Giardiasis: Symptoms, Treatment and Travel Advice for UK Patients

Giardiasis is an infection of the small intestine caused by a microscopic parasite called Giardia lamblia (also known as Giardia intestinalis). While it is one of the most common waterborne diseases worldwide, it is also found frequently in the UK. The parasite is particularly hardy because it exists in two forms: the active trophozoite and the dormant, protective cyst.

These cysts can survive for weeks in cold water or soil. Once ingested, the stomach acid activates them, and the parasites attach themselves to the lining of the small intestine, interfering with the body's ability to absorb fats and carbohydrates. In the UK, cases are often linked to contaminated tap water in rural areas, lakes, rivers, or through contact with infected animals or people.

How to Spot a Giardia Infection

Unlike many bacterial causes of food poisoning which resolve in 48 hours, giardiasis symptoms typically appear one to two weeks after exposure and can last for several weeks if untreated. According to NHS guidance, the hallmark signs include:

• Foul-smelling diarrhoea: Often described as greasy, pale, or frothy, and rarely contains blood.
• Stomach cramps and bloating: Significant abdominal discomfort and a feeling of pressure.
• Flatulence and burping: Often with a distinct 'eggy' or sulphur-like smell.
• Nausea: A general feeling of being unwell or sick.
• Weight loss and dehydration: Caused by malabsorption of nutrients as the parasite disrupts the gut lining.

It is important to note that some people may carry the parasite without showing any symptoms at all, but they can still spread the infection to others through poor hygiene.

When travelling abroad, particularly to regions with developing sanitation systems, the risk of giardiasis increases. However, hikers and campers in the UK are also at risk if they drink from seemingly 'clear' streams or 'wild' water sources.

Preventative Measures

• Water Safety: Only drink bottled water with an unbroken seal or water that has been boiled for at least one minute. Avoid ice in drinks unless you are certain it was made from purified water.
• Food Hygiene: Stick to hot, thoroughly cooked food. Avoid salads or fruits that may have been washed in local tap water.
• Hand Washing: Wash your hands thoroughly with soap and water after using the toilet, changing nappies, or handling animals. Alcohol-based gels are less effective against Giardia cysts than traditional hand washing.
• Swimming Safety: Try not to swallow water when swimming in lakes, rivers, or public pools.

In the UK, the National Institute for Health and Care Excellence (NICE) suggests that diagnosis is typically confirmed through a stool sample analysis (typically a 'stool ova, cysts, and parasites' test). Because Giardia is shed intermittently, doctors may sometimes request multiple samples over several days to ensure an accurate result.

The primary treatment involves antibiotics. The most commonly prescribed medication is metronidazole. A typical course might consist of taking the tablets for 5 to 7 days, or a high-dose 2g 'stat' dose, depending on the clinician's preference and the patient's history. Tinidazole is another effective alternative. It is crucial to avoid alcohol during and for 48 hours after a course of metronidazole to prevent a severe 'disulfiram-like' reaction, which causes intense nausea and vomiting.

If you have returned from travel or have been in contact with livestock and are experiencing persistent bloating and 'greasy' diarrhoea, it is time to seek medical advice. You can speak to a GP online UK to discuss your symptoms and travel history.

An online doctor can assess whether your symptoms align with giardiasis rather than typical travellers' diarrhoea. They can provide advice on how to manage dehydration at home and, if appropriate, issue a private prescription for the necessary antibiotics. This is a convenient option for those who may be unable to secure a face-to-face appointment at their local surgery during their recovery period. Furthermore, if you require a sick note due to the nature of your job (especially if you work in food handling or healthcare), an online consultation can facilitate this process.

Recovery from giardiasis usually takes about a week after starting treatment, though the bowel habits may take a little longer to return to completely normal due to temporary lactose intolerance caused by the infection. During this time, it is advisable to avoid dairy products.

To prevent spreading the infection to your household:

• Do not share towels or flannels.
• Disinfect toilet handles and taps frequently.
• Stay away from work or school until you have been free from diarrhoea for 48 hours.
• Wait at least two weeks after your symptoms have completely stopped before going swimming in public pools.