Self-Study Modules on Tuberculosis
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2: Epidemiology of Tuberculosis
Epidemiology is the study of diseases and other health problems
in groups of people. Epidemiologists determine the frequency and pattern
(the distribution) of health problems in different communities. In
other words, they find out who has a specific health problem, how
often the problem occurs, and where the problem occurs. Using this
information about who, when, and where, epidemiologists try to determine
why the health problem is occurring.
Public health officials use epidemiologic information to design
ways to prevent and control the diseases in the community. By finding
out who is at risk for a specific health problem, they can target
their prevention and control strategies at people who are at risk.
This module examines recent trends in TB
in the United States and describes groups of people who are at higher
risk for TB infection and TB disease.Groups of people who are at
higher risk for TB vary from area to area; state and local health
departments are responsible for determining specifically who is
at risk in their area.
After working through this module, you will be able to:
- Describe how the number of TB cases reported in the United States
has changed recently.
- List four factors that have contributed to the increase in the
number of TB cases.
- List the groups of people who are more likely to be exposed
to or infected with M. tuberculosis.
- List the groups of people who are more likely to develop TB
disease once infected.
- Describe the evidence that suggests that the HIV epidemic has
contributed to the increase in the number of TB cases.
- List the racial and ethnic groups that are disproportionately
affected by TB.
- Explain what TB disease in children indicates about the spread
of TB in homes and communities.
Look for the following new terms in this module and in the glossary.
case rate – the number of cases that occur during
a certain time period, divided by the size of the population during
that time period; the case rate is often expressed in terms of a
population size of 100,000 persons
case reporting – informing the state or local
health department when a new case (an occurrence) of TB disease
has been diagnosed or is suspected
close contacts – people who spend time with someone
who has infectious TB disease
contact investigation – a procedure for interviewing
a person who has TB disease to determine who may have been exposed
to TB. People who have been exposed to TB are screened for TB infection
epidemiology – the study of the distribution and
causes of disease and other health problems in different groups
foreign-born persons – people born outside of
the United States; foreign-born persons from areas of the world
where TB is common (for example, Asia, Africa, Latin America, and
the Caribbean) are more likely to become exposed to and infected
with M. tuberculosis
health care facilities – places where people receive
health care, such as hospitals or clinics
infection control procedures – measures to prevent
the spread of TB
residential facilities – institutions where people
live, such as nursing homes, correctional facilities, or homeless