As medical officer for a warship of 600, one of my duties was to ensure that our crew was fully immunized. This could be a daunting task given the constant turnaround of personnel, periodic influenza shots, and the immunization of the entire crew when the ship changed its theater of operations. Immunizations or travel shots can be an inconvenient detail in the preparation for a long voyage, but they are an absolutely necessary part of pre-voyage planning.
Immunizations exist for essentially two reasons. The first is to protect you from illness when you are exposed to a harmful bacteria or virus for the first time. The second is to protect populations at risk from contracting an illness brought in by you, a traveler from another part of the world. The ease with which the countries of Europe subjugated the local populations of the Americas can be attributed in great part to the lethal consequences of exposing native populations to diseases carried in the blood and stores of Old World explorers. For a similar reason, many countries today will bar your entry from another country where yellow fever is rife without proof of your vaccination status.
For the average sailor, the value of immunizations lies in the preventive health measure they incur as well as the proof that as a visitor you are generally free of specific communicable disease.
Choosing your immunizations
Your choice of which immunizations to get will depend on several factors. Specifically, what you will need will depend on what immunizations you have had in the past, your current state of health, your destination, and the length of time you plan on staying there. Your best resource for obtaining immunizations is a certified travel medicine clinic. Bear in mind that many immunizations come as a series of injections delivered over several weeks, although many have abbreviated protocols for persons leaving sooner. Again, consult a qualified travel medicine clinic and plan at least three months in advance if possible.
The bare minimum for all sailors includes an up-to-date tetanus/diphtheria immunization (Td). School children in the U.S. receive a series of injections while in grade school. This confers a good level of immunity that should last approximately 10 years after the final immunization, usually when one is 10 years old. From then on, it a good idea to have a tetanus booster every five to 10 years. If you are a sailor planning a long voyage, say a three-year circumnavigation, you should have had a tetanus shot in the last five years to cover you for the length of your voyage. If you should sustain a deep, dirty wound, like that from a rusty filet knife, you should receive a tetanus booster if it has a been more than five years since your last immunization. Low-risk clean wounds do not require such an aggressive immunization strategy, and a tetanus shot within 10 years is sufficient.
If you did not receive the standard tetanus/diphtheria immunization as a child, you can still receive a three-part immunization as an adult that will confer full immunity.
Difficult to treat
Tetanus and diphtheria are serious diseases. Both are difficult to treat and are a common cause of death worldwide. Both are also entirely preventable. If you are going overseas you must have this immunization.
If you are traveling to the equatorial Africa, or slowly transiting the Panama Canal, you should also receive a yellow fever shot. The immunization is recommended for people staying in those vicinities for more than a month. Having immunity to yellow fever can prevent you from suffering the same fate as the thousands of Frenchmen who died from it while building the Panama Canal. Transmitted by mosquitoes, yellow fever is also entirely preventable through the use of effective anti-mosquito measures such as screens for all hatches, as well as the judicious use of effective mosquito repellents. These measures can also protect you against the other mosquito-borne scourges of malaria and dengue fever.
Unlike tetanus/diphtheria immunization, yellow fever immunization is not available everywhere but rather through designated medical clinics. For a list of the clinic nearest you, contact the Center for Disease Control (CDC) in Atlanta by phone or visit the Internet addresses listed in the accompanying sidebar. The URL for the American Society of Tropical Medicine and Hygiene is very useful, as is the CDC Travel Medicine home page (see sidebar).
Contraindications to receiving a yellow fever shot are allergy to eggs, a compromised immune system from disease or chronic steroid use, pregnancy, and being less than nine months of age. Last, you should receive the mumps/measles rubella vaccine (MMR). Again, if you were enrolled in the U.S. school system, chances are good that you have already received a full immunization as a child. If you are an adult born in 1957 or after, you should receive a booster as an adult. It is important to note that these three diseases are also found worldwide, frequently presenting in epidemic fashion. Therein lies a significant threat; epidemics in less-developed countries frequently overwhelm the local health care infrastructure, leaving little resources for those taking ill in the middle or at the end of the outbreak.
If you are pregnant or planning on becoming pregnant in the next three months, do not receive the MMR vaccine: it is composed of a live attenuated virus that could adversely affect the unborn child within you.
If you are voyaging overseas, immunizations for tetanus and MMR are essential. If you are traveling to the tropics, yellow fever must also be considered.Immunizations for prolonged travel
If your plans include a long layover in a developing country or close work with native populations you should also consider broadening your immunization coverage.
Hepatitis A This is a self-limited infection of the liver. It is curable with rest and supportive care. There are two ways to prevent Hepatitis A. For short-term travelers, you can receive a gamma globulin shot. This will protect you for three months only. If your plans include a longer stay, consider active immunization. Like yellow fever, the series of immunizations required for hepatitis A is available through a certified travel medicine clinic. You should consider hepatitis A if you will be living in a country with poor sewage management leading to contaminated drinking water.
Hepatitis B There are three immunizations for hepatitis B, delivered over the course of six months. Hepatitis B is a serious, sometimes fatal disease of the liver. It is contracted in a way similar to HIV, through sharing of body fluids or blood from the infected to the uninfected. Hepatitis B is found everywhere and is particularly prevalent in developing countries. Immunization is recommended for anyone living and working in a developing country for more than a few months.
I would advise a cholera vaccination for any person who will be living for more than three months in a country with poor sewage or drinking water contaminated with sewage. The new version of this vaccination is generally considered effective for three years. It is strongly recommended for people taking antiulcer medications or antacids. The acid environment of your stomach is the first line of defense against cholera. Anything that compromises the acid production will increase your susceptibility to infection. The vaccination will enhance your immunity and you can continue your medications.
This is a mosquito-borne disease of Southeast Asia and countries bordering on the South China Sea. This immunization is generally recommended to anyone who plans on traveling to the mountain highlands of any of these countries.
This illness is found in the same places you will find cholera and polio. The vaccine is advisable if you are planning on living there for more than a month. The immunizations come as an injection or in oral form. If you have been previously vaccinated, consider a booster if it has been more than five years since your last injection.
For ocean sailors or circumnavigators, I would advise any or all of the above if you plan on visiting and touring for extended periods of time in affected countries. To learn which countries are affected with which diseases, or to double-check your itinerary against a database on worldwide disease, visit the CDC Travel Medicine home page (see sidebar). Alternatively, you can visit a travel medicine clinic or read about it in The International Travel Health Guide, also noted in the sidebar.
Polio Every U.S. citizen should be have been vaccinated against polio as a child. If you are traveling to a less developed country where it is present, obtain a booster shot before you go. Polio can be found wherever you find cholera, typhoid, and hepatitis A.
Rabies If you will be handling animals or traveling to an area with a high incidence of rabies, consider vaccination in advance. Rabies is found worldwide and is especially prevalent in the developing world. Caution itself may be the best preventative. Nocturnal animals like raccoons and bats, when they are found outdoors in the middle of the day, should be assumed to have rabies. Any person suspected of having been bitten by a rabid animal should seek medical attention immediately. Rabies is a horrible disease ending in madness and a painful death. Consider a vaccination if you plan on living away from modern medical care for any serious length of time.
Yellow fever has been reported in remote Trinidad. Hepatitis A and B are also endemic, but of low prevalence. Only long-term travelers should take precaution.
Dengue fever is found throughout the Caribbean, including Puerto Rico and the Virgin Islands. The only cure is to prevent contact with an infected mosquito. Fortunately, it is a self-limited disease, but it mimics malaria quite closely when it hits.
Avoid countries with poor water sanitation if possible. The island of Hispañola, which comprises Haiti and the Dominican Republic, as well as Trinidad and Tobago, probably have the worse water quality of all the islands and countries of the region. Interestingly, they also have the highest rates of diarrheal diseases, HIV, and hepatitis. Caution is advised when visiting these countries.
In general, if you plan to travel or cruise just the Caribbean, an up-to-date tetanus shot and MMR are sufficient.South America
Yellow fever and cholera have been reported in Mexico, Central America, and the equatorial countries of South America. Polio and typhoid are also naturally occurring. Hepatitis A and B are very common. There is a particularly higher-than-average risk for rabies in Mexico, El Salvador, Guatemala and Honduras.
Recommended immunizations for this area are: tetanus/diphtheria, yellow fever, and MMR for prolonged travel to these regions. Further, rabies, cholera, and typhoid vaccinations are recommended for anyone staying in remote areas of theses countries for more than one month.South Pacific/Oceania
Cholera, hepatitis, and typhoid are well known in the South Pacific. Special caution should be taken to prevent mosquito bites as they carry a multiplicity of illnesses, including malaria, dengue fever, and filariasis.
Recommend immunizations are: tetanus/diphtheria and MMR. Cholera and typhoid vaccinations are recommended for anyone staying more than one month in Vanuatu, Tuvalu, or Fiji. Vaccination for Japanese encephalitis should be had by all staying or traveling to the highlands of Southeast Asia, the Philippines, Malaysia, and Indonesia.
Plan your vaccination strategy early, especially if you are traveling overseas to multiple destinations over the course of several years, e.g., a long circumnavigation. Consult with a qualified travel medicine clinic. Like all issues of safety at sea, prevention and planning are the essential elements of success.