Tuberculosis epidemiology and demographics

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2], Dima Nimri, M.D. [3], Tarek Nafee, M.D. [4]

Overview

In 2019, a total of 8,920 TB cases were reported in the US (incidence of 2.7 cases/100,000 persons). This was an overall decrease by approximately 1.1% from 2018, with a reported 9,021 cases. In 2015, about 10.4 million people developed symptomatic TB and 1.8 million died from the disease. In 2014 there were 9 421 reported cases in the United States, with an incidence of 3.0 per 100 000 persons. Since 1990, the mortality rate of TB has been steadily decreasing. The prevalence of TB increases with age and it is more prevalent in older men. Racial and ethnic minorities have a higher prevalence of TB than non-Hispanic whites. TB is an important cause of death in people who are coinfected with HIV, with approximately a third of deaths among these patients being due to TB. In 2015, 60% of TB cases worldwide occurred in 6 countries: South Africa, Indonesia, Nigeria, Pakistan, India, and China. The WHO has identified 24 other high-burden TB countries including Bangladesh, Congo, Columbia, Cambodia, Korea, Brazil, Ethiopia, Myanmar, Mozambique, Thailand, Angola, Vietnam, Kenya, Central Africa, Russia, Liberia, Zimbabwe, Namibia, Philippines, Tanzania, Sierra Leone, Zambia, Papua New Guinea, Lesotho.

Epidemiology

• Worldwide, in 2015, about 10.4 million people developed symptomatic TB.

• 1.17 million of these cases occurred among people with HIV.

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

• 400,000 of these cases occurred among people with HIV.

• In the United States, a total of 9,421 cases were reported in 2014.

• This represents an incidence of 3.0 cases per 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)
• 
  TB Global Mortality in 2015. - WHO 2016 TB Report)
• 
  Image 5 - TB is in the top 10 causes of death in 2015. - WHO 2016 TB Report)

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 TB cases world wide occurred in six countries:

South Africa

• The incidence of tuberculosis in South Africa is 834 per 100,000 of the overall population.
• The mortality of tuberculosis (excluding HIV-TB coinfection) in South Africa is 46 per 100,000 of the overall population.

Indonesia

• The incidence of tuberculosis in Indonesia is 395 per 100,000 of the overall population.
• The mortality of tuberculosis (excluding HIV-TB coinfection) in Indonesia is 40 per 100,000 of the overall population.

Nigeria

• The incidence of tuberculosis in Nigeria is 322 per 100,000 of the overall population.
• The mortality of tuberculosis (excluding HIV-TB coinfection) in Nigeria is 99 per 100,000 of the overall population.

Pakistan

• The incidence of tuberculosis in Pakistan is 270 per 100,000 of the overall population.
• The mortality of tuberculosis (excluding HIV-TB coinfection) in Pakistan is 23 per 100,000 of the overall population.

India

• The incidence of tuberculosis in India is 217 per 100,000 of the overall population.
• The mortality of tuberculosis (excluding HIV-TB coinfection) in India is 36 per 100,000 of the overall population.

China

• The incidence of tuberculosis in China is 67 per 100,000 of the overall population.
• The mortality of tuberculosis (excluding HIV-TB coinfection) in China is 2.6 per 100,000 of the overall population.

Tuberculosis in the United States

After the resurgence of TB in the mid-1980s, the number of case counts steadily increased, peaking in 1992. Since the 1992 TB resurgence peak in the United States, the number of TB cases reported has decreased annually. The year 2014 marked the twenty-second year of decline in the total number of TB cases reported in the United States since the peak of the resurgence. In 2014, a total of 9,421 cases were reported from the 50 states and the District of Columbia (DC). This represented a decline of 1.5% from 2013. The number of cases per 100,000 in 2013 and 2014 has been stable at a 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, case rates in most age groups declined 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 higher risk of developing progressive disease. Infants are more prone to the development of tuberculosis following infection with M. tuberculosis. Tendency for the disease to disseminate and evolve into miliary tuberculosis. Common involvement of: Lymph nodes Bones Extrapulmonary foci Good prognosis, even in the absence of treatment, often with spontaneous healing. Cavitary tuberculosis has an higher risk of relapse.
Adolescents	Commonly affects lower regions of the lungs and presents with hilar adenitis Hilar calcification is rare Common in immunocompromised and dark-skinned patients Towards young adulthood, the disease tends to occur in apical regions.
Midadulthood	If infection is acquired during mid adulthood, the disease has a better prognosis, possibly due to the existence of less necrotic tissue.
Elderly	Elderly patients have a weaker immune system. Therefore, latent disease, acquired at younger ages, may progress into active tuberculosis with postero-apical predominance. A large group of elderly patients are TST negative because: they have never been infected; they have lost the hypersensitivity reaction; or because they have completely cleared previous infections. These patients are susceptible of reinfection. Tuberculosis in these patients often presents as lower or middle lobe pneumonitis, seldom with pleural effusion. Similar to childhood tuberculosis, with less degree of lymphadenopathy Higher death rate

Gender

In 2012, 410,000 women died of TB in the United States, including 160,000 who were HIV-positive. Of the overall TB deaths among HIV-positive people, 50% were women. TB rates tend to increase with age, ranging from a low, of less than 1 per 100,000 in children aged 5 - 14 to a high of 6.9 per 100,000 in men 65 years and older. As age increased, the case rate increased faster in men than in women; the rates in men 45 years and older were approximately more than twice those in same-age women.

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 observed 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

Several important factors contribute to the disproportionate burden of TB in minorities. In persons who were born in countries where TB is endemic, the disease may result from infection acquired in the country of origin. Unequal distribution of TB risk factors, such as HIV infection, may also contribute to increased exposure to TB or to an increased risk of developing TB once infected with M. tuberculosis.

• Image 7 shows a declining trend in TB rates by race/ethnicity during 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. Rates were consistently higher in minority racial and ethnic groups than in non-Hispanic whites, and were highest in Asians, Native Hawaiians and Other Pacific Islanders, particularly 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)