“Shots” for Hikers

2001, March/April Adirondac Adirondoc

One of the major advances of 20th century medicine, at least as measured in terms of lives saved, has been the availability of safe and effective immunizations. Tetanus, diphtheria, polio and similar diseases, which killed or crippled members of our grandparents’ generation, are almost unheard of today. As drug-resistant bacteria evolve, the usefulness of antibiotics, another 20th century advance, is likely to decline. This gives immunization an ever-increasing importance in the battle between man and microbe.

Updating one’s personal immunization status is a part of preventive health care. With the increasing number of vaccines, it is no longer possible to make “one size fits all” recommendations. Age and disease history are major factors determining the appropriate immunization schedule. The potential for exposure to illness is another. The time before one sets out on an extended trek is an excellent opportunity to review vaccination status.

All of these recommendations are aimed at individuals setting out for an extended trip in northeastern North America. I realize that many readers extend their travels well beyond our continent. Immunization (as well as preventive antibiotic) recommendations for such travel are beyond the scope of this column. Fortunately, there is an excellent resource for such travelers and their physicians. The Centers for Disease Control and Prevention maintains a web site (www.cdc.gov}, from which one can link to a “travelers’ health” site for up-to-date health recommendations for travel anywhere.

TETANUS This devastating disease results from contamination· of wounds with the causative organism. Wounds with gross soil contamination are a particular risk. These injuries, of course, are quite common on wilderness treks. Fortunately, tetanus is almost completely preventable with appropriate immunization.

Three or more doses of the tetanus vaccine (“toxoid”) are considered a full series in an adult. If the last dose was administered within the past ten years, no further protection is required after injury. The only exception to this is if the wound is seriously contaminated, in which case a booster dose of toxoid is administered if the last dose was more than five years ago. For the average backpacker, therefore, the recommendation would be to receive a tetanus booster before a trek if it has been more than 10 years since the last booster. If definitive health care is available within a few days, as is usually the case in the Northeast, such a recommendation should confer adequate protection to anybody. In some parts of the country, however, evacuation from the wilderness may be a more prolonged endeavor. Therefore, a toxoid dose within the last five years is currently recommended by at least one national organization prior to travel in extremely remote wilderness settings.

INFLUENZA Most healthy adults consider the “flu” little more than a prolonged cold. In fact, true influenza is a very serious illness, and has probably killed more people and changed the course of history more than any other disease.

Immunization for influenza is an annual affair, because of the changing ecology of strains of the virus. Universal influenza immunization is not recommended. Instead, specific at-risk groups are “targeted” for the vaccine. These groups include the elderly, those with chronic illnesses, and those in at-risk occupations (e.g. health care). To these groups, I would add backpackers.

The close sleeping arrangements and shared cooking utensils of a typical camping trip make for the ideal conditions for spread of respiratory infections such as influenza. If one member of a group was “incubating” the virus at the start of the trip, it would be a simple matter for the disease to spread to everyone quickly. Consequently, for a trip of any more than a couple of days during the flu season, I highly recommend that everyone in the party be immunized.

RABIES Rabies is an extraordinarily rare illness in the United States, but carries a virtual 100 percent mortality when it does occur. The majority of cases in our country result from spreading by bats. Safe and effective immunization procedures are now available for the prevention of rabies; fortunately, these can be used after exposure. Currently, rabies immunization is recommended for any individual sustaining a bite from a wild mammalian carnivore or a bat. Since transmission of the virus has occurred after physical contact with bats short of actual bites, physician advice should be sought after any bat exposure.

Certain at-risk individuals, such as animal workers, should receive rabies immunization as a routine preventive measure. While this is certainly not the case for the average hiker or backpacker, another group of outdoor enthusiasts may be at risk. Caves are notorious dwellings for these critters, and cavers should consider “pre-exposure” rabies immunization.

LYME DISEASE A new vaccine for the prevention of Lyme disease was licensed in December 1998. This product, given as an initial series of three doses, appears to be safe and effective. While it is recommended for individuals who live, work and recreate in Lyme-endemic areas, whether it should be given in anticipation of a single backpacking trip is not at all clear. I would suggest reviewing the matter with one’s personal physician. Regardless of immunization status, the first line of defense against this disease, as well as the other tick-borne disorders, is prevention of tick exposure. I discussed this in detail in a recent column. (Adirondac, May/June 2000).

Blood-borne diseases. Over the past decade, the health care industry has become exceedingly conscious of the potential spread of some diseases by contact with body fluids. This is most dramatically illustrated by the proliferation of the latex glove in hospitals, clinics. ambulances and similar settings. Interestingly, this concern has spilled over to the wilderness traveler. Latex gloves are provided in even the most bare-bones backcountry first aid kit. While I would never question caution, I must confess to a mild amusement watching hikers help place a moleskin over a friend’s blister while wearing gloves!

What I find amusing about this scenario is a lack of consistency. Among the diseases which can be spread to health care workers by contact with body fluids, one predominates: hepatitis B. A very effective immunization is now available for this infection. Thus, it makes no sense to stick latex gloves into one’s pack for fear of contracting disease on the trail without also receiving an immunization against the one disease which it is possible to acquire.

As I have opined in previous columns in this series, the yield of the “routine physical” in healthy adults is very small. In terms of potential health benefit, time with a physician spent reviewing immunizations is probably much more important than the customary “take a deep breath and cough.”

Dr. Bev Connelly, an infectious disease and immunization specialist at Children’s Hospital in Cincinnati, provided valuable help in the preparation of this column.

Editor’s Note: According to a February Associated Press story, the Food and Drug Administration has received reports from Lyme vaccine recipients that they have suffered possible side effects.

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Topics: Readiness