has responded to the tuberculosis bacterium. Like the IGRA a time gap between exposure and a positive test result exists. This test cannot discriminate between a latent infection and a manifest affection. Hence, for positively tested persons, an additional X-ray is necessary.
Furthermore, the test cannot discriminate between an acute infection and an immune reaction from an earlier vaccination. So these false-positively tested persons also have to be X-rayed. Moreover, the skin test reaction has to be examined by a physician two days after the solution was injected. This may be a problem for seamen on ships with short demurrage.

An X-ray of the lung shows only well developed pulmonary disease, latent infections cannot be identified. Using only this method without IGRA or a skin test, a second X-ray is necessary about two months after contact with the index patient, because of a delayed expression of the infection. X-ray is obligatory in symptomatic persons after contact with tbc. Symptoms could be cough and expectoration, malaise or lost of body weight.

Literature

Heymann DL (ed.): Control of communicable diseases manual, 19^th edition, American Public Health Association 2008

Bowman C, Bowman W, Bohnker BK, Riegodedios A, Malakooti M. US Navy and Marine Corps conversion rates for tuberculosis skin testing (1999-2002), with literature review. Mil Med 2006;171:608-612.

Pai M, Menzies D: The new IGRA and the old TST. AJRCCM 2007; 175: 529-531 Needs a marker in the text