When his team took a tick apart to look for the new bug, they found it in the ovaries. And, when they looked closely at electron micrographs of infected ovarian tissues, they could see that the microbes were intracellular – living not in the cytoplasm of tick ova, but within their mitochondria.

“We’d never seen anything like this before,” Lo says, as he opens the image files on his laptop on a rainy afternoon in Sydney. “They seem to get in between the inner and outer mitochondrial membranes and eat the mitochondria up. In the end you’ve just got this empty sack.”
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says he wasn’t aware of any other bacteria that live inside mitochondria. “It’s pretty surprising to see a bacterial species living inside the mitochondrion, which itself was a bacterium,”