give an account of some important diseases of human beings.
Important viral diseases of human beings are:
(i) influenza - influenza is commonly called flu. It is caused by an influenza virus (Myxovirus influenza). There exist theree types of influenza viruses - A, B and C. A and B types of influenza viruses are important because these are respobnsible for causing of disease epidemics throughout the world. The inhaled virus attacks the epithelial cells in the mucous membrane of nose, throat and upper respiratory tract. Influenza is spread mainly from person to person contact and by droplet infection via sneezing, coughing and talking.
(ii) Jaundice - Jaundice or hepatitis is the diseases of liver. Since liver is a very important organ in the body, so its inflammation due to jaundice affects digestion adversely. Jaundige is caused by viral infection. The types of hepatitis are : hepatitis A, Hepatitis A. Hepatitis B, Hepatitis C, hepatitis D, Hepatitis E or Hepatitis G. Except for type B which is a dNA virus, all the other are RNA viruses. Hepatitis is spread mostly by food and water contaminated with hepatitis Virus.
(iii) AIDS - AIDS stands for acquired immuno Deficiency Syndrome. It is a fatal disease. The (HIV) AIDS virus atacks white blood cells (WBCs) or lymphocytes of human being and weakens the human body's immunity or self - defence mechanism. AIDS becomes prone to many other infections or diseases.
(iv) Polio - Poliomyelities or polio is a disease of the nervous system caused by one of the smallest known virus. Called polio viurs. The virus enters the bady through the food and water and reaches the intestine and from there it enters the CNS or central nervous system via blood stream and lymphatic systems. Children between the age of 6 months to 3 years are msot prone to polio infection. Polio is transmitted among children by the faeco-oral route and through the direct contact, dirty hands, contaminated food or milkd and files.