The Royal Society says that the annual number of disease outbreaks and types of diseases causing them have both increased since 1980, although the fraction of the population affected has actually decreased. I assume this last trend has to do with population growth. I am not sure this should be comforting. If there are more outbreaks and more different types, it seems like there would be more potential for something really bad to emerge and then get out of control. But this article isn’t really about that, it’s just a presentation of the data.

Our analyses indicate that the total number of outbreaks and richness of causal diseases have each increased globally since 1980 (figure 1a). Bacteria and viruses represented 70% of the 215 diseases in our dataset and caused 88% of outbreaks over time. Sixty-five per cent of diseases in our dataset were zoonoses that collectively caused 56% of outbreaks (compared to 44% of outbreaks caused by human-specific diseases). Non-vector transmitted pathogens were more common (74% of diseases) and caused more outbreaks (87%) than vector transmitted pathogens (table 1). Salmonellosis caused the most outbreaks of any disease in the dataset (855 outbreaks reported since 1980). However, viral gastroenteritis (typically caused by norovirus) was responsible for the greatest number of recorded cases: more than 15 million globally since 1980.

It’s interesting how we tend to be less afraid of diseases that are more common and more afraid of ones that are less common, even though a given person would be more likely to suffer from a common disease. Of course, this analysis doesn’t take into account the severity of the disease and suffering caused, which should certainly be a factor in what kinds of controls and research we invest our efforts and money in.