Real World article
(written from a Production point of view)

Tefler was a USS Voyager crewmember mentioned in a deleted scene cut from the Star Trek: Voyager episode "Friendship One".

In the final draft of the script, it establishes that Neelix was in the middle of describing his day to a photograph of his sister, Alixia, as he prepared for bed. The scene picks up with him explaining that "Ensign Tefler checked into Sickbay with another case of "food poisoning". The Doctor requisitioned my Aurellian beef stew... but he didn't find any pathogens... of course."

This may have been a tie-in for continuity to the previously established Crewman William Telfer, however since the reference was a throwaway line, in both the literal and physical sense, a connection cannot be firmly established.

It is worth noting that Telfer had previously been established as a hypochondriac, hence Neelix's apparent disbelief of the crewman's claims of illness (as evidenced by the emphasis he put on the term "food poisoning") and his own subsequent certainty that nothing was wrong with his food.