The species Giardia duodenalis ( also known as Giardia lamblia ) has eight genotypes ( denoted A – H ), which are referred to as assemblages [ 4 ] . Current findings suggest that not all assemblages are found in humans . A and B are most commonly found in humans and animals , and are considered zoonotic [ 4 ] . Groups C and D are not currently found in humans , but are found in dogs [ 4 ] . Promoting good hand hygiene is important due to the zoonotic risk , especially in immunosuppressed individuals .
It can be assumed that most cases will not be checked for the specific genotype ( to check the zoonotic risk ), so it may be safer to approach all cases as potentially zoonotic to reduce the likelihood of infection . VNs can educate owners on the importance of good hand hygiene and how to reduce the risk of environmental spread with effective cleaning products and protocols .
Pathogenesis
Giardia infections can cause a decrease in some intestinal enzymes , especially lipase , due to the toxins released by trophozoites and T-cell activation . This can reduce the absorption of nutrients , water and electrolytes , contributing to the malabsorptive diarrhoea caused by increased intracellular junctions and shortening of the brush border microvilli [ 2 ] .
Clinical signs
Clinical signs of giardiasis include diarrhoea ( which may be watery and persistent ), steatorrhea , vomiting , flatulence , weight loss and abdominal discomfort [ 2 ] .
However , some patients may show no clinical signs , and this should be taken into consideration in multipet households . In both animals and humans , young or immunosuppressed individuals are more likely to show clinical signs .
Diagnosis
Giardiasis can be diagnosed using an enzyme-linked immunosorbent assay ( ELISA ) test , but a faecal flotation test is preferable . Even if treatment is successful , an ELISA test will give a positive result for approximately 6 weeks after infection . Therefore , it is not considered reliable after primary diagnosis of a symptomatic patient , and is not appropriate for further screening .
Faecal flotation can be used at any stage , from initial diagnosis up to 5 days post treatment to confirm efficacy . It can also be used at a later date if reinfection is suspected . For best results , it is recommended to take samples over a 3-day period , due to the intermittent shedding of cysts in the faeces .
Figure 2 . The morphology of a Giardia lamblia ( also known as Giardia duodenalis ) trophozoite and cyst .
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