Surveillance of Wastewater to Monitor the Prevalence of Gastroenteritis Viruses in Chiba Prefecture (2014-2019).

BACKGROUND: In Japan, sentinel surveillance is used to monitor the trend of infectious gastroenteritis. Another method of pathogen surveillance, wastewater-based epidemiology, has been used recently because it can help to monitor infectious disease without relying on patient data. Here, we aimed to determine the viral trends reflected in the number of reported patients and number of gastroenteritis virus-positive samples. We focused on gastroenteritis viruses present in wastewater and investigated the usefulness of wastewater surveillance for the surveillance of infectious gastroenteritis. METHODS: Real-time polymerase chain reaction was used for viral gene detection in wastewater. The number of reported patients per pediatric sentinel site and number of viral genome copies were compared for correlation potential. The number of gastroenteritis virus-positive samples reported by National Epidemiological Surveillance of Infectious Disease (NESID) and the status of gastroenteritis viruses detected in wastewater were also evaluated. RESULTS: Genes of norovirus genotype I, norovirus genotype II, sapovirus, astrovirus, rotavirus group A, and rotavirus group C were detected in wastewater samples. Viruses were detected in wastewater during periods when no gastroenteritis virus-positive samples were reported to NESID. CONCLUSION: Norovirus genotype II and other gastroenteritis viruses were detected in wastewater even during periods when no gastroenteritis virus-positive samples were found. Therefore, surveillance using wastewater can complement sentinel surveillance and is an effective tool for the surveillance of infectious gastroenteritis.

Polio vaccination coverage and seroprevalence of poliovirus antibodies after the introduction of inactivated poliovirus vaccines for routine immunization in Japan.

In Japan, the oral poliovirus vaccine (OPV) was changed to 2 types of inactivated poliovirus vaccine (IPV), the standalone conventional IPV (cIPV) and the Sabin-derived IPV combined with diphtheria-tetanus-acellular pertussis vaccine (DTaP-sIPV), for routine immunization in 2012. We evaluated polio vaccination coverage and the seroprevalence of poliovirus antibodies using data from the National Epidemiological Surveillance of Vaccine-Preventable Diseases (NESVPD) from 2011 to 2015. Several years before the introduction of IPV in 2012, OPV administration for children was refused by some parents because of concerns about the risk of vaccine-associated paralytic poliomyelitis. Consequently, in children aged <1 years who were surveyed in 2011-2012, polio vaccination coverage (45.0-48.8%) and seropositivity rates for poliovirus (type 1: 51.7-65.9%, type 2: 48.3-53.7%, and type 3: 15.0-29.3%) were decreased compared to those surveyed in 2009. However, after IPV introduction, the vaccination coverage (95.5-100%) and seropositivity rates (type 1: 93.2-96.6%, type 2: 93.1-100%, and type 3: 88.6-93.9%) increased among children aged <1 years in 2013-2015. In particular, seropositivity rates and geometric mean titers (GMTs) for poliovirus type 3 in <5-year-old children who received 4 doses of IPV (98.5% and 247.4, respectively) were significantly higher than in those who received 2 doses of OPV (72.5% and 22.9, respectively). Furthermore, in <5-year-old children who received 4 doses of either DTaP-sIPV or cIPV, the seropositivity rates and the GMTs for all 3 types of poliovirus were similarly high (96.5-100% and 170.3-368.8, respectively). Our findings from the NESVPD demonstrate that both the vaccination coverage and seropositivity rates for polio remained high in children after IPV introduction.

Surveillance of immunity acquired from poliovirus immunization including vaccination with the Sabin strain-derived inactivated vaccine.

In Japan, routine immunization for polio using the oral polio vaccine (OPV) was suspended in September 2012; subsequently, an immunization program with inactivated polio vaccines (IPVs), the conventional IPV (cIPV) derived from virulent strains, and IPV derived from Sabin strains (sIPV), was introduced. However, the immunity induced by sIPV is not well characterized. This study assessed and compared neutralizing antibodies produced against poliovirus in cases who received doses of OPV or IPV. Serum samples (n = 1186) were collected yearly between 2013 and 2016 as part of the National Epidemiological Surveillance of Vaccine-Preventable Disease. The neutralizing antibody titers for Sabin strain types 1, 2, and 3 in 224 children, aged between 0 and 90 months, were assessed. Seropositive rates after vaccination with OPV or IPV were more than 90%. Neutralizing antibody titers for Sabin type 1 after vaccination with IPV were lower than those with OPV, while those for Sabin types 2 and 3 after vaccination with IPV were significantly higher than those with OPV. Analyses of antibody titer dynamics revealed that the decay of antibody titers for Sabin types 1, 2, and 3 in cases vaccinated with IPV was steeper than those with OPV. Thus, our study showed that although IPV induced a sufficient level of neutralizing antibody, the immunity induced by IPV was not maintained as long as that by OPV. Our study suggested that a long-term survey should be conducted for polio vaccination using IPV and that it might be necessary to consider booster vaccination for IPVs.

Clinical value of enzyme immunoassay that detects rubella-specific immunoglobulin M immediately after disease onset.

A total of 300 patients with nucleic acid test-confirmed rubella, mostly adults, were investigated to determine the clinical value of a rubella-specific IgM test using an EIA kit. IgM titers increased after rash onset, the median IgM titer being significantly higher 3 days post-onset than on previous days (P < 0.0001). Similarly, the IgM-positive rate at 3 days post-onset (61.5%) was significantly higher than on previous days (P < 0.0001). This IgM test against rubella at 3 days or more post-disease onset provides the clinically relevant information.

Coxsackievirus B5 Aseptic Meningitis in Infants in Chiba Prefecture, Japan, in 2016.

BACKGROUND: Infantile aseptic meningitis is a rare infection of the central nervous system. Coxsackievirus B5 (CVB5) is an enterovirus that is sometimes associated with aseptic meningitis and encephalitis. CASE PRESENTATION: We report on three isolated infants with aseptic meningitis caused by CVB5 in the spring and summer of 2016 with nearly identical 404-bp CVB5 Viral Capsid Protein 1 (VP1) sequences. In addition, viral analysis of sewage samples from Chiba Prefecture in 2016 showed similar 404-bp CVB5 VP1 sequences from May to September 2016. CONCLUSION: These results indicate that viral screening of sewage water may help detect occult outbreaks of viral infection, particularly for enterovirus strains.

The First Case of Zika Virus Isolated from a Japanese Patient Who Returned to Japan from Fiji in 2016.

Outbreaks of Zika virus (ZIKV) infection in tropical and subtropical regions are a cause of worldwide concern and represent a public health emergency. ZIKV was isolated from a 17-year-old patient with fever and maculopapular rash. The patient returned to Japan from the Republic of Fiji in late April 2016. The complete genome sequence of the ZIKV isolate (ZIKV/Hu/S36/Chiba/2016), which might be the first strain to be isolated in Japan, was identified and reported.

Evaluation of sensitivity of TaqMan RT-PCR for rubella virus detection in clinical specimens.

BACKGROUND: An easy and reliable assay for detection of the rubella virus is required to strengthen rubella surveillance. Although a TaqMan RT-PCR assay for detection of the rubella virus has been established in Japan, its utility for diagnostic purposes has not been tested. OBJECTIVES: To allow introduction of the TaqMan RT-PCR into the rubella surveillance system in Japan, the sensitivity of the assay was determined using representative strains for all genotypes and clinical specimens. STUDY DESIGN: The detection limits of the method for individual genotypes were examined using viral RNA extracted from 13 representative strains. The assay was also tested at 10 prefectural laboratories in Japan, designated as local reference laboratories for measles and rubella, to allow nationwide application of the assay. RESULTS: The detection limits and amplification efficiencies of the assay were similar among all the representative strains of the 13 genotypes. The TaqMan RT-PCR could detect approximately 90% of throat swab and urine samples taken up to 5days of illness. These samples were determined positive by a highly sensitive nested RT-PCR. CONCLUSIONS: The TaqMan RT-PCR could detect at least 10 pfu of rubella virus. Although the sensitivity was somewhat lower than that of the conventional nested RT-PCR, the TaqMan RT-PCR could be more practical to routine tests for rubella laboratory diagnosis and detection in view of the rapid response and reducing risks of contamination.

[Epidemiological study of respiratory viruses detected in patients under two years old who required admission because of lower respiratory disease].

The etiologic role of recently identified respiratory viruses for lower respiratory tract disease (LRTD) remains unclear in Japan. The purpose of this study was to investigate the prevalence of respiratory viruses in young children with LRTD. We prospectively examined 721 children who were under two years old and admitted to a single medical center in Japan with LRTD between April 2007 and March 2012. Viral nucleotic acids were taken from their nasal swabs. Each sample was examined with (RT-) PCR for respiratory syncytial virus (RSV), enterovirus (EV), human metapuemovirus (hMPV), human bocavirus (HBoV), parainfluenzavirus (PIV), and adenovirus (AdV). We detected at least one virus agent in 466 (65%); 83 patients (12%) were co-infected with different viruses. No virus was detected in 255 patients (35%). RSV (27%) was most common, followed by EV (11%), hMPV (6.9%), HBoV (3.3%), PIV (2.9%), and AdV (2.2%). Seasonal distribution was seen in each virus. Infants under 6 months old were frequently positive for RSV or EV. In 20 patients (2.8%) who required mechanical ventilation because of respiratory failure, 18 patients were positive for RSV nospace between "and/or" EV.

A novel complex recombinant form of type 48-related human adenovirus species D isolated in Japan.

Recently, new genotypes of human adenoviruses (HAdVs) have been reported and many of them have been found to be recombinant forms of different known types of HAdV species D (HAdV-D). The objective of this study was to document the evolutionary features of a novel isolate (HAdV_Chiba_E086/2012) obtained from the eye swab of a patient with conjunctivitis in Japan. Viral DNA was extracted from the isolate to sequence the whole genome by the Sanger method and aligned with available genome sequences of HAdV-Ds. The phylogenetic trees of the nucleotide sequences of the penton base, hexon, and fiber genes and the E3 region showed that HAdV_Chiba_E086/2012 is closest to HAdV genotype 65 (HAdV-GT65), HAdV-48, HAdV-GT60 and HAdV-22 at 98%, 99%, 95% and 98% identity, respectively, suggesting that this isolate is a novel recombinant form to be designated as P65H48F60. Further phylogenetic and recombination analyses of the genome alignment of the new isolate implied that nested recombination events involving HAdV-GT59, GT65, 48, GT60, 22, and some ancestral lineages or their close relatives have shaped its genome. These results showed that HAdV_Chiba_E086/2012 is the first HAdV-48-related HAdV found in Japan, which has the most complicated evolutionary history among the known HAdVs so far.