c Norovirus (NoV) is considered a major cause of nonbacterial gastroenteritis among people of all ages worldwide, but the natural course of infection is incompletely known. In this study, the pattern of circulation of NoVs was studied among 146 children and 137 adults in a small community in southwestern Cameroon. The participants provided monthly fecal samples during a year. NoV RNA was detected in at least one sample from 82 (29%) of the participants. The partial VP1 region could be sequenced in 36 NoV GII-positive samples. Three different genotypes were identified (GII.1, GII.4, and GII.17), with each genotype circulating within 2 to 3 months and reappearing after a relapse period of 2 to 3 months. Most infections occurred once, and 2 episodes at most within a year were detected. No difference in the frequency of NoV infection between children and adults was recorded. The same genotype was detected for a maximum of 2 consecutive months in 3 children only, suggesting that a less than 30-day duration of viral shedding in natural infection was common. Reinfection within a year with the same genotype was not observed, consistent with short-term homotypic immune protection. The study revealed that NoV strains are circulating with a limited duration of viral shedding both in the individuals and the population as part of their natural infection. The results also provide evidence of cross-protective immunity of limited duration between genotypes of the same genogroup.

Enteroviruses (EVs) often infect humans, presenting as endemic or epidemic infections. In this study, the diversity of infecting EVs was studied among 146 children and 137 adults in a small community in Cameroon. The participants provided 2,458 fecal samples during 1-year monthly collection; 10 or more samples were obtained from 55%. Partial 5'UTR-VP4 region could be sequenced in 393/547 PCR positive samples obtained from 119 children and 85 adults. EV-RNA was detected in at least one sample from 235 participants (83%) during the study period. A total of 121 different strains were identified, 66 infected only children, 29 only adults, and 26 infected both children and adults. There were children with up to five episodes with different strains, and adults with up to four such episodes. Infants aged <5 years were significantly more often EV infected compared to older participants. Infections with species EV-C constituted two third of all cases, and overall EV infections were more common during the rainy season. Species EV-B more often infected children than adults. Most strains were detected only for certain months of the year; however five strains were observed during the time spans of 5-10 months. Two strains were excreted up to eight months in three children and one adult. In 11 of the 128 families with paired samples the child and the adult were infected simultaneously by the same strain, indicating common source of infection. The study revealed a surprising complexity of EV ecosystem in a single community.