Health: The Ultimate Treasure
How communicable diseases spread
Find out how diseases spread from one person to another.
Every communicable disease is caused by a pathogen. Pathogens get in through the air we breathe, through dirty food or water, and in other ways.
How they travel from person to person:
- air: when an infected person coughs or sneezes;
- direct contact: such as shaking hands;
- indirect contact: sharing an infected person's things, such as a towel or comb;
- dirty food and water;
- vectors: insects such as mosquitos and houseflies that carry the pathogen.
A vector is a living carrier: a mosquito sucks blood from a person with dengue, picks up the pathogen, and passes it into the next person it bites, without falling ill itself. A towel can carry germs too, but it isn't alive, so it is not called a vector.
Table 3.1, short version:
| How it spreads | Disease | Caused by | Where / main signs and symptoms |
|---|---|---|---|
| air | common cold, influenza | virus | nose and throat: blocked nose, sore throat, fever, cough, body ache |
| air | chickenpox | virus | mild fever, itchy rash, blisters |
| air | measles | virus | fever, sore throat, reddish rash |
| air | tuberculosis (TB) | bacteria | lungs: cough, fever, tiredness, no appetite, night sweats |
| water and food | hepatitis A | virus | liver: tiredness, fever, nausea, jaundice |
| water and food | cholera | bacteria | intestine: diarrhoea, dehydration |
| water and food | typhoid | bacteria | intestine: headache, stomach discomfort, fever, diarrhoea |
| water and food | ascariasis | roundworms | worms in stool, poor appetite, poor growth, weight loss |
| insects | malaria | protozoa | skin and blood: high fever, heavy sweating, chills that come and go |
| insects | dengue (break-bone fever) | virus | fever, headache, muscle and joint pain, nausea |
Notice that TB is caused by bacteria: not only viruses spread from person to person.
The precautions follow the routes:
- keep yourself and your surroundings clean, and practise basic hygiene every day;
- wash your hands with soap and water to remove pathogens;
- cover your mouth and nose when you cough or sneeze, and wear a mask in crowded places;
- don't share towels, handkerchiefs or combs;
- keep your home, food and water clean;
- stay at home and rest when you're unwell: you recover faster, and you don't pass the disease on.
Some infections are caused by worms living inside us, especially in the gut. They feed on the food we eat, so we stay hungry and grow poorly. They are parasites: living things that live in or on another living being. They usually spread through dirty food, water or soil, or contact with infected people or animals.
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