Case history
A 32-year-old man returns from a 4-week holiday to rural India. He presents with a 10-day history of frequent but small-volume, greasy, foul-smelling, yellowish stools with tendency to float. He admits to camping and drinking water from a freshwater stream while on the trip. His male sexual partner has also developed bloating symptoms for the past 2 days. He also describes nausea, frequent belching with a sulfur smell, abdominal bloating, and flatulence. The only positive finding on physical exam is mild distention of the abdomen with no tenderness, masses, or organomegaly.
Other presentations
Patients may present with watery diarrhea without malabsorption and/or malaise and generalized abdominal discomfort precipitated by eating with little or no diarrhea. Symptoms can wax and wane with periods of diarrhea and constipation. Children may present with weight loss and failure to thrive or other growth delays.[5]Rosado JL, Caamaño MC, Montoya YA, et al. Interaction of zinc or vitamin A supplementation and specific parasite infections on Mexican infants' growth: a randomized clinical trial. Eur J Clin Nutr. 2009 Oct;63(10):1176-84.
http://www.ncbi.nlm.nih.gov/pubmed/19623197?tool=bestpractice.com
[6]Al-Mekhlafi MS, Azlin M, Nor Aini U, et al. Giardiasis as a predictor of childhood malnutrition in Orang Asli children in Malaysia. Trans R Soc Trop Med Hyg. 2005 Sep;99(9):686-91.
https://www.doi.org/10.1016/j.trstmh.2005.02.006
http://www.ncbi.nlm.nih.gov/pubmed/15992838?tool=bestpractice.com
Nutritional deficiency for fat-soluble vitamins, vitamin B12, folate, protein and amino acids, and D-xylose and disaccharides has been described.[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
[7]Leung AKC, Leung AAM, Wong AHC, et al. Giardiasis: an overview. Recent Pat Inflamm Allergy Drug Discov. 2019;13(2):134-43.
https://www.eurekaselect.com/article/98976
http://www.ncbi.nlm.nih.gov/pubmed/31210116?tool=bestpractice.com
Extraintestinal manifestations are uncommon, but may include uveitis, reactive arthritis, sacroiliitis, erythema multiforme, biliary tract disease, and urticaria.[7]Leung AKC, Leung AAM, Wong AHC, et al. Giardiasis: an overview. Recent Pat Inflamm Allergy Drug Discov. 2019;13(2):134-43.
https://www.eurekaselect.com/article/98976
http://www.ncbi.nlm.nih.gov/pubmed/31210116?tool=bestpractice.com
[8]Halliez MC, Buret AG. Extra-intestinal and long term consequences of Giardia duodenalis infections. World J Gastroenterol. 2013 Dec 21;19(47):8974-85.
https://www.doi.org/10.3748/wjg.v19.i47.8974
http://www.ncbi.nlm.nih.gov/pubmed/24379622?tool=bestpractice.com
Postinfectious intestinal and extra-intestinal symptoms are common. Long-term sequelae of prolonged but asymptomatic infection are under investigation and may include growth restriction and reduced cognitive potential.[8]Halliez MC, Buret AG. Extra-intestinal and long term consequences of Giardia duodenalis infections. World J Gastroenterol. 2013 Dec 21;19(47):8974-85.
https://www.doi.org/10.3748/wjg.v19.i47.8974
http://www.ncbi.nlm.nih.gov/pubmed/24379622?tool=bestpractice.com
[9]Rogawski ET, Bartelt LA, Platts-Mills JA, et al. Determinants and impact of Giardia Infection in the first 2 years of life in the MAL-ED birth cohort. J Pediatric Infect Dis Soc. 2017 Jun 1;6(2):153-160.
https://www.doi.org/10.1093/jpids/piw082
http://www.ncbi.nlm.nih.gov/pubmed/28204556?tool=bestpractice.com
[10]Donowitz JR, Alam M, Kabir M, et al. A prospective longitudinal cohort to investigate the effects of early life Giardiasis on growth and all cause diarrhea. Clin Infect Dis. 2016 Sep 15;63(6):792-7.
https://www.doi.org/10.1093/cid/ciw391
http://www.ncbi.nlm.nih.gov/pubmed/27313261?tool=bestpractice.com