So what's bugging you? That latest virus that's going around the office got you down, or are you the victim of a nasty bacterium that's rapidly multiplying within your body?

What's the difference? Just pop a pill and modern medicine will take care of your ills. It's not necessarily the case. There are big differences between illness caused by viruses and those caused by bacteria.

Unlike bacteria, viruses are not living organisms. They need living hosts, like people, to multiply. Once lodged in some of your cells, they can take over the way the cells act, reproducing the virus instead of keeping your body feeling at its best. Pop an antibiotic and the virus won't even notice.

Some illnesses caused by bacteria – like strep throat and tuberculosis – are best battled with a course of antibiotics. Other bacteria-caused illnesses – such as Vancomycin-resistant enterococcus – actually get worse when you're on antibiotics.

Emerging diseases – such as SARS, West Nile Virus and C. difficile – may have us all on edge. Seems there's no safe place to hide from disease.

Infections that originate in hospitals, or nosocomial infections, infect about 250,000 Canadians a year and kill about 8,000 of them. And treating those infections costs health-care systems at least $100 million every year.

Because these infections are usually resistant to commonly used antibiotics, they are sometimes dubbed "superbugs."

Patients who catch superbugs can double their hospital stay, first recovering from the illness that brought them to hospital and then recovering from the infection.

The best defence against these bacteria and viruses is information. This section of CBC News is a collection of background information on several diseases, conditions and health issues that you may have questions about.