Preventing, Treating and Controlling Infectious Disease

In short: Epidemics are prevented by stopping a disease from spreading, with hygiene, quarantine, vector control and contact tracing, and by vaccination, which gives immunity without illness. Antibiotics treat only bacterial infections, and overusing them makes bacteria resistant.

Starting point: what you already know

• Pathogens spread by contact, droplets, food and water, and vectors (see Pathogens and the Spread of Disease).
• Memory cells give long-term immunity (see The Immune Response).
• Antibiotics kill bacteria but not viruses.

Stopping the spread

Vaccination

A vaccine contains antigens from a pathogen in a harmless form: killed or weakened pathogens, pieces of the pathogen, an inactivated toxin, or mRNA instructions to make one pathogen protein. The body makes antibodies and memory cells without the person getting sick.

Herd immunity: when enough people are immune, the pathogen cannot find new hosts and stops spreading. This protects people who cannot be vaccinated, such as newborn babies and people having chemotherapy. Measles is very infectious, so about 95% of people need to be immune.

Smallpox was declared eradicated in 1980 after a worldwide vaccination program. It is the only human disease ever wiped out.

Treating disease

Antibiotics kill bacteria or stop them growing, for example by damaging their cell walls (penicillin) or their ribosomes. They do not work on viruses, because viruses have no cell wall or ribosomes of their own.

Antivirals slow viruses from copying themselves inside cells, for example drugs for HIV, influenza and COVID-19.

Antifungals treat fungal infections like tinea and thrush.

Antibiotic resistance

When antibiotics are overused or a course is not finished, bacteria with resistance mutations survive and multiply (natural selection). Some bacteria, like MRSA (golden staph resistant to many antibiotics), are now very hard to treat. To slow resistance:

• only use antibiotics for bacterial infections,
• take the whole course as prescribed, and
• reduce their use in farm animals.

Aboriginal and Torres Strait Islander knowledge of medicine

Aboriginal and Torres Strait Islander peoples have used many plants for healing for thousands of years. For example, the leaves of the smoke bush and emu bush were used by some groups to treat wounds and infections. Scientists have since found antibacterial chemicals in many of these plants. Tea tree oil, used by the Bundjalung people of northern New South Wales, is now known to kill many bacteria and fungi.

This knowledge belongs to the communities who hold it. Under ICIP principles and benefit-sharing laws, research must have the community's consent, credit the knowledge holders and share any benefits fairly. Using traditional knowledge without permission to make a commercial product is called biopiracy.

Quick summary

• Hygiene, sanitation, quarantine, isolation, vector control and contact tracing stop the spread of disease.
• Vaccines give memory cells without illness. Herd immunity protects those who cannot be vaccinated.
• Antibiotics treat bacterial infections only. Antivirals treat viral infections.
• Overuse of antibiotics leads to resistant bacteria through natural selection.
• Aboriginal bush medicine knowledge is valuable and is protected by ICIP: research needs consent and benefit sharing.

Quiz