Epidemiology of Disease

Epidemiology of Disease

• Epidemiology involves the study of the distribution and determinants of health-related events among populations.
• Key terms to describe epidemiology of disease include incidence, prevalence, morbidity, and mortality.

Chain of Infection

• The chain of infection consists of an infectious agent, a reservoir, a portal of exit, a mode of transmission, a portal of entry, and a susceptible host.

Factors Influencing Epidemiology

• The dose of the infecting agent, incubation period, and characteristics of the host population can influence the epidemiology of a disease.
• A higher dose of the infecting agent can increase the severity of the disease.
• The incubation period is the time between exposure to the agent and the onset of symptoms.
• The characteristics of the host population, such as age, sex, and immune status, can affect the spread of disease.

CDC and WHO

• The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) are involved in the surveillance, detection, and response to infectious diseases.
• The CDC focuses on disease prevention and control in the United States, while the WHO has a global scope.

Eradication of Disease

• Disease eradication is possible when a disease is solely dependent on humans for its survival, and there is a highly effective diagnostic tool and a highly effective treatment or vaccine.
• Examples of eradicated diseases include smallpox and rinderpest.

Emergence of Diseases

• Six factors that contribute to the emergence of diseases include:
• Changes in human demographics and behavior
• Environmental changes
• Climate changes
• Antimicrobial resistance
• Animal reservoirs and vectors
• Globalization and trade

Hospital-Acquired Infections (HAIs)

• HAIs are infections that are acquired by patients during their stay in a healthcare facility.
• The most common types of HAIs include urinary tract infections, surgical site infections, and pneumonia.
• Causes of HAIs include inadequate hand hygiene, contaminated medical equipment, and inadequate sterilization and disinfection.

Reservoirs of Infectious Agents

• Four reservoirs of infectious agents in healthcare settings include:
• Patients
• Healthcare workers
• Visitors
• Contaminated medical equipment and environment

Mechanisms of Transmission

• Three mechanisms by which infectious agents can be transferred to patients in healthcare settings include:
• Direct contact
• Indirect contact
• Airborne transmission

Roles of ICCs and CDC

• Infection Control Committees (ICCs) are responsible for preventing and controlling nosocomial infections in healthcare facilities.
• The CDC provides guidance and support to healthcare facilities to prevent and control nosocomial infections.