Below are some interesting scraps to explore regarding the difference between (causal) explanation and description.
YOUTUBE -EppQw9JHD8 A series of five parts of a four-hour interview filmed in late June and early July 2008 by Alan Macfarlane, of the historian of science, Professor Simon Schaffer of the University of Cambridge. For a higher quality, downloadable, version with a detailed summary, please see www.alanmacfarlane.com
For Latour, such description could grow or shrink to encompass any frame of inquiry. A historian could expand the scope of inquiry to a multi-national account, or delve into Pasteur's laboratory notebooks, and just chart more alliances of people, instruments, objects, and so forth.
On the other hand, for Schaffer, there was always a proper frame of inquiry: the failure to look to crucial challenges to Pasteur, especially that of the German Robert Koch, was an essential weakness in Latour's account of the rise of Pasteur: Latour - can explain this shift in loyalty [of the Revue Scientifique] by reference to Pasteur's experiments alone, and the good behaviour of microbes, because he deliberately omits their most potent enemies (188, Schaffer's emphasis) - kvond.wordpress.com 
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