A man has been flown from Cairns to Brisbane in a critical condition after testing positive to diphtheria.
The 27-year-old was flown to Prince Charles Hospital last night, with Queensland Health confirming he was infected within Australia.
The Cairns and Hinterland Hospital and Health Service is contacting all people the man was in contact with in an effort to trace the infection and prevent its spread.
Health officials are at a loss as to how the man contracted the contagious and potentially life-threatening illness.
A Department of Health spokeswoman said the man hadn't done any international travel recently.
It is understood he wasn't vaccinated against diphtheria, and health officials have stressed the importance of being immunised.
Diphtheria is a contagious and potentially life-threatening infection caused by a toxin (poison) made by bacteria.
There are four different types of diphtheria:
• classical respiratory diphtheria
• laryngeal diphtheria
• nasal diphtheria and
• cutaneous diphtheria (skin lesions).
It is not known what type the Queensland patient is suffering from.
Symptoms usually begin two to five days after exposure to the bacteria but sometimes appear up to 10 days after exposure. Symptoms will depend on the type of diphtheria infection. Experts say symptoms range from sore throats and mucus, to ulcers on limbs.
The Department of Health rushed to find locals that may have come into contact with the man since he contracted the illness.
A spokeswoman said several people were treated with vaccinations this morning as a precautionary measure.
Cases of diphtheria are rare in Australia due to the introduction of an effective vaccine, but a century ago diphtheria was the most common infectious cause of death, according to Queensland Health. Outbreaks still occur in countries with low vaccination rates.