Gastro outbreak: how does it spread, and how can we stop it? A gastroenterologist explains


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Vincent Ho, Western Sydney UniversityOn Monday, Victorian health authorities released figures showing they’d received 389 reports of “gastro” outbreaks so far in 2021.

The health department said this was four times higher than the average.

There are many different types of bacteria and viruses that can cause gastroenteritis. But in this instance it’s most likely to be a virus called “norovirus”.

It’s a very contagious virus that passes between people quite easily. Studies estimate the reproduction number (or R₀) for norovirus in the population to be around 2, but this can go as high as 14 in an outbreak with no intervention. In other words, during an outbreak at a childcare centre without any control measures, one child can potentially infect an average of 14 other children. By contrast, the R₀ for COVID-19 is estimated to be between 2 and 4.




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How does it spread?

Over the course of the COVID-19 pandemic, we’ve learned a lot about how the coronavirus spreads. We’ve learned it transmits mostly by respiratory droplets, smaller aerosols that can hang in the air that you can then breathe in, and less commonly via surfaces.

But what about gastro? Gastro caused by norovirus spreads primarily via the “foecal-oral route” — basically, when particles from someone’s poo end up in someone else’s mouth. You can also pick up the virus by coming into contact with someone’s vomit.

Most commonly this happens because you touch a surface or a person contaminated with this virus and then touch your mouth. It can spread rapidly in childcare centres because kids often play very physically, and they might not understand proper physical distancing and handwashing in the way adults do.

It can also spread very easily in places like cruise ships.




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It can take between 12 and 72 hours to develop symptoms after coming into contact with norovirus. Symptoms include vomiting, diarrhoea, stomach pains, and nausea. It generally takes a few days to recover, and isn’t doesn’t usually require serious medical attention. But it might be worth contacting your GP if your symptoms haven’t resolved in three days. Make sure to drink as much water as you can so you don’t get dehydrated.

If you have these symptoms make sure you stay home, and don’t return to work, school or childcare until 48 hours after your symptoms resolve. Returning earlier can mean you spread the virus.

Children at a childcare facility
Gastro caused by norovirus can spread very easily in childcare centres. Thorough handwashing and disinfecting are our best defences against it.
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Norovirus is very resistant

Some of you might be wondering how a virus survives in a state that endured such a long COVID-19 lockdown last year.

Well — norovirus is a very hardy virus. Research suggests it’s able to survive long periods on different surfaces and across varied temperatures. It’s often present at low levels across different environments, and in many types of food, for example oysters. It can survive in water for many months.

We can’t really eliminate this virus, but we can mitigate it’s spread.

How can we stop it?

The gold standard method is washing your hands thoroughly for 20 seconds with soap and water.

I suspect many of us have become a bit complacent with handwashing and instead are slapping on alcohol-based hand sanitiser when we can, although this is anecdotal.

However, even though hand sanitiser is convenient, it doesn’t work as well against norovirus as thorough handwashing does.

One study even suggests that using both methods simultaneously — washing your hands with soap and water and also applying hand sanitiser — actually increases the number of bacteria on your hands, though the exact way this occurs is unknown.

It’s best to simply wash your hands for 20 seconds. But disinfecting surfaces is also important. If someone in your home or workplace is vomiting due to a gastro type illness, make sure you very quickly disinfect the nearby surfaces. You want to wear gloves and properly disinfect surfaces using hot water with a detergent, or even bleach, both of which can kill norovirus.

Parents, childcare workers and teachers should also teach kids good hygiene and handwashing skills. And, for us grownups, we should follow our own advice.




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The Conversation


Vincent Ho, Senior Lecturer and clinical academic gastroenterologist, Western Sydney University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Cruise ships can be floating petri dishes of gastro bugs. 6 ways to stay healthy at sea this summer



Norovirus is the most common cause of gastro outbreaks on cruise ships.
From shutterstock.com

Leesa Bruggink, Victorian Infectious Diseases Reference Laboratory

A cruise can be the perfect summer holiday. But cruise ships, with hundreds, even thousands of people in close quarters, can also be a hotbed of germs.

In particular, cruises are somewhat notorious for outbreaks of gastro. One study, which looked at close to 2,000 cruises docking in Sydney, found 5% of ships reported they’d had a gastro outbreak on board.

If you’re about to head off on a cruise, there’s no need to panic. There are some precautions you can take to give yourself the best chance of a happy, gastro-free holiday.

What causes gastro?

Viruses are the leading cause of acute gastroenteritis in Australia. Norovirus is the main culprit, causing an estimated 2.2 million cases of gastro each year.

Norovirus is usually transmitted from person-to-person via the faecal-oral route, where virus particles found in the stool of one person end up being swallowed by another person.

Extremely large numbers of virus particles are shed in faeces and vomit, yet a person only needs to ingest a very small number of virus particles to catch the infection.




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Norovirus is hardy and can resist acid conditions (like those in the gut) and moderate temperatures (at which we wash clothes or reheat food, for example). Further, many chemicals used in cleaning products and hand sanitisers don’t effectively remove norovirus.

The main symptoms of gastro caused by norovirus are diarrhoea and vomiting. Symptoms normally only last for a short period (two to three days), and will stop on their own. The main risk is dehydration, which is of most concern for young children and the elderly.

Norovirus is the number one viral cause of gastro in Australia.
From shutterstock.com

Norovirus on cruise ships

Generally, a cruise ship will declare a “gastro outbreak” once 2-3% of passengers or crew are ill with gastro symptoms. So on a ship of 2,000 passengers, 40-60 people would need to be unwell before an outbreak is declared.

An Australian study found 5% of cruise ships that arrived in Sydney between 2007 and 2016 reported gastro outbreaks (98 out of 1967). Of the outbreaks with a known cause, 93% were from norovirus.

Reports pop up in the news from time to time when there’s a significant outbreak, like when the Sea Princess recorded 200 cases of gastro caused by norovirus in 2018.




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How does it spread?

You can be infectious with norovirus before symptoms appear and even after they resolve, so a person might unknowingly bring norovirus onto a cruise with them.

On a cruise ship, norovirus is mainly spread directly from person to person. This is not surprising as many activities on a cruise involve mixing with other passengers in a reasonably closed space.

While a handshake is a normal greeting, it’s a fairly unsanitary practice. A recent study suggested a “fist-bump” should be promoted on cruises, while a modified version dubbed the “cruise-tap” (where only two knuckles are touched) could be even better.

If you do catch gastro on a cruise, you’ll probably be asked to stay in your room so as not to give it to other passengers.
From shutterstock.com

The other way norovirus typically spreads is from touching contaminated surfaces. A person with norovirus may not wash their hands properly (or at all) after going to the toilet, leaving many invisible norovirus particles on their hands.

When this person touches surfaces (for example hand rails, buttons in the lift, or utensils at the buffet) they leave behind norovirus particles. Other people can then touch these surfaces and transfer the particles to their own hands. Then, if they put their hands to their mouth, they can give themselves the virus.




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It’s rare to inhale norovirus particles from the air, but it can occur, usually if someone with the virus vomits nearby.

While norovirus can be found in food, cruise ships have strict food handling practices to prevent the spread of illnesses such as norovirus. Though this doesn’t mean it’s unheard of.

How to avoid catching norovirus

It’s impossible to completely eliminate the risk of catching norovirus, but there are some things you can do to minimise your risk:

  • wash your hands well and frequently, especially before eating
  • don’t rely on hand sanitisers (hand washing is always better)
  • don’t share food, drinks or eating utensils
  • don’t touch food with your hands
  • reduce unnecessary contact with communal surfaces
  • leave the area if someone vomits.



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If you do get gastro symptoms on a cruise, it’s important you tell the medical personnel as soon as possible and follow their instructions.

You may be asked to stay in your cabin for a short period so as not to infect other passengers; just as you would wish another infected passenger not to spread the virus to you and your family.

The sooner the crew can identify a gastro case, the sooner they can start extra clean-up procedures and take further precautions to prevent an outbreak. Also, if you tell medical personnel, they may be able to provide medication and organise appropriate food to be delivered to your room.

Above all, to minimise the risk of gastro spoiling your cruise, wash your hands thoroughly and often.The Conversation

Leesa Bruggink, Senior Scientist, Enteric Viruses Laboratory, Victorian Infectious Diseases Reference Laboratory

This article is republished from The Conversation under a Creative Commons license. Read the original article.

My Fight with CFS … Part 1


I have Chronic Fatigue Syndrome (CFS), or as I prefer to call it, Chronic Fatigue Immune Dysfunction Syndrome (CFIDS). It is an extremely misunderstood and debilitating illness. I have read that the average time for a person to be ill with CFS is 18 months. I have had it for 18 years more or less. It has cost me a lot to be suffering from this illness and it impacts on my life on a daily basis. Some days are not too bad, while others are extremely terrible.

My journey with CFS began in the aftermath of the Newcastle earthquake of the 28th December 1989. In early 1990, while working at Hawkins Masonic Village repairing roofs damaged by the earthquake (it was raining and many roofs were leaking), I began to feel persistently unwell. I decided to see my doctor who put it down as some sort of stomach bug, most likely Gastroenteritis. After two weeks of medication it was becoming clear that I did not have Gastroenteritis and something more sinister was the cause of my intensifying illness.

Within weeks I had begun to develop all of the debilitating symptoms of CFS and what was worse for me they were all intensifying their effects upon me. What was wrong with me was now something of a mystery, but it was clear I was very ill and getting worse.

When I was younger I had Hyperthyroidism and so the doctor assumed that this was what was wrong with me again, despite the fact that blood tests indicated I no longer had an issue with that disorder. I was placed on medication for Hyperthyroidism and monitored. The medication had no effect on my illness and my patience with ‘witch doctoring’ was running out. I pleaded with my doctor to send me to someone else – a specialist. But who would be useful to see?

A friend had recently been diagnosed with CFS by an Immunologist and eventually I prevailed with my doctor to send me to him. Eventually I was able to set up an appointment and so my time with Doctor Sutherland of the Royal Newcastle Hospital Immunology Department had begun.

By this time I was suffering a myriad array of symptoms, with varying degrees of intensity depending on what week I was asked. Among the most debilitating of these symptoms was a persistent headache that no amount of painkilling or other medication had any impact upon. The headache was like a migraine that wouldn’t go away. It would last for an 18 month stretch this first time, bringing with it an intolerance of bright light, noise, etc. These things caused me immense head pain.

I was also suffering numerous nose bleeds (which I often get when I am very ill), fevers and chills, brain fog (a situation where you seem to know what is going on yet you have an inability to act in a logical manner – some times the sense of knowing what is happening disappears altogether), painful eyes, chronic fatigue in the muscles and extreme soreness, tiredness to the point of sleeping at a drop of a hat (I was sleeping for over 18 hours a day with no relief to my tiredness, headaches, etc), loss of strength in my limbs, constant nausea, inability to think or concentrate, etc.

By this time I was already having time away from work, with being away for weeks at a time being the norm – thankfully they were quite understanding of the fact that I was very ill.

At my lowest point during these first two years I was reduced to being bed-ridden, using a cane for stability when walking and at times was unable to walk. I was sleeping above 18 hours a day with no benefit from it.

During this time of extreme illness I was subjected to innumerable blood tests and other tests, which all revealed little at all as to the cause of my illness. A process of careful elimination under the care of Dr. Sutherland brought the diagnosis of CFS, as well as a psychological evaluation.

There was no cure to be found, with the only helpful advice having come from Dr. Sutherland. He told me to try and rest, then to slowly build myself up again. Walk one block for a week, then two blocks the following week, etc. If I overdid it I would be back in a heap again in no time. I needed to be able to read my own situation to know when I should try to rebuild my life. This advice has helped me through the last 18 years.

I struggled with the illness for 18 months or so and I also struggled with the enigma associated with the illness. That I was sick was not believed by all and this has been a constant stereotype I have been confronted with throughout my illness. I often found myself questioning whether I was sick or whether it was some mental thing. It was a relief when a doctor finally gave me a name for the illness and confirmed I was indeed very ill.

There were times (as there has been since) when I thought that dying would be a better alternative than to be as sick as I was, with no life and the prospect of endless years of severe illness. Suicide was something that popped into my head from time to time, but thankfully it didn’t stay there for long.

At times I found myself not knowing what I was doing, where I had been, etc. At one point I waited behind a parked car, waiting for it to turn the corner only to realise ½ an hour or so later that the car was parked. I found myself having gone shopping with a load of groceries I didn’t need and never had used before. It was like having a form of early onset Dementia.

After about 18 months I began to get better – or so I thought. I was well enough to knock back participation in a trial medication experiment for CFS sufferers which would involve a lengthy stay in hospital and a 50% chance I would receive the placebo.  I declined the invitation being concerned I would loose my job as a result of being in hospital for so long.

My health began to improve and I thought I was finally over the illness. During this time I lost contact with Dr. Sutherland who left the hospital because of a dispute with NSW health at the time. Many doctors left the public system at the time.

NEXT: The illness returns