Into how many main types are diseases classified?

What is health according to Hippocrates and the Indian Ayurveda system of medicine?

In terms of chemical structure,an antigen is a type of .........

'Vaccination' was invented by

Consider the following statements:
$I.$ People should get vaccinated to avoid infection.
$II.$ Vaccination is available against polio,cholera,typhoid,tuberculosis,and many other diseases.
$III.$ Eradication of vectors is necessary for diseases like malaria and filariasis.
$IV.$ Dengue and chikungunya are both spread by $Culex$ mosquitoes.
Which of the statements given above are correct?

Which of the following substances is produced and released into the environment by an insect to influence the behavior of other members of the same species?