One of Australia's worst diphtheria outbreaks has officially claimed its first fatality after tests confirmed the disease was the probable cause.
However, authorities say the rate of cases has dramatically dropped in the Northern Territory at the centre of the outbreak following a vaccination blitz.
NT Health on Tuesday confirmed a man's death in April was diphtheria-related after autopsy results from an overseas laboratory were returned.
"The final toxicology tests have come back demonstrating that the diphtheria bug is producing a toxin that can cause these health effects," NT Chief Health Officer Paul Burgess said.
"We now say that is probable as the cause of death for that individual."
He also dismissed reports that a second man had died from the disease on Sunday.
