The mystery of post-trek fever: Why symptoms show up after you return

After completing a challenging trek, some individuals experience a variety of symptoms such as fever, fatigue, body aches, and headaches despite feeling healthy during the trek. This phenomenon is commonly referred to as "trek fever", although it is not a specific medical diagnosis. According to Dr. Manjusha Agarwal, a Consultant-Internal Medicine at Gleneagles Hospital Mumbai, several factors can contribute to this delayed illness.

The body's immune defenses may be temporarily weakened due to the intense physical activity involved in trekking. Additionally, exposure to new environments and underlying viral infections can become apparent after the trek. Factors such as dehydration, poor nutrition, inadequate sleep, extreme weather conditions, and a physically demanding trek combined with inadequate recovery can increase the likelihood of feeling unwell after the trek.

It is not uncommon for infections acquired during travel or trekking to manifest after a 2-3 day incubation period. Trekkers, especially beginners, may experience delayed symptoms that are not necessarily related to the trek. If symptoms persist beyond 48 hours or exceed 101°F, or are accompanied by severe symptoms such as breathing difficulty, chest pain, persistent vomiting, confusion, or severe weakness, medical attention should be sought.

To avoid falling ill after a trek, it is recommended to stay well hydrated, eat balanced meals, get adequate sleep, maintain hand hygiene, drink safe water, and use insect repellents when necessary. Gradually building fitness rather than suddenly pushing the body beyond its usual capacity can also help reduce physical stress.