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Health and Hygiene | Term 1 Unit 6 | 7th Science - Diseases | 7th Science : Term 1 Unit 6 : Health and Hygiene

Chapter: 7th Science : Term 1 Unit 6 : Health and Hygiene


A disease is the functional or physical change from a normal state that affects the health of a person by causing disability or discomfort.


A disease is the functional or physical change from a normal state that affects the health of a person by causing disability or discomfort. The following are reasons that could leads to the development of disease in an individual.

1. Infection caused by disease-causing microbes

2. Lack of balanced diet

3. Poor lifestyle and unhealthy habits

4. Malfunctioning of one or more body parts or organs


Different kinds of sickness and their causes

The prevention and treatment of sickness can be considered in two groups for their better understanding. They are, communicable and non-communicable disease.


1. Communicable Diseases

Communicable diseases are those thatspread from one person to another. Healthy persons must be protected from people with communicable diseases. Diseases spread through contaminated air, water, food or vectors (insects and other animals)


Health Risks


1. a. Diseases Caused by Bacteria

In this lesson, you will study about some communicable disease (like tuberculosis, Cholera and Typhoid), which are caused by microbes and spread through air, water and some other organisms also.



TB is caused by Mycobacterium tuberculae and spreads from one person to another person through air by spitting and prolonged contact with sharing materials of the patient. The symptoms are fever, weight loss, chronic cough, bloody spitting and difficulty in breathing.

Prevention and treatment

* BCG vaccination,

* Giving special attention to the patient,

* Regular medication like DOT



Cholera is caused by Vibrio cholera and spread through the consumption contaminated food or water. The symptoms of Cholera is Vomiting, severe diarrhea and cramps in legs.

Prevention and treatment

* Good hygienic practices like, washing hands before eating.

* Avoid eating uncovered food from street vendoers.

* Drinking boiled water.

* Getting Vaccination against cholera



Typhoid is caused by Salmonella typhi and spreads by contaminated food and water. The symptoms are Anorexia, headache, rashes on abdomen, dysentery and high fever up to 1040F.

Prevention and treatment

* Drinking boiled clean water

* Proper disposal of sewage

* Vaccination


1.b. Disease Caused by Virus

Viral diseases are extremely widespread infections caused by many type of viruses. In this lesson you will learn about some disease caused by viruses like, Hapatitis, Chickenpox and Rabies.



Hepatitis is one of the most dangerous and fatal diseases caused by Hepatitis virus-A, B, C, D, E. Its mode of transmission is Contaminated water, sharing of needles and blood transfusion. The symptoms of hepatitis is loss of appetite, (Anorexia), vomiting, eyes and urine in yellow color.

Prevention and treatment

* Drinking boiled water,

* Proper cleaning of hands



Chickenpox (chicken pox), also known as varicella, is a highly contagious infection caused by the varicella zoster virus. . This disease spreads through air and contact with an infected person. Its symptoms is appearance of rashes on the whole body, fever, headache and tiredness.

Prevention and treatment

The chickenpox (varicella) vaccine is the best way to prevent chickenpox Special attention should be given to the infected persons. Special  attention  should  be  given  to  the  infected persons.



Rabies is a fatal disease. Which is transmitted by the bite of the infected dog, rabbit, monkey, cat etc. The virus present in the saliva of dog enters the brain via neurons. The symptoms of rabies is hydrophobia (extreme fear for water), fever for 2 – 12 weeks and exaggerations in behavior.

Prevention and treatment

* In early stages rabies is very difficult to detect

* After an animal is bitten it usually takes two to twelve weeks to shows any symptoms and it may take as long as two years also.

* Fatality can be prevented by timely vaccination before the onset of symptoms.


A vaccine is abiological preparation that provides active acquired immunity to a particular disease. Vaccines like (BCG,Polio, MMR) are given at early child wood to protect from other diseases.


Visit nearby Primary Health Centre and collect information about the vaccination given to the children of 0-15 years. Meet a doctor or a health worker in the hospital and enquire about the types of vaccines are available there? disease can be prevented by their usage? Collect the list about the age it should be given?


2. Non-Communicable diseases

Communicable diseases do not spread from person to person. They are caused by other factors. Therefore, it is important to know which sickness are communicable and which are not. They are never caused by germs, bacteria, or other living organisms that infect the body. Antibiotics, or medicines that fight against germs do not help to cure non-communicable diseases.


Problems caused by wearing out of body parts:

* Rheumatism, heart attack, epileptic seizures, stroke, migraine headach. Cataract and cancer


Problems caused by external harmful agents entering the body:

* Allergies, asthma, poisons, snakebite, cough from smoking, stomach ulcer, alcoholism.


Problems caused by a lack of trace elements in the body:

* Anemia, pellagra, night blindness and xerophthalmia, goiter and hypothyroidism.


Problems caused by Malnutrition.

* Nutritious food is needed for a person to grow well, work hard, and stay healthy. Many common sicknesses are caused by malnutrition.

Leucoderma is a non–communicable diseases caused by partial or total loss of pigmentation in the skin. (melanin pigment). This condition affects any age, gender and ethnicity. There is no cure. It does not spread by touching, sharing food and sitting together.


Specific health problems of children Anaemia

It is caused by eating food with less iron content and can also caused due to feeding some other foods instead of breast milk. Severe anemia in children may leads to hookworm infection, chronic diarrhoea and dysentery. In recent day school going children, especially the girls are affected by anemia. The Government of Tamil Nadu provides weekly iron folic tablets to all the girls in the schools of all areas.

The signs of anemia are:

* Pale or transparent skin, The inner surface of eye lids are pale, white fingernails, pale gums, weakness and fatigue.

* In severe cases, face and feet may be swollen, the heartbeat is rapid and with shortness of breath.

* Children and women who eats mud are usually anemic.

Treatment and prevention of anemia:


Consuming iron containing food Sources

* Food – Moringa leaves, Dates, Liver (Sheepand Chicken), Green, green leafy vegetables like beans, peas, lentils and Greed banana.

* Pills - Cod liver oil tablet, Ferrous sulfate.

As a general rule, iron supplements should be given orally, not to be injected, because it leads to dangerous.


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