*Purpose: Norovirus gastrointestinal infection has been identified as a cause of significant morbidity among immunocompromised hosts, particularly hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT) recipients. It can cause severe disease with prolonged diarrhea, which is often complicated by dehydration, malnutrition, kidney injury, rejection, and mortality. We describe the clinical characteristics and outcomes of this infection in a large cohort of kidney transplant patients.

*Methods: We conducted a single center, retrospective chart review study of adult patients (age >18 years) who were recipients of kidney or kidney-pancreas transplant and had norovirus infection, diagnosed by positive PCR testing during the time period from January 2015 through March 2020.

*Results: A total of 72 renal transplant recipients were reviewed. 37(51%) patients were female. Median age was 53 years. 26% allografts were from living donors. 11% had simultaneous pancreas kidney transplant. Most patients (95%) received T cell depleting agents for induction. 28% had other concomitant infections at the time of diagnosis. The mean duration of diarrhea was 54 days (0-771) and 24 (33.3%) patients had diarrhea for longer than 30 days. 47 patients (65%) were hospitalized, of which 14.9% required ICU level of care. 70% required administration of IV fluids. Average length of stay was 7.5 days (1-111). Immunosuppression was reduced in 64% of the patients. 12 (17%) patients received nitazoxanide. Renal failure (defined as > 20% reduction in baseline GFR) occurred in 24 (35.3%) patients, of which 16.7% required renal replacement therapy. The average weight loss was 2.3% and 0.3% of total body weight(TBW) at 1 and 6 months post diagnosis respectively. In patients with diarrhea for longer than 30 days, average weight loss was 3.7% and 2% of TBW at 1 and 6 months respectively. 5 patients had biopsy proven allograft rejection by 1 year of diagnosis and 8 received treatment for rejection. 6 (9.1%) patients died by 1 year and one was attributed to norovirus infection.

*Conclusions: Norovirus infection led to severe diarrheal disease in our cohort. Significant number of patients developed prolonged diarrhea, acute kidney injury, and required hospitalization. Reduction of immunosuppression was the most commonly implemented strategy.Clinicians must have a high suspicion for this illness and obtain PCR testing for timely diagnosis and appropriate management.

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