Viral Diseases
(Virion: Poison)
Ø Virus These are the smallest organisms which are not visible to the naked and can be seen only with help of electron microscope. These were first observed by Charles Chamberland later the name virus given by Friedrich Loeffler and Paul Frosch They are round, rod and bullet shaped. It is mainly composed of three parts namely: · Genetic material (Nucleic acid): made either from DNA or RNA. · Protein coat (Capsid): Protects the genes. · Envelope (Lipid membrane): Surrounds the protein coat when they are outside the cell. 
Ø Entry of Virus particle ü A virus particle attaches to the host cell known as adsorption. ü The particle releases its DNA or RNA into the host cell (invades the cellular enzymes)known as entry. ü The cellular enzymes start making new virus particles called replication. ü
The virus particle
created by the cell come together to form new viruses known as assembly. ü
The newly formed viruses
kill the cell so that they may break free and search for a new host cell known
as release. 
Ø Diseases These are the infectious agent which can replicate only inside the living cells of an organism. When virus enters the body it invades the body cells and reproduces. If the body‘s immune system is unable to fight with the virus it multiplies and spreads to other cells repeating the process leading to wide spread infection. Diseases caused
by viruses in Human beings
|
Disease
|
Virus
|
Affected part
|
Transmission
|
Incubation Period
|
Symptoms
|
Treatment(Vaccines)
|
|
Mumps
|
Paramyxovirus(PMV)
|
Parotid
glands, Gonads(testes & ovaries)
|
saliva,
discharges from nose & throat
|
16 – 18 days
|
pain in
parotid glands
|
Mumps or MMR
|
|
Measles
|
Rubeola
virus(RV)
|
Respiratory
passage, eye, skin
|
sneezing
& coughing
|
10 – 12 days
|
watery
eyes (red), swelling of eyelids etc.,,
|
Measles
or MMR
|
|
Chicken
pox
|
Varicella
Zoster Virus(VZV)
|
All over
the body (especially stomach & chest)
|
direct
contact, sneezing & coughing
|
14 – 16 days
|
Pustules, scabs, feeling unease, dry cough etc.,
|
Pox
|
|
Poliomyelitis
|
Enterovirus(EV)/Poliovirus(PV)
|
CNS (Central
Nervous System), Lymphatic system.
|
stool,
saliva droplets
|
6 – 12 days
|
Sore
throat, aseptic meningitis, constipation etc.,
|
Sabin
|
|
Small
pox
|
Variola
virus(VV)
|
All over the body (especially stomach & chest)
|
direct
contact, sneezing & coughing
|
7 – 17 dyas
|
Pustules,
scabs swellings etc.,
|
Pox
|
NOTE: For all of these
diseases, fever and head ache are common symptoms
| 
