Epidemiologic Triangle

“Tuberculosis (TB), a multisystem disease with myriad presentations and manifestations, is the most common cause of infectious disease–related mortality worldwide. Although TB rates are decreasing in the United States, the disease is becoming more common in many parts of the world. In addition, the prevalence of drug-resistant TB is increasing worldwide. TB is caused by M tuberculosis, a slow-growing obligate aerobe and a facultative intracellular parasite. The organism grows in parallel groups called cords (as seen in the image below). It retains many

AC, is a painful and debilitating condition affecting 2% - 10% of the population (Neviaser and Hannafin, 2010: Cadogan and Mohammed, 2016). Statistical data indicates a higher prevalence in women (59% - 70%), a mean onset age of 50 - 60 years (Cadogan and Mohammed, 2016). The average condition duration presents for 30.1 months but ranges from 1 - 3.5 years (Hand et al, 2008) placing a considerable burden upon individuals and health care services. The non-dominant arm is slightly more affected then the dominant arm (Hand, Clipsham, Rees and Carr, 2008: Levine, Kashyap, Bak, Ahmad, Blaine, and Bigliani, 2007) and the risk of recurrence on the contralateral side within 5 years of the first occurrence is 6%–17%, recurrence in the

There is a trade-off between rate of transmission and duration of infection. If a pathogen can gain increased reproduction by using host resources, or doing anything that helps itself and hurts the host, that tactic can be selected for. A pathogen gains from leaving the host mobile, which generally entails leaving the host alive. A virus spreads only if an infected individual passes the virus on to more than one new host.

Once the virus has entered a host cell, the virus releases the RNA strand to be replicated and form more viruses until

At first I struggled with understanding the question: choose an epidemiologically prevalent psychological disorder and write a research paper. As my preschool teacher taught us, I broke down the sentence and define every single word. Referring to the term "Epidemiology" I came across the epidemiological triangle. The picture of the triangle (Miller, 2002, p. 63, Figure 3.1) refers to the interactions among the host, agent, and environment, which produce a disease state. This triangle specify the prevalence and distribution of disease within a population by person, place and time. The word "prevalence" in a psychological aspect refers to a number of diseases that are present in a particular population at a certain time. "Looking at prevalence

Viruses are not known as living like cells as living things require nutrition and viruses do not. A virus is not live; it is unable to absorb nutrients, produce or excrete waste; so viruses attach themselves to living organism known as a host to survive and gain the nutrition they need. They also need the host to be able to move and reproduce as they unable to do this alone. Viruses have to inject its viral DNA into the host cell it has invaded in order to get the host to reproduce for it.

Viruses do not have the chemical machinery needed to survive on their own. They, thus seek out host cells in which they can multiply. These viruses enter the body from the environment or other individuals from soil to water to air via nose, mouth, or any breaks in the skin and seek a cell to infect.

The type of organisms that can cause infection are predominately bacteria, the excessive buildup of the single, yet simple prokaryotic cells can often lead to a virus. Due to them being so small as well as being asexual producers, the virus cell finds a place in our body and waits. The cells wait for when our immune system becomes weaker with an illness, our defense system already backed up trying to fight off the other bad bacterial cells, before tricking one of your cells into thinking that it’s a virus cell by attaching itself into the regular, healthy cell, intrude into it and release its DNA. The changed cell will now travel around, tricking other cells and multiplying, leading to a viral infection.

Infectious disease is the result of complex interactions between the biological agent, the host, and their environment. This is often viewed as a triad {Anderson, May, 1982}. (Ryan, 2009).

A virulent virus is more severe, the cell of the living host is completely taken over by the viral genome. Once inside the host cell, the viral genome replicates and kills the host cell upon exit. An example of this is HIV. HIV is a virus that presents immunodeficiency, the immune system being comprised results in a weakened ability to fight off infection. HIV is transmitted through blood and some bodily fluids (NHS 2014). The virion RNA integrates with the host DNA producing replications of the viral RNA, these replications form buds on the outer membrane of the host cell, these detach from the host cell and find new cells to infect, the host cell is eventually destroyed.

Humans and animals are common sources of infection they can also be carriers and incubate the disease this can happen because of poor hygiene. Infection can be divided into two main groups these are exogenous and endogenous sources. A source of infection is endogenous when an infectious agent comes from a person’s body this is usually from the person’s own flora. But the exogenous sources of infection tend to introduce organisms from inside or outside the person’s

The immune system, which is the part of the body that protects against diseases, viruses, bacteria, cancerous cells, and fungi, contains white blood cells. White blood cells are the central part of the defense and produce several types of cells. CD4+ lymphocytes, one type of white blood cells, identify disease-causing agents and then warn another type of blood cells, B cells, to develop antibodies. The antidotes then constrain the recognized disease-carrying agents and type of white blood cells, killer T cells, destroy them. Since viruses have to live in the host cells, HIV invades CD4+cells, replicates itself, resulting in the death of the cell in 112 days. The reproduced bacteria then infect the other cell and soon enough the number

The molecular pathway of HIV is similar to most viruses as it begins it’s cycle during the transfer of bodily fluids from one infected person to another non infected person. Once this occurs HIV must attempt to cross the cell layer this can occur through tears in the skin or open wounds. The chance of this happening depends on the viral load or the amount of exposure. Once crossing the cell layer the virus comes into contact with immune cells which attempt to destroy the viruses. These immune cells or CD4 cells serve as the host cells for HIV. The host cell can be a variety of immune cells such as macrophages, dendritic, t helper cells and perhaps most importantly damage B cells. The damage of B cells is significant because they are memory cells that essentially store the recipes to make antibodies to various diseases and viruses they have been exposed to in the past. The immune cells attempt to take up the viruses and destroy them. However, a gene called Vpu facilitates the production of the a protein that prevents immune cells from being able to destroy it. Vpu prevents the destruction of itself by the immune system which then allows them to invade the host cell. Once inside the cell the virus begins its cycle and unpacks its genetic information. Then the process

A lot of the time when a virus come into contact with the host or as we may know it, the cell, it can insert its genetic material into its host, literally taking over the host's functions. Some viruses may remain dormant inside host cells for long periods, causing no obvious change in their host cells, but once stimulated new viruses are formed, self-assemble, and burst out of the host cell, killing the cell and going on to infect other cells. All this is just a constant battle between the host and cell. Without a host cell, viruses cannot carry out their life-sustaining functions or reproduce. They cannot synthesize proteins, because they lack ribosomes and must use the ribosomes of their host cells to translate viral messenger RNA into viral proteins. Viruses cannot generate or store energy, but have to derive their energy, and all other metabolic functions, from the host cell. Sometimes the virus will not be in the cell but outside functioning as coat for the protein. Viruses cause a number of diseases in humans most commonly heard of ones are, smallpox, the common cold, chickenpox, influenza, shingles, herpes, polio, rabies, ebola, hanta fever, and AIDS are examples of the diseases caused by viruses. Even some types of cancer but not all. As Sun Tzu wrote in The Art of War, “All warfare is based on deception”. He could have easily been describing the ancient battle between virus and host

Chance plays a role in all infectious diseases. A person could be in the wrong place at the wrong time. What happens after depends on the amount of host factors. All infectious diseases start at the surface of the host. The only exception is certain intrauterine transmitted infections. The initial barrier is the skin, respiratory tract, or the gastrointestinal tract. The specific surface involved relates to how the microorganism reaches the host.