Friday, September 30, 2011

The Great Influenza by John M. Barry Part 1

The Great Influenza is Barry's magnum opus, a well-written, impeccably researched, and infinitely interesting work about the influenza pandemic of 1918. The book as the byline claims, tells the epic story of the deadliest plague in history. Divided into 10 parts, Barry begins by outlining the state of science in America in the century prior to the 1900's and moves on to tell the story of how the world, largely unprepared, coped with such a highly infectious outbreak. I will be discussing this book in several posts over the next few days.

In Part I The Warriors, Barry provides a detailed history of medicine and how physicians viewed disease and undertook the practice of medicine up until the late 1800's. By the 1800's enormous advances had been made in many areas of science with the exception of medicine, which was practiced very much the same as it was in the days of Galen and Hippocrates. This began to change in France with the use of objective measurements such as temperature, pulse rate and blood pressure. Some rejected the use of measurements, saying that they turned the human body into an object, but this application of mathematics to medicine allowed doctors to become detectives and to make discoveries about the causes of disease and to design real treatments for their patients.

Part I is a magnificent and interesting account of the attitudes and practices that prevailed within the 1800's medical world in America which was largely behind that of their European counterparts. In the 1800's for example, most medical students could barely write and having a degree was not a requirement for admission to a medical school. There were many medical schools in the country but they hired uneducated doctors. Many doctors had There were no medical laboratories in America, so doctors went overseas to learn the latest techniques, only to return and be unable to practice what they had learned.

The founding of Johns Hopkins University in Baltimore, in 1876, and its medical school in 1893 was an attempt to change this situation. It would be an institution that would change how science was studied in America and how medicine was practiced. Ultimately, by the time the pandemic arrived in 1918, the changes in American medicine as a result of the Johns Hopkins would result in America having the researchers and the knowledge to confront it.

Barry writes in detail how William Henry Welch, a physician who studied chemistry but who himself never produced a significant body of research, was to transform Hopkins into an influential and cutting-edge institution. Welch had the ability "to identify those with the promise to do what he had not done" and to inspire. Because Hopkins combined a medical school with a hospital, graduate students were afforded the opportunity to examine the sick, make diagnoses, conduct laboratory experiments and undertake research. These students then graduated and took this approach with them to other schools, transforming them.

Welch turned Hopkins into a major influencing force in American medicine revolutionizing the way doctors were trained, how medicine was practiced and developing public health. An interesting fact was that Hopkins got its medical school from a $500,000 endowment from a group of women who had founded Bryn Mawr College, contingent upon the new school accepting women!
Throughout this part of the book, Barry sets the stage for America's medical researchers and how they were unknowingly being prepared to uniquely deal with the pandemic.

In Part II The Swarm, Barry eloquently explains the nature of viruses touching on genes and sterochemistry. He discusses the mechanisms involved in viral attacks on cells in the respiratory track and the immune system's response.

The influenza virus has the unique ability to enter a cell, rather than fuse with it and therefore to effectively hide from the immune system. Within 10 hours, between 100,000 and 1 million new viruses have been replicated and release into the body to attack new cells. Unlike other viruses, the influenza virus, which is an RNA virus, is capable of mutating and adapting rapidly - another reason why it is difficult to attack.

We learn what constitutes a normal immune response and what immunity is (a response to a new infection without symptoms). Barry provides the reader with all the basics needed to understand what happens during an invasion by a virus including how the body mounts an attack on an invader, the development of antibodies and the antigens of viruses.

The most interesting parts of this chapter detail how influenza has developed a way to evade the immune response. Two receptors on the virus, hemagglutinin and neuraminidase mutate quickly by shifting into different forms - this is known as antigen drift. It becomes apparent in this chapter that John Barry has an excellent ability to enable his readers to visualize the concepts he is discussing through the use of examples that are familiar and easy to understand. A prime example is his discussion of antigen drift - when mutations occur in the virus so that the immune system no longer recognize the antigen. Antigen drift is what public health experts monitor each year in order to adjust flu vaccines.

Viruses also undergo antigen shift which is more encompassing with radical change in hemagglutinin or neuraminidase or both. In this case, the infection spreads rapidly because few people have antibodies to fight the infection.

Hemagglutinin occurs in fifteen known shapes while neuraminidase has nine basic shapes. Both occur in different combinations with subtypes. Virologists use these antigens to identify the specific virus they are investigating by using H and N combinations. Hence H1N1 refers to a specific combination of hemagglutinin and neuraminidase.

In the next post on this book, we will discuss how America entering World War I created conditions conducive to the development of a pandemic.

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