The Spread of Diseases

• A communicable disease is a disease that can be transmitted from one organism to another.
• A pathogen is a microorganism that causes disease.
• The four types of pathogen are: bacteria, viruses, fungi and protists.
• Pathogens can spread by air, water or direct contact.
• Bacteria make you ill by producing toxins that damage tissues.
• Viruses make you ill by reproducing rapidly inside cells, damaging or destroying them.
• Three viral diseases include: measles, HIV and tobacco mosaic virus.
• Two bacterial diseases include: salmonella and gonorrhea.
• Rose black spot is a fungal disease.
• Malaria is a protist disease that is spread from person to person by mosquito bites, and causes recurrent fevers.
• Four methods of controlling the spread of communicable diseases include:

  Good hygiene.

  Isolating infected individuals.

  Controlling vectors.

  Vaccination.
• Vaccines contain small quantities of a dead or inactive form of a pathogen.
• Vaccination stimulates the body to produce antibodies against a specific pathogen - if the same pathogen re-enters the body, white blood cells rapidly produce the correct antibodies.
• Herd immunity is when of a population is vaccinated against a disease, meaning it is less likely to spread.