Pathogens
Introduction
Infectious diseases are caused by microorganisms such as bacteria, viruses, parasites and fungi that can be spread, directly or indirectly, from one person to another. Some are transmitted through insect bites while others are caused by ingesting contaminated food or water.
How these diseases spread depends on the specific disease or infectious agent. Some ways in which communicable diseases spread are by:
- Physical contact with an infected person, e.g. through touch (staphylococcus), sexual contact (gonorrhoea, HIV), faecal/oral transmission (hepatitis A), or droplet (influenza)
- Contact with contaminated surfaces or objects (Norovirus), food (Salmonella, E. coli), blood (HIV, hepatitis B), or water (botulism)
- Insect or animal bites capable of transmitting the disease (Malaria caused by mosquitoes and Lyme disease caused by tick bites)
- Airborne, such as tuberculosis or measles.
Over the past two centuries, tremendous achievements have been made in controlling infectious diseases. Simple measures such as improved sanitation, food safety, and modern advances in antimicrobials and vaccination programmes have dramatically reduced and eradicated many communicable diseases in Northern Ireland. However, with new microorganisms and diseases emerging, it is important to remain vigilant.
Surveillance and control are crucial for protecting the public’s health because infectious diseases can significantly impact the population. Reporting cases of infectious diseases is important in planning and evaluating disease prevention and control programs and in detecting common-source outbreaks. It is likely that everyone will be affected by an infectious disease at some point in their lives. It is important to learn about the causes of infectious diseases and ways to prevent their spread.
This section of the manual will consider some of the most common infectious diseases/organisms. The table includes the incubation period, infection control precautions, transmission route, period of infectivity, and duration of isolation precautions for a list of diseases/organisms.