Septicemia is a severe and often deadly blood infection and is a form of sepsis, defined as an infection of tissues by bacteria. Noxious bacteria do considerable damage by attacking tissue, including blood. However, when they die or when their cell walls rupture, they release a poison (endotoxin), which may do more harm than the bacterial attack itself. Sunlight and vitamin D may have a protective affect on preventing this often-deadly disease.
Much of this information comes from two excellent papers, one by Dr. William Grant, who alerted me to this research, and the other from Dr. N Mookherjee and colleagues.
Sepsis accounts for 500,000 emergency-room hospital visits per year in the USA, and the typical stay is nearly five hours. It is one of the most deadly of medical conditions and often results in multiple organ failure and death. There are about 750,000 cases per year, and about 3% of all hospital admissions result in a case of sepsis.2 Sepsis is one of the top-ten causes of death in the USA and the second leading cause of hospital-associated deaths outside of coronary intensive care units. In North America sepsis and its related disorders kill more people than heart attacks, colon cancer, breast cancer or AIDS. And in the case of severe sepsis, antibiotics have not improved survival. They may, in fact, worsen the condition.
Dr. Grant points out that septicemia incidence is highest in the winter and lowest in the autumn, that rates are also generally highest in the Northeast and lowest in the Southwest, and that African Americans (who have lower levels of vitamin D) have 1.7 to 4.3 times higher incidence rates than do whites. There is also a rapid increase in risk with age, and several other chronic and infectious diseases are closely associated with that increase. All of these factors indicate vitamin D deficiency; therefore, such a deficiency could play a strong causal role in septicemia, especially since deficiency inhibits the production of cathelicidins, which not only break down the cell walls of noxious germs, but also help to reduce the endotoxins resulting from the breakdown.  
In my book, I discuss the fact that in Australia, melanoma rates have skyrocketed since 1980 when the anti-sun campaign began in earnest. Sepsis rates jumped simultaneously and both diseases coincided with the widespread use of sunscreens. The same is true for viral respiratory infections, most cancers, congestive heart failure1 and several other diseases that follow similar patterns. Dr. Grant states that the incidence and prevalence features of sepsis are similar to the epidemiological features of vitamin D deficiency based on summertime solar UVB light that produces vitamin D.
There is another indication that vitamin D deficiency is at least partially responsible for the alarming death rate from septicemia and for the hospital deaths that this deadly disease causes: when vitamin D levels are low, parathyroid hormone (PTH) levels tend to by high. Consider that among older hospital patients with hip fractures, high PTH is associated not only with accelerated bone loss, but also with a doubling of injury to the heart and an 18.5 times increase in the risk of hospital death when compared to patients with high levels. Certainly, there is no downside to educating the public of the need to keep levels of vitamin D high, as it likely affords significant protection against this emerging killer, septicemia.
 Grant, W. Solar ultraviolet-B irradiance and vitamin D may reduce the risk of septicemia.
Dermato-Endocrinology 1:1, 1-6; January/February 2009.
 Mookherjee, N. et al. Cathelicidins and functional analogues as antisepsis molecules. Expert Opinions on Therapeutic Targets 2007;11:993-1004.
 Wang, H. et al. National estimates of severe sepsis in United States emergency departments. Crit Care Med 2007;35:2461-2.
 Danai P. et al. Seasonal variation in the epidemiology of sepsis. Crit Care Med. 2007;35:410–15.
 Danai P. et al. The epidemiology of sepsis in patients with malignancy. Chest. 2006;129:1432–40.
 Giacometti, A. et al. Cathelicidin peptide sheep myeloid antimicrobial peptide-29 prevents endotoxin-induced mortality in rat models of septic shock. Am J Respir Crit Care Med 2004;169:187-94.
 Giacometti, A. et al. The antimicrobial peptide BMAP-28 reduces lethality in mouse models of staphylococcal sepsis. Crit Care Med. 2004;32:2485–90.
 Cirioni O. et al. LL-37 protects rats against lethal sepsis caused by gram-negative bacteria. Antimicrob Agents Chemother. 2006;50:1672–9.
 Montague M, et al. Slip! Slop! Slap! and SunSmart, 1980-2000: Skin cancer control and 20 years of population-based campaigning. Health Educ Behav. 2001;28:290–305.
 Fisher, A. et al. Relationships between myocardial injury, all -cause mortality, vitamin D, PTH, and biochemical Bone turnover markers in older patients with hip fractures. Ann Clin Lab Science 2007;37:222-232.