Tuberculosis caused by M. tuberculosis is one of the deadliest  infectious disease and also the leading cause of death in HIV positive individuals (statistics from CDC at the end of the blog). 

TB has been around for thousands of years. In 19th century people were sent to sanetoriums as way to keep them away from healthy people as well to get the benefits of sun and open air.  There is a good amount of research coming out to show that the beneficial effects of sun on TB patients are in a large part due to increase levels of vitamin D synthesis in the skin. Vitamin D works by binding to a nuclear receptor and regulating the transcription of vit D responsive genes.

Vit D  affects innate immune responses by suppressing TH1 type autoimmune like responses and by promoting regulatory and Th2 responses.  Vitamin D can also induce expression of defensins which can work directly against pathogens. For more information read the review.

There is also epidemiological data to support the link between vit. D insufficeincy and TB ( people migrating from tropic to temeperate latitude has lower levels of vitamin D and higher incidence of TB ). The same may also be true for other infections (low incidence of H. pylori infection in women on vit D supplements).  Accumulation of such data eventually may pressure FDA to revise the RDA allowance of vitamin D higher than current 400IU.

By request, a micrograph is attached below. Look out for the long, purple rods. Mtb is usually stained using Ziehl-Nielssen stain or Löwenstein-Jensen stain for light microscopy.

src:Wikipedia commons

Tuberculosis statistics (source:CDC)

• Tuberculosis Cases
  • 2000: 16,377
  • 2001: 15,989
  • 2002: 15,075
  • 2003: 14,874
  • 2004: 14,502
  • 2005: 14,080
  • 2006: 13,779

   

• Tuberculosis Deaths
  • 2000: 776
  • 2001: 764
  • 2002: 802
  • 2003: 711
  • 2004: 657
  • 2005: 246

   

• Tuberculosis Cases According to Race (2006)
  • Hispanic: 4,066
  • American Indian / Alaska Native: 167
  • Asian: 3,298
  • African American: 3,737
  • Native Hawaiian / Pacific Islander: 56
  • White: 2,403
  • Multiple Races: 35
  • Unknown / Missing Race: 17

   

• Tuberculosis Cases According to Age (2006)
  • 0 - 14 years: 807
  • 15 - 24 years: 1,540
  • 25 - 44 years: 4,702
  • 45 - 64 years: 4,053
  • 65 years and older: 2,676
  • unknown age: 1