The last anthrax death in Scotland was in 2006
Health officials have confirmed that a second heroin user, who tested positive for anthrax, has died.
The man was being treated at Glasgow Royal Infirmary. Last week, a man with the infection died in the city's Victoria Infirmary.
A woman who tested positive for anthrax is also being treated there. A further drug user has died but tests have yet to confirm the presence of anthrax.
Meanwhile, a fourth case of anthrax has been confirmed in Lanarkshire.
The patient, who is a drug-injecting heroin user, is being treated at Monklands District General Hospital.
Dr Syed Ahmed, consultant in public health medicine, said: "There have been no new drug injecting heroin users with infections admitted to hospitals in the west of Scotland since the weekend.
"I urge all drug injecting heroin users to be extremely alert and to seek urgent medical advice if they experience an infection.
"Drug injecting is extremely risky and dangerous. The possible presence of a batch of heroin contaminated with anthrax makes drug injecting even riskier and even more dangerous."
Anthrax is an acute bacterial infection most commonly found in hoofed animals such as cattle, sheep and goats.
It normally infects humans when they inhale or ingest anthrax spores, but cannot be passed from person to person.
The last previous death from anthrax in Scotland was in 2006 when Christopher Norris died after inhaling the spores.
The 50-year-old craftsman, from Stobs, near Hawick, made drums with materials such as untreated animal hides.