EPIDEMIOLOGY & BIOSTATISTICS
CHAPTER 2 : TERMS USED IN EPIDEMIOLOGY INVESTIGATION
MIND MAP

THE EPIDEMIOLOGY TRIANGLE

EPIDEMIOLOGY TERMS

Disease: a response by a living organism to form invasion by a foreign substance/injury which causes an alteration of normal functioning.

Pathogens : organisms such as bacteria, viruses, or parasites that are capable of producing diseases

Pathogenesis : the development, production, or process of generating a disease

Pathogenicity : the potential ability and strength of a pathogenic substance to cause disease

AGENT

The 4 factors contribute to the outbreak of a disease

  1. Role of the host
  2. Agent
  3. Environmental circumstances
  4. Time

HOST

The agent is the cause of the disease:

  • Bacteria, virus, protozoa, fungi
  • Chemicals (solvents), Radiation, heat, natural toxins (snake or spider venom)

There are 6 types of agents:

  • Biological
  • Physical
  • Chemical
  • Mechanical
  • Nutritional
    Social

The host is an organism, usually human or animal, which are exposed and harbors the disease

Different people may have different reactions to the same agent.

There are 4 factors of host:

  • Demographic
  • Biological
  • Socio-economic
  • Lifestyle

ENVIRONMENT

There are 3 factors of environment:

  • Physical
  • Biological
  • Psycho-social

TIME

Most infectious diseases have an incubation period, between when the host is infected and when disease symptoms occur.

LEVELS OF DISEASE

Diseases have a range of seriousness, effect, duration, severity, and extent and are classified into 3 levels:

  • Acute: severe of short duration, and often treatable. usually, the patient either recovers or dies.
  • Subacute: intermediate in severity and duration, having some acute aspects to the disease for longer duration and with a degree of severity. The patient is expected to eventually heal.
  • Chronic: less severe but long or continuous duration, lasting over a long time period, if not a lifetime. The patient may not fully recover and the disease can get worse over time. Life not immediately threatened, but maybe over the long term

MUHAMMAD SAIFUL ISLAM BIN BAHARUDIN
(012021071984)
KESAVAN SUPPIAH
(012021021498)