This study aimed to investigate the epidemiological characterizations and pathogen spectrum of hand, foot, and mouth disease (HFMD) in Yantai City, Shandong Province, China, during 2011-2015, and to study the nucleotide evolution and amino acid variation of coxsackievirus A16 (CV-A16) epidemic strains that caused HFMD. The HFMD epidemic began to rise in March, and became prevalent from May to August, reached its peak in June, and then declined in September every year, children aged one to 5 years-old had the highest incidence rate whereas the incidence in children under 6 months was very low, and there were more males than females. Enterovirus nucleic acid detection using real-time reverse transcription polymerase chain reaction was performed on 2130 clinical specimens collected from patients with HFMD between 2011 and 2015, and 2012 enterovirus positive samples were detected, including 678 CV-A16, 639 EV-A71, and 695 other enteroviruses. In total, 60 CV-A16 isolates were randomly selected each year for virus isolation, of which 33 CV-A16 strains were randomly selected for further characterization because CV-A16 is the predominant serotype that caused HFMD in Yantai City, and a phylogenetic tree based on the VP1 region was constructed. All 33 CV-A16 strains belonged to the Bla and B1b genotypes, with a nucleotide similarity of 87.9-100% and deduced amino acid similarity of 98.6-100%. Compared with the reference strain Tainan/5079/98 (AF177911), amino acid mutations were identified at positions 11, 23, 25, 31, 99, 145, and 289, where differences were observed among 33 strains, indicating a unique mutation map of CV-A16 in Yantai City. Our findings demonstrate the etiologic characteristics of HFMD, provide supporting evidence for the prevention and control of HFMD, and open a promising avenue for vaccine development against HFMD, by targeting CV-A16.

This study aimed to analyse the pathogenic spectrum and epidemiological characteristics of infectious diarrhea in Yantai City, Shandong Province, China and provide a reference for its prevention and control. A total of 713 stool specimens collected within 3 days of diarrhea onset from January to December 2017 at secondary or higher hospitals in Yantai City were tested for 10 causative pathogens, using real-time polymerase chain reaction (RT-PCR). The top two rotaviruses and norovirus were analysed for typing and geographical distribution. The total positive rate was 46.56% (332/713), and 268 of 713 specimens contained at least one pathogen; 64 had at least two pathogens, accounting for 19.28% of the positive specimens (64/332). The positivity rates of rotavirus (RV), norovirus (NoVs) GI, norovirus (NoVs) GII, enterovirus universal (EV), enteric adenoviruses (EAdV), sapovirus (SaV), astrovirus (Astv), Salmonella (SE), Listeria monocytogenes (LiMo), and Vibrio parahaemolyticus (VP) were 20.06% (143/713), 1.82% (13/713), 12.84% (89/713), 10.66% (76/713), 4.07% (29/713), 0.42% (3/713), 2.38% (17/713), 1.54% (11/713), 1.82% (13/713), and 1.54% (11/713), respectively. Infectious diarrhea showed a high prevalence in young children aged 1-5 years, accounting for 48.6% of the total number of cases. Bacterial diarrhea was predominant in summer, and viral diarrhea was distributed throughout the year, without a significant seasonal pattern. Rotavirus is dominated by G9P , accounting for 81.82%, while norovirus is dominated by the GII type and has diverse characteristics. The aetiology of infectious diarrhea in Yantai is mainly viral, with RV, NoVs, EV, EAdV, and Astv being the most frequent pathogens. Continuous surveillance of infectious diarrhea diseases can help us understand its epidemiological and pathogenic characteristics, thereby taking targeted preventive and control measures in different seasons.

Purpose: Rotavirus (RV) ranked first among infectious diarrhea-causing pathogens in Yantai from 2017 to 2019. This study investigated the seroserotypes of RV in Yantai, Shandong, from 2017 to 2019 to identify the dominant serotypes and explore the epidemic pattern, aiming to effectively reduce the infection rate, better guide vaccination, and help in epidemiological prevention and control. Methods: A total of 2227 human diarrhea samples were collected from 2017 to 2019 in Yantai. The VP7 (G serotype) and VP4 (P serotype) genes of 467 RV-positive samples were amplified using two-round nested reverse transcription–polymerase chain reaction for G/P genotyping. Results: The genotyping results of RV in Yantai from 2017 to 2019 revealed that G9 was the dominant serotype for all G serotypes, P[8] was the dominant serotype for all P serotypes, and G9P[8] was the dominant serotype for all G/P combinations. G9 serotype accounted for 60.84%, 95.65%, and 83.76% of the total RV samples collected in 2017, 2018, and 2019, respectively. P[8] accounted for 75.52%, 94.69%, and 88.89% of the RV-positive samples collected in 2017, 2018, and 2019, respectively. G9P[8] accounted for 60.84%, 94.69%, and 83.76% of the total RV samples collected in 2017, 2018, and 2019, respectively. Of the total 467 samples from 2017 to 2019, G2P[4] accounted for 3.64% (17/467), G3P[8] for 1.28% (6/467), and G1P[8] for 0.86% (4/467). Conclusion: This study revealed the epidemiological characteristics of RV infection and the development pattern of dominant serotypes in Yantai in recent years, guiding the selection of RV vaccines. The prioritization of vaccines containing G9 serotype for infants in Yantai in recent years is recommended.

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BackgroundAnalysis of the pathogenic spectrum, epidemiological characteristics and molecular epidemiological features of important pathogens of infectious diarrhea in Yantai City, Shandong Province, 2018–2019, were analyzed to provide a reference basis for the prevention and control of infectious diarrhea.MethodsA total of 1514 stool specimens were collected within 3 days of the onset of diarrhea in secondary or higher hospitals in Yantai from 2018–2019, and all specimens were tested for the presence of seven major viruses and three major bacteria by employing reverse transcription ploymeraer chain reaction (RT-PCR). Population and seasonal analyses were also performed on positive samples for infectious diarrhea. The top two ranked rotavirus and norovirus were focused on genotyping and analysis of geographical distribution.ResultsThe study showed that the high prevalence of infectious diarrhea in Yantai, Shandong Province, for two consecutive years in 2018 and 2019 was in young children aged 1–5 years, accounting for 48.6% of the total number of cases. Viral diarrhea was distributed throughout the year with no obvious seasonal distribution, while bacterial diarrhea was predominant in summer. Of 1514 stool specimens, the total positive rate of specimens was 43.92% (665/1514). One pathogen was detected in 507 specimens, two pathogens in 107 specimens, and three pathogens in 44 specimens, with mixed infections accounting for 22.71% of positive specimens (151/665). Viral diarrheal pathogens accounted for 93.23% (620/665) of positive samples. The percentages of positive samples for Rotavirus (RV), Norovirus GI, Norovirus GII, Enterovirus universal (EV), Enteroadenovirus (EAdV), Sapovirus (SaV), Astrovirus (Astv), Salmonella (SE), Listeria monocytogenes (LiMo), and Vibrio parahaemolyticus (VP) were 48.57%, 3.61%, 15.34%, and 10.68% of the total positive samples.ConclusionsThis study analyzed in detail the composition of infectious diarrhea pathogen spectrum, pathogen alternation pattern, seasonal distribution and population distribution of pathogens in Yantai City, Shandong Province, 2018–2019, to provide a basis for improving relevant local preventive measures and reducing the disease burden.