People traveling in the wilderness can acquire infectious diseases. These can be caused by organisms such bacteria, viruses, protozoans, or fungi. They can be transmitted through drinking contaminated water, or by transmission from one person to another.

Does anyone know of any reliable, quantitative data comparing the probabilities of getting different infectious diseases while hiking in the wilderness?

Quantitative doesn't mean it has to be high precision -- even order of magnitude numbers would help in sorting out what are the more important risks. It would be good to differentiate symptomatic infections from asymptomatic ones, and to avoid data that are confounded by a normal background rate of infection. (E.g., giardia has a 3-7% prevalence in the US, and is almost always asymptomatic.)

Related questions on diseases acquired in the wilderness:

Why are people so worried about Giardia?

How do you avoid Norovirus on the AT?

  • 5
    In what area? I think the profile will be different between the Rockies, the African jungles, etc.
    – Erik
    Commented Apr 9, 2016 at 2:00
  • @Erik: Good point, but I would be happy with any data from anywhere.
    – user2169
    Commented Apr 9, 2016 at 18:22

1 Answer 1


Numbers: You are asking the right questions.

From 30 years of running about 4 weeks of trips annually:

About 1 trip in 5 we would have an 'epidemic' of upset stomach and loose bowels. Usually this was attributed to poor dish washing. Adding a hotwater/bleach cycle to the daily routine eliminated the problem within 2-3 days. "Cup borrowing" was a significant factor in the spread.

In that same period, we have had occasional problems with what we later suspected was giardia. I figured this on any case of loose bowels that lasted longer than 5 days. Incidence -- Once every few years.

Notes; Group size was typically about 30 individuals.

Expeditions were evenly split between 3 week and 1 week.

1 week expeditions took place in the Canadian Rockies in Willmore Wilderness, or in Bigrock Clearwater Recreational Area.

3 week trips were by canoe in the Churchill River Watershed, but usually not on the main river.

No water purification was used.

  • No water purification was used. -- In view of that, why would you attribute it to poor dish washing? Commented Apr 15, 2016 at 3:57
  • 1
    @CareyGregory: Water purification is not necessary in pristine backcountry areas in North America. The belief that people get wilderness-acquired diarrhea from drinking untreated water, in these environments, is contradicted by modern scientific evidence. The evidence is that wilderness-acquired diarrhea, in these areas, comes from hand-to-mouth contamination.
    – user2169
    Commented Apr 15, 2016 at 4:30
  • @CareyGregory I attribute it to poor dishwashing because the 'grubs' in the group -- the ones who didn't bother to clean their cup and spoon, seemed to be more likely to get sick; while staff usually set an example of keeping a clean cup, and not borrowing/loaning cups only rarely got sick. Commented Apr 15, 2016 at 13:54
  • 1
    @BenCrowell Trips I did included the Red Deer River, both the South and North Saskatchewan Rivers, the Athabasca and the Nechako River where they go through widespread agricultural zones. I was more concerned about crop chemical residues than I was about disease. Hiking trips included large regions that have quad access, as well as horse access. Not pristine. Commented Apr 15, 2016 at 14:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.