Health concerns for long distance hikers include a number of water and vector borne diseases. Infectious diarrhea can be caused by viruses, bacteria, and protozoan parasites, the most common being Giardia and Cryptosporidium. Transmission for water borne disease is typically fecal-oral, or contaminated food and water. Without diagnostic testing, it can be difficult to determine the specific cause of wilderness-acquired diarrhea.
In May 2013, Public Opinion Online reported a viral outbreak of Norovirus on the Appalachian Trail, considered to be one of the worst in AT history. Norovirus has a 12 - 48 hour incubation period and can cause 24 - 60 hours of diarrhea, vomiting, and dehydration. Even after recovery, those affected can be still be contagious for up to two weeks, thereby putting fellow hikers and campers at risk.
Vector borne diseases are caused by infectious agents transmitted through blood-sucking ticks, mites, lice, fleas, and biting flies. The term "vector" refers to any arthropod which transmits disease through feeding activity. Though Lyme Disease is the most common, there are several other tick-borne diseases present along the AT, including Ehrlichiosis and Rocky Mountain Spotted Fever.
