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Overview of environmental health principles 4 of 19 Epidemiologic triangle model of disease causation A common model used in public health illustrates the relationships among an agent, a host and the environment.
It applies to biological, chemical and physical agents. For a disease or injury to occur, the basic elements of disease or injury causation and an adequate chain of transmission i. View example 1 and example 2 to learn more.
Disease occurs when an outside agent capable of causing the disease or injury meets a host that is vulnerable to the agent in an environment that allows the agent and host to interact. These basic concepts help guide the selection of health strategies to prevent health problems.
One of the key jobs for the EH professional is to intervene at any point in order to reduce the hazard to health. CDC Move your mouse over the above links to learn more. When done, click the forward arrow to continue. Chain of transmission Agent, host, and environment alone are not sufficient to cause an epidemic; an adequate chain of transmission must be present.
This process requires a source for the agent, a portal of exit, a mode of transmission, and a portal of entry.
Here are two examples of this model. Agent This is an entity that causes the injury or disease. An agent can be biological, chemical or physical. For example, Campylobacter bacteria present on raw chicken is an agent. Anhydrous ammonia in a storage tank is also an agent.
Radioactive waste stored at a nuclear power plant is an agent. Host The host is the human, or, more generically, the organism, that is susceptible to the agent. Some hosts are more susceptible than others. Children are more vulnerable to many agents than healthy adults.
Immuno-compromised individuals, such as people on chemotherapy, are more susceptible to some agents. Environment The environment consists of the conditions that are not part of either the agent or the host, but that influence their interaction.
A wide variety of factors, including physical, climatologic, biologic, social, and economic conditions can come into play. Humans working at a disaster scene Environment: A disaster scene at which food brought by volunteers is served to people working on the disaster Source for the agent: Chicken that was not properly prepared or was undercooked, was delivered to the disaster scene and was not held at proper temperature Portal of exit: Chicken is served by volunteers to workers at the disaster Mode of transmission: Chicken juices with infective quantities of Campylobacter Portal of entry: The best intervention at this point for an EH professional is to embargo the chicken when it is found to be at improper temperature, and to dispose of it.
This would break the chain of transmission between the source and the portal of exit. During a disaster, a foodborne illness among disaster workers would make the situation worse. Anhydrous ammonia, a chemical stored in liquid form that becomes gaseous when exposed to air Environment: Humans living near the scene of the disaster Source for the agent: Tank cars containing the anhydrous ammonia Portal of exit: A train derailment that caused tank cars containing the agent to break open, releasing the chemical Mode of transmission: Through the air as a toxic cloud.
Inhalation of ammonia can cause irritation and burns of the respiratory tract, chest pain, and shortness of breath, and may lead to suffocation Portal of entry: Inhaling vapors through the respiratory system Intervention: Following the derailment the best intervention is to evacuate people from the area.
This would break the chain between the mode of transmission and the portal of entry.HPV Epidemiology. The commonality of HPV among sexually active adults, and the likelihood that sexually active adults will become infected within their lifetime was another major factor behind the .
Tarkowski TA, Koumans EH, Sawyer M, et al. Epidemiology of human papillomavirus infection and abnormal cytologic test results in an urban adolescent population. J Infect Dis ; Winer RL, Lee SK, Hughes JP, et al.
Genital human papillomavirus infection: incidence and risk factors in a cohort of female university students.
Human papillomavirus (HPV) vaccination is one such example, yet immunization rates remain low. In this educational activity, leading clinicians will review the epidemiology of HPV infection as well as the short- and long-term benefits of HPV immunization.
epidemiology STDs are among the most common infectious diseases and can be caused by bacterial, viral, and parasitic pathogens. Annually, an estimated million sexually transmitted infections occur in the United States alone.
Hpv Epidemiology Triangle. HPV Epidemiology and HPV Lisa Rooney NSG/ May 24, Dr. Phelps Epidemiology and HPV Epidemiology, What? Is that even an English word? Epidemiology is the study of health and health concerns in a population with an emphasis on establishing cause and effect.
Epidemiology I ntroduction. Human papillomavirus (HPV) is one of the most common STDs. More than 40 types of HPV are sexually transmitted and can infect the genital tract.
Genital HPV types are divided into two groups, based on their association with cancer.