Assignment

THE SIGNIFICANCE OF TUBERCULOSIS IN THE UNITED STATES 1

THE SIGNIFICANCE OF TUBERCULOSIS IN THE UNITED STATES 7

COH 315: Introduction to Epidemiology

National University

The significance of Tuberculosis in the United States

Tuberculosis (TB) is a common infectious bacterial disease that affects the lungs and in rare cases, other parts of the body such as kidney and bones. TB poses a considerable threat to public health despite popular misconceptions that it is a disease of the past. The disease affects almost one-third of world population and are responsible for 1.5 million deaths every year mostly in developing countries. TB is much less common in the United States of American and according to statistics, only about 10,500 people were diagnosed with the disease in 2011. However, TB causes disproportional infections among people with weak immune systems and foreign-born populace (Glaziou et al., 2013).

TB burden

According to 2011 statistics, African and South East Asia regions carry the heaviest TB burden. African region leads the rest of the world in the number of TB deaths, prevalence, and incidence. The Americas region has one of the least world’s TB burden compared to the rest of the region. The number of TB deaths, excluding HIV in Americas region stands at two per 100,000, while that of Africa and South-East Asia is 26 per 100,000. The TB and HIV prevalence rate (per 100,000 population is 293 in Africa, 271 for South-East Asia, 170 for Eastern Mediterranean, 56 for Europe, and 35 for the Americas. The number of HIV-positive incident TB cases rate per 100,000 people is 102 for Africa, 8 for South-East Asia, 4 for the Americas, 3 for Europe, and one in the Eastern Mediterranean (Glaziou et al., 2013).

Distribution and prevalence

According to Van Sighem et al. (2015), the United States has maintained data on newly diagnosed cases of TB infection since 1953. TB statistics show that the rate of infections dropped on annual rate of 2.3 percent between 1953 and 1985. During that period, the number of new TB cases declined by 74 percent from 84,304 cases to 22,201 cases. The TB infection rate changed its decline trend and started increasing between 1985 and 1992 because of HIV/AIDS co-infection. During the 1985-92 period, the number of TB infection rose by 20 percent to reach 26,673. Statistics show that the increased TB infection rate during 1985-1992 period contributes to over 64,000 extra TB cases in the U.S. alone. The federal government initiated strategies intended at reversing the rising rate of TB infections that included committing extra resources in order to support TB prevention programs. The government efforts included support programs targeting HIV-infected people, giving the high-risk populations preventive therapy, and wider screening. Statistics show the number of TB cases dropped significantly during the period 1992-2011. The rate of TB infection rate decreased from 10.5 to 3.4 per 100,000 persons, representing a 76 percent decrease.

Demographics (Ethnic) factors

Although tuberculosis affect people of all races, statistics show that TB affects certain subgroups in a disproportionate way. Different demographic factors such as age, sex, ethnicity, race, and country of origin show disparity in TB prevalence. Age is a major factor in TB prevalence since statistics show TB cases increases as the age increases. The 2011 U.S TB case rate shows that the TB infection rate is lowest among children aged zero -14 years whose prevalence rate stands at 0.9 per 100,000. People above 65 years have the highest TB infection rate (5.4 per 100,000) compared with the other age groups, who recorded lower rates. For instance, the infection rate among people aged 15- 24 years, 25-44 years, 45-64 years was 2.4, 4.1, and 4.0 per 100,000 respectively. Statistics show that men are 62 percent more likely to get TB infections than women are, with a male TB prevalence rate of 4.2 per 100,000. The TB incidence in men and women decreased by 50 percent, but TB incidence decrease among men was greater than that of women (Walter et al., 2014).

According to Lim et al. (2013), race and ethnicity groups show a significant disparity in the number of TB incidence. The 2011 statistics indicate that 83 percent of all TB cases in the United States occur among racial and ethnic groups excluding non-Hispanic whites. American Indian/Native Alaska and the Native Hawaiian or Pacific Islanders accounted for less than one percent of the TB cases. The whites accounted for 16.0 percent, Blacks 23.0 percent, Hispanic, 29.0 percent, and the Asian 30.0 percent. Between 2004-2010 period, Hispanic had the highest TB cases. TB incidence has gone down since 1993 having declined by 50 percent in all racial/ethnic groups with the exception of Asians.

Figure 1: TB infection rates by race/ethnicity groups

1993 1995 1997 1999 2001 2003 2005 2007 2009 2011

Rate

Comparing the TB cases among racial/ethnic groups, Asians TB cases is 26 times that of non-Hispanic whites, 8 times that of Blacks, 20 times that of Hispanic Native Hawaiians, and 7 times that of Hispanics.

Foreign- born persons

The 2011 data indicate that foreign-born persons accounted for 62 percent of all TB cases. The health report indicates that for the last eleven years foreign-born persons have been contributing the biggest percent of TB burden. This represents a different scenario compared to 1993 statistic that show foreign-born persons contributing less than 30 percent of annual TB cases. Although the overall TB cases have declined since 1993, the rate has been less substantial among foreign-born persons. The 2011 data show that foreign-born persons were 11.5 times more likely to get infected that the U.S-born persons. The 2011 TB prevalence rate among the U.S-born and foreign-born persons stood at 1.5 and 17.2 per 100,000 respectively. Among the foreign-born persons, the Asians and Hispanic accounts fro 80 percent of the foreign-born TB cases. The numbers of cases among the foreign-born persons according to countries of origin include Mexico (1,432), India (502), China (376), Philippines (757), Haiti (187), Vietnam (546), and Guatemala (166). TB rates among immigrant communities are high because the countries of origin lack adequate screening and tuberculosis prevention therapy (Walter et al., 2014).

TB prevalence rates by state

The 2011 data show a continued decline in TB case rates in 29 states and an increase in 16 states including the District of Columbia. The rates of TB cases in 38 states were below the United States’ national average of 3.4 per 100,000. However, the rate of TB cases in twelve states and the District of Columbia was above 3.4 per 100,000. The states of California, New York, Texas, and Florida each reported 500 TB cases or more according to 2011 data. The data also indicate that over 50 percent of TB cases were in the foreign-born persons in 32 states. In addition, foreign-born population accounted for 70 percent of reported cases of TB in seventeen states. Foreign-born population account for 100% of TB cases reported in North Dakota, 85% and 84% in Minnesota and Massachusetts respectively. The highest percent of TB case rates among the U.S-born persons occurred in the states of Mississippi and Montana at 80% and 88% respectively(Lim et al., 2013).

Risk factors

According to Van Sighem et al. (2015), an HIV/AIDS infection is a major risk factor for the development of Tuberculosis. The human immunodeficiency virus diminishes the body’s ability to resist infection, thus increasing the likelihood of getting TB infection. HIV weakens a person’s immune system and thus increases chances of developing TB. World Health organization data indicate that TB account for 23 percent of HIV/AIDS deaths worldwide. For those individuals infected with TB, the rate of developing active TB among the HIV-positive patient is 30 times that of the HIV-negative people. Data shows that 1.1 million HIV-positive people globally developed TB in 2011, this represent 13 percent of all TB cases. HIV has been identified an important determinant of the rising incidence of TB among poor populations. The 2011 data indicate that 6 percent of all TB cases in the United States were HIV-related; the rate was even higher (10.0 %) among 25-44 year olds (Suthar et al., 2012).

Behavioral risk factors

Studies show people who smoke tobacco and those who consume alcohol are at a higher risk of developing active TB on exposure than non-tobacco smoker and non-alcohol consumers. Studies associate cigarette smoking to increased rate of TB infection. According the studies, cigarette smokers have a higher risk of TB infection and developing active TB than nonsmokers do. Marginalized populations, such as homeless and prisoners exposed to injection drug abuse have a higher chance of getting TB infection (Basu et al., 2011).

Occupational risk factors

According to Lim et al. (2013), scientific studies show that proximity to infectious TB case increases the risk of becoming infected with TB Mycobacterium and developing active TB. Studies show that people in close contact with TB cases such as health care workers, caregiver, and household contact are at higher risk of TB infection.

Slow socioeconomic status

Studies have shown that rapid urbanization and social economic status (SES) influence an individual’s susceptibility to TB infection. Studies show that people with low SES have a higher risk of TB infection because they are exposed to other TB risk factors such as alcoholism, indoor air pollution, and malnutrition. A person with low SES are also exposed to poor ventilation, crowded housing area, and unsafe cooking facilities (Glaziou et al., 2013).

Malnutrition

Malnutrition both at macro- and micro-deficiency is an important risk factor because it impairs human immune response, thus increasing the risk of developing active TB. According to studies, malnourished children have twice the chances of developing TB disease than well-nourished children. In addition, malnourished adults have six to ten times chances of developing active TB than well-nourished adults (Cegielski, Arab & Cornoni, 2012).

Diabetes

Studies have shown that diabetes also increases the risk of developing active TB. Studies also show diabetes patients have three times chances of developing TB than people without diabetes. Diabetes also increases the risk of TB death by 1.89 times and five times if a patient suffers from diabetes mellitus.

Conclusion

Since 1979, TB death rates have been on a downward trend except 1985-1992 periods during the advent of HIV/AIDS. The number of reported TB cases in the United States has continuously reduced since 1993 and by 2011, the rate of TB infection stood at 3.4 per 100,000 persons. The TB burden in America is not as bad as in the other regions in the world; however, TB is serious health problem the federal government has made an effort to address. Many factors contribute to increased TB incident in U.S, they include HIV/AIDS, behavioral factors (alcoholism and tobacco use), immigrants’ issues, social economic status, and occupational factors. Eliminating TB infection in the United States will require a concerted effort in prevention, diagnosis, treatment, and complete reporting.

References

Basu, S., Stuckler, D., Bitton, A., & Glantz, S. A. (2011). Projected effects of tobacco smoking on worldwide tuberculosis control: mathematical modelling analysis. Bmj, 343, d5506.

Cegielski, J. P., Arab, L., & Cornoni-Huntley, J. (2012). Nutritional risk factors for tuberculosis among adults in the United States, 1971–1992. American journal of epidemiology, kws007.

Glaziou, P., Falzon, D., Floyd, K., & Raviglione, M. (2013). Global epidemiology of tuberculosis. Semin Respir Crit Care Med, 34(1), 3-16.

Lim, S. S., Vos, T., Flaxman, A. D., Danaei, G., Shibuya, K., Adair-Rohani, H., ... & Aryee, M. (2013). A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010. The lancet, 380(9859), 2224-2260.

Suthar, A. B., Lawn, S. D., Del Amo, J., Getahun, H., Dye, C., Sculier, D., ... & Granich, R. M. (2012). Antiretroviral therapy for prevention of tuberculosis in adults with HIV: a systematic review and meta-analysis. PLoS Med, 9(7), e1001270.

van Sighem, A., Nakagawa, F., De Angelis, D., Quinten, C., Bezemer, D., de Coul, E. O., ... & Phillips, A. (2015). Estimating HIV incidence, time to diagnosis, and the undiagnosed HIV epidemic using routine surveillance data. Epidemiology (Cambridge, Mass.), 26(5), 653.

Walter, N. D., Painter, J., Parker, M., Lowenthal, P., Flood, J., Fu, Y., ... & Reves, R. (2014). Persistent latent tuberculosis reactivation risk in United States immigrants. American journal of respiratory and critical care medicine, 189(1), 88-95.

White 1993.0 3.6 3.1 2.5 2.3 2.1 1.8 1.6 1.5 1.3 0.8 Black 1993.0 23.8 23.0 20.0 16.0 14.0 12.0 11.0 9.0 8.0 5.6 Hispanic 1993.0 19.8 17.0 14.0 11.5 10.5 9.700000000000001 8.9 7.3 6.7 5.3 Asian 1993.0 41.3 42.3 36.0 33.0 32.0 30.0 26.0 27.2 23.0 20.1 Native Hawaiian/Other Pacific Islanders 1993.0 16.1 13.8 22.3 16.3 15.8 American Natives or Alaska Natives 1993.0 14.1 15.3 11.5 10.5 10.2 10.0 9.8 8.5 6.3 5.5