Why do viruses cause disease?

I know that viruses may overtake cellular mechanism and replicate overtaking further cells. Why does this, however, cause widespread symptoms such as flu, nausea etc...??
Thanks

Reply 1

Rob da Mop

15

A lot of the nasty symptoms of flu are due to a general inflammatory response. The immune system recognises the virus in the respiratory tract and starts releasing cytokines to attract more immune cells, stimulate mucus production and generally boost your chances of getting rid of the infection. Pyrogenic cytokines cause a fever, increased mucus production and things affecting the respiratory epithelium cause coughs and snottiness, inflammation of the respiratory epithelium makes you congested etc.

Reply 2

username459260

OP

16

Original post by Rob da Mop

A lot of the nasty symptoms of flu are due to a general inflammatory response. The immune system recognises the virus in the respiratory tract and starts releasing cytokines to attract more immune cells, stimulate mucus production and generally boost your chances of getting rid of the infection. Pyrogenic cytokines cause a fever, increased mucus production and things affecting the respiratory epithelium cause coughs and snottiness, inflammation of the respiratory epithelium makes you congested etc.

this may sound like a silly question but why then does our body try to eliminate the virus? if the immune response causes so much damage why not let the virus carry on doing what it is doing?

Reply 3

Rob da Mop

15

Original post by jsmith6131

this may sound like a silly question but why then does our body try to eliminate the virus? if the immune response causes so much damage why not let the virus carry on doing what it is doing?

As far as your body's concerned something like flu or a nasty infectious disease is atypical. You clear out a lot of infections just randomly and that's your immune system succeeding. However, it does also need to clear infections. Flu infects and kills cells which if left unchecked would wreck your respiratory tract. All the symptoms you get are used by the body to get rid of the infection. The mucus coughs up pathogens, fever helps fight infection (enzymes and that), all the cytokines and inflammation cause the immune response to be active in clearing the pathogens.

Reply 4

mich32elle

5

Original post by jsmith6131

this may sound like a silly question but why then does our body try to eliminate the virus? if the immune response causes so much damage why not let the virus carry on doing what it is doing?

Our body then tries to eliminate the virus to avoid it reproducing and settling in the body which would lead to greater damage (the virus would lead to chronic infections, would damage body tissues etc.) than that caused by the immune response.

Reply 5

username459260

OP

16

thanks

Why do viruses cause disease?

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