Non-infectious disease

Diseases you can't catch

Non-infectious diseases are not caused by pathogens and can't spread from person to person. In Australia they cause most deaths: heart disease, dementia, stroke, lung cancer and diabetes are all near the top of the list. Many are chronic, meaning they last a long time, often for life. Most have more than one cause.

Asbestos is a mineral once used widely in Australian houses and was mined at Wittenoom in Western Australia until 1966. Breathing in its tiny fibres can cause a cancer of the lining of the lungs called mesothelioma, often 20 to 50 years later. Australia has one of the highest rates of mesothelioma in the world, and all use of asbestos was banned in 2003. Old asbestos sheeting should only be removed by licensed workers.

How cancer starts

Your cells divide to grow and to replace worn-out cells. Genes control when a cell divides and when it stops. Each time a cell copies its DNA, there is a small chance of a mistake, a mutation. Mutations can also be caused by mutagens such as UV light, chemicals in tobacco smoke and X-rays.

Most mutations do no harm, and cells have ways of repairing damaged DNA or destroying themselves if it can't be fixed. The immune system also kills many abnormal cells. But if a cell builds up mutations in several of the genes that control division, it can start dividing over and over without stopping. That is cancer. Because several mutations are usually needed, most cancers take years to develop, and the risk rises steeply with age.

• A benign tumour grows slowly in one place, often inside a capsule, and doesn't spread. It may still need to be removed if it presses on something important, such as the brain.
• A malignant tumour is cancer. It invades the tissue around it, and cells can break off and travel in the blood or lymph to start new tumours elsewhere. This spread is called metastasis, and it is what makes cancer so dangerous.

Treating cancer

Cancers are treated with surgery to remove the tumour, radiotherapy (beams of high-energy radiation aimed at the tumour), and chemotherapy (drugs that kill rapidly dividing cells). Because chemotherapy also affects normal fast-dividing cells, side effects include hair loss and a weakened immune system. Newer immunotherapy drugs help the patient's own immune system recognise and attack cancer cells. Finding cancer early makes a huge difference, which is why Australia runs free screening programs for bowel, breast and cervical cancer.

Two Australian success stories

Sun protection. In 1981 the Cancer Council launched the "Slip! Slop! Slap!" campaign, with a cartoon seagull telling Australians to slip on a shirt, slop on sunscreen and slap on a hat. "Seek shade" and "slide on sunglasses" were added later. Australian schools adopted "no hat, no play" rules, and melanoma rates in younger Australians have since started to fall. The UV index is now shown in weather forecasts; protection is recommended whenever it is 3 or above, which in most of Australia is most of the year.

Smoking. A large Australian study found that up to two in every three long-term smokers die from a disease caused by smoking. Through advertising bans, tax increases, smoke-free laws and graphic warnings, the share of Australian adults who smoke daily has fallen from about one in three in 1980 to around one in ten. In 2012, Australia became the first country in the world to require plain packaging on cigarettes. The newest challenge is vaping: e-cigarettes deliver highly addictive nicotine, and since 2024 they have only been legal in Australia from pharmacies.

Disease, research and fairness

Some diseases fall hardest on particular communities. Rheumatic heart disease starts with an ordinary infection: a strep throat or infected skin sores caused by group A streptococcus bacteria. In some people the immune response to the bacteria also attacks the valves of the heart, scarring them permanently. The disease itself is not infectious, and it has almost disappeared from wealthy communities. Yet First Nations children and young adults in some remote communities in northern and central Australia have some of the highest rates in the world. The causes include crowded housing, which helps the bacteria spread, and limited access to clinics. Researchers, health services and Aboriginal community-controlled organisations are working on better housing, early diagnosis with portable heart scans, regular penicillin injections to prevent repeat attacks, and a vaccine against group A strep. It is a clear example of how health depends on living conditions as well as on biology.