---
title: "How Communicable Diseases Spread"
description: "Bacteria, viruses, fungi and protists spread through air, water, direct contact or a vector, and each route points at a different way to break the chain. Uses named human and plant diseases."
canonical: https://lightmysky.com/learn/science/how-communicable-diseases-spread-mt_o__-bF814q
source: https://lightmysky.com/learn/science/how-communicable-diseases-spread-mt_o__-bF814q.md
retrieved: 2026-09-12
---

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# How Communicable Diseases Spread

Bacteria, viruses, fungi and protists spread through air, water, direct contact or a vector, and each route points at a different way to break the chain. Uses named human and plant diseases.

Subject: Science · Area: The Human Body · Ages 15 to 16
Page: https://lightmysky.com/learn/science/how-communicable-diseases-spread-mt_o__-bF814q

## Ready when they can

- Sorts named diseases by pathogen type and by route of spread.
- Explains why a virus needs a host cell to reproduce while most bacteria do not.
- Picks a control measure that matches a given route of transmission and says why it works.

## Lesson: How germs travel and how to stop them

Four pathogen types cause communicable disease: bacteria, viruses, fungi and protists. Bacteria are single cells that mostly reproduce alone. A virus cannot reproduce without a host cell, since it must hijack the cell to copy itself.

Germs move by routes. Coughs launch some through the air, dirty water carries others such as cholera, touch passes colds, and vectors ferry germs between hosts. A vector is a living carrier such as a mosquito, which spreads malaria when it feeds.

**Example.** Each route points at its own block. Masks and ventilation block airborne spread, clean water blocks waterborne spread, handwashing and isolation block touch, and bed nets block mosquito vectors. Match the block to the route and say why it works: it cuts the exact path the germ travels.

**Tip.** Answer in two steps. Name the route the germ uses, then pick the control that cuts that route. If the question names malaria, the route is a mosquito vector and the answer involves nets or draining breeding sites.

**Recap.** Name the pathogen and its route, then cut that exact route to stop the spread.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Pathogens & the Immune System](https://lightmysky.com/learn/science/pathogens-and-the-immune-system-mt_1VIE8FlZvL)

## Opens up

- [Innate Immunity: Pattern Recognition, Complement and Inflammation](https://lightmysky.com/learn/science/innate-immunity-pattern-recognition-complement-and-inflammation-mt_3TcgoOGI0L)
- [Epidemiology: Incidence, the Reproduction Number and Tracking an Outbreak](https://lightmysky.com/learn/science/epidemiology-incidence-the-reproduction-number-and-tracking-an-outbreak-mt_f2tT08sEki)
- [Vaccination and Antibiotic Resistance](https://lightmysky.com/learn/science/vaccination-and-antibiotic-resistance-mt_XmDqQONako)