The insect considered to be the greatest mechanical carrier of diseases is . . . . . . .

Which of the following three scientists were awarded the Nobel Prize in $1945$ for the discovery and development of penicillin?
$(i)$ Alexander Fleming
$(ii)$ Louis Pasteur
$(iii)$ Walther Flemming
$(iv)$ Ernst Chain
$(v)$ Howard Florey
$(vi)$ Oswald Avery

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?

$A$ physical or functional change that causes discomfort or disability under normal conditions is known as:

In beri-beri,

"Maintenance of personal and public hygiene is necessary for the prevention and control of many infectious diseases." Justify the statement giving suitable examples.