Giardia lamblia

• Giardiasis is caused by Giardia lamblia and other intestinal flagellates

  
• Objectives

  • Classification
  • Morphology
  • Transmission
  • Clinical Presentation
  • Diagnosis
  • Treatment
• Trophozoite

  • 5-15µm X 9-21µm
  • Teardrop shaped
  • Two nuclei
  • Four pairs of flagella
  • Claw shaped median body/bodies
  • Ventral sucking disk
  • Exhibits a tumbling or swimming motion
  • Multiplication by binary fission
• Cyst

  • Oval shaped, 6-10µm X 8-12µm
  • Presence of two pairs of nuclei (equal sized) with central karyosomes
  • Transverse claw-shaped median bodies
  • Longitudinal axostyle
  • Bilaterally symmetrical
• Infection is worldwide found in all climates and countries
• Children are more frequently infected than adults
• Prevalence is higher in areas of poor sanitation
• Transmission of Giardiasis

  1. By ingestion of viable cysts

  2. Contamination of food

  3. Contamination of surface water

  4. Direct-fecal-oral transmission

  
• Transmission can occur with as few as 10-25 cysts and incubation period is 3-25 days or longer
• Infections

  • Can be abortive/transient or chronic
  • Disease manifestations range from minor to fulminant diarrhoea
  • Severe malabsorption and life-threatening malnutrition
• Trophozoites multiply and colonize the upper part of the small intestine

  
• The large numbers of trophozoites present in the bowel suggest a direct effect on intestinal function

  
• Enterocytes are usually damaged as a result of the initiation of a cytokine reaction leading to diarrhoea
• Biopsies of the intestine normally show varying degrees of mucosal inflammation with crypt hypertrophy, villous blunting, and mucosal infiltration with mononuclear inflammatory cells
• Usually there is disruption of the brush border
• Symptoms of Giardiasis

  • Asymptomatic passage of cysts
  • Chronic diarrhoea
  • Malabsorption
  • Weight loss
  • Diarrhoea with foul-smelling greasy stools
  • Gas
  • Bloating
  • Abdominal cramps
  • Malaise
  • Flatulence
  • Nausea
  • Anorexia
  • Fever
  • Vomiting
• Vomiting occurs in one fourth of patients and fever in 20% of patients
• Usually no tenesmus or gross blood in stool
• In chronic infection there is severe malabsorption of fat, Vitamin A & B12, and protein
• Giardiasis can occur in the stomach and could be associated with Helicobacter pylori infection

  
• Microscopy techniques for diagnosis

  • Cyst and trophozoites in faeces
  • Trophozoites in duodenal fluids
  • Examination of mucosal biopsies
  • ELISA kits for detection of antigens in stool
• Treatments for Giardiasis

  • Metronidazole
  • Nitroimidazoles
  • Nitrofurans
  • Benzimidazoles
  • Paramomycin
  • Tinidazole
• Giardia lamblia is a common non-pathogenic intestinal flagellate of man

  
• Flagella of Giardia lamblia are 5 (or may vary)
• Giardia lamblia is distinguished from T. vaginalis and T. tenax by the fact that its undulating membrane runs the whole length of its body
• Giardia lamblia has a worldwide distribution
• Giardia lamblia is usually non-pathogenic
• Giardia lamblia is suspected to be the largest intestinal flagellate of man

  
• Incidence of Giardia lamblia is very low about 10% but could be higher in hyperendemic regions
• Giardia lamblia is sometimes associated with traveler’s diarrhoea and opportunistic infections in HIV patients
• No treatment is recommended for non-pathogenic intestinal flagellates

  
• Prevention of Giardia lamblia infection depends on improved personal hygiene and upgraded sanitary conditions