While Melbourne usually doesn't have the dangerous wildlife that Australia is known for, that doesn't mean that a home in this city is 100 percent safe. Even something as simple and as unassuming as a carpet can contain dangerous contagions and bacteria that can cause sickness if left unchecked. To be fair, these harmful microbes are present everywhere, but this only stresses the importance of getting rid of them as quickly as possible.
Molds are possibly the most common microbes in the carpet; albeit also one of the hardest to kill. Coming in various shapes and thriving in different environments, molds are also quite difficult to identify since the relatively-harmless molds (like Alternaria) can resemble the potentially-lethal ones (like Stachybotrys). The difficulty in killing them comes from the fact that molds originate as spores which are virtually invisible to the naked eye until they've grown large enough to be noticeable.
Salmonella bacteria are also commonly found in carpets, especially in households with pets, and can cause digestive problems like diarrhea. This bacteria is one reason why it is never wise for your kids to pick up food that fell from the table since Salmonella is quite resilient even though it has a short life. The Norovirus is similarly resilient though it can survive for six weeks; and causes similar problems, but is more commonly found in dusty areas.
Always make sure your carpets are well-washed to keep your home clean. For this, it's best to call carpet cleaning professionals.