Sapovirus: an emerging pathogen in kidney transplant recipients?

Diarrhea is an important cause of morbidity and mortality in immunocompromised patients. After including sapovirus to the viral gastroenteritis screening of our institution's laboratory, we noticed an increase in sapovirus infections among kidney transplant recipients. Therefore, we assumed former gastrointestinal tract infections with unidentified pathogens could have been caused by sapovirus. To better understand the characteristics of a sapovirus infection in a high-risk group we initiated this study.

Over a period of 6 months, all transplant recipients with diarrhea and later identified viral/unknown pathogens were included. Kidney function, levels of immunosuppressants and  c-reactive protein, acid-base balance, onset of symptoms and time of hospitalization were analyzed.

Among 13 hospitalized kidney transplant recipients sapovirus was detected in four patients, while in the remaining nine, three were diagnosed with norovirus, one with cytomegalovirus, one with inflammatory bowel disease and in four patients no pathogen was identified. Even though statistically not significant, creatinine levels at admission tended to be higher in sapovirus patients (median: sapovirus: 3.3 mg/dl (1.3; 5.0), non-sapovirus: 2.5 mg/dl (1.1; 4.9), p = 0.710). Also, Tacrolimus levels showed the same trend (sapovirus: 13.6 ng/ml (12.9; 13.6), non-sapovirus: 7.1 ng/ml (2.6; 22.6), p = 0.279). On discharge creatinine levels improved equally in both groups (sapovirus: 1.7 mg/dl (1.4; 3.2), non-sapovirus: 2 mg/dl (1.0; 3.6), p = 0.825).

In high-risk patients, early symptomatic treatment remains crucial to protect the transplant`s function. In our cohort all patients recovered well. Larger cohorts and longer follow-up times are needed to detect the long-term consequences and a potential need for further research regarding specific treatment.

The study has been registered on DRKS (trialsearch.who.int), Reg. Nr. DRKS00033311 (December 28th 2023).