She writes at the top of her voice all the time. The book reads like a series of newspaper articles. But she can't shake off her background in science reporting for the New York Times. Only molecular biologists will object to that. Primers for the polymerase chain reaction, for example, become fishhooks for catching genes. Rather than explain methods, she invents metaphors for them. Kolata is good at not letting technical details get in the way of her narrative. From these specimens, polymerase chain reaction allowed RNA sequences of a novel influenza A virus to be characterised. So far, the most fruitful source of material has turned out to be lung tissue embedded in paraffin wax that was taken by US army pathologists at postmortem examination of soldiers who had died at army camps during the pandemic. The bodies hadn't been buried deeply enough to keep them frozen. A few years ago, a similar enterprise, this time in Spitzbergen, also failed. In the 1950s, the bodies of four flu victims were disinterred from graves in the Alaskan permafrost, but attempts to grow the virus from tissue samples were unsuccessful. Kolata tells the story of the various attempts to track it down.

Influenza viruses weren't identified until 1933, and the nature of the agent that caused the 1918 pandemic has been a mystery until recently. In England and Wales alone, official deaths from influenza numbered 200 000-more than the current annual number of deaths from heart disease. An estimated 25% of the world's population suffered a clinical infection, and global mortality may have been higher than 40 million.

It's about the influenza pandemic that gripped the world in 1918, killing more people in a few months than the armies of the first world war slaughtered on the battlefields of Flanders, northern France, and Gallipoli in four years. If you think negative strand RNA viruses are giving us a bad time at the moment, read this book to recalibrate your perspective.

Flu by gina kolata