Yeah, avoid Norovirus as well.
If it’s around in a hut, you are likely to get horribly sick, although this is quite rare. Most of the time, trampers aren’t carrying the virus, ventilation is reasonable, and hut numbers are low.
As the name suggests, it’s a virus, but unlike the flu or Covid-19, it has a tough protein shell that alcohol can’t break down.
Unlike Giardia, it hits like a train after a 12 to 48 hour incubation period, so you suffer while still hiking.
The symptoms are horrendous: sudden, explosive vomiting, watery diarrhoea, and muscle aches. That makes it hard to carry a heavy pack, days away from medical care or a comfortable bed.
There are no antivirals to deal with the virus. You just need to sip clean, safe water and think that things, both good and bad, don’t last. It’s useful to replace lost electrolytes, or make your own from a mixture of salt, sugar, and boiled water. The virus is way too small for most water filters (eg, Sawyer Squeeze, Katadyn BeFree, or Platypus QuickDraw) to remove, so boiling, UV or chemical treatment with Aquatabs or Katadyn Micropur is required.
But you usually get over it quickly, within 1 to 3 days.
Norovirus is relatively common back in civilisation, particularly in daycare centres and nursing homes. However, this virus affects humans only and is not found in other animals, so it’s not sitting in backcountry water sources.
Infected humans can produce billions of viruses, and it takes as few as 18 particles to be ingested for them to start reproducing prolifically in the intestines. It is not a respiratory illness because it doesn’t replicate in the lungs, though projectile vomiting can create temporary airborne clouds in a small hut or bunkroom.
Did I mention you should avoid huts with suspected outbreaks?
The virus spreads initially through poor toilet hygiene, then to water tank taps, door handles, benches, plastic-covered mattresses, etc, and its tough protein coating allows it to persist on surfaces for weeks. That makes it extremely contagious in crowded huts, and then it travels to adjacent huts as new trampers arrive at infected huts and carry it to the next. You can get stray diarrhoea on your footwear and spread it around that way. It’s pretty messy!
Despite the quick recovery from symptoms, people can remain contagious for another 2 to 3 weeks, although you are most infectious in the vomiting/diarrhoea phase. So, keep up strict hand hygiene for at least two weeks after symptoms resolve.
Hand sanitiser doesn’t eliminate the virus. Instead, wash your hands with soap for 20 seconds, and the virus is rinsed away in the lather. Most common surface cleaners are also ineffective. Surface decontamination requires diluted chlorine bleach.
2017 Travers-Sabine Outbreak: In January 2017, 34 people reported severe vomiting and diarrhoea at Blue Lake Hut on the Travers-Sabine circuit. Eliminating the virus required complete decontamination, and Blue Lake Hut was closed for a week while the water tank was drained and sterilised. All huts in the vicinity were deep-cleaned and sterilised, including those on the Travers-Sabine circuit as well as Sabine, Hopeless, Cupola, Angelus, and Bushline huts.
The best precaution is to avoid any hut in the area where norovirus is rumoured to be present.