Could it be beneficial to artificially induce fever in a person who has an illness if they are not already experiencing fever?
No, not really. Pretty much the only use of hyperthermia in medicine is in the treatment of cancer. If you google "use of hyperthermia in medical treatment", you'll likely only find two kinds of hits: those for cancer treatment and those for malignant hyperthermia (a side effect of some psychotropic drugs.) The hyperthermia used to kill resistant cancer cells is high enough to destroy proteins (~113°-114°) and very localized; your entire body raised to this temperature would result in death very quickly. Lower (i.e. physiological) levers of "hyperthermia" (or hyperpyrexia) would not kill the cells.
At the turn of the century, there were many who believed in the therapeutic use of hyperthermia in the form of hot baths, hot springs, and even injection of infectious agents to produce fever(!), but the practice has fallen into disuse, probably because there were no studies which supported it.
However, hyperthermia isn't good for you; it is something to treat seriously. When the cause isn't known, the efforts used to treat it can amount to many unnecessary tests and treatments (as seen in the accident victim in the fourth reference. When it's present in a moderate amount, it can still be dangerous:
When fever occurs, many physiological stresses take place. Some of these include increased oxygen consumption as a response to increased cell metabolism, increased heart rate, increased cardiac output, increased leukocyte count, and an increased level of C-reactive protein. Oxygen consumption increases by 13% for every 1°C increase in body temperature, provided no shivering occurs. If shivering is present, oxygen consumption may increase by 100% to 200%. Some cytokines released during fever states also induce physiological stress. These cytokines can trigger accelerated muscle catabolism by causing weight loss, loss of strength, and negative nitrogen balance. Physiological stress can be manifested by decreased mental acuity, delirium, and seizures, which are more frequent in children.
It is likely beneficial in the presence of infection:
Heat shock proteins are one of the more recently studied fever-responsive proteins. These proteins are produced during fever states and are critical for cellular survival during stress. Studies suggest that these proteins may have anti-inflammatory effects by decreasing the levels of proinflammatory cytokines. Fever also triggers other beneficial effects, including an increase in the phagocytic and bacteriocidal activity of neutrophils and enhanced cytotoxic effects of lymphocytes. Some bacteria become less virulent and grow slower at the higher temperatures associated with fever. Increased levels of C-reactive protein promote phagocytic adherence to invading organisms, modulate inflammations, and encourage tissue repair.
In the absence of infection, there is no benefit to systemic elevation of temperature. For the disadvantages of continued elevated metabolic rate, one need only look at hyperthyroidism to see the deleterious effects, the worst being cardiotoxicity, even in subclinical hyperthyroidism, as well as dementia, atrial fibrillation, ventricular hypertrophy, miscarriage, perinatal morbidity and mortality, decreased exercise tolerance, etc.
Years ago, one of the most common self-inflicted illnesses was hyperthyroidism - people taking thyroid hormone replacement unnecessarily - usually because of the weight loss that occurs with elevated metabolic states. Interestingly, efforts are underway to isolste and manufacture a thyroid-hormone like substance which will cause decreased weight without cardiotoxic effects.
Hyperthermia in Cancer Treatment
HYPERPYREXIA PRODUCED BY BATHS
ARTIFICIAL FEVER IN THE TREATMENT OF GONORRHEAL OPHTHALMIA
Thyrotoxicosis in a patient with multiple trauma
Fever: Facts, Fiction, Physiology <- Easy reading and informative
Metabolic Effects of Thyroid Hormone Derivatives