234 ENVIRONMENTAL SCIENCE
Infective period: Three weeks after the symptoms are observed. Symptoms: The patient
coughs frequently and its severity increases at night loss of appetite insomnia, weakness
persists. Immunization: Vaccine is prepared from dead bacillus and is administered along
with D.P.T. (Diphtheria, pertusis, tetanus).
- TUBERCULOSIS
It is a chronic bacterial disease and highly infectious. Tuberculosis spreads through air
and affect the lungs of the person. It is caused by tubercle bacillus. This is prevalent both
in tropical and temperate climate.
Spread of disease: Tuberculosis spreads in the following manner:
(a) The infection spreads by inhalation of droplets expelled by the patient through,
sneezing, coughing, yawning etc.
(b) Through direct contact
(c) Infected articles, clothes, utensils, etc. may spread the disease.
Incubation period: Incubation period is about four to six weeks.
Symptoms: Initially, the patient feels easily exhausted, fatigue doing ordinary work and
feels excessive fatigue. Loss of appetite, hoarseness of throat, pain in the chest due to
infected lungs. Patient sweats profusely at knight and feels weak.
Immunization: Child should be given B.C.G. (Bacillus Chalmette Guerine) vaccine by
intra-dermal injection within the first three months of age.
Control and prevention: Following steps need to be undertaken to control the spread of
tuberculosis:
- Health and general sanitary conditions of the community should be taken good care
of. Every human being should live in fresh air and sunshine. - Workers of cotton and ginning mills, coalmines, tobacco bidi making etc. should
wear protective shield to prevent inhalation of dust or silica dust. - Patient should be isolated. The disinfections of clothes, utensils, articles rooms etc.
should be properly ensured.
- CHOLERA
Cholera is an acute infectious disease caused by the infection of intestinal canal,
characterized by sudden vomiting, watery diarrhea, cramps in legs and leads to fast
dehydration.
Pathogenic organisms: Cholera producing microorganisms are Vibrio species and they
can belong to two sub-groups:
- Vibrio cholerae
- Vibrio El tor
Vibrio cholerae: Vibrio cholerae is found in stools and vomits of the patient. It is active,
mobile and grows in alkaline medium. It dies at 55°C in minutes. In contaminated water the
organism can survive for two weeks. Insects, particularly housefly disseminates this disease.