ENVIRONMENTAL SCIENCE : HUMAN POPULATION AND ENVIRONMENT 233
(d) Through blood: AIDS, malaria, yellow fever, dengue, filarial, etc., are some of the
diseases which spread through blood.- DIPHTHERIA
It is an acute infectious and communicable disease caused by involvement of respiratory
system. The microorganisms of this disease attack the tonsils, trachea, nasal passage and
sound box and secrete a false membrane of oxotoxin, which cause inflammation. In severe
conditions it causes difficulty in breathing. This disease is quite common among the children
of the age of 6 months to five years. It can also occur up to the age of 15 years. The mortality
rates are 50% in respect of diphtheria occurring below the age of 5 years.
Pathogenic organism: The microbes spreading diphtheria belong to bacillus group and
are of three types:
- C. Diphtheria gravies
- C. Diph. Intermedius
- C. Diph. Miti
Mode of spread: The spread of this disease may be by:
(a) Direct contact chiefly through the carriers, whether sick or healthy. Nasal
carriers are more dangerous than throat carriers.
(b) Indirect transmission through infected articles such as, clothes, toys, utensils,
etc.
Incubation period: It is of 2 to 5 days duration when the microbes enter the body.
Infective period: After the patient shows the symptoms of diphtheria and the period
when microorganism leave the body is of 2-5 weeks on an average.
Symptoms: Initially the patient feels weak, nausea, and loses appetite and alertness.
Immunization: D.P.T. (Diphtheria, Whooping cough, Tetanus) vaccine is introduced to
the child at the age of 6 weeks to 9 months in three doses. This vaccine is given at the
interval of one month. A booster dose is given at the age of 2 years.
Prevention and Control- The patient should be isolated.
- Disinfections of the home, bedding clothes, toys, utensils, etc., is done thoroughly.
- WHOOPING COUGH OR PERTUSIS
Whooping cough or pertusis is an acute respiratory infections disease caused by Bacillus
pertusis involving trachea, bronchi and bronchioles creating intense cough. Whooping cough
occurs in all ages. Effect of cold weather and in colder regions enhances the incidence of
disease.
Spread of disease: Since it is an infectious disease main source is the nasal discharge
and cough. It spreads directly from person to person.
Incubation period: It is of seven to fourteen days.