Chronic infection with Giardia was associated with prolonged alterations in duodenal mucosa lymphocytes. However, important differences were not observed in major lymphocyte populations between patients in whom long-term postinfectious functional gastrointestinal disorders did or did not develop, according to findings of a study published in Clinical Infectious Diseases.

Giardiasis is a risk factor for the development of postinfectious functional gastrointestinal disorders. Although the underlying cause of functional gastrointestinal disorders remains undefined, it is believed to be multifactorial. Previous research has suggested that persistent low-grade inflammation with increased numbers of mucosal B and T lymphocytes could be an important contributing factor. In the current study, researchers examined alterations in duodenal mucosal lymphocytes during and after Giardia gastroenteritis in patients who developed post-infectious functional gastrointestinal disorders and those who did not.

Participants included 28 people with chronic giardiasis, 66 people with persistent abdominal symptoms following an acute Giardia infection (a symptom characteristic of postinfectious functional gastrointestinal disorders), 19 people who had recovered from giardiasis, and 16 healthy controls. In this cohort, researchers measured duodenal mucosal intraepithelial lymphocytes and lamina propria CD3, CD4, CD8, and CD20 lymphocytes.

Results showed that duodenal CD4 intraepithelial lymphocyte levels were significantly elevated in patients with chronic giardiasis but then levels declined. This was followed by an upward trend after 1 year in both the group with postinfectious functional gastrointestinal disorders, as well as in the recovered patient group. Duodenal lamina propria crypt CD4 T cell levels were also decreased in the group with chronic giardiasis and remained low for approximately 14 months before normalizing in patients with postinfectious functional gastrointestinal disorders and in those who had recovered. In addition, lamina propria CD20 cells were persistently elevated in all groups exposed to Giardia.

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“The findings implicate a cautionary approach to studies of [postinfectious functional gastrointestinal disorders] not including a recovered control group,” wrote the researchers.

Reference

Dizdar V, Hausken T, Larum OD, Gilja OH, Langeland N, Hanevik K. Prolonged duodenal mucosal lymphocyte alterations in patients with and without post infectious functional gastrointestinal disorders after Giardia infection [published online November 30, 2018]. J Infect Dis. doi: 10.1093/infdis/jiy690