History and exam
Key diagnostic factors
common
diarrhoea
Usually sudden in onset and may be initially watery with no mucus, pus, or gross blood. Patient may describe their stools as greasy and foul smelling.
frequent belching
Belching often has a sulfur smell.
Other diagnostic factors
common
abdominal bloating and discomfort
Generalised abdominal discomfort and cramps may be precipitated by eating.
malaise
Non-specific symptom.
weight loss
Due to malabsorption in chronic giardiasis.
uncommon
nausea and vomiting
Nausea and vomiting may occur.
Risk factors
strong
contaminated water/food
domestic animals living in or around the house
Children in such households are 2-5 times more likely to be infected, but animals may not be the definitive source for Giardia in these children.[43][44] Zoonotic transmission is thought to be relatively uncommon.[45][46] Analysis of giardiasis outbreaks in the US between 1971 and 2011 concluded that only 1.2% resulted from animal contact.[46]
weak
hypogammaglobulinaemia
Associated with a higher incidence of giardiasis, particularly in patients with immunoglobulin A deficiency.[47]
young age
Occurs in all age groups, but highest incidence rates are seen in children aged 0-4 years.[16]
male sex
day-care centre attendance
oral-anal sexual contact
recent antibiotic use
Antibiotics may prolong alterations in the microbiota and decrease colonisation resistance, thereby increasing the risk of infection.[18]
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