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Common Diseases in Human Beings - Viral Diseases

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Topics

  • Introduction
  • Common diseases
  • Viral Diseases

Introduction:

Viruses are the smallest intracellular obligate parasites, which multiply within living cells. Outside the living cells, they cannot carry out the characteristics of a living organism.

Viruses invade living cells, forcing the cells to create new viruses. The new viruses break out of the cell, killing it and invade other cells in the body, causing diseases in human beings.

Viral diseases are generally grouped into four types on the basis of the symptoms produced in the body organs.

  1. Pneumotropic diseases (influenza-infected respiratory tract)
  2. Dermotropic diseases (measles and chickenpox affect skin and subcutaneous tissues).
  3. Viscerotropic diseases (blood and visceral organs affected by yellow fever and dengue fever).
  4. Neurotropic diseases (polio and rabies affect the central nervous system)

Common diseases:

1) Common cold

It is an infection that affects the nose and respiratory passage. Causative organism: Rhinoviruses (group of viruses)  

Mode of transmission: through inhalation of droplets resulting from the infected person directly or transmitted through contaminated objects like pens, books, cups, computer parts, towels, etc.  


 

Symptoms: Nasal congestion and discharge, sore throat, coughing, sneezing, headache, tiredness, hoarseness, etc. are the symptoms that last for 3 to 7 days. 

  • The common cold is caused by some 100 types of Rhino viruses. 
  • Rhinoviruses are a group of viruses that cause the common cold. They infect the nose and respiratory passage but not the lungs.

2) Nipah virus

Nipah virus is a zoonotic virus (transmitted from animals to humans) and is also transmitted through contaminated food. In infected people, it causes a range of illnesses, from asymptomatic infection to acute respiratory illness and fatal encephalitis.

Viral Diseases

Some of the diseases caused by viruses in humans are as follows:

Sr. No Diseases Causative Agent Site of Infection Mode of Transmission Symptoms
1 Common cold Rhino viruses Respiratory tract Droplet infection Nasal congestion and discharge, sore throat, cough, headache
2 Mumps Mumps virus (RNA virus), paramyxovirus Salivary glands Saliva and droplet infection Enlargement of the parotid glands
3 Measles Rubella virus (RNA virus), Paramyxo virus Skin and respiratory tract Droplet infection Sore throat, runny nose, cough, fever, reddish rashes on skin, neck, and ears
4 Viral hepatitis Hepatitis B virus Liver Parenteral route, blood transfusion Liver damage, jaundice, nausea, yellowish eyes, fever, and pain in abdomen
5 Chicken pox Varicella-Zoster virus (DNA virus) Respiratory tract, skin, nervous system Droplet infection and direct contact Mild fever with itchy skin, rash, and blisters
6 Poliomyelitis Polio virus (RNA virus) Intestine, brain, spinal cord Droplet infection through faecal-oral route Fever, muscular stiffness and weakness, paralysis, respiratory failure
7 Dengue fever (breakbone fever) Dengue virus or Flavi virus (DENV 1-4 virus) Skin and blood Mosquito vector (Aedes aegypti) Severe flu-like illness with sudden onset of fever, painful headache, muscle and joint pain
8 Chikungunya Alpha virus (Toga virus) Nervous system Mosquito vector (Aedes aegypti) Fever and joint pain, headache, joint swelling
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