Ah, so that's one way to identify the villain: round up everyone who's sick! Hehe.
Yeeah but that'd get everybody who's been chasing him too ;)
Our writer Emily had this idea: a human brain might adapt to manipulating the electrical bonds between atoms to such an extent that it can learn the electrical configuration of organisims as a 'pattern', but you can only adapt so far. So what happens when the body's electrical structure gets changed too many times in a row? A lot of cells die and a lot of internal processes are thrown off a bit. The human biological response to unspecified trauma is 'hey, we don't know what it is but we can always burn it out, turn up the heat!' You usually get a fever after trauma, such as breaking a leg or having major surgery, so it was reasoned that Changing too much would cause the same thing.
So long explanation short: there's a lot of stubborn Bothare out there tonight who'll be pretty sick ;)
Going even further, the body's pain receptors should probably shut off during a transformation, too. Because rearranging your parts like that would hurt like hell.
Oh yeah, they do, and sometimes that is a problem in its own right: a higher than normal proportion of Bothare kids have no sense of pain. We're looking forward to later in the story, when we've gotten past 'let's just survive' and we can start exploring all these little intricacies with you readers :D