ICSE Class 6 Biology Chapter 5 Diseases and First-aid

Unit 5

Diseases and First-aid

Learning Objectives

Communicable and non-communicable diseases

Causes of communicable diseases

Preventive measures for communicable diseases

Basic idea of first-aid

Transmission Of Diseases

The malfunctioning of the body is called a disease. Diseases are caused by either microorganisms or due to deficiency of certain nutrients in our diet. Microorganisms enter our body through food, water or by contact with an infected person. Diseases can be broadly classified into following two categories.

When we cough, sneeze or spit, the germs spread to about 20 feet around us.

1. Communicable Diseases

These diseases are caused by the entry of disease producing organisms called pathogen in the body. These diseases spread very rapidly from person to person through personal contact or through air, water and the food we eat.

Depending upon the causative agent, communicable diseases are of five types:

(i) Bacterial diseases e.g. diphtheria, tetanus, typhoid, tuberculosis, cholera, etc.

(ii) Viral diseases e.g. mumps, measles, polio, smallpox, chickenpox, rabies etc.

(iii) Protozoan diseases e.g. malaria, amoebiasis, kala azar, sleeping sickness, etc.

(iv) Helminth diseases e.g. taeniasis, ascariasis, filariasis, etc.

(v) Fungal diseases e.g. ringworm, athlete's foot, etc.

Spread Of Communicable Diseases

These diseases spread in four ways - through contact, through air, through insects and by having infected food and water.

Diseases spread through contact

Diseases like common cold, chickenpox, smallpox, measles, whooping cough and ringworm are spread through contact. They can spread by sharing the same soap, towel, comb, clothes, bedding, utensils, etc. which have been used by a person suffering from these diseases.

Droplet infection through air

These diseases are caused when a healthy person breathes air which has germs of diseases like common cold, cough, flu, chickenpox, scarlet fever, diphtheria, etc. When the infected person coughs, sneezes, spits or laughs, the germs of these diseases go into the air. Diseases spread directly on exposure to sprays of droplets of saliva during sneezing or coughing. When other people breathe this air, they get infected.

Diseases spread through insects

Malaria, dengue, plague, yellow fever, sleeping sickness and kala azar are diseases caused by the bite of insects like sandflies, fleas, bugs and mosquitoes which carry the germs. When they bite a healthy person, they pass on the germs.

Malaria is caused by the female anophele mosquito which carries the germ from the blood of a sick person to a healthy person.

Malaria is transmitted by the bite of an infected anophele mosquito. During the bite, it inoculates the germs into the body of a healthy person. Dengue is transmitted by a mosquito called Aedes aegypti. Houseflies carry germs of typhoid and cholera. When flies sit on sputum or garbage, they pick up the germs from the source and leave them on the exposed food or the other articles that a person handles and uses. The insect which transmits the disease is called a vector.

Diseases spread through infected food and water

Cholera, diarrhoea, food poisoning, jaundice, typhoid, tuberculosis and dysentery are all caused by having contaminated food and water. These diseases mostly affect the digestive system. The carrier of these germs are mostly houseflies. They carry the germs from garbage and sewers and deposit them on uncovered food and other things. Therefore we should eat food which is covered and prepared with clean hands, in clean utensils and under hygienic conditions.

Diseases spread through healthy people

There are some diseases that spread through healthy persons who carry the germs that cause cholera, typhoid, measles, mumps and dysentery. These people are called carriers. They carry the germs and transfer them to other people though they themselves do not suffer from these diseases.

Basic Rules To Prevent Infection

(i) Proper sanitation

(ii) Disposal of garbage in covered bins

(iii) Do not allow stagnant water near your house as it is the breeding ground for mosquitoes.

(iv) Drink clean and boiled water.

(v) Follow rules for personal cleanliness

(vi) Avoid eating exposed items.

(vii) Use your own comb, towel and handkerchief.

(viii) Wash your hands with a soap, before eating meals/food.

(ix) Cover your mouth and nose with a tissue or handkerchief while sneezing/coughing.

(x) Isolate the patient in case of a contagious disease like chickenpox.

(xi) Vaccination and immunization: We should protect ourselves and our family members against common diseases like typhoid, cholera, pox, whooping cough and tuberculosis, etc. This can be done by taking vaccination against the disease.

The disease phenylketonuria if untreated can cause problems with brain development, leading to progressive mental retardation, brain damage and seizures.

2. Non-communicable Diseases

These diseases cannot be transmitted from an infected person to a healthy person. These diseases affect only the person who is suffering from it.

Non-communicable diseases can be categorised into five types:

(i) Deficiency diseases e.g. beri-beri, scurvy, nightblindness, goitre, etc.

(ii) Degenerative diseases e.g. heart attack, arthritis, diabetes, etc.

(iii) Allergies e.g. eczema, asthma, bronchitis, etc.

(iv) Social diseases like alcoholism, drug addiction, etc.

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