Plus-Hex CLINICAL
Background
Giardia is a prevalent genus of zoonotic protozoan parasites found mainly in dogs , cats , lagomorphs and rodents . Globally , in dogs , the Giardia population prevalence is estimated to be approximately 15 % [ 1 ] , but this varies depending on the source and could be as high as 30 % [ 2 ] .
Signs of infection by Giardia ( giardiasis ) include diarrhoea , which may be watery and persistent , steatorrhea , vomiting , flatulence , weight loss and abdominal discomfort , but many cases do not display clinical signs and may never receive a positive diagnosis . This means that the true number of cases in the population may be greater than estimated .
Veterinary nurses ( VNs ) can play an important role in educating clients on the most effective treatment and hygiene protocols , to increase treatment efficacy , minimise the likelihood of reinfection and help reduce the risk of giardiasis and other zoonotic infections .
Learning outcomes
• Identify the prevalence of Giardia worldwide
• Discuss the clinical signs , diagnosis and treatment of giardiasis
• Understand the environmental considerations in relation to reinfection
• Recognise the VN ' s role in client education
Introduction
Giardia starts its life cycle ( Figure 1 [ 3 ] ) in the form of a cyst . The cyst is ingested by the host in contaminated food or water , or via faeces , soil or an animal ' s hair . Once ingested , two trophozoites are released from each cyst ( Figure 2 , page 8 ). The trophozoites usually live in the proximal portion of the small intestine and migrate down the intestine during the course of infection , absorbing nutrients and multiplying by binary fission before encysting in the small or large intestine [ 2 ] .
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Cysts and trophozoites are passed in stools , but trophozoites do not survive in the environment
Cysts can survive several months in cold water . Infection occurs through the ingestion of cysts in contaminated water or food , or via cysts on hands / fomites
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In the small intestine , excystation releases trophozoites ( each cyst produces two trophozoites ) |
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The trophozoites multiply in the proximal small bowel where they are free or attached to the mucosa |
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Encystation occurs as the parasites transit towards the colon , with the cyst being the stage found most commonly in nondiarrheal faeces |
Figure 1 . The life cycle of Giardia parasites . Adapted from Centers for Disease Control and Prevention [ 3 ] . i , infective stage ; d , diagnostic stage
Volume 40 ( 2 ) • April 2025
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