A Condition of the body in which the organ system or part does not function properly.

It is a disturbance of a body structure or function.

It can make a person;

1. Physically or mentally ill

2. Limits his or her activities

3. Leads to death

A person or a doctor of medicine who studies human diseases as they affect the society.

A person who studies epidemic disease.

Agent Factors

Host Factors

Environmental Factors

Social Factors

Include the organisms that cause an infectious disease

These can be;

BacteriaVirusRicketsiaeProtozoaFungi

Bacteria have 3 shapes1. Spherical shape are called coccus2. Rod shape bacteria are called

bacillus3. Twister rod like corkscrew is

called sprillum

Bacteria are abundant in air, soil, water, food and the body

Not all bacteria are harmful

Bacteria that causes disease are called pathogens

EXAMPLES OF BACTERIAL DISEASE

Tetanus Gonorrhea Diphtheria Tuberculosis Scarlet Fever Pneumonia Whooping cough Food poisoning Typhoid Syphilis

CURE: Antibiotics

Viruses are smaller than bacteria and can only be seen with the aid of electron microscope.

The science that deals with the study of viruses is called VIROLOGY.

Ricketsiae are tiny microorganisms much like bacteria.

They are midway of bacteria and viruses having both characteristics.

They live in the cell of host like mites, lice thick and fleas. These are carriers of diseases that infects man and animals.

Protozoa are singled cell animals but much larger than bacteria.

They thrive mostly in dirty tropical areas

The ff. disease are caused by protozoa:

1. Malaria – carried by female anapheles mosquito

2. Amoebic dysentery – caused by amoeba3. Trypanosome – Sleeping sickness caused

by a protozoa transimitted through the bite of tsetse fly.

Fungi are saprophytes and may be small single-celled like yeast

Infections like athletes foot, ringworm are caused by skin fungus

Are attributes of individuals that may increase or decrease their susceptibility to certain disease

They include genetic factor, immunity, health related behaviours and person’s general state of health.

A host factor that offers special protection against disease is immunity

Are extrinsic biological, social, and physical factor that influence the probability of developing an infection.