Giardiasis

Giardiasis is an infection of the small intestine by a microscopic parasite called Giardia. It spreads through water, food, or surfaces contaminated with faeces of infected people or animals. In India, it's a common cause of prolonged diarrhoea, especially in children and in areas with unsafe water.

How it spreads

• Drinking contaminated water — the most common route
• Food prepared or washed with contaminated water
• Swimming in contaminated water (rivers, untreated pools)
• Direct contact with an infected person or animal
• Poor hand hygiene

Symptoms

Usually start 1-3 weeks after exposure and can last weeks:

• Watery, foul-smelling diarrhoea
• Stomach cramps and bloating
• Greasy stools that float
• Nausea
• Loss of appetite, weight loss
• Fatigue
• Dehydration

Some people have no symptoms but can still spread the infection. In children, repeated or prolonged giardiasis can cause failure to thrive.

Diagnosis

Stool tests — usually several samples, because the parasite is shed intermittently. In India, stool microscopy is widely available; antigen tests are more sensitive.

Treatment

A course of antiparasitic medicine prescribed by a doctor usually clears the infection. Rehydration matters — ORS for diarrhoea. Avoid dairy for a few weeks after, as temporary lactose intolerance is common.

Prevention

• Drink safe water — boiled, filtered, or bottled
• Wash hands with soap before eating and after the toilet
• Wash fruits and vegetables well
• Avoid swallowing water from rivers, streams, or untreated pools
• Treat infected family members to prevent re-infection