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Life Sciences => Cells, Microbes & Viruses => Topic started by: scientizscht on 12/04/2019 19:40:59

Title: If viruses die after 24h in air, why aren't they eradicated during summer?
Post by: scientizscht on 12/04/2019 19:40:59

Hello!

During summer, where there are no infections, why don't viruses get extinct?
The environment is harsh for them and there aren't many human hosts to maintain them.

Thanks!

Title: Re: If viruses die after 24h in air, why aren't they eradicated during summer?
Post by: Kryptid on 12/04/2019 21:21:49

Viruses can remain dormant inside of their hosts until the opportune time to start another infection reveals itself.

Title: Re: If viruses die after 24h in air, why aren't they eradicated during summer?
Post by: scientizscht on 12/04/2019 22:59:03

Quote from: Kryptid on 12/04/2019 21:21:49

Viruses can remain dormant inside of their hosts until the opportune time to start another infection reveals itself.

I know this for herpes, but I have never heard of it for rhinoviruses...

Title: Re: If viruses die after 24h in air, why aren't they eradicated during summer?
Post by: Kryptid on 12/04/2019 23:06:16

This may be of some interest: https://www.sciencedaily.com/releases/2004/04/040426055429.htm

And this: https://en.wikipedia.org/wiki/Virus_latency

Title: Re: If viruses die after 24h in air, why aren't they eradicated during summer?
Post by: evan_au on 13/04/2019 02:10:43

Quote from:  scientizscht

During summer, where there are no infections, why don't viruses get extinct?

For the influenza virus, the peak season for infection is in winter.
- But some still circulates around in summer - so you can't say there are no infections.
- Even more important (in case you hadn't noticed), the Earth is a sphere, and when it is summer in one hemisphere, it is winter in the other hemisphere.
- So while influenza is less frequent in your hemisphere, it is running amok in the other hemisphere, and travellers regularly transport it from one hemisphere to another
- By the time winter returns, the virus strains have mutated enough so that your body doesn't recognise them, and you may catch a new strain of the virus

Quote

The environment is harsh for (viruses) and there aren't many human hosts to maintain them

.
Many viruses have hosts apart from humans - influenza also infects chickens and pigs, both of which live in close proximity to people, in many countries.

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viruses get extinct

The focus for virus extinction has been on smallpox (hopefully successful already?) and polio (actually increasing in some areas that had previously eradicated it). For both these viruses, humans are the only host.
- But it has taken a massive, multinational vaccination programme to achieve it
- And it only takes a warzone where the vaccination teams can't reach, or rumors that the vaccine will make you sterile (seriously!), and the disease persists, and can reinfect other areas.
- Smallpox causes obvious blisters on all infected people, in many cases leaving lifetime scars on the face. And a large fraction of babies die from it. This is a clear and present danger, not requiring many reminders.
- Polio causes cold-like symptoms for most people, but only has a major impact on about 1% of people infected - and the cause of the death or disability may not be obvious. Selling polio vaccination has been much tougher!

See: https://en.wikipedia.org/wiki/Eradication_of_infectious_diseases