Tuberculosis epidemiology and demographics

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]; Associate Editor(s)-in-Chief: Mashal Awais, M.D.[3]; João André Alves Silva, M.D. [4], Dima Nimri, M.D. [5], Tarek Nafee, M.D. [6]

Overview

In 2019, about 8,920 TB cases were documented in the US with an incidence of 2.7 cases/100,000 persons. This represented a decrease by 1.1% from 2018. In 2015, about 10.4 million people developed symptomatic TB and 1.8 million died from the disease. In 2014, approximately 9,421 cases were documented in the United States, with an incidence of 3.0 cases/100 000 persons. Since 1990, there has been a decrease in the mortality rate . TB is more prevalent in older men. Racial and ethnic minorities have a higher prevalence of TB than non-Hispanic whites. Coinfection with HIV is an important leading cause of death in TB. In 2015, 60% of the worldwide TB cases were in 6 countries: South Africa, Indonesia, China, Pakistan, India, and Nigeria. The WHO reported 24 other high-burden TB countries including Bangladesh, Korea, Columbia, Cambodia, Congo, Brazil, Ethiopia, Myanmar, Philippines, Thailand, Liberia, Vietnam, Kenya, Central Africa, Russia, Angola, Zimbabwe, Namibia, Mozambique, Tanzania, Sierra Leone, Zambia, Papua New Guinea, and Lesotho.

Epidemiology

• Worldwide, in 2018, there were approximately 10 million individuals with incident TB and about 1.5 million TB-related deaths.
  • Approximately 862,000 of these cases were in patients coinfected with HIV ^[12]
• Worldwide, in 2015, approximately 10.4 million people had symptomatic TB.

• 1.17 million of these cases occurred were in patients coinfected with HIV.

• Worldwide, in 2015, about 1.8 million people died from TB.

• 400,000 of these cases were in patients coinfected with HIV.

• In the United States, in 2014, approximately 9,421 cases were reported with an incidence of 3.0 cases/100 000 persons.

Incidence and Mortality

Worldwide Tuberculosis

• Over 95% of TB deaths occur in low- and middle-income countries, and it is among the top three causes of death for women aged 15 to 44.
• The TB death rate dropped 45% between 1990 and 2012.
• In 2015, 3 million lives were saved by the global TB response.

• 

  Incidence of All Forms of TB in 2015. - WHO 2016 TB Report)

• 

  Trend in TB incidence from 2000 to 2015. - WHO 2016 TB Report)

• 

  TB mortality trends (2000-2015) - WHO 2016 TB Report)

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  TB Global Mortality in 2015. - WHO 2016 TB Report)

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  Image 5 - TB is in the top 10 causes of death in 2015. - WHO 2016 TB Report)

• 

  Trends in Estimated Incident Tuberculosis 2000-2018 (TB)[1]

Global Regional Incidence & Mortality

The following global regional trends in TB incidence are observed from 2000 to 2015:

Global Incidence and Mortality of Tuberculosis and HIV, By Region (2015)

	African Region	American Region	Eastern Mediterranean Region	European Region	South-East Asian Region	Western-Pacific Region
Incidence (per 100 000)	275	27	116	36	246	86
Incidence of Multi-Drug Resistant TB (per 100 000)	11	1.1	6	14	10	5.5
Mortality (excluding HIV-TB coinfection) (per 100 000)	45	1.9	12	3.5	37	4.8
Mortality (only HIV-TB coinfection) (per 100 000)	30	0.59	0.46	0.54	3.9	0.31
Total new cases in 2016	1 333 504	230 519	484 733	297 448	2 656 560	1 361 430
Table adapted from WHO Global Report 2016

TB and HIV

Immunosuppression secondary to HIV is strongly associated with incidence of TB and its subsequent complications. Tuberculosis contributes to a considerable proportion of HIV/AIDS related deaths.

• 

  Incidence of TB and HIV in 2015 - WHO 2016 TB Report)

• 

  Trend in TB and HIV mortality (2000-2015) - WHO 2016 TB Report)

• 

  Estimated TB and HIV deaths in 2015 - WHO 2016 TB Report)

Tuberculosis in Endemic Countries

In 2015, 60% of the worldwide TB cases were reported in six countries:

South Africa

• The incidence of tuberculosis was reported as 834 per 100,000 of the general population.
• The mortality rate of tuberculosis (excluding HIV-TB coinfection) was reported as 46 per 100,000 of the general population.

Indonesia

• The incidence of tuberculosis was reported as 395 per 100,000 of the overall population.
• The mortality rate of tuberculosis (excluding HIV-TB coinfection) was reported as 40 per 100,000 of the overall population.

Nigeria

• The incidence of tuberculosis was reported as 322 per 100,000 of the general population.
• The mortality rate of tuberculosis (excluding HIV-TB coinfection) was reported as 99 per 100,000 of the general population.

Pakistan

• The incidence of tuberculosis was reported as 270 per 100,000 of the general population.
• The mortality rate of tuberculosis (excluding HIV-TB coinfection) was reported as 23 per 100,000 of the general population.

India

• The incidence of tuberculosis was reported as 217 per 100,000 of the general population.
• The mortality rate of tuberculosis (excluding HIV-TB coinfection) was reported as 36 per 100,000 of the general population.

China

• The incidence of tuberculosis was reported as 67 per 100,000 of the general population.
• The mortality rate of tuberculosis (excluding HIV-TB coinfection) was reported as 2.6 per 100,000 of the general population.

Tuberculosis in the United States

TB resurge occurred in the mid-1980s since when the number of cases steadily increased with a peak occurred in 1992. Following this peak, the number of reported TB cases has decreased annually. The year of 2014 represented the twenty-second year of decline in the reported TB cases in the United States since that peak. In 2014, approximately a total number of 9,421 cases were reported in the 50 states and the District of Columbia (DC). This was considered a decline of 1.5% from 2013. The number of TB cases per 100,000 in 2013 and 2014 was at a stable rate of 3.0.

Image 1 - Reported TB Cases United States, 1982–2014- Center for Disease Control and Prevention(CDC)

Image 2 - TB Case Rates,* United States, 2014- Center for Disease Control and Prevention(CDC)

Demographics

Age

In 2014, TB cases in most age groups decreased by approximately 70% from the 1993 values. Below is the comparison between the case rates (per 100 000 persons) of these two years, according to different ages:

Age	Case rate in 1993	Case rate in 2014
>65 years	17.7	4.8
45 - 64 years	12.4	3.5
25 - 44 years	11.5	3.4
15 - 24 years	5.0	2.2
< 15 years	2.9	0.8
Data provided by the CDC

Image 4 - TB Case Rates* by Age Group United States, 1993–2014- Center for Disease Control and Prevention(CDC)

Image 5 - Reported TB Cases by Age Group, United States, 2014- Center for Disease Control and Prevention(CDC)

Depending on the age of the patient, tuberculosis may have different clinical manifestations, progression, and prognosis:

Factor	Influence
Infants and Children	Younger age (< 5 years) is associated with a higher risk of developing progressive disease. Infants are more prone to the development of tuberculosis following infection with M. tuberculosis. Higher risk of miliary tuberculosis. Common involvement of: Lymph nodes Bones Extrapulmonary foci Usually have a good prognosis; spontaneous healing occurs even in the absence of therapy. Cavitary tuberculosis has a higher risk of relapse.
Adolescents	The lower regions of the lungs are usually affected with the presentation of hilar adenitis Hilar calcification is rare Common in immunocompromised and dark-skinned patients In young adults, the disease tends to affect the apical regions of the lung.
Midadulthood	If the infection occurs during mid-adulthood, the disease carries a better prognosis, possibly due to the presence of less necrotic tissue.
Elderly	Elderly patients have a weaker immune system. Consequently, latent disease, acquired at younger ages, has a higher risk f progression to active tuberculosis with posterior-apical predominance. A lot of elderly patients are TST negative because they have no prior TB infection; they have lost the immune/hypersensitivity reaction; or because they have completely cleared previous infections. These patients are at risk of reinfection. Tuberculosis in those patients usually presents as middle or lower lobe pneumonitis, rarely with pleural effusion. Similar to tuberculosis in childhood, with less degree of lymphadenopathy Higher death rate

Gender

In 2012, there were 410,000 total deaths in women as a result of TB in the United States, 160,000 of them were HIV-positive. Out of the total TB deaths among HIV-positive people, 50% were women. TB rates tend to increase with age, ranging from a low rate of less than 1 per 100,000 in children aged 5 - 14 to a high rate of 6.9 per 100,000 in men aged 65 years and older. With age increasing, the case rate increases faster in men than in women; the rates in men aged 45 years and older were approximately more than double the case rate in women of the same age.

Image 6 - TB Case Rates by Age Group and Sex, United States, 2014- Center for Disease Control and Prevention(CDC)

Race

The highest TB rates was reported in Asians, a decline from 29.9 per 100,000 persons in 2003 to 17.8 in 2014.

Racial/ethnic groups	Case rate in 2003	Case rate in 2014
Non-Hispanic blacks or African-Americans	11.7	5.1
Hispanics	10.3	5.0
American Indians and Alaska Natives	8.2	5.0
Non-Hispanic whites	1.4	0.6
Native Hawaiian or Other Pacific Islanders	16.2	16.9
Data provided by the CDC

The disproportionate burden of TB in minorities is due to many factors. In persons who were born in countries where TB is endemic, the disease can be a result of an acquired infection in their country of origin. Unequal distribution of TB risk factors, such as HIV infection, leads to increased TB exposure or to an increased risk of developing TB after infection with with M. tuberculosis.

• Image 7 shows that TB rates are decreasing by race/ethnicity in the last 12 years.

• Image 8 shows that above the age of 5, there is an increased risk of TB with age across all racial and ethnic groups. The case rates were higher in minority racial and ethnic groups than in non-Hispanic whites and were highest in Asians, Native Hawaiians and Other Pacific Islanders, especially in the adult age groups.

• Image 9 shows that in 2014, 85% of all reported TB cases occurred in racial and ethnic minorities, whereas 13% of cases occurred in non-Hispanic whites. Persons reporting two or more races accounted for 2% of all cases

Image 7 - TB Case Rates by Race/Ethnicity, United States, 2003–2014- Center for Disease Control and Prevention(CDC)

Image 8 - TB Case Rates by Age Group and Race/Ethnicity, United States, 2014- Center for Disease Control and Prevention(CDC)

Image 9 - Reported TB Cases by Race/Ethnicity, United States, 2014- Center for Disease Control and Prevention(CDC)