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Name:________________________________________________________________________ GCH 412 Incidence and Prevalence Please circle the correct answer: 1. Nearly 8% of persons aged ≥12 years (6% of males and 10% of females) report current depression. Females have higher rates of depression than males in every age group. IncidencePrevalence 2. Hispanic/Latinos continue to be disproportionately affected by HIV infection. In 2010 (the year for which data is most readily available), Hispanics/Latinos comprised 21% of the new HIV infections. The rate of new HIV infections for Hispanics/Latinos was three times the rate for whites. IncidencePrevalence 3. As of December 31, 2009 there were 16,721 residents of DC living with HIV/AIDS. This accounts for approximately 3.2% of the population over 12 years of age. IncidencePrevalence 4. Down syndrome continues to be the most common chromosomal disorder in babies. Each year, about 6,000 babies are born with Down syndrome, which is about 1 in every 700 babies born. IncidencePrevalence 5. Researchers estimated that in 2008 about 1 out of every 1,200 people (children, teens, and adults) living in the United States had Down syndrome. This means that in 2008 about 250,700 children, teens, and adults were living with Down syndrome in the United States. IncidencePrevalence Note: These statistics are courtesy of the CDC. Incidence and Prevalence Calculations Silicosis is a chronic lung disease caused by breathing in tiny bits of silica dust. Silica is a major component of sand, rock, and mineral ores. Individuals who work in occupations where they are exposed to silica dust, for example mining and construction, are at risk for developing silicosis. It generally takes 15 to 20 years for the disease to develop. Inhaled silica dust can cause fluid build-up and scar tissue in the lungs, which can stiffen the lungs and make it very difficult to breathe. Individuals with silicosis are at increased risk for lung infections, tuberculosis. Silicosis cannot be cured and may ultimately lead to respiratory failure. The Dig Deep Mining Company’s Office of Occupational Health evaluated 1265 miners for silicosis. Of the 1265 miners, 425 had been at the company for 15 or more years. The remaining 840 had been at the mine for 1ess than 15 years. All the miners were evaluated for silicosis using a chest x-ray. Overall, 112 cases of silicosis were identified, including 19 in the group that had worked at the Dig Deep Mine for less than 15 years. 1. Calculate the (circle: prevalence/incidence) in each group at the beginning of the study Group Circle: Incidence/Prevalence All the individuals who were initially examined and did not have silicosis were examined again 5 years later. At this point in time, there were 106 cases of silicosis overall with 82 cases in the miners who had worked at the mine for 15 or more years. 2. Calculate the (circle: prevalence/incidence) in each group at the beginning of the study Group Circle: Incidence/Prevalence 3. In which group are the incidence and prevalence rates the highest? Based on what you know about silicosis, why might you see these differences? According to the Centers for Disease Control and Prevention, Lyme disease is caused by the bacterium Borrelia burgdorferi and is transmitted to humans through the bite of infected blacklegged ticks. Typical symptoms include fever, headache, fatigue, and a characteristic skin rash called erythema migrans (bull’s eye rash). If left untreated, infection can spread to joints, the heart, and the nervous system. Repellents that contain 20% or more DEET (N, N-diethyl-m-toluamide) are recommended to prevent the disease. A population of 6,175 northern Virginia residents who spent more than 15 hours per week working outdoors in wooded areas was recruited for a study to determine the effectiveness of DEET in preventing Lyme disease. Of these individuals, 3,125 used DEET sprays as recommended for Lyme disease prevention. The remaining individuals did not use DEET. During the physical examination, 191 cases of Lyme disease were identified, including 124 cases among the no DEET usage group. All of the individuals who were initially examined and did not have signs or symptoms of Lyme disease were followed by repeat examination over the next year. These follow-up exams identified 259 new cases of Lyme disease in the total group, including 88 cases in DEET usage group. 1. Calculate the (circle: incidence/prevalence) rates of Lyme disease in each study group at the beginning of the study: Group Circle: Incidence/Prevalence 2. Calculate the (circle: incidence/prevalence) rates of Lyme disease in each study group at the end of the follow up year. Group Circle: Incidence/Prevalence