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Infectious Disease

Infectious diseases are caused by organisms - such as bacteria, viruses, fungi or parasites. A person may become ill with an infectious disease through contact with another infected person (directly or indirectly), an insect or animal carrying disease, or contaminated food or water.

Infectious diseases include:
  • Foodborne, airborne, and waterborne illnesses
  • Zoonotic diseases, which spread from animals to people
  • Vaccine-preventable diseases, Hepatitis A, Hepatitis B, pertussis, influenza, HPV, and measles
  • Respiratory virus infections including Respiratory Syncytial Virus (RSV), Enterovirus, and Rhinovirus
  • Human Immunodeficiency Virus (HIV) infections
  • Sexually transmitted diseases
  • Healthcare-associated infections (HAIs), which are infections that patients get while receiving medical treatment for another condition
  • Bloodborne disease like Hepatitis C
Infectious diseases are a major cause of illness, disability, and death. For example, CDC estimates that each year roughly 1 in 6 Americans (or 48 million people) get sick, 128,000 are hospitalized, and 3,000 die of foodborne diseases. Infectious diseases are also associated with substantial healthcare costs. Healthcare-associated infections alone account for billions of dollars of health care costs in the United States each year.

Many infectious disease illnesses and deaths are preventable. By monitoring disease incidence and studying how and why infectious diseases spread, public health aims to stop illness from spreading and prevent diseases from occurring in the future.
Every living organism is at risk of illness from infectious diseases. Some factors that are associated with the probability of becoming ill with infectious disease include:
  • Individual health status
  • Age
  • Immunization status
  • Community immunization status
  • Environmental conditions
  • Region or location of residence
  • Proximity to sources of disease transmission
  • Occupation
  • Behavior
  • Drug use (including injecting drugs)

Illness with infectious disease occurs when an individual is exposed to a disease causing pathogen by the correct mode of transmission while that individual is particularly susceptible to the pathogen.
To reduce the risk of illness it is important to control infectious disease by disrupting disease transmission. This can be accomplished by:
  • Vaccination: Infectious diseases that are vaccine preventable are controlled by giving immunity to vaccinated individuals. The more people that are vaccinated in a community the less likely an infectious disease is able to spread and make people ill.
  • Hand Washing: Hand washing decreases the amount of infectious diseases that we are exposed to by physically removing pathogenic organisms from our hands.
  • Food Safety and Water Quality: Following good food safety and handling practices decreases the quantity of pathogenic organisms that are ingested.
  • Stay Home When Sick: When sick stay home to prevent spreading illness to others.
  • Use Precautions: When outdoor use insect repellent and protective clothing to protect yourself from insects that may carry infectious diseases
  • Condoms: Consistent and correct use of latex condoms reduces the risk of sexually transmitted disease (STD) and human immunodeficiency virus (HIV) transmission. Abstaining from sexual activity, or being in a long-term mutually monogamous relationship with an uninfected partner are also ways to avoid the transmission of STDs and HIV.
  • Clean Needles: Sharing needles with others who may be infected with a bloodborne disease such as HIV or Hepatitis C is a direct route for the virus to enter the blood stream. Using clean needles and not sharing them will reduce the risk of spreading disease.
Reportable infectious diseases in the United States are tracked by local, state, and federal government utilizing a cooperative relationship with clinicians and laboratorians. When an individual is identified with an infectious disease clinicians and laboratorians report to their local or state health department. All disease specific information is collected regarding the infectious disease event and is then reported to the CDC. The information collected can be used for many purposes at many different jurisdictional levels such as to:
  • Educate the public
  • Guide policy and public health decisions
  • Alert clinicians to aid in diagnosis
  • Educate the medical community
  • Implement public health interventions, including during epidemics
  • Provide partner services
  • Describe infectious disease in different populations
  • Identify risk factors for disease

The information collected during the disease investigation process has all personal identifiers removed and the data is then available to the public. This de-identified public data is used by both public and private entities for research and business development, further supporting the importance of tracking infectious diseases.
Various reports regarding infectious diseases can be found on the Bureau of Epidemiology website at:

The information provided above is from the Department of Health's Center for Health Data IBIS-PH web site ( The information published on this website may be reproduced without permission. Please use the following citation: " Retrieved Thu, 25 April 2019 22:09:49 from Department of Health, Center for Health Data, Indicator-Based Information System for Public Health Web site: ".

Content updated: Mon, 11 Feb 2019 15:18:19 MST