TB: It Will Suprise You

Tuberculosis (TB) is the common term for Mycobacterium tuberculosis which is a bacteria that can infect the human body, commonly the lungs and potentially kidney and other vital organs. TB disease is caused by bacteria that are either active or latent in the body. Active TB is a highly contagious air-born disease. TB is often thought of as a disease only prevalent in third world countries and the homeless but the recorded cases in Missouri alone are shocking. Missouri had 80 cases of TB in 2010, 60 cases in 2009, 93 cases in 2008, and 118 cases in 2007. Incidence of infection in Missouri has been lower in recent years but the number of cases is still a concern for such a dangerous disease. Recent research is currently underway to determine if diabetes mellitus is a cause or additional concern related to latent TB. The close connection between a communicable disease and a chronic disease is a growing concern globally and it should also be a local concern. Additionally, a vaccine to prevent TB infection is still in the research and testing stage in the UK.
TB is often overlooked in the United States because health issues like heart disease, tobacco use, and cancer overshadow diseases that aren’t as prevalent. Though TB is not as prevalent in Missouri as in third-world countries, the disease is still present. There was a pediatric case of TB in a rural Missouri high school resulting in four active cases (three of them family members) and 64 latent cases (two of them family) (Phillips, Carlile & Smith, 2004). The initial student with TB showed evidence of TB in a chest X-ray six months before being diagnosed, which could have prevented infection of the active disease to family and fellow students (Phillips, Carlile, & Smith, 2004). Through this example it is easy to see how contagious TB is even in areas with lower populations the disease can spread rapidly from person to person. If Missouri residents were more aware of the dangers of TB then it would go a long way toward preventing the spread of this contagious disease.

TB becomes a problem when the immune system is compromised which explains why up to half of patients who are infected with HIV/AIDS die from TB (CDC, http://www.cdc.gov/hiv/resources/factsheets/hivtb.htm). TB can also affect diabetic patients whose immune systems are compromised. In a research study to observe the connection diabetes has with tuberculosis they found that, diabetes is an important risk factor for TB (Dooley &Chaisson, 2009). Diabetics are not more susceptible to the bacteria itself because the bacteria is air born and infection depends on whether the patient is exposed to the bacteria not the state of their immune system. Diabetics are more likely to jump from a latent form of TB to an active form of TB with a compromised immune system because the bacteria are allowed to multiply. The active form of TB creates problems for public health because the disease is contagious (can be spread to other people) and symptoms are not always obvious in the early stages of the disease so diagnoses is tricky. Another serious concern is that diabetes changes the way the TB disease is presented, affecting glucose levels and the patient’s glycemic control (Dooley &Chaisson, 2009). This study also found that the connection between diabetes and TB was more prevalent in youth and adolescents (Dooley & Chaisson, 2009). The majority of diagnosed TB patients (with or without diabetes) are between the ages of 25 and 44 (CDC, http://www.cdc.gov/tb/statistics/reports/2009/table4.htm). This leads researchers to believe that either diabetic patients are more likely to contract TB at a younger age or younger diabetic patients have weaker immune systems because they neglect their diabetes. “Diabetic patients who needed more than 40 units of insulin per day were twice as likely to develop tuberculosis as those using lower doses, thus linking severity of diabetes mellitus with risk of tuberculosis (Dooley & Chaisson, 2009)”. Though TB is dangerous researchers are working on collecting more information on the impact to public health and developing a vaccine to prevent infection.

A common vaccine used in third world countries to prevent TB infection is known as the BCG vaccine (or bacilli Calmette-Guerin vaccine). The vaccine is not able to stop the spread of infection if the bacteria are already present in the patient (whether in the active or latent form). The BCG vaccine is only commonly used in children in third world countries who are often exposed to the disease (CDC, http://www.cdc.gov/tb/publications/factsheets/prevention/BCG.htm). The three main problems that arise with a TB vaccine include cost, interference with tuberculin skin tests, and lifespan of the vaccine. The BCG vaccine is a highly cost effective vaccine in third world countries where the incidence of infection is greater but it would not be cost effective in the United States. The vaccine is only guaranteed to last for up to 15 years and is known to interfere with tuberculin skin tests (CDC, http://www.cdc.gov/tb/publications/factsheets/prevention/BCG.htm). The BCG vaccine is widely used because it is cheap and safe but it is not able to prevent TB when the patient already has latent TB and its effects are short lived (Marx, 2011). This is problematic because if the patient becomes infected after the vaccine becomes ineffective then they cannot be diagnosed with TB using the tuberculin skin test. There is a new vaccine that has only been tested on animals so far, but it has been proven more effective than the BCG vaccine (Marx, 2011). The new vaccine lasts longer than the BCG vaccine, it will not prevent TB infection but there is the possibility of a booster shot that will be able to postpone active TB (Marx, 2011). The booster shot will enable patients to remain protected from becoming infected with the TB bacteria for a longer period of time. Though the new vaccine has not been tested on humans yet, there is research currently underway to prevent the spread of TB.

References:

Department of Health and Human Services Centers for Disease Control and Prevention Fact Sheet: TB and HIV/AIDS. Retrieved April 4, 2011from: .

Department of Health and Human Services Centers for Disease Control and Prevention: Reported Tuberculosis in the United States, 2009. Retrieved April 4, 2011 from: .

Department of Health and Human Services Centers for Disease Control and Prevention Fact Sheet: BCG vaccine. Retrieved April 4, 2011 from: .

Dooley K. E. & Chaisson R. E. (2009). Tuberculosis and diabetes mellitus: convergence of two epidemics. Lancet Infectious Diseases, 9(12), 737-746.

Phillips L., Carlile J., & Smith D. (2004). Epidemiology of a tuberculosis outbreak in a rural Missouri high school. Pediatrics, 113(6), 514-9.

Marx H. L. (2011). Bureau of communicable disease control and prevention – Missouri Department of Health and Senior Services.

Stevenson C. R., Critchley J. A., Forouhj N. G., Roglic G., Williams B. G., Dye C., & Unwin N. C. (2007) Diabetes and the risk of tuberculosis: a neglected threat to public health? Chronic Illness, 3(3), 228-245.