His chronicle of his trip, The naturalist on the River Amazons, became a bestseller when it was published in 1863.
Hot flashes and nausea are most commonly caused by hormonal imbalances in the body, most notably, by sex hormones. For women, a decrease in estrogen is often to blame, whereas in men, testosterone deficiency can create the problem. Sometimes, the symptoms occur for reasons not related to those hormones at all.
Other cancers. Certain cancers, particularly lymphomas and leukemias, may cause night sweats and fevers that feel like hot flashes. But these usually come with other symptoms, such as weight loss, decreased appetite, or pain.