Infectious diseases and transmission

Learning objectives

• Connect pathogens with transmission routes.
• Distinguish antibiotics from antiviral action.
• Explain selection for resistance.

The big idea

Infectious diseases involve pathogens with different biological properties. Cholera bacteria can spread through contaminated water, tuberculosis through airborne transmission and malaria through a mosquito vector; control must address the relevant route.

Antibiotics act on susceptible bacterial processes. Resistance can arise through mutation or acquired genes, then spread when selection favours resistant variants. Public-health outcomes also depend on infrastructure, access and coordinated prevention rather than the pathogen alone.

Investigate and explain

Using the worked example as supplied data, predict the effect of changing one condition. Draw a labelled model, record your reasoning and identify a variable that would need controlling. No human, animal or microbial experiment is required.

No exact PhET model is claimed for this topic. Use diagrams and supplied-data reasoning instead.

Open the interactive investigation

Check your understanding