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Category: Bacterial Pathogenesis; Clinical Microbiology
Epidemiology and Host Factors, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555819866/9781555819859_Chap02-1.gif /docserver/preview/fulltext/10.1128/9781555819866/9781555819859_Chap02-2.gifAbstract:
Tuberculosis is an ancient infection that has plagued humans throughout recorded and archeological history. It is always a surprise to those of us who live in Western countries that even today the infection remains the cause of higher rates of morbidity and mortality than any other infection in the world. This is because of its great prevalence in the densely populated developing countries; however, the incidence of tuberculosis is grossly underreported in these countries. According to estimates of the World Health Organization (WHO), in 2014 there were approximately 9.6 million active cases, of which 3 to 4 million cases were infectious, with positive sputum smears ( 1 ). Deaths due to tuberculosis occur in 1.5 million people worldwide each year ( 1 , 2 ). The estimates are that a death from tuberculosis occurs every minute. Thus, tuberculosis is still a major cause of disease and death, and its elimination will be extremely difficult as long as poverty, overpopulation, and multidrug-resistant (MDR) disease characterize large portions of the earth. Human immunodeficiency virus (HIV) is already deemed the number one preventable cause of death in developing countries ( 3 ).
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Theoretical concept of the development of tuberculosis (TB) in a community. Tuberculosis is assumed to appear for the first time at zero. The death rate, rate of morbidity, and rate of contacts are shown in reference to a living population. All these curves show a steep ascending limb and a prolonged exponentially decelerated descending limb. Adapted from reference 5 with permission of the American Thoracic Society.
Theoretical concept of the development of tuberculosis (TB) in a community. Tuberculosis is assumed to appear for the first time at zero. The death rate, rate of morbidity, and rate of contacts are shown in reference to a living population. All these curves show a steep ascending limb and a prolonged exponentially decelerated descending limb. Adapted from reference 5 with permission of the American Thoracic Society.
Rate of tuberculosis mortality, morbidity, and contacts at two extreme theoretical urban and rural settings. These two imaginary communities are assumed to remain isolated from the rest of the world. The variation in death rates between countries or communities can be explained by the difference in urbanization, both in time and in space. From reference 5 with permission of the American Thoracic Society.
Rate of tuberculosis mortality, morbidity, and contacts at two extreme theoretical urban and rural settings. These two imaginary communities are assumed to remain isolated from the rest of the world. The variation in death rates between countries or communities can be explained by the difference in urbanization, both in time and in space. From reference 5 with permission of the American Thoracic Society.
Tuberculosis mortality rates per 100,000 persons in the United States. SM, streptomycin. Adapted from reference 116 with permission.
Tuberculosis mortality rates per 100,000 persons in the United States. SM, streptomycin. Adapted from reference 116 with permission.
Major factors that determine transmission of infection from a source case to contacts and natural history of tuberculosis in infected contacts.
Major factors that determine transmission of infection from a source case to contacts and natural history of tuberculosis in infected contacts.
Tuberculosis mortality by age and sex—a theoretical presentation. A, Period at height of epidemic; B, period at intermediate state; C, period at end of wave. Adapted from reference 5 with permission of the American Thoracic Society.
Tuberculosis mortality by age and sex—a theoretical presentation. A, Period at height of epidemic; B, period at intermediate state; C, period at end of wave. Adapted from reference 5 with permission of the American Thoracic Society.
Tuberculosis case rates by age group and sex, United States, 2014. Rates tended to increase with age. The rates in men 45 years or older were approximately twice those in women of the same age. Reprinted from reference 46 .
Tuberculosis case rates by age group and sex, United States, 2014. Rates tended to increase with age. The rates in men 45 years or older were approximately twice those in women of the same age. Reprinted from reference 46 .
Reported tuberculosis (TB) cases, United States, 1982 to 2014. The resurgence of TB in the mid-1980s was marked by several years of increasing case counts until its peak in 1992. Case counts began decreasing again in 1993, and 2014 marked the 22nd year of decline in the total number of TB cases reported in the United States since the peak of the resurgence. From 1992 until 2002, the total number of TB cases decreased 5% to 7% annually. From 2002 to 2003, however, the total number of TB cases decreased by only 1.4%. An unprecedented decrease occurred in 2009, when the total number of TB cases decreased by more than 10% from 2008 to 2009. In 2014, a total of 9,421 cases were reported from the 50 states and the District of Columbia. This represents declines of 1.5% from 2013 and 64.7% from 1992.
Reported tuberculosis (TB) cases, United States, 1982 to 2014. The resurgence of TB in the mid-1980s was marked by several years of increasing case counts until its peak in 1992. Case counts began decreasing again in 1993, and 2014 marked the 22nd year of decline in the total number of TB cases reported in the United States since the peak of the resurgence. From 1992 until 2002, the total number of TB cases decreased 5% to 7% annually. From 2002 to 2003, however, the total number of TB cases decreased by only 1.4%. An unprecedented decrease occurred in 2009, when the total number of TB cases decreased by more than 10% from 2008 to 2009. In 2014, a total of 9,421 cases were reported from the 50 states and the District of Columbia. This represents declines of 1.5% from 2013 and 64.7% from 1992.
Estimated HIV coinfection in persons reported with tuberculosis (TB), United States, 1993 to 2014. Shown are minimum estimates of HIV coinfection among persons reported with TB from 1993 through 2014. Since the addition of the request for HIV status to the individual TB case report in 1993, incomplete reporting has provided a challenge to calculating reliable estimates, although reporting improved substantially beginning in 2011. Results from the cross-matching of TB and AIDS registries have been used to supplement reported HIV test results. For all ages, the estimated percentage of HIV coinfection in persons who reported HIV testing (positive, negative, or indeterminate test results) with TB decreased from 48% to 6% overall from 1993 to 2014 and from 63% to 9% among persons aged 25 to 44 years during this period.
Estimated HIV coinfection in persons reported with tuberculosis (TB), United States, 1993 to 2014. Shown are minimum estimates of HIV coinfection among persons reported with TB from 1993 through 2014. Since the addition of the request for HIV status to the individual TB case report in 1993, incomplete reporting has provided a challenge to calculating reliable estimates, although reporting improved substantially beginning in 2011. Results from the cross-matching of TB and AIDS registries have been used to supplement reported HIV test results. For all ages, the estimated percentage of HIV coinfection in persons who reported HIV testing (positive, negative, or indeterminate test results) with TB decreased from 48% to 6% overall from 1993 to 2014 and from 63% to 9% among persons aged 25 to 44 years during this period.
Tuberculosis cases by race/ethnicity in the United States, 2014. A total of 83% of reported cases occurred in racial ethnic minorities, whereas 17% of cases occurred in non-Hispanic whites. Hispanics are the largest group. Data from reference 46 .
Tuberculosis cases by race/ethnicity in the United States, 2014. A total of 83% of reported cases occurred in racial ethnic minorities, whereas 17% of cases occurred in non-Hispanic whites. Hispanics are the largest group. Data from reference 46 .
Number of tuberculosis (TB) cases in U.S.-born versus foreign-born persons, United States, 1993 to 2014. This graph illustrates the increase in the percentage of cases occurring in foreign-born persons during this period, from 29% in 1993 to 66% in 2014. Overall, the number of cases in foreign-born persons remained virtually level, with approximately 7,600 to 8,000 cases each year until 2009, when the number dropped to 6,961. That decreasing trend continued until 2013, with the number of foreign-born cases dropping to 6,189. However, in 2014, the number of foreign-born cases increased to 6,215. The number in U.S.-born persons decreased from more than 17,000 in 1993 to 3,188 in 2014.
Number of tuberculosis (TB) cases in U.S.-born versus foreign-born persons, United States, 1993 to 2014. This graph illustrates the increase in the percentage of cases occurring in foreign-born persons during this period, from 29% in 1993 to 66% in 2014. Overall, the number of cases in foreign-born persons remained virtually level, with approximately 7,600 to 8,000 cases each year until 2009, when the number dropped to 6,961. That decreasing trend continued until 2013, with the number of foreign-born cases dropping to 6,189. However, in 2014, the number of foreign-born cases increased to 6,215. The number in U.S.-born persons decreased from more than 17,000 in 1993 to 3,188 in 2014.
Reported cases of tuberculosis by anatomic site. Data from reference 117 .
Reported cases of tuberculosis by anatomic site. Data from reference 117 .
Countries of birth for foreign-born persons reported with tuberculosis in the United States, 2014. Data from reference 46 .
Countries of birth for foreign-born persons reported with tuberculosis in the United States, 2014. Data from reference 46 .
Trends in tuberculosis (TB) cases in foreign-born persons, United States, 1993 to 2014. The percentage of TB cases accounted for by foreign-born persons increased from 29% in 1992 to 66% in 2014.
Trends in tuberculosis (TB) cases in foreign-born persons, United States, 1993 to 2014. The percentage of TB cases accounted for by foreign-born persons increased from 29% in 1992 to 66% in 2014.
Trends in advanced pulmonary tuberculosis (APT) adjusted for selected risk factors, 1993 to 2006. Bars, APT; squares, age adjusted; triangles, foreign-born adjusted; circles, HIV adjusted; line, unadjusted. Reprinted from reference 105 with permission.
Trends in advanced pulmonary tuberculosis (APT) adjusted for selected risk factors, 1993 to 2006. Bars, APT; squares, age adjusted; triangles, foreign-born adjusted; circles, HIV adjusted; line, unadjusted. Reprinted from reference 105 with permission.
Incidence of active tuberculosis in persons with a positive tuberculin test by selected risk factors a
Incidence of active tuberculosis in persons with a positive tuberculin test by selected risk factors a
Relative risk for developing active tuberculosis by selected clinical conditions a
Relative risk for developing active tuberculosis by selected clinical conditions a
Risk factors for TST conversion in Canadian hospitals a
Risk factors for TST conversion in Canadian hospitals a