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Principles of Epidemiology

Patricia Hammock IHP 330 Final Milestone Southern New Hampshire University Spring 2021 Salmonella is a gastrointestinal illness that is caused by bacteria. Salmonella bacteria typically live in animal and human intestines and are shed through feces. Humans become infected most frequently through contaminated water or food, pets, or exposure to human or animal feces. "Salmonella infection is more common in the summer months (June, July, and August) than winter" (CDC). Anyone can get the salmonella infection. According to the CDC "Its more sever to people over the age of 65 and below the age of 5". Anyone with a weakened immune system is also likely to develop a serious illness. Some individuals may never have any symptoms. Some of the major risk factors include failure to washing hands after using the restroom, caring for a sick person, before preparing food and after handling raw meats and eggs. However, consumption of raw/undercooked eggs has consistently been identified as the primary risk factor for human. Salmonella is usually contracted through the consumption of contaminated food. These foods mainly consist of eggs, meat, poultry and milk). "Salmonella can pass through the entire food chain from animal feed, primary production, and all the way to households or food-service establishments and institutions." (WHO, 2018). Food consumption is not the only way one can contract the salmonella. Another mode of transmission includes person-to-person. Salmonella is contagious and transmitted from one person to the next by direct contact. "A number of Salmonella species can be transmitted from animals (snakes, turtles, chickens, hamsters, cats and dogs) to humans, usually by direct contact." (Davis, 2020) Incidence and Prevalence are used for different purposes and to answer research question by factoring the change in numbers. Incidence reflects the number of new cases of a disease and is reported as a risk rate or incidence rate. The formula for incidence rate is number of new cases divided by population at risk multiplied by population size. Prevalence reflects the number of existing cases of disease. Prevalence is calculated as number of people with same characteristics divided by total people in sample. According to the case study, there about 86 cases reported each year for incidence of 6.8 per 100,000 population, and salmonella killed 4 people per year. Mortality is accurately calculated by the number of deaths divided by the number of people at risk multiplied by (usually 1000 individuals). "The odds ratio is sometimes called the cross-product ratio because the numerator is based on multiplying the value in cell "a" time the value in cell "d," whereas the denominator is the product of cell "b" and cell "c." (CDC). For example (100x7920)/ (1900x80)=5.2 Disease Exposed A= 100 Not exposed C=80 Total 180 No Disease B=1900 D=7920 9820 Total 2000 8000 10,000 Risk 5.0% 1.0% The case study was conducted in Trinidad and Tobago between the years 1988 and 1997 During this time, an increasing number of cases had been reported and an outbreak of diarrhea had become a public health concern