Gastroenteritis in Christchurch: A Comprehensive Guide to Recovery and Relief

Gastroenteritis—commonly known as "gastro" or a "tummy bug"—is one of the most frequent reasons families visit our Wigram and Hornby clinic. While often considered a simple inconvenience, gastro is a significant health issue in New Zealand, affecting approximately 200,000 people annually through food-associated illnesses alone.

At 1 Health, we see firsthand how quickly a household can be sidelined by an outbreak. This guide, authored by Dr. Bernard Teo (Specialist GP), provides a deep dive into managing symptoms, preventing dehydration, and knowing when "just a bug" requires professional medical intervention.

1. Understanding the Cause: Bacteria, Viruses, or Parasites?

Gastroenteritis is an infection of the digestive system that leads to inflammation in the stomach and intestines. In New Zealand, the causes are varied:

• Bacterial: Campylobacter is the most common bacterial culprit in NZ, often followed by Salmonella and Shigella.

• Viral: Norovirus and rotavirus are highly contagious and frequently cause outbreaks in schools, care homes, and shared community spaces.

• Parasitic: Giardia and Cryptosporidium are often linked to contaminated water or contact with animals.

Knowing the cause is less important than managing the symptoms, as the vast majority of cases are "self-limiting," meaning they will resolve on their own with proper home care.

2. Recognising the Symptoms: When Does It Start?

Symptoms typically emerge between a few hours and two days after exposure. While every patient is different, most experience:

• Nausea and projectile vomiting.

• Watery, loose, or even bloody diarrhoea.

• Abdominal cramps and low-grade fever.

• Profound fatigue and loss of appetite.

Most Christchurch residents will see an improvement within two to three days, but the highly contagious nature of the illness means you must stay home until you have been symptom-free for at least 48 hours.

3. The Golden Rule of Recovery: Hydration

The single most important step in treating gastro is preventing dehydration. This is critical for children under five and adults over 70, who are much more vulnerable to complications.

How much should you drink?

For adults, the goal is at least 2 litres of fluid per day, plus an additional 200 mL after every loose stool.

What to drink:

• Oral Rehydration Solutions (ORS): Products like Enerlyte are ideal as they replace both fluids and essential electrolytes.

• Home-Made Solution: If you can't get to a pharmacy, mix 1 litre of cooled boiled water with 8 teaspoons of sugar and 1 teaspoon of salt.

What to avoid: Stay away from undiluted fruit juices, fizzy drinks, and sports drinks. Their high sugar content can actually draw more water into the gut, making diarrhoea worse.

4. Advanced Treatment: When Oral Rehydration Isn't Enough

For most, small sips are enough. However, if vomiting is severe, 1 Health provides clinical options that bypass the need for a long wait at the Christchurch Hospital Emergency Department.

IV Fluid Therapy in Wigram

When dehydration is severe or a patient simply cannot keep fluids down, Intravenous (IV) fluids may be required. At 1 Health, we can assess and administer IV therapy in-clinic, restoring your hydration and electrolyte balance promptly.

Medication Options

• Loperamide (Imodium): Useful for adults with mild diarrhoea but should never be used for children or if blood is present in the stool.



• Antiemetics: In severe cases, a single dose of anti-vomiting medication (like ondansetron) can provide the window of relief needed for oral rehydration to succeed.