Jen-Shiou Lin

Human infection with avian influenza A H6N1 virus: an epidemiological analysis

Summary Background Avian influenza A H6N1 virus is one of the most common viruses isolated from wild and domestic avian species, but human infection with this virus has not been previously reported. We report the clinical presentation, contact, and environmental investigations of a patient infected with this virus, and assess the origin and genetic characteristics of the isolated virus. Methods A 20-year-old woman with an influenza-like illness presented to a hospital with shortness of breath in May, 2013. An unsubtyped influenza A virus was isolated from her throat-swab specimen and was transferred to the Taiwan Centres for Disease Control (CDC) for identification. The medical records were reviewed to assess the clinical presentation. We did a contact and environmental investigation and collected clinical specimens from the case and symptomatic contacts to test for influenza virus. The genomic sequences of the isolated virus were determined and characterised. Findings The unsubtyped influenza A virus was identified as the H6N1 subtype, based on sequences of the genes encoding haemagglutinin and neuraminidase. The source of infection was not established. Sequence analyses showed that this human isolate was highly homologous to chicken H6N1 viruses in Taiwan and had been generated through interclade reassortment. Notably, the virus had a G228S substitution in the haemagglutinin protein that might increase its affinity for the human α2-6 linked sialic acid receptor. Interpretation This is the first report of human infection with a wild avian influenza A H6N1 virus. A unique clade of H6N1 viruses with a G228S substitution of haemagglutinin have circulated persistently in poultry in Taiwan. These viruses continue to evolve and accumulate changes, increasing the potential risk of human-to-human transmission. Our report highlights the continuous need for preparedness for a pandemic of unpredictable and complex avian influenza. Funding Taiwan Centres for Disease Control.

Hospital-based surveillance and molecular epidemiology of rotavirus infection in Taiwan, 2005-2007.

To determine the distribution of rotavirus strains and facilitate vaccine policy decisions in Taiwan, active hospital-based gastroenteritis surveillance was conducted in three sentinel hospitals. From 1 January 2005 to 31 December 2007, a total of 3435 children less than 5 years old with gastroenteritis were enrolled. The presence of rotavirus was documented by enzyme immunoassay (EIA), and the G and P genotypes were determined by reverse transcription-polymerase chain reaction (RT-PCR) and sequencing methods. Results confirmed that 856 (25%) of these gastroenteritis admissions were EIA-positive for rotavirus and 448 (52%) of the rotavirus positive admissions were less than 2 years old. The most prevalent rotavirus genotypes were G1P[8] (40%), followed by strains G3P[8] (27%), and G9P[8] (17%). These data will help inform decisions as to whether rotavirus vaccine should be considered for inclusion into Taiwans National Immunisation Programme.

Diverse origin of P[19] rotaviruses in children with acute diarrhea in Taiwan: Detection of novel lineages of the G3, G5, and G9 VP7 genes†

We previously reported the detection of genotype P[19] rotavirus strains from children hospitalized with acute dehydrating diarrhea during a 5‐year surveillance period in Taiwan. The characterization of five P[19] strains (0.4% of all typed), including three G3P[19], a novel G5P[19], and a unique G9P[19] genotype is described in this study. Phylogenetic analysis of the VP4, VP7, VP6, and NSP4 genes was performed, which demonstrated novel lineages for respective genotypes of the VP4 and the VP7 genes. The sequence similarities of the P[19] VP4 gene among Taiwanese human strains was higher (nt, 91.5–96.2%; aa, 93.7–97.6%) than to other P[19] strains (nt, 83.5–86.6%; aa, 89.4–94.1%) from different regions of the world. The VP7 gene of the three G3P[19] Taiwanese strains shared up to 93.4% nt and 97.5% aa identity to each other but had lower similarity to reference strain sequences available in GenBank (nt, <90.1%; aa, <95.6%). Similarly, the VP7 gene of the novel G5P[19] strain was only moderately related to the VP7 gene of reference G5 strains (nt, 82.2–87.3%; aa, 87.0–93.1%), while the VP7 gene of the single G9P[19] strain was genetically distinct from other known human and animal G9 rotavirus strains (nt, ≤92.0%; aa, ≤95.7%). Together, these findings suggest that the Taiwanese P[19] strains originated by independent interspecies transmission events. Synchronized surveillance of human and animal rotaviruses in Taiwan should identify possible hosts of these uncommon human rotavirus strains. J. Med. Virol. 83:1279–1287, 2011.

Epidemiology and Clinical Peculiarities of Norovirus and Rotavirus Infection in Hospitalized Young Children with Acute Diarrhea in Taiwan, 2009

BACKGROUND/PURPOSE Acute diarrhea is one of the most common morbidities in pediatrics worldwide. We conducted a study to investigate the incidence of norovirus in young children hospitalized with acute diarrhea in Taiwan and its clinical peculiarity compared with rotavirus gastroenteritis. METHODS Between January and December, 2009, patients younger than 5 years and admitted to hospital with acute diarrhea were randomly selected; and their stool samples were collected and tested for presence of rotavirus and norovirus by enzyme immunoassay and reverse transcription-polymerase chain reaction, respectively. The clinical manifestations and laboratory findings of the enrolled patients were analyzed. RESULTS A total of 989 cases were enrolled with a mean age of 21.6 ± 13.7 months and a male proportion of 56.0%. Rotavirus and norovirus was detected in 20.2% and 14.6% of all patients, respectively. Genogroup II was the predominant strain of norovirus (80.6%). Children aged 6-36 months accounted for the majority of patients positive for rotavirus and norovirus (73.0% and 81.3%, respectively). The incidences of norovirus and rotavirus infection were higher during winter and early spring. Most patients with rotavirus and norovirus diarrhea experienced vomiting (74.9%vs. 74.8%, respectively) and fever (94.7%vs. 71.3%, respectively). CONCLUSION Most young diarrheal patients presenting with vomiting were likely to have norovirus or rotavirus infection. Patients with norovirus diarrhea experienced an absence of, or low-grade fever and longer duration of vomiting compared with those positive for rotavirus infection. A family history of current gastroenteritis may suggest the possibility of norovirus infection.

Effectiveness of 2 rotavirus vaccines against rotavirus disease in taiwanese infants

Background: Two rotavirus (RV) vaccines (Rotarix and RotaTeq) are available on the private market in Taiwan, but are not recommended for routine use. We examined RV vaccine effectiveness (VE) against severe RV acute gastroenteritis (AGE) among Taiwanese infants to inform policymakers on the potential benefits of national RV vaccine introduction. Methods: From May 2009 to April 2011, a case-control assessment of VE against severe RV AGE was conducted at 3 hospital-based surveillance sites in Taiwan. Case-patients included children aged 8–35 months, hospitalized with laboratory-confirmed RV AGE. Controls included children age-matched within 1 month of age of the case-patient, hospitalized with RV-negative AGE or seen for non-AGE illnesses at the same hospitals. Vaccination history was confirmed through vaccination card or hospital record review. VE was calculated as (1 − odds ratio of vaccination)×100%. Results: We enrolled 184 case-patients with RV AGE, 904 RV-negative AGE and 909 non-AGE controls. Two-dose Rotarix series VE against RV gastroenteritis hospitalization was 90.4% [95% confidence interval (CI): 70.3%, 98.1%) and 92.5% (95% CI: 77.1%, 98.5%) with RV-negative AGE and non-AGE controls, respectively. Three-dose RotaTeq series VE was 96.8% (95% CI: 82.3%, 100%) and 97.1% (95% CI: 84%, 100%) with RV-negative AGE and non-AGE controls, respectively. Conclusions: Both vaccines provided excellent protection against severe RV AGE hospitalization. Addition of RV vaccination into Taiwan’s National Immunization Program could substantially decrease AGE hospitalizations among children <3 years. Our findings should help inform policymakers in Taiwan and other similar Asian countries when deciding whether to include RV vaccination into their national immunization programs.

Identification of porcine rotavirus-like genotype P[6] strains in Taiwanese children.

The molecular characterization of genotype P[6] rotavirus strains collected from children admitted to hospital with acute dehydrating diarrhoea during a 6-year surveillance period in Taiwan is described in this study. In total, three G4P[6] strains, one G5P[6] and one G12P[6] were characterized by sequencing and phylogenetic analysis of the VP4, VP7, VP6 and NSP4 genes. Whilst all four genes of the single Taiwanese G12P[6] strain clustered with the respective genes of globally common human rotavirus strains, the G4 and G5 strains showed remarkable similarities to porcine rotavirus strains and putative porcine-origin human P[19] strains reported previously from Taiwan. The overall proportion of porcine rotavirus-like strains in Taiwan remains around 1 % among hospitalized children; however, the circulation and sporadic transmission of these heterotypic strains from pigs to humans could pose a public-health concern. Therefore, continuation of strain monitoring is needed in the vaccine era to detect any possible vaccine breakthrough events associated with the introduction of such heterologous rotavirus strains.

Clinical and epidemiologic features of severe viral gastroenteritis in children: A 3-year surveillance, multicentered study in Taiwan with partial rotavirus immunization

AbstractThe global epidemiological landscape of childhood acute gastroenteritis (AGE) is changing after the introduction of 2 effective rotavirus vaccines in 2006. A comprehensive evaluation for viral etiology of childhood AGE in Taiwan, where rotavirus vaccination was provided by the private sector since 2006, is lacking.From 2009 to 2011, children younger than 5 years of age with AGE who were hospitalized at 3 sentinel hospitals were enrolled in this surveillance study. Stool specimens were tested for rotavirus, norovirus, enteric adenovirus, and astrovirus. The epidemiologic and clinical information was collected by questionnaire-based interviews and chart reviews.Viral agents were detected in 1055 (37.5%) of 2810 subjects, with rotavirus (21.2%) being the leading cause of disease, followed by norovirus (14.9%), enteric adenovirus (3.74%), astrovirus (2.10%), and a mixture of at least 2 of 4 above-mentioned viruses (4.06%). The majority (56%) of the viral AGE occurred in children <2 years of age. Rotavirus and norovirus were detected more frequently in cool seasons (P < 0.0001 for both), whereas no seasonal variation was observed for adenovirus and astrovirus. Adult households with diarrhea and a Vesikari score >10 were independent factors respectively associated with an increased risk of norovirus (adjusted odds ratio [aOR] 9.034, P = 0.0003) and rotavirus (aOR, 3.284, P < 0.0001) infections. Rotavirus immunization and female gender were protective factors against rotavirus (aOR, 0.198, P < 0.0001) and astrovirus (aOR, 0.382, P = 0.0299) infections, respectively.Rotavirus and norovirus are the 2 most important viral agents of childhood AGE in Taiwan with partial rotavirus immunization. In addition, different enteric viruses are associated with distinct epidemiologic and clinical features.

Astrovirus gastroenteritis in hospitalized children of less than 5 years of age in Taiwan, 2009

BACKGROUND/PURPOSE Acute gastroenteritis is a common illness in children under 5 years old. Although rotavirus is a leading cause, other viruses including astrovirus are also important, but have been the subject of limited studies. This is a prospective study to investigate astrovirus gastroenteritis in hospitalized children in Taiwan. MATERIAL/METHOD From January 2009 to December 2009, children below 5 years of age admitted to three hospitals in Taiwan due to acute gastroenteritis were eligible for this study. Stool specimens were sent for the detection of astrovirus by reverse transcriptase polymerase chain reaction; once positive for astrovirus, the sequencing and phylogenetic analysis of each strain was performed. RESULTS A total of 989 children were enrolled during the study period. The overall positive rate of astrovirus was 1.6%, ranging from 1.03% to 2.26% in different hospitals, while rotavirus accounted for 20.2% of the patients. Six of the 16 children (37.5%) with astroviral infection had documented coinfection with rotavirus. The median age of infection was 28.2 months. The seasonal distribution of astrovirus peaked from April to June. Diarrhea alone (40% vs. 2.1%, p < 0.0001) was significantly more commonly seen than the triad of fever, vomiting and diarrhea (30% vs. 71%, p = 0.0062) in children with astroviral infection alone than in those with rotaviral infection alone. The mean duration of diarrhea was significantly longer in patients with mixed infection than those with astroviral infection alone (6.8 vs. 4.2 days, p = 0.013). Respiratory symptoms were noted in 10 children (62.5%). Serotype HAstV-1 was the most common (68.8%). CONCLUSION Astrovirus accounted for 1.6% of infections in children under 5 years hospitalized with acute gastroenteritis in Taiwan. Compared with those caused by rotavirus, the incidence of gastroenteritis in hospitalized children caused by astrovirus was low and the disease severity was mild.

Human infection with novel G3P[25] rotavirus strain in Taiwan.

Genotype P[25] rotaviruses are rare and to date have been reported to occur only in a few countries of mainland Asia. Here we report the molecular characterization of a novel human rotavirus genotype combination, G3P[25], detected in a 17-month-old child hospitalized due to severe gastroenteritis during 2009 in central Taiwan. Sequencing and phylogenetic analysis of the VP4 gene demonstrated a distinct origin from other strains bearing the P[25] VP4 gene, whereas the VP7, VP6 and NSP4 gene phylogenies identified common origins with cognate genes of other, presumed human-porcine reassortment Taiwanese strains. These results suggest that interactions between human and animal strains appear to contribute to the generation of genetic and antigenic diversity of rotavirus strains, with potential public health importance in Taiwan.

Molecular epidemiology of human G2P[4] rotaviruses in Taiwan, 2004-2011.

In 2006, two rotavirus vaccines (Rotarix and RotaTeq) became available on the private market in Taiwan. Although vaccine coverage is currently low, molecular surveillance of rotavirus strains can provide pertinent information for evaluation of the potential impact of vaccine introduction and infection control. During January 2008-December 2011, children aged <5 years hospitalized with acute gastroenteritis were enrolled from sentinel surveillance hospitals in three geographic areas of Taiwan. Fecal specimens collected from enrolled patients were tested for rotavirus by enzyme immunoassay and reverse transcriptase-polymerase chain reaction. For genotyping, gene specific primer sets were used to amplify and sequence the genes encoding the neutralization antigens, VP7 and VP4. The resulting sequences were then subjected to phylogenetic analysis. In brief, a total of 4,052 fecal specimens were tested and 742 (18%) samples were positive for rotavirus. The annual range of rotavirus positive specimens varied between 16% and 20.7%. Of all specimens, genotype G1P[8] (63.3%) was the predominant strain, followed by G2P[4] (12.5%), G3P[8] (11.7%), and G9P[8] (5.1%). Uncommon strains were also detected in low percentages. We observed that the rotavirus positivity rate steadily decreased from 21% to 16% during 2008-2010, then slightly increased to 20% in 2011, when an increase in the number of G2P[4] cases was observed. Sequence and phylogenetic analysis was carried out to help understand any potential changes of G2P[4] rotaviruses over time. A number of G2P[4] strains collected between 2004 and 2011 were analyzed in detail and our analyses showed marked genetic and antigenic variability in the VP7 and VP4 genes. The Taiwanese strains could be classified into two major G2 VP7 lineages (IV and V) and two major P[4] VP4 lineages (IV and V) and several minor sublineages within lineage IV. Lineage V within both G2 and P[4] represented newly recognized genetic variants of the respective genotypes. The distribution of individual combinations of the G2 and P[4] (sub)lineages showed some temporal variations. This study provides further evidence for the great genetic diversity among G2P[4] strains and helps understand the epidemiological trends of these strains among children in Taiwan.