Which systemic condition negatively affects a person's ability to sweat?

Cystic fibrosis is a genetic disorder that significantly impacts the body's ability to produce sweat effectively due to mutations in the CFTR gene. This affects the normal balance of salt and water in various epithelial tissues, including those in the sweat glands. In cystic fibrosis, the sweat glands fail to reabsorb chloride and sodium effectively, leading to the production of sweat that is much saltier than normal. This condition can lead to dehydration and electrolyte imbalances, particularly in hot climates where sweating is crucial for thermoregulation.

In contrast, miliaria (also known as heat rash) relates to obstruction of sweat glands and does not fundamentally impair the sweat production mechanism itself. Typhoid fever can cause fever and illness that might affect sweating, but it does not have a direct and lasting impact on the ability to sweat as cystic fibrosis does. Hypotension, or low blood pressure, may influence bodily functions but is not a direct cause of impaired sweating. Hence, cystic fibrosis is the specific systemic condition that negatively affects a person's ability to sweat.