Effect of Latitude on Seasonality of Tuberculosis, Australia, 2002–2011 - - Emerging Infectious Disease journal - CDC

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Effect of Latitude on Seasonality of Tuberculosis, Australia, 2002–2011 - - Emerging Infectious Disease journal - CDC





Table of Contents
Volume 18, Number 11–November 2012

Dispatch

Effect of Latitude on Seasonality of Tuberculosis, Australia, 2002–2011

Article Contents

• The Study
• Conclusions
• References
• Figure 1
• Figure 2
• Table
• Suggested Citation

Jennifer H. MacLachlan , Caroline J. Lavender, and Benjamin C. Cowie

Author affiliations: Victorian Infectious Diseases Reference Laboratory, North Melbourne, Victoria, Australia (J.H. MacLachlan, C.J. Lavender, B.C. Cowie); Victorian Infectious Diseases Service, Parkville, Victoria, Australia (B.C. Cowie); and University of Melbourne, Parkville (B.C. Cowie)

Suggested citation for this article

Abstract

Seasonal variation in tuberculosis diagnoses recently has been reported in various populations. In Australia, seasonality of tuberculosis diagnoses was more pronounced in areas where UV exposure is reduced and vitamin D deficiency is more prevalent. Our findings suggest vitamin D deficiency as a factor in disease activation.

Tuberculosis profoundly affects human health, with 5.7 million new or recurrent cases reported and >1 million deaths attributed to the infection by the World Health Organization in 2010 (1). Tuberculosis has afflicted humans for millennia, and the potential of sunlight in prevention and treatment has been recognized for more than a century. Before the introduction of antimycobacterial therapy, several therapeutic approaches for tuberculosis were attempted. One example was creation of sanatoria, a positive aspect of which was thought to have been exposure to sunlight:

The ultraviolet rays are absorbed and are beneficial to the general health, even counterbalancing a deficiency in vitamins, to some extent. They have been… used as a treatment for tuberculosis of bones and joints, in which they seem to have a direct effect on the bacteria (2).

The nexus between exposure to sunlight and risk for active tuberculosis has been increasingly recognized, with a putative mechanism being vitamin D deficiency that reduces the ability of macrophages to kill intracellular Mycobacterium tuberculosis (3). Vitamin D deficiency has been associated with latent (4) and active (5) tuberculosis, and seasonality in the number of tuberculosis diagnoses has recently been reported in several regions (3,6).