List three harmful effects of infectious disease.

The number of dengue cases has increased in Sana's village in the last one year. She read in her textbook that diseases like dengue spread through mosquitoes which breed in stagnant water. She immediately suggested to her friends that they should kill the mosquitoes in water bodies in the locality. They also took the help of the nearest municipal office.
$(a)$ Which preventive measures do you suggest for the prevention of such diseases caused by mosquitoes? Mention any two measures.
$(b)$ Which values are displayed by Sana in taking this initiative?
$(c)$ Suggest one school activity to promote such values in school students.

State in tabular form the modes of transmission of each of the following diseases:
$(a)$ Syphilis
$(b)$ Tuberculosis
$(c)$ Jaundice
$(d)$ Japanese encephalitis

Study the given chart carefully and fill in the blanks $(a)$,$(b)$,and $(c)$:

$S$.No.	Name of the disease	Causative organism	Mode of transmission
$1$. Polio	$(a)$	Infection of virus directly/orally
$2$. $(b)$	Lyssa virus	Virus enters human body with saliva of an infected animal
$3$. Typhoid	Salmonella typhi	$(c)$

Write the names of three diseases caused by viruses. Give a full account of any one of them.

Fill in the blanks:
$(a)$ Pneumonia is an example of . . . . . . disease.
$(b)$ Many skin diseases are caused by . . . . . . .
$(c)$ Antibiotics commonly block biochemical pathways important for the growth of . . . . . . .
$(d)$ Living organisms carrying the infecting agents from one person to another are called . . . . . . .