아이야~ ری ٹویٹ کیا
One of the clear lessons of the hantavirus outbreak is that *chance* makes a huge difference to how a disease can spread.
The Andes strain of the virus causes 100s of human infections every year, but most burn out almost immediately.
Occasionally, there is a bigger outbreak fueled by human-to-human transmission but these are rare.
The pattern is a feature of almost all zoonotic spillover events, millions of which happen each year involving thousands of different pathogens.
Mercifully, most go nowhere. They flare then vanish.
Now enter *chance* – a series of unforeseen but often predictable environmental circumstances or events.
A wet market, a trunk road, a game of beer-pong … or in this case, a hop-on-hop-off international cruise with connecting flights.
The map below shows the 12 countries that passengers flew to after disembarking one leg of the cruise in St Helena in late April.
30 passengers disembarked there, one dead, but no one knew then about the disease to which they had been exposed.
The outbreak has been serious, with three dead and at least five suspected cases so far.
About 150 remain on the ship, while hundreds of potential secondary contacts are being traced and asked to isolate around the world.
Nevertheless, the chances are that *this* outbreak will die out too.
The virus does not appear to spread efficiently enough to sustain itself, even with the circumstances it has been handed.
But here’s the thing: it’s a numbers game.
Look again at that map and consider where we would be if the virus was more infectious, or had mutated to become so.
It is why the World Health Organization and pandemic planning is so important.
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