2025, Summer Adirondac Adirondoc
Although I have covered the topic of immunizations for backpackers a few times in the past, it is an area of medicine with rapid developments and as such demands occasional updates. At a very basic level, immunizations are a method of teaching our immune system to recognize a potential disease-causing microbe and disable it before it can result in disease. Most disease-causing microbes enter our bodies either through the respiratory tract (e.g., influenza, coronavirus, measles) or gastrointestinal (band to mouth) tract (e.g., polio, hepatitis A, norovirus). Camping provides an ideal setup for such diseases to spread: sleeping closely together in tents, group food preparation and eating, limited options for hand washing, etc.
Most infectious diseases require a period of incubation in the body before disease actually develops; this period ranges from a few days to over a week. Thus, if one is exposed on a weekend campout, the patient will likely be back in the front country by the time symptoms develop. On extended treks, however, the potential for disease spread within a group is substantial, and symptoms could begin in remote areas.
We should begin with immunizations for the common respiratory illnesses: influenza, coronavirus, and respiratory syncytial virus (RSV). Although most of the public attention recently has been directed at coronavirus, all three of these are very common conditions, and while for most healthy adults the diseases they cause are bothersome but not serious, they are each capable of causing severe illness and death. Globally, these illnesses account for about 2.5 million deaths annually.
All three are mainly spread by the inhalation of infectious particles in the air from the cough secretions of other infected individuals. I can imagine no more effective way to accomplish this than by several folks sharing the small enclosed space of a tent for several hours!
The influenza and coronaviruses mutate (change) frequently, so vaccines are continually “tweaked” to target the most current strains. This results in the need for annual immunization for both of these. The RSV vaccine is new. A one-time dose is recommended for everyone over seventy-five years of age and anyone over sixty years of age with an underlying medical condition. There is no reason why all three cannot be administered simultaneously.
Another vaccine-preventable respiratory disease is caused by the bacteria Pneumococcus. Although this produces a severe disease, it is not “contagious” in the same sense as the other three, and not a particular concern to the camper. All adults over fifty should receive immunization for Pneumococcus (imprecisely called “pneumonia vaccine”).
Although gastrointestinal infections are by far the major cause of trek disruption (reports of widespread norovirus infection in back country travelers are exploding, as we have discussed previously in this column), very few of these are vaccine-preventable. One exception is hepatitis A, a serious liver disease which can be spread by contact through water and food. There is a very effective vaccine available for this disease; it is probably a reasonable choice for anyone, although there is no elevated risk for North American backpackers. Travelers to specific other regions, however, should definitely receive this.
I am frequently asked about two other conditions associated with outdoor pursuits. Rabies is an exceedingly rare but almost uniformly fatal disorder associated with exposure to some wild animals. Although certain occupational groups (zoo workers, veterinarians) receive routine rabies immunization, the vaccine is otherwise only given (always along with rabies immune globulin) on a case-by-case basis after animal exposure. Local health departments have clear protocols for deciding when to advise the vaccine, and should be consulted immediately after exposure.
Tetanus is actually the vaccine about which I receive the most questions. This disease results when wounds become contaminated with a specific bacterium. Everyone should have a tetanus vaccine booster every ten years. For most wounds, a tetanus vaccine within the past ten years should suffice. Physicians will recommend a booster for anyone with a particularly complex and dirty wound if the vaccine has not been given within the past five years. Such injuries are virtually unheard of in backpacking, and if they were to occur, they would be seen by a physician anyway. Today, tetanus vaccine is typically given combined with some other diseases (diphtheria, whooping cough), which while serious themselves are not specific concerns to the back country user.
For anyone today, the annual visit to one’s health-care provider should be an opportunity to review and update immunization status. As I have said before, this may be the most important part of the pre-trek physical examination. Finally, remember that these recommendations are only for North America. Increasingly, folks are extending their travels to more exotic locations. These present the risk of a host of diseases, many unheard of by most of us. Dengue, malaria, yellow fever, and typhoid, for example, are serious risks in certain locales and all may be prevented by vaccine or medication. This is a very specialized area of medicine, however, and a travel or wilderness medicine specialist should be contacted for current, specific recommendations. The CDC website (cdc.gov/vaccines/ hep/by-disease/index.html) has been a useful source of information for decades. Hopefully, this continues.
~Tom Welch, MD, is a physician at Upstate Medical University in Syracuse and an active member of the Wilderness Medical Society. He is a licensed professional guide and a certifying instructor for the Wilderness Education Association, and has guided groups in the Adirondacks, Montana, and Alaska. More information is available at his website and blog, adirondoc.com. Sarah Long, MD, an internationally known vaccine expert and past member of the CDC’s Advisory Committee on Immunization Practices ( and a proud Alaska native) reviewed this column and provided helpful suggestions.
Topics: COVID-19, General First Aid, Hygiene, Infections, Snake Bites, Vaccines, emergencies