Question

Principles of Epidemiology and Disease Transmission. Consider the differences between direct and indirect transmission. Provide a scenario for each. As a health educator, how would you work to educate one individual in each scenario to prevent disease transmission in the future?

Answer 1

DIRECT AND INDIRECT TRANSMISSION

Direct contact transmission occurs when there is physical contact between an infected person and a susceptible person.

• Person-to-person contact
• Droplet spread

Indirect contact transmission occurs when there is no direct human-to-human contact. Contact occurs from a reservoir to contaminated surfaces or objects, or to vectors such as mosquitoes, flies, mites, fleas, ticks, rodents or dogs.

• Airborne transmission
• Contaminated objects
• foods and drinking water
• Animal-to-person contact
• Insect bites (vector-borne disease)
• Environmental reservoirs

Principles of Epidemiology and Disease Transmission:

Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.

A number of models of disease causation have been proposed. Among the simplest of these is the epidemiologic triad or triangle, the traditional model for infectious disease. The triad consists of an external agent, a susceptible host, and an environment that brings the host and agent together. In this model, disease results from the interaction between the agent and the susceptible host in an environment that supports transmission of the agent from a source to that host.

Epidemiologic Triad

Agent originally referred to an infectious microorganism or pathogen: a virus, bacterium, parasite, or other microbe. Generally, the agent must be present for disease to occur; however, presence of that agent alone is not always sufficient to cause disease. A variety of factors influence whether exposure to an organism will result in disease, including the organism’s pathogenicity (ability to cause disease) and dose.

Host refers to the human who can get the disease. A variety of factors intrinsic to the host, sometimes called risk factors, can influence an individual’s exposure, susceptibility, or response to a causative agent. Opportunities for exposure are often influenced by behaviors such as sexual practices, hygiene, and other personal choices as well as by age and sex. Susceptibility and response to an agent are influenced by factors such as genetic composition, nutritional and immunologic status, anatomic structure, presence of disease or medications, and psychological makeup.

Environment refers to extrinsic factors that affect the agent and the opportunity for exposure. Environmental factors include physical factors such as geology and climate, biologic factors such as insects that transmit the agent, and socioeconomic factors such as crowding, sanitation, and the availability of health services.

preventing disease transmission

for preventing the spread of disease

• wash your hands or use hand sanitizer before handling food and after shaking hands
• always wash with soap and water if your hands are visibly soiled
• try to minimize touching your mouth or nose with your hands
• avoid sick people, if possible
• wear disposable gloves to avoid contact with blood and feces
• use disposable gloves when caring for an ill person
• cover your mouth when you sneeze and cough and wash your hands afterward
• teach children not to put their hands or objects in their mouths
• sanitize toys and changing tables
• Get proper vaccinations
• Don’t touch sick or dead animals.
• Use insect repellent and mosquito netting.
• Verify the Diagnosis
• Determine if the Case is Infectious or Possibly Infectious:
• Minimize the Duration of the Case's Infectivity
• Put into Effect Practices for Preventing Transmission