Читать книгу Principles of Virology, Volume 2 - Jane Flint, S. Jane Flint - Страница 40
Methods Used by Epidemiologists
ОглавлениеWe have considered some of the terms that epidemiologists use, but how do these scientists monitor and develop strategies to control the spread of viruses in populations? An investigation begins at the site of an outbreak, where as much descriptive data as possible about the infected individuals and the environment are gathered. In cases of viral infections in humans, information on recent travel, lifestyle, and preexisting health conditions is considered, along with the medical records of infected individuals to generate a testable hypothesis about the origin of the outbreak. The word “descriptive” can have a negative connotation in virology, often used to imply the opposite of “mechanistic.” However, in epidemiology, descriptive studies are essential to establish or exclude particular hypotheses about the origins of an outbreak. Indeed, descriptive epidemiology was the cornerstone for the discovery of human immunodeficiency virus during the AIDS epidemic in the 1980s (Box 1.7).
Following the descriptive phase, analytical epidemiological methods are used to test hypotheses using control populations in either retrospectively or prospectively focused studies. Clinical epidemiology focuses on the collection of biospecimens, such as blood, sputum, urine, and feces, to search for viral agents or other pathogens and to help determine the potential route of transmission. Once specimens are collected, nucleic acid sequencing is often performed on the samples to deter mine the nature of the infectious agent, or to define how genetic variants may have spread within a population. Studies may also include serological analyses, in which antibodies in the blood that implicate previous infection are identified.