Theory:

Hepatitis, Chickenpox and rabies are some of the diseases that are caused by viruses.
Hepatitis:
Causes:
It is one of the most dangerous fatal disease that is caused the Hepatitis A, B, C, D and E virus.
 
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A boy suffering with hepatitis A

Modes of transmission:
Consumption of contaminated water, sharing of needles and blood transfusion are some of the modes of transmitting this disease.
 
Symptoms:
Loss of appetite, anorexia, vomiting, yellowing of eyes and urine are some of the symptoms.
 
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Symptoms of Hepatitis A
 
Prevention and treatment:
  • Consuming boiled water.
  • Cleaning and washing of hands.
  • Vaccinating regularly.
Chickenpox:
Causes:
It is also known as varicella. It is a highly contagious infection that is caused by the Varicella-zoster virus.
 
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Varicella zoster
 
Modes of transmission:
It is a disease that spreads through the air and by getting in contact with the infected person.
 
Symptoms:
Presence of rashes on the whole body, fever, headache and tiredness are some of the symptoms.
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An individual affected with chicken pox
 
Prevention and treatment:
  • The best way to prevent chicken pox is by getting vaccinated.
  • Special attention should be given to the infected persons.
Vaccine:
The agents that are similar to the disease-causing agents, but when it enters the body, it stimulates the immune system to prevent the body from getting infected by the actual disease are known as vaccines.
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Vaccine shield
 
The biological preparations that provide active immunity against a particular disease are known as vaccines. Certain vaccines such as the BCG (bacille Calmette-Guerin), MMR (Measles, Mumps, Rubella) and Polio are given at early child wood to protect from other diseases.
Reference:
https://upload.wikimedia.org/wikipedia/commons/6/6a/A_young_boy_suffering_from_Hepatitis-A.png
https://www.flickr.com/photos/johnbullas/7413215958/
https://commons.wikimedia.org/wiki/File:Chickenpox_Adult_back.jpg
https://www.freepik.com/free-vector/cartoon-vaccination-campaign-illustration_13859994.htm#page=1&query=vaccination&position=14