Giardiasis

Introduction

Giardiasis is a parasitic infection caused by Giardia lamblia. It is a case that can be seen worldwide but more common in developing countries.

Giardiasis is spread by the faeco oral route.

Pathogenesis of Giardiasis

Invasion of the upper small intestine by the parasite evokes inflammation, leading to progressive villous atrophy.

Giardia intestinalis infection causes enterocytes damage and loss of brush border of the epithelial cells of the intestine.

This leads to shortening of microvilli and altered epithelial barrier function.

Symptoms or Clinical features of Giardiasis

Acute disease: watery diarrhoea with abdominal bloating
Chronic disease: diarrhoea, steatorrhoea and weight loss from malabsorption syndrome with lactose intolerance, xylose malabsorption and vitamin B deficiency

Complications of Giardiasis

Diseases related to Vitamin B deficiency.

Occasionally, the under listed complications could occur

reactive arthritis
irritable bowel syndrome, and
recurring diarrhea that can last for years.

Among children in particular, severe giardiasis may delay physical and mental growth, slow development, and cause malnutrition.

Differential diagnoses

Other causes of upper gastrointestinal malabsorption such as coeliac disease and tropical sprue

Investigations and Diagnosis

Full blood count
Stool microscopy and faecal fat assessment
Jejunal biopsy

Treatment objectives

Rehydrate adequately
Eradicate parasite
Replace deficient nutrients

Drug treatment

Metronidazole

Adult:

2g orally daily for 3 days or 400 mg 8 hourly for 5 days or 500mg 12 hourly for 7 -10 days

Child:

1-3 years: 500 mg orally daily preferably in divided doses
3-7 years: 600-800 mg daily in divided doses
7-10 years: 1 g daily in divided doses for 3 days

Tinidazole