Posting #2 - Incidence and prevalence of HIV & TB globally and in the US

Epidemiology of Tuberculosis (TB):

• TB infection affects approximately 1/3 of the world's population, with 9.2 million new infections, and resulted in 1.7 million deaths in 2006 (World Health Organization [WHO], 2008).
  
• In the US, 13,299 new cases of TB were reported in 2007, and 644 deaths from TB were reported in 2006. A study in 1999-2000 estimated that 11.2 million people in the US have latent tuberculosis infection (LTBI; Bennett et al., 2008).
• The highest prevalence is in South and South-East Asia, followed closely by Sub-Saharan Africa.
• Poverty and malnutrition disproportionately affect women, leading to increased rates of TB disease in women. Tuberculosis is a leading killer of women between 15 and 44 years worldwide, with 1 million dying of TB per year. (World Health Organization [WHO], 2009).

Epidemiology of Human Immunodeficiency Virus (HIV):

• HIV affects approximately 33 million people worldwide, infected 2.7 million new people, and resulted in 2.0 million deaths in 2007 (World Health Organization [WHO], 2007a).
  
• In the US, an estimated 1.2 million people live with HIV in 2007 (World Health Organization [WHO], 2007b), 56,000 new cases of HIV infections occurred in 2006 (Hall, et al., 2008), and 22,000 people died of AIDS in 2007 (World Health Organization [WHO], 2007b).
• The highest prevalence is in Sub-Saharan Africa, outdistancing all other regions.
• Of those living with HIV worldwide, 47% are adult women and 6% are children under 15. 13.5% of those who die of AIDS are children under 15. In Sub-Saharan Africa, the hardest hit region, the estimated percentage of people receiving antiretroviral therapy has increased from 2006 to 2007, but is still only 30%.

Epidemiology of TB/HIV co-infection:

• 700,000 people globally live with a co-infection of HIV and TB (as of 2006), and it is estimated that 230,000 of co-infected people will die from their TB infection in 2008 . In the US, an estimated 1400 people developed a co-infection of HIV and TB, while 134 of co-infected people died of their TB infection in 2006 (World Health Organization [WHO], 2008). The numbers tested in 2006 are equivalent to 12% of TB case notifications globally, and 22% of notified cases in the African Region.
• The highest prevalence is in Sub-Saharan Africa.
• HIV is the main reason for not being able to meet WHO TB control targets worldwide. In Sub-Saharan Africa, HIV/AIDS is dramatically aggravating the epidemic of TB

References

Bennett, D. E., Courval, J. M., Onorato, I., Agerton, T., Gibson, J. D., Lambert, L., et al. (2008). Prevalence of tuberculosis infection in the United States population: The national health and nutrition examination survey, 1999-2000. American Journal of Respiratory Critical Care Medicine, 177, 348-55.

World Health Organization. (2007a). Global summary of the AIDS epidemic, December 2007. Retrieved 1/4/09 from http://www.who.int/hiv/data/en/

World Health Organization. (2007b). Epidemiological Fact Sheet on HIV and AIDS, United States of America. Retrieved from http://apps.who.int/globalatlas/predefinedReports/EFS2008/index.asp

World Health Organization. (2008). Global health atlas: Data query. Retrieved 1/1/09 from http://www.who.int/globalatlas/dataQuery/default.asp

World Health Organization. (2009). Frequently asked questions about TB and HIV. Retreived 7/20/2009 from http://www.who.int/tb/hiv/faq/en/

Tracy Maier

Posting #1 - Increased replication of HIV at TB sites

I realize this is an older article, but I wanted to start here to be able to expound on the theme of the synergy between HIV and TB. Studies over the past dozen years have been exploring the increased replication of HIV that occurs at site of active TB infection.

30 patients with a co-infection of pleural TB and HIV-1 were studied as a higher prevalence of pleural TB has been associated of HIV-1 and is less likely to be resolved in patients with pleural TB.

Several factors were found by this study to indicate that pleural space may be a reservoir for HIV-1 and aid in its replication during a TB infection. First, the study found that HIV-1 viral load and HIV-1 transcriptional elements were higher in both pleural cellular and extracellular spaces as compared to blood cellular and extracellular spaces, respectively. This was independent of plasma CD4 count. TNF-α, which is known to induce HIV-1 replication, was also greatly increased in pleural fluid as compared to plasma. In the pleural space, β-chemokines, a chemoattractant of monocytes, that act as a competitor for attachment site CCR5 were at reduced levels, while MCP-1, a β-chemokine that attaches to CCR-2 instead, was at an elevated level. In addition, CCR5 was upregulated in the mononuclear cells of the pleural space in the presence of TB. All of these findings show an enhanced activation of HIV-1 in the presence of pleural TB.

This study is the one of the baseline studies for research into inner workings of the interaction between these two diseases. This line of research is also giving us valuable information into each of the diseases separately.

Tracy