Discussion - Modes of HIV Transmission
Chapter 7 discusses the different modes by which HIV can be transmitted from person to person. The chapter tells us that the evidence for assigning risks to different levels of activities comes from two main sources: theoretical biological analysis and empirical epidemiological data, bolstered by lab data.
"Theoretical biological analysis" means that scientists have learned many different things about the HIV virus by growing it in the lab. In the movie "And the Band Played On" you will remember that one reason it took so long to isolate the virus in the beginning was that is was difficult to grow in the laboratory. That's related to certain biological properties of the HIV virus. For example, the virus itself is not a living organism. No virus can grow on its own. Every type of virus need to grow inside a cell, called a host cell. Each type of virus has its own range of host cells, and it can only gain entry to that cell by binding to a specific receptor on the cell's surface. The HIV, for example, can only get into cells by binding to a receptor known as the CD4 receptor, which only lives on the surface of a few types of cells. If a cell doesn't produce the CD4 receptor, the virus can't get in. How efficiently a virus can infect a person is related to how it moves from person to person (mode of transmission). The ability of the virus to be transmitted is also a factor of its "stability", that is, how long it can live outside the body, how long it can live at room temperature once it leaves the body, whether it can live on surfaces once it dries out, etc. Every virus is different. So based on what the scientists learn about a certain virus, they can predict how plausible it would be for it to be transmitted under certain conditions.
Regardless of what the scientists predict about the plausibility of infection, they must weight it against actual data. "Empirical data" is true data that has been obtained from an actual situation. Epidemiologists have learned a lot about how HIV is transmitted by exhaustive questioning of HIV patients and the people with whom they've had contact. They have learned what type of contact and activities can be associated with the transmission of the disease. This has allowed them to come up with a series of recommendations about the risk factors of contracting the HIV.
In this discussion, each of you should write us a comment about something new that you learned from reading this chapter. Discuss the biological reason for the surprising finding. With so many questions up in the air, and so many abstract factors surrounding this disease, it is comforting to realize that the scientific thought process and data collection have given us a way to sort it all out. Epidemiology has removed at least some of the fear and panic associated with disease.
Attachment:- Chapter 7.rar