Infection and immunity
Infection and immunity

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Infection and immunity

Session 1: Introducing human infectious diseases


Most people on Earth experience at least one episode of an infectious disease every year. Although the majority recover, hundreds of millions suffer severe or long-term health effects as a direct result of an infection and around 10 million people – many of them children – lose their lives. In the 1960s, it was widely believed that the threat to health from infectious diseases would be overcome by advances in methods of prevention and treatment. Unfortunately these predictions have proved to be optimistic because of the rapidly increasing threat from ‘emerging infectious diseases’.

This first session of the course presents an overview of infectious diseases and discusses emerging infectious diseases.

In the following video, Dr Claire Rostron, Senior Lecturer in Health Sciences at The Open University, and one of the course authors, will introduce some exciting concepts to be covered in the course.

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CLAIRE ROSTRON: Infectious diseases are diseases that can be passed between people and sometimes between people and animals by infectious agents known as pathogens. An example could be influenza, commonly known as the flu, or meningitis or smallpox. In contrast, there are other diseases known as non-communicable diseases, such as arthritis or asthma, that cannot be transmitted between people and between people and animals. There isn't a risk of catching arthritis just by being next to someone who already has arthritis.

Sometimes it's obvious that there is a risk of infection. For example, in places where there is a lack of clean water and sanitation. Pathogens don't have to be transmitted directly from one person to another or from an animal to a person.

Often, however, the risk of infection is less obvious. This hospital laboratory tests for the presence of pathogens and may appear to be perfectly clean. But the lab coats which are being worn for protection are also potential carriers of infectious agents. Any non-living object in the environment that could transmit an infectious agent is known as a fomite.

The possibility of pathogens being transmitted via this route is why hospital doctors in the UK now rarely wear neckties that could drape across a person during a medical examination. In fact, it would be good laboratory practise for the individuals in this image to routinely wear and change gloves and to routinely clean and change their protective clothing.

In this Open Learn course, you will learn about some of the different routes of transmission as well as some examples of the pathogens that are transmitted via these different routes. But now, let's make a start by looking at some of the categories of infectious diseases, as well as how we go about diagnosing them.

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