Do viruses die?

Viruses exist at the boundary of what counts as life, and most scientists now agree they don't make the cut.

1st August 2011

Asked by: Anonymous

Strictly speaking, viruses can’t die, for the simple reason that they aren’t alive in the first place. Although they contain genetic instructions in the form of DNA (or the related molecule, RNA), viruses can’t thrive independently. Instead, they must invade a host organism and hijack its genetic instructions.

That said, it makes sense to talk of how long viruses can remain viable and capable of infection. Some – including the influenza virus, and HIV, the virus responsible for AIDS – can’t survive for more than a few hours outside a host organism unless kept under carefully controlled conditions.

But others, notably the deadly smallpox virus, can easily remain infectious for years. Historians now believe that dormant smallpox viruses brought to Australia by British doctors in 1787 could have caused a mass outbreak of smallpox among Aborigines two years later.

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