We’ve all been there: having a really bad bout of diarrhoea or vomiting after eating something. Sometimes, it’s accompanied by fever and body aches. Definitely not a nice feeling.

​What is stomach flu (gastroenteritis)?

Most commonly referred to as ‘food poisoning’ or ‘stomach flu’, you usually get gastroenteritis after eating something bad, for example; food that was not cooked properly, or food that was left out for too long.

Worldwide, norovirus annually causes on average, 685 million total cases of acute gastroenteritis. 

"Gastroenteritis (stomach flu) is a very common viral illness that is usually transmitted through contaminated food or from person to person. It is usually self-limiting and it is important to stay hydrated and consume adequate amounts of fluids during the course of illness," advised Dr Ginny Quek, Consultant from Sengkang Community Hospital (SKCH), SingHealth Community Hospitals (SCH), a member of the SingHealth group.

She added, "Vulnerable populations such as pregnant females and the very elderly should seek medical advice early in order to prevent complications. That is why it is important to check your food before consumption and maintain good personal hygiene. Clean hands saves lives!" 

What happens during gastroenteritis is that your digestive system (stomach and intestines) becomes inflamed (red and swollen) because of bacterial or viral infection.

Signs of food poisoning include fever, abdominal pain, vomiting and diarrhoea. The symptoms may cause discomfort but it is also a sign that your body is trying to fight off the infection.

Since you’re here (and probably having problems with stomach flu), let’s answer some quick, frequently-asked questions:

1. How long does stomach flu (gastroenteritis) last?
   Stomach flu symptoms usually clear within  two to three days. In severe cases, a full recovery can take longer.

2. Will stomach flu (gastroenteritis) heal itself?
   Stomach flu is a self-limiting illness that heals by itself without medical treatment. You may choose to take some medications to manage the symptoms but do not self-medicate with antibiotics!

3. How contagious is stomach flu (gastroenteritis)?
   Stomach flu is contagious and can spread when sharing food, utensils, or touching contaminated surfaces.

4. How to prevent stomach flu (gastroenteritis) from spreading?
   Avoid physical contact, and don’t share food or utensils. Also, remember to wash your hands regularly!

4 Ways to prevent gastroenteritis

As they say, prevention is better than cure. Make sure you and your loved ones don’t get gastroenteritis again by following these four tips.

1. Be food safe when preparing and cooking at home

Food safety starts in the kitchen, when you’re cooking food at home. Cases of food poisoning are usually caused by bacteria, viruses or parasites in contaminated food or drinks.

Norovirus is the most common cause of viral gastroenteritis / stomach flu. Of course, it’s difficult to control food safety when you’re eating out, but you can do it at home to prevent food poisoning.

When you’re preparing, cooking or serving food, practise these food safety tips:

a) Wash cutting boards and utensils

Use detergent (any kind of supermarket dishwashing detergent will do) to wash all your cutting boards and knives 

b) Wash your hands

Wash your hands with soap and water before and after preparing food. Wear disposable gloves if you have cuts or grazes on your hands, as bacteria can infect you when it goes in through the wound.

c) Cook raw meat thoroughly

Raw meat is the most common source of harmful bacteria that causes gastroenteritis. You might worry that fully cooked meat is tougher and harder to eat. But if you don’t cook meat properly, you risk leaving bacteria on it.

To be safe, you should cook meat to at least 72°C to kill campylobacter and staphylococcus aureus bacteria. Use a food thermometer (cleaned and disinfected) to check the inner temperature of cooked food.

Pay attention to the details in these types of food:

• Steamboats (hot pot, hot plates and Korean BBQ)
  Whlst, popular delicious and a great way to share meals with friends and family. But they also have a higher risk of contamination. That’s because the oil or soup temperature might not be hot enough to cook all your raw ingredients thoroughly. 
  The next time you go for a communal hot pot meal, check that your steamboat ingredients are cooked completely before eating. The meat and fish shouldn’t have any raw (pink, red or transparent) parts.

• Molluscs, shellfish (like mussels and oysters)
  Some of these have heat-resistant bacteria. That means the bacteria inside cannot be destroyed by short cooking times.
  If you’re preparing them at home, boil or steam the shellfish for at least 5-9 mins. Then, discard those with shells that haven’t opened up after cooking. When you’re eating shellfish outside, you can use this method to check too.
  

  When buying shellfish, get from licensed suppliers

  

  Shellfish and other molluscs (oyster, clams) filter seawater to feed, and often contain biotoxins from the sea. If you’re not careful, eating these biotoxins can cause bad food poisoning.
  

  Remember what we mentioned earlier about heat-resistant bacteria in shellfish? These biotoxins may not be removed even with cooking. So, it’s important to get shellfish that’s been tested and certified safe for humans to eat.

  Make sure you buy shellfish from SFA (Singapore Food Authority)-approved suppliers - you can check the list here. Don’t eat shellfish that you find in the wild (from the beach and sea, or shellfish that someone gives you from overseas).

• Unpasteurised milk
  In Singapore, we don’t usually drink unpasteurised or raw milk (milk that hasn’t been processed to kill bacteria).
  All milk sold in local supermarkets is pasteurised according to compulsory AVA guidelines. Pasteurisation is a process that kills all harmful bacteria in milk, making it safe for humans to drink.
  But if you travel overseas, you can’t always be sure that all milk is pasteurised. For example, farm stay holidays might let you drink fresh milk straight from cows on the farm. Be careful - that’s raw milk which hasn’t been pasteurised.
  Raw milk contains harmful bacteria like E. coli. When you’re overseas, always check that milk has been pasteurised before drinking it. Most commercial milk brands will state it on the packaging; if you don’t know where the milk comes from, don’t drink it!

• Dried or cured deli meat
  Dried or cured deli meat (meat from the deli section at the supermarket) can also be contaminated with E. coli and other bacteria during processing and packaging. 
  Even though the meat has been dried or cured, it’s not always safe because it can go bad. Check the smell and appearance. If you notice that the meat is moist, sticky, soft or has a weird smell, don't eat it.
  

• Leftovers or food left out for too long
  Leaving food outside is convenient if you need to slowly eat it. But bacteria can grow on food left at room temperature. Pack and put any leftovers in the fridge to prevent bacterial growth.
  Health Promotion Board (HPB) recommends heating leftovers up to at least 74°C (check temperature with a food thermometer) before eating.

• Don’t drink untreated water
  Singapore's tap water has been treated and is safe to drink. But there may be harmful bacteria in your kitchen from raw meat that could get into your household water. Make sure your water is safe. Boil water before drinking or cooking, and keep raw meat away from water jugs, bottles, and cups.
  When travelling, don’t drink water directly from the tap because you won’t know whether it’s been treated or not. Boil it first, or drink bottled water.
  In outdoor places overseas, like national parks, don’t drink water straight from the wild, even if it’s from a ‘pure’ or ‘naturally clean’ source like a spring or river. Water outside isn’t always clean and can contain toxic chemicals like lead and heavy metals. 

Practicing food safety also includes:

• Don’t share food or utensils with an infected person
  You can spread or get infected with norovirus and other food poisoning bacteria if you share utensils and food with an infected person.

• Don’t eat raw food if you are from a vulnerable group
  Vulnerable groups include pregnant women, the elderly, infants and young children with weakened immune systems. 
  If you’re from this group, you’ll usually have more severe symptoms of food poisoning. Avoid raw food to save yourself the distress and trouble.

2. Store raw and cooked food properly

Campylobacter, salmonella and staphylococcus aureus bacteria usually come from raw chicken and meat. Store food properly and prevent cross-contamination with these storage tips:

a) Store raw meat separately

Wrap raw meat in plastic bags (ziploc bags are good for airtight protection) and keep them in plastic containers.

Separate them from other food (especially ready-to-eat food) in your refrigerator.

b) Separate raw and cooked meat

Keep raw meat in the freezer and refrigerate cooked meat to prevent cross-contamination.

c) Store cooked food properly

HPB recommends keeping leftover cooked food at temperatures at or below 4°C. Put them in plastic containers and refrigerate them within 2 hours of serving.

Keep food warm (like rice, porridge, soup, baked food) above 60°C to stop bacterial growth.

Your oven, rice or soup cooker will usually have a ‘keep warm’ setting, so you can just use that. Otherwise, leave the food to simmer on low heat (use a small flame) in your pot or pan.

3. Maintain good personal hygiene

Parasites in water contaminated by poop can cause cryptosporidium and giardiasis infections (these are types of infections that cause food poisoning). Practise good personal hygiene to prevent accidentally eating such bacteria.

a) Wash your hands after using the toilet, changing diapers, or cleaning children and elderly

Bacteria from poop and urine stay on your hands after using the toilet or cleaning up people.

Keep your hands clean by washing with soap and water after you’re done. Dry them with tissue paper, as bacteria can remain on cloth towels.

b) Use bleach-based cleaning solution

Normal cleaning solutions may not kill all bacteria. When you’re cleaning the toilet at home, use a bleach-based cleaning solution (be careful not to get it in your eyes or mouth).

If you or someone in your home has gastroenteritis, make sure you clean the toilet and sink area regularly (best to do it after they use the toilet). Wash your hands after handling everyday items (clothes, room door handle, etc.) or touching others to prevent spreading it around.

c) Avoid touching your face frequently

You might touch a bus railing or toilet door handle with bacteria on it, and this bacteria can get into your digestive system through your eyes, nose and mouth when you touch your face.

d) Shower after swimming

Swimming pools contain chlorinated water, but chlorine doesn’t always kill all bacteria. Try not to swallow pool water and always shower with soap after swimming.

e) Wash your hands after handling animals

Animals can carry bacteria on their skin, fur, or poop. Wash your hands after handling or cleaning them.

4. Take medication as advised by your doctor

Take antibiotics only with doctor’s advice

Antibiotics can cause diarrhoea as a side effect. You should only take antibiotics if it is necessary and after seeking medical advice from a doctor.

If you're wondering how to avoid antibiotics? By preventing infections. 

This starts with maintaining good personal hygiene and getting vaccinated to protect against common diseases like measles and influenza.

If you do need antibiotics, only take the prescribed dose as your doctor advises - do not self-medicate.

Ref: H24

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Good Gut Health: 4 Ways to Protect Your Digestive System

Gastric Pain: Common Causes, How to Prevent and Treat

10 Easy Ways to a Healthier Liver

7 Tips to Reduce Belching or Burping

Irritable Bowel Syndrome (IBS): What to Eat and Avoid