Giardiasis

Giardiasis symptoms vary from asymptomatic passage of cysts to acute self-limiting diarrhoea or chronic diarrhoea. It is associated with growth restriction in children.

Diagnosis is by detection of cysts or trophozoites in a stool sample or by molecular-based detection of antigens or parasite-specific nucleic acids.

Microscopy with direct fluorescent antibody testing is the gold standard for diagnosing giardiasis.

Tinidazole, metronidazole, or nitazoxanide is recommended as first-line treatment.

Transmission is via the faecal-oral route. Personal hygiene is key to prevention.

Giardiasis is an enteric infection caused by a eukaryotic, flagellated, binucleated protozoan parasite called Giardia duodenalis (formerly known as Giardia lamblia or Giardia intestinalis).[1]Center for Disease Control and Prevention. CDC Yellow Book 2024: health information for international travel. Section 5: travel-associated infections & diseases - ​giardiasis. May 2023 [internet publication]. https://wwwnc.cdc.gov/travel/yellowbook/2024/infections-diseases/giardiasis ​ First described in 1681, it is a major cause of diarrhoeal disease in human beings and other mammals.[2]Ankarklev J, Jerlström-Hultqvist J, Ringqvist E, et al. Behind the smile: cell biology and disease mechanisms of Giardia species. Nat Rev Microbiol. 2010 Jun;8(6):413-22. http://www.ncbi.nlm.nih.gov/pubmed/20400969?tool=bestpractice.com [3]Escobedo AA, Almirall P, Robertson LJ, et al. Giardiasis: the ever-present threat of a neglected disease. Infect Disord Drug Targets. 2010 Oct;10(5):329-48. http://www.ncbi.nlm.nih.gov/pubmed/20701575?tool=bestpractice.com ​​ Children and immunocompromised people may present with weight loss and faltering growth, or other developmental impairments, due to gut dysfunction and nutritional deficiencies.[4]Giallourou N, Arnold J, McQuade ETR, et al. Giardia hinders growth by disrupting nutrient metabolism independent of inflammatory enteropathy. Nat Commun. 2023 May 18;14(1):2840. https://www.nature.com/articles/s41467-023-38363-2 http://www.ncbi.nlm.nih.gov/pubmed/37202423?tool=bestpractice.com