Prevalence of norovirus among visitors from the United States to Mexico and Guatemala who experience traveler's diarrhea

Abstract

Traveler's diarrhea (TD) is the most common infectious illness acquired by visitors to developing nations. The purpose of this study was to utilize molecular diagnostic techniques to determine the prevalence of norovirus (NoV) in TD occurring among visitors from the United States to Guatemala and Mexico. Stool samples (n = 54) were collected from 34 TD cases and analyzed for NoV by reverse transcription-PCR and oligoprobe confirmation. The overall prevalence of NoV was 65%. Interestingly, all NoV-positive stool samples were identified as genogroup I NoVs, and time spent at travel destinations was found to be an important factor in determining the frequency of infection (P = 0.003). Eleven NoV-positive stool samples also tested positive for enterotoxigenic Escherichia coli, indicating that dual infections with this leading bacterial cause of TD were very common. Results of this study suggest that NoV infection is a frequent occurrence among travelers to Mexico and Guatemala who experience episodes of TD. In addition, the simple molecular detection method utilized here will serve to facilitate more in-depth epidemiological studies of this emergent viral pathogen in travelers and other at-risk populations.

FIG. 1.

RT-PCR (A) and Southern oligoprobe (B) results for a subset of NoV-positive stool samples obtained from the CDC. Each stool sample was analyzed separately with GI or GII primers and probes. Lanes 1 and 8, digoxigenin-labeled DNA marker; lanes 2 to 6 and 9 to 13, GI or GII NoV-positive stool samples, respectively; lanes 7 and 14, GI and GII negative controls, respectively.

FIG. 2.

RT-PCR (A) and Southern oligoprobe (B) results for a representative subset of TD samples. Each stool sample was analyzed separately with GI or GII primers and probes. Lanes 1 and 15, digoxigenin-labeled DNA marker; lanes 2 to 9 and 16 to 23, GI and GII 10⁻³ dilutions of heat- released RNA amplifications of TD stool samples, respectively; lanes 10 and 24, GI and GII negative controls, respectively; lanes 11 and 25, PV amplicons; lanes 12 and 26, HAV amplicons; lanes 13 and 27, space; lanes 14 and 28, GI and GII positive controls, respectively.