Director of Communicable Diseases Christine Selvey said older Australians in particular should ensure they are up to date with their tetanus jab.
"Tetanus is a rare, but potentially fatal disease. Vaccination is the best protection," Dr Selvey said on Thursday.
The bacterial infection mostly occurs in older people, usually women, whose vaccination has lapsed.
A Sydney woman in her 80s died on April 1 from tetanus, following two other recent cases - another woman in her 80s from Sydney as well as a woman in her 70s from northern NSW.
They are the first cases reported in NSW since 2019 and the death is the first since 1993.
"This serves as a reminder for all older Australians to check their tetanus vaccination status," Dr Selvey said.
In all cases, tetanus was acquired from a minor leg wound that was contaminated by garden soil.
If the bacteria gets into wounds, it produces a toxin that attacks the nervous system. The disease does not spread person to person.
Adolescents and adults who have never had a tetanus shot should receive three doses, and booster doses at 10 and 20 years after the primary course.
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