6 Conclusion

As you reach the end of this free course you should consider some of the important points that the study of flu raises.

1. A single pathogen can produce different types of disease in different people. Genetic variation in a pathogen can also affect the type of disease it produces. To understand this we need to know something of the genetic and social differences in the host population, and of the diversity of the pathogen.
2. The symptoms of a particular disease may be produced by different pathogens or by a combination of pathogens. To understand this requires some knowledge of pathology and cell biology.
3. Some diseases, such as flu, affect humans and several other animal species, whereas others are more selective in their host range. The basic biology of different pathogens underlies these differences.
4. Flu is a disease that can be contracted several times during a lifetime, but many other infectious diseases are only ever contracted once. To understand this we need to look at how the immune system reacts to different pathogens, and how responses vary depending on the pathogen.
5. Outbreaks of flu occur regularly, but some epidemics are much more serious than others. This requires an understanding of aspects of virology, immunology, evolutionary biology and epidemiology.