I've been following the story. Very sad to hear the little one didn't make it
In the wild, elephants live in matriarchal societies where young female elephants are able to "learn" how to care for their young by watching the older females of their group rear their young. Yes, occasionally, first time wild elephant mothers abandon their babies, for much the same reason the captive mother abandoned her baby - it was sick. Unfortunately, there is no elephant medicare to help in these situations.
The vets and other zoo staff did their best to care for the sick infant, but in the end it was not enough. Elephants are highly social and live in complex societies. I have a whole bunch of if only's going around in my head, but, ultimately, infant mortality is an utterly sad fact of life
