Introduction to Epidemiology.pptx - Introduction to Epidemiology \u4f55\u71d5 \uff08 He Yan \uff09 Main content \u2022 Definition of epidemiology \u2022 Epidemiologic

Introduction to Epidemiology.pptx - Introduction to...

This preview shows page 1 - 8 out of 45 pages.

Introduction to Epidemiology 何燕 ( He Yan
Image of page 1
Main content Definition of epidemiology Epidemiologic Approach Two types of epidemiology
Image of page 2
PATIENT PROFILE A 29-year-old previously healthy man was referred to the U niversity of California at Los Angeles (UCLA) Medical Center with a history of fever, fatigue, lymph node enlargement, an d weight loss of almost 25 lb over the preceding 8 months. He had a temperature of 39.5 C, appeared physically waste d, and had swollen lymph nodes. Laboratory evaluation rev ealed a depressed level of peripheral blood lymphocytes. T he patient suffered from simultaneous infections involving Candida albicans (fungus) in his upper digestive tract, cyto megalovirus( 巨细胞病毒 )in his urinary tract, and Pneumoc ystis carinii ( 肺孢子虫 ) in his lungs. Although antibiotic the rapy was administered, the patient remained severely ill. 3
Image of page 3
This patient was not the first to be referred to the UCLA Medical Center with this clinical presentation. Within the preceding 6 months three other previously healthy young men with recent histories of weight loss, fever, and lymph node enlargement had been examined. All had P carinii p neumonia and C albicans infections. Why were four patients with similar symptoms appearing at about the same time in the same location? Suspecting that the illnesses in these four patients might be related, the UCLA physicians notified public health officials and pr epared a descriptive report of their findings for publicatio n. 4
Image of page 4
Recognizing the potential for the widespread emergence of th is new, unexplained, and debilitating( 衰弱的 ) condition, the Centers for Disease Control and Prevention (CDC) establishe d a special task force to collect more detailed information on the affected persons. In addition, the CDC issued a formal request to report such p atients to all state health departments. Between June and N ovember 1981, 76 instances ( cases ) of P carinii pneumo nia were identified in persons who did not have known predis posing illnesses and were not taking immunosuppressants. A few months later, the disease that afflicted these patients was named the acquired immune deficiency syndrome (AID S). 5
Image of page 5
6 Beyond their clinical similarities, the sentinel cases shared other features as summarized in Table 1. All four patients were previously healthy homosexual men in their early 30s ( personal characteristics ) who resided in Los Angeles (place) and first became ill in the 9 months ending in June 1981 (time) . These three dimensions— person, place, and time —are the features traditionally used to characterize patterns of disease occurrence. Person, Time, and Place Individual risks and disease occurrence is examined in terms of geographic location and calendar time. Time and Place are used to link individuals Chain of transmission, e.g., infectious diseases Clustered event, e.g., infectious disease, environmental exposures
Image of page 6
Characteristics of sentinel cases of AIDS in Los An geles, 1981 Characteristics of sentinel cases personal attributes Age early 30s Gender male Prior health good Sexual preference homosexual Place of occurrence Los Angeles Time of occurrence Oct.19,1980 to June 19,1981
Image of page 7
Image of page 8

You've reached the end of your free preview.

Want to read all 45 pages?

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes