An earlier report suggested the man fell ill from of the bite of a white-tailed spider in Birchip in the Wimmera but experts have ruled out the possibility that the venom from any spider in Australia could cause a flesh-eating condition that requires amputation. Instead, they said, a spider bite – like any other abrasion – could serve as a "port of entry" for bacteria to enter the human body.

The condition of a man who lost both his legs after contracting an infection through what is thought to be a spider bite has stabilised, as experts rule out the possibility that the venom from any spider in Australia could cause a flesh-eating condition that requires amputation.

Filipino man Terry Pareja was visiting family in rural Victoria in February when he came down with a fever and noticed his foot was swollen. He went to the local medical clinic and was referred to Wimmera Base Hospital in Horsham, where, they said, doctors told them it appeared he had been bitten by a spider.

There, his right leg was amputated, and his spleen and part of his bowel were removed, according to his family. A spokeswoman from Wimmera Healthcare Group said the amputation had been performed "to treat a necrotising (flesh-eating) skin infection."

Soon after, he was flown by air ambulance to The Alfred hospital in Melbourne, where his left leg was amputated, too, and he was put on a dialysis, because his kidneys were suffering, his family said.

Mr Pareja's family said doctors told them he had contracted a bacterial infection that was eating away at his flesh, and that it was possible his arms might also need to be amputated.

But, after spending over a month in hospital, Mr Pareja appears to be on the mend. His family said that a surgeon at The Alfred told them Tuesday that the treatment had been effective in eliminating the bacteria from his body.

"We don't believe he's still at risk of losing his arms or other organs," his family told Fairfax Media on Wednesday. "We're really hoping the bacteria are no longer there. He's improving. He's putting up a fight."

The Alfred hospital declined to comment on the exact circumstances surrounding Mr Pareja's illness, out of respect for the patient's privacy, but was able to confirm that his condition was now serious but stable.

Reports on Mr Pareja's condition raised the eyebrows of experts, who were quick to deny that spiders in Australia could cause an infection of the sort he was suffering from.

"Flesh-eating illnesses cannot be caused by spiders," said Ken Walker, an entomologist at the Melbourne Museum.

The myth that white-tailed spiders can cause ulcerated wounds was debunked years ago, he said. "They cannot."

Rather, he said, Mr Pareja's condition sounded like it bore similarity to the Bairnsdale ulcer (also known as Buruli ulcer), which is an infectious disease that can result in extensive damage to human flesh.

Bairnsdale ulcer is caused by Mycobacterium ulcerans, which can be found in soil, he explained.

"Because it's in the soil, all you need is an open wound and you can get these Mycobacterium ulcerans," he said. "And they're necrotising, which means the skin and flesh dies and has to be removed through skin grafts or amputation."

Dr Kenneth Winkel, the former director of the Australian Venoms Research Centre at Melbourne University, was also doubtful Mr Pareja's condition was caused by the spider's venom. 

"There is no history of specific skin or limb infections consistently caused by spider bites in Australia," he said.

"There have been occasional definite reports of fungal or bacterial infections occurring after Australian spider bites but this is a risk for any skin wound. Mycobacterial infections, AKA the Bairnsdale or Buruli ulcer, do not present in the same manner as this patient and have not been attributed to spider bites. Such ulcers are painless and slow growing."

Dr Winkel said a spider's bite, like that of any animal, "may have simply been a port of entry for a flesh eating bacteria to infect his body."

The hospitals that have treated Mr. Pareja declined to name the infection they believe he is suffering from.

While most spider bites cause local pain, Dr Winkel added, anyone who notices they have been bitten by a spider should act quickly to sanitise the wound and keep it clean, so as to avoid infection.