Fecal cytokines and markers of intestinal inflammation in international travelers with diarrhea due to Noroviruses.

The intestinal immune and inflammatory responses of Norovirus (NoV) are poorly defined. The objective of this study was to investigate fecal cytokine and lactoferrin profiles in response to NoV gastroenteritis in travelers. Both fecal cytokines and fecal lactoferrin were measured for NoV-associated diarrhea (N = 7), mixed infection of NoV and enterotoxigenic E. coli (ETEC)-associated diarrhea (N = 10) and in pathogen-negative diarrhea cases (N = 19). Both IL-2 and IFN-gamma were significantly increased in NoV-associated diarrhea specimens, suggesting a predominant Th1 immune response to NoV infection in the gut. When a mixed infection of NoV and ETEC occurred, a combined Th1/Th2 response was observed suggesting a dual immune response secondary to infection by both pathogens. Intestinal inflammation associated with increased fecal lactoferrin, important in bacterial enteric infection, was not found in NoV-associated gastroenteritis.