Scott Beattie, 43, worked as head stalker at Wyvis Estate, Glenglass, near Evanton, Ross-shire, where he lived on a farm with his partner, Louise Sutherland, and young sons Duncan and Marcus.
His death certificate reveals he suffered multiple organ failure, and suggests further test results could provide more information.
Lyme disease – which is spread by ticks often carried by deer – is a bacterial infection that rarely proves fatal and is usually treatable with antibiotics.
Mr Beattie died in Raigmore Hospital, Inverness, on December 4. His death was reported to the procurator-fiscal and the Crown Office Scottish Fatalities Investigation Unit is carrying out an inquiry.
A Crown Office spokesman said: "The investigation into the death is ongoing and the family will be kept updated."
An NHS Highland spokeswoman added: "As is standard, sudden deaths are referred to the procurator-fiscal".
Wyvis Estates factor Hugh O'Donnell said: "Scott was a greatly valued employee, a good friend and fantastic son, partner and father."
The bloodsucking ticks that carry the Lyme bug, borreliosis, usually feed off birds, deer and sheep. For anyone bitten by an infected tick, symptoms include a "target-like" rash of concentric circles, sometimes described as "like an RAF roundel or an archery target".
Professor Hugh Pennington, Emeritus Professor of Bacteriology at Aberdeen University, said the condition could be considered an "occupational disease" for farmers and estate workers and they ought to be given information on how to protect themselves and seek treatment.
However, he added he would be "very surprised" if the disease itself had caused Mr Beattie's death. He said: "That would be very uncommon. It is a chronic disease that is treatable through antibiotics. It can affect the heart, brain, nerves, joints and skin, but most people do get better. If it is combined with something else there is a theoretical possibility it could be fatal.
"The disease has a skin rash associated with it at the site of the bite, which is how most patients first notice it. People can be ill for quite a while before it is realised they have it."
If left untreated, Lyme disease can also cause neurological symptoms, including meningitis, palsy and encephalitis.
Researchers from the National Lyme Borreliosis Testing Laboratory have said the disease is on the rise in Scotland.
Wendy Fox, chairwoman of the tick-awareness charity Borreliosis and Associated Diseases UK, encouraged people to be vigilant. She said: "Some areas are considered highly endemic but you can pick up Lyme disease anywhere. People with overgrown gardens in urban areas can be bitten and we are seeing more cases of urban acquired infection."
Mr Beattie is survived by his partner and sons, as well as his parents and two brothers.
His funeral is being held at his home on the Wyvis Estate today.