Entry of infection into human body:
Organisms may enter the body in one of the three ways: i. Digestive tract- swallowed in food or water.
Respiratory tract - breathed in with air.
Skin and mucus membranes - through a wound, weakened surface or injection.
Organisms leave the body of an infected person in the following ways.
Excreta - faeces and urine.
Coughing, sneezing and sputum.
Pus and wound discharges.
Blood, eg mosquito bites and injection needle.
Each type of organisms has its own special path for leaving an infected person and going into a healthy person. Examples are as follows.
Faecal to oral route:
Faeces may contain:
Intestinal parasites or ova of worms.
Amoeba causing dysentery.
Bacteria causing cholera, typhoid fever or dysentery.
Viruses of polio or hepatitis.
From the faeces, the organisms may get into drinking water. Flies and dirty hands act as carriers and spread infection by oral route. Children may suck the dirty fingers and organisms enter the body.
Faecal to oral route infection can be prevented by means of:
Hand washing before preparing or eating food.
Eating only clean food, kept free from flies.
Getting rid of flies and breeding places.
Protecting the water supply and drinking boiled water.
Use of latrines, or covering the faeces with earth.
Proper hand washing with soap after defecation.
Faeces to skin:
Hookworm ova passed in faeces, hatch into larvae on the ground. Then the larvae can bite through the skin, usually through bare feet and grow into adult worms in the intestines. Hookworm disease can be prevented if people use latrines and wear slippers.
The tetanus bacillus lives in the intestines of man and animals and is present in cowdung and soil. It enters into the body through a wound or a new born baby' s umbilical cord. The best way to prevent tetanus is by immunization with tetanus toxoid.