Japanese Encephalitis Virus Transmitted Via Blood Transfusion, Hong Kong, China.

Japanese encephalitis virus (JEV) is a mosquitoborne virus endemic to China and Southeast Asia that causes severe encephalitis in <1% of infected persons. Transmission of JEV via blood transfusion has not been reported. We report transmission of JEV via blood donation products from an asymptomatic viremic donor to 2 immunocompromised recipients. One recipient on high-dose immunosuppressive drugs received JEV-positive packed red blood cells after a double lung transplant; severe encephalitis and a poor clinical outcome resulted. JEV RNA was detected in serum, cerebrospinal fluid, and bronchoalveolar lavage fluid specimens. The second recipient had leukemia and received platelets after undergoing chemotherapy. This patient was asymptomatic; JEV infection was confirmed in this person by IgM seroconversion. This study illustrates that, consistent with other pathogenic flaviviruses, JEV can be transmitted via blood products. Targeted donor screening and pathogen reduction technologies could be used to prevent transfusion-transmitted JEV infection in highly JEV-endemic areas.

Population-Based Pediatric Hospitalization Burden of Lineage-Specific Influenza B in Hong Kong, 2004-2014.

BACKGROUND: Influenza B virus has been perceived to cause less disease burden and milder disease compared with influenza A, but recent studies suggest that influenza B does have a significant impact. We aimed to estimate the burden of influenza B virus infections on hospitalizations in Hong Kong, in the context of virus lineage changes over time. METHODS: The pediatric age-specific rates of influenza B hospitalization in Hong Kong for 2004-2014 were estimated based on admissions to 2 hospitals that together catered for 72.5% of all pediatric admissions on Hong Kong Island. Influenza B virus was detected by immunofluorescence and culture on nasopharyngeal aspirates. Lineage typing was performed by real-time reverse-transcription polymerase chain reaction. RESULTS: A total of 5085 children were recruited on 1 designated day each week, year-round during the 11 years, and 221 (4.3%) tested positive for influenza B. Hospitalization rates were highest in children aged 2 to <5 years with year-to-year variation. Victoria-lineage viruses appeared to be associated with a greater fraction of influenza B hospitalizations in children than of influenza B infections in the general community. Influenza B did not cause significant hospitalization in infants <1 year of age. CONCLUSIONS: We report one of the first population-based, age- and lineage-specific studies of pediatric hospitalization for influenza B. We found that changes in lineage were associated with higher hospitalization rates and documented that Victoria lineage viruses were associated with greater pediatric hospitalization burden compared with Yamagata lineage viruses.

First Report of a Fatal Case Associated with EV-D68 Infection in Hong Kong and Emergence of an Interclade Recombinant in China Revealed by Genome Analysis.

A fatal case associated with enterovirus D68 (EV-D68) infection affecting a 10-year-old boy was reported in Hong Kong in 2014. To examine if a new strain has emerged in Hong Kong, we sequenced the partial genome of the EV-D68 strain identified from the fatal case and the complete VP1, and partial 5'UTR and 2C sequences of nine additional EV-D68 strains isolated from patients in Hong Kong. Sequence analysis indicated that a cluster of strains including the previously recognized A2 strains should belong to a separate clade, clade D, which is further divided into subclades D1 and D2. Among the 10 EV-D68 strains, 7 (including the fatal case) belonged to the previously described, newly emerged subclade B3, 2 belonged to subclade B1, and 1 belonged to subclade D1. Three EV-D68 strains, each from subclades B1, B3, and D1, were selected for complete genome sequencing and recombination analysis. While no evidence of recombination was noted among local strains, interclade recombination was identified in subclade D2 strains detected in mainland China in 2008 with VP2 acquired from clade A. This study supports the reclassification of subclade A2 into clade D1, and demonstrates interclade recombination between clades A and D2 in EV-D68 strains from China.

Recombinant coxsackievirus A2 and deaths of children, Hong Kong, 2012.

A natural recombinant of coxsackievirus A2 was found in 4 children with respiratory symptoms in Hong Kong, China, during the summer of 2012. Two of these children died. Vigilant monitoring of this emerging recombinant enterovirus is needed to prevent its transmission to other regions.

Genetic characterization of EV71 isolates from 2004 to 2010 reveals predominance and persistent circulation of the newly proposed genotype D and recent emergence of a distinct lineage of subgenotype C2 in Hong Kong.

BACKGROUND: Enterovirus 71 (EV71) is a common etiological agent of hand, foot and mouth disease (HFMD) in children. EV71 epidemics have been reported in Hong Kong in recent years, and yet the genetic information of EV71 strains circulating in our locality is limited. The objective of this study was to investigate the genetic evolution of these EV71 isolates in Hong Kong over a 7-year period. METHODS: Twenty-two EV71 isolates from Hong Kong during 2004-2010 were included for phylogenetic analysis using partial VP2-VP3, 2C and 3D regions. Eight EV71 strains were selected for complete genome sequencing and recombination analysis. RESULTS: Among the 22 EV71 isolates, 20 belonged to subgenotype C4 and 2 belonged to subgenotype C2 based on the phylogenetic analysis of partial VP2-VP3, 2C and 3D gene regions. Phylogenetic, similarity plot and bootscan analyses using complete genome sequences of seven EV71 isolates of subgenotype C4 supported that the "double-recombinant" strains of subgenotype C4 persistently circulating in Hong Kong should belong to a newly proposed genotype D. Further analysis revealed two clusters, subgenotypes C4b and C4a (proposed genotypes D1a and D1b respectively), with "genotype D1b" strains being predominant in recent years in Hong Kong. A distinct lineage of EV71 subgenotype C2 has emerged in Hong Kong in 2008. The evolutionary rate of EV71 was 3.1 × 10-3 nucleotide substitutions per site per year similar to that of other enterovirus, such as EV68, but was relatively lower than those of echovirus 30 and poliovirus. Molecular clock analysis using VP1 gene dated the time to the most recent common ancestor of all EV71 genotypes to 1900s, while the EV71 "double-recombinant" strains of "genotype D" were detected as early as 1998. CONCLUSIONS: This study provides the molecular basis for proposing a new "genotype D" of EV71 and assigning a discrete lineage of subgenotype C2. EV71 strains of "genotype D" have been circulating in Hong Kong for over 7 years, with "genotype D1b" being predominant.

Scarlet fever epidemic, Hong Kong, 2011.

More than 900 cases of scarlet fever were recorded in Hong Kong during January-July, 2011. Six cases were complicated by toxic shock syndrome, of which 2 were fatal. Pulsed-field gel electrophoresis patterns suggested a multiclonal epidemic; emm12 was the predominant circulating type. We recommend genetic testing of and antimicrobial resistance monitoring for this reportable disease.

Hong Kong experiences the 'Ultimate superbug': NDM-1 Enterobacteriaceae.

We report the second imported case of New Delhi metallo-beta-lactamase (NDM-1) Enterobacteriaceae encountered in Hong Kong soon after the patient's arrival in the territory for medical care. As NDM-1 is spreading throughout the world via international travel, being an international city, Hong Kong was always expected to encounter the same public health threat. This case also illustrates the importance of active surveillance of at-risk patients in preventing the spread of this 'superbug'.

Ceftibuten resistance and treatment failure of Neisseria gonorrhoeae infection.

Neisseria gonorrhoeae infections have been empirically treated in Hong Kong with a single oral 400-mg dose of ceftibuten since 1997. Following anecdotal reports of the treatment failure of gonorrhea with oral extended-spectrum cephalosporins, the current study was undertaken to determine the antimicrobial susceptibility pattern and molecular characteristics of isolates of N. gonorrhoeae among patients with putative treatment failure in a sexually transmitted disease clinic setting. Between October 2006 and August 2007, 44 isolates of N. gonorrhoeae were studied from patients identified clinically to have treatment failure with empirical ceftibuten. The ceftibuten MICs for three strains were found to have been 8 mg/liter. These strains were determined by N. gonorrhoeae multiantigen sequence typing to belong to sequence type 835 (ST835) or the closely related ST2469. The testing of an additional eight archived ST835 strains revealed similarly elevated ceftibuten MICs. The penA gene sequences of these 11 isolates all had the mosaic pattern previously described as pattern X. Of note is that the ceftriaxone susceptibility results of these strains all fell within the susceptible range. It is concluded that ceftibuten resistance may contribute to the empirical treatment failure of gonorrhea caused by strains harboring the mosaic penA gene, which confers reduced susceptibility to oral extended-spectrum cephalosporins. Screening for such resistance in the routine clinical laboratory may be undertaken by the disk diffusion test. The continued monitoring of antimicrobial resistance and molecular characteristics of N. gonorrhoeae isolates is important to ensure that control and prevention strategies remain effective.

Human tryptophanyl-tRNA synthetase is an IFN-γ-inducible entry factor for Enterovirus.

Enterovirus A71 (EV-A71) receptors that have been identified to date cannot fully explain the pathogenesis of EV-A71, which is an important global cause of hand, foot, and mouth disease and life-threatening encephalitis. We identified an IFN-γ-inducible EV-A71 cellular entry factor, human tryptophanyl-tRNA synthetase (hWARS), using genome-wide RNAi library screening. The importance of hWARS in mediating virus entry and infectivity was confirmed by virus attachment, in vitro pulldown, antibody/antigen blocking, and CRISPR/Cas9-mediated deletion. Hyperexpression and plasma membrane translocation of hWARS were observed in IFN-γ-treated semipermissive (human neuronal NT2) and cDNA-transfected nonpermissive (mouse fibroblast L929) cells, resulting in their sensitization to EV-A71 infection. Our hWARS-transduced mouse infection model showed pathological changes similar to those seen in patients with severe EV-A71 infection. Expression of hWARS is also required for productive infection by other human enteroviruses, including the clinically important coxsackievirus A16 (CV-A16) and EV-D68. This is the first report to our knowledge on the discovery of an entry factor, hWARS, that can be induced by IFN-γ for EV-A71 infection. Given that we detected high levels of IFN-γ in patients with severe EV-A71 infection, our findings extend the knowledge of the pathogenicity of EV-A71 in relation to entry factor expression upon IFN-γ stimulation and the therapeutic options for treating severe EV-A71-associated complications.

Corynebacterium kroppenstedtii Is an Emerging Cause of Mastitis Especially in Patients With Psychiatric Illness on Antipsychotic Medication.

This retrospective study of patients with Corynebacterium kroppenstedtii infections revealed a predominance of mastitis and a potential association with psychiatric illnesses. At least one third of our patients with C kroppenstedtii mastitis had psychiatric illness, and >92% received antipsychotic medications. Drug-induced hyperprolactinemia may be an important modifiable risk factor in these patients.

Hospital-based vaccine effectiveness against influenza B lineages, Hong Kong, 2009-14.

BACKGROUND: We estimated vaccine effectiveness (VE) against pediatric influenza B hospitalizations in Hong Kong year round between November 2001 and October 2014. METHODS: We conducted a test-negative year-round study, enrolling children 6 months to 17 years of age admitted to two hospitals in Hong Kong with a febrile acute respiratory infection. Children were tested for influenza A and B. Conditional logistic regression was used to estimate overall and lineage-specific vaccine effectiveness comparing influenza vaccination history of the trivalent influenza vaccine (TIV) among patients testing positive for influenza B versus negative for influenza A and B, adjusting for age and sex and matching by calendar week of recruitment. RESULTS: Of the 6013 children included in the analysis, 262 tested positive for influenza B. Vaccination coverage was low: 6.5% in the influenza B positive children when compared with 8.8% in children who tested negative for both influenza A and B (p=0.248). Overall, VE was 47.6% (95% CI: 10.0, 69.4%) against influenza B hospitalization despite variable co-circulation of both lineages in all years. VE for Victoria-like virus calculated from 3 years when the vaccine was lineage-matched was 59.1% (95% CI: 6.2, 82.2%). Lineage-matched VE for Yamagata-like virus was -8.8% (95% CI: -215.4, 62.5%) in a clade mismatch season. With wide confidence intervals, we were unable to demonstrate cross-lineage protection: VE against the mismatched B/Yamagata-like virus was 9.5% (95% CI: -240.4, 76.0%) in 2011/12 and against mismatched B/Victoria-like virus in 2013/14 was 42.7% (95% CI: -368.6, 93.0%). CONCLUSIONS: TIV conferred an overall VE of 47.6% (95% CI: 10.0, 69.4%) against influenza B hospitalization in children despite variable co-circulation of both lineages in all years. Lineage-matched VE for Yamagata-like virus was poor and may be related to clade mismatch. Cross-lineage protection was not observed.

Acute fulminant subacute sclerosing panencephalitis with absent measles and PCR studies in cerebrospinal fluid.

This report describes an atypical case of rapidly progressive subacute sclerosing panencephalitis presenting as transient visual agnosia and myoclonus in a 14-year-old male. There were no typical periodic complexes in serial electroencephalographic monitoring; cerebrospinal fluid measles antibody titer was negative. The diagnosis was made by molecular and histologic examination of open brain biopsy tissue.

Ciguatera fish poisoning in Hong Kong--a 10-year perspective on the class of ciguatoxins.

The present study used liquid chromatography-tandem mass spectrometry (LC-MS/MS) to investigate retrospectively ciguatoxin (CTX)-positive samples as determined by mouse bioassay (MBA) in the past 10 years in Hong Kong. The results showed that Pacific CTXs (P-CTX-1, -2 and -3) were the most commonly observed toxins found in the samples, indicating Pacific Ocean areas as the most important origin of ciguatera fish poisoning. Clinical diagnosis from ciguatera patients also revealed the predominance of neurological illnesses in most cases, supporting intoxication of Pacific origin. This study demonstrated the ability of laboratory analysis to identify and quantify Pacific CTXs in suspected fish samples, so as to support the clinical diagnosis of ciguatera. Comparative analysis (Student's t-test and Spearman's rank correlation analysis) on the two CTX detection methods showed approximate linearity for overall P-CTXs (P-CTX-1, -2 and -3)/P-CTX-1 alone as derived by LC-MS/MS and total toxicity levels (P-CTX-1 equivalent) as determined by MBA. The LC-MS/MS method coupled with the rapid extraction method could allow the detection of trace amount of CTXs at levels below the clinically relevant limit, 0.1 ppb P-CTX-1 in fish flesh. For practical application, the adoption of a two-tiered approach for testing, chemical analysis by LC-MS/MS for toxic fish screening, coupled with biological assay by MBA for final toxicity confirmation, was proposed for first-line screening of CTX in potentially contaminated fish samples in the market, with an aim to minimizing the use of laboratory mice and at the same time providing reasonably effective means for routine analysis.

The effectiveness of influenza vaccination in preventing hospitalizations in children in Hong Kong, 2009-2013.

BACKGROUND: Influenza vaccination is widely recommended every year to protect individuals against influenza virus infection and illness. There are few published estimates of influenza vaccine effectiveness against hospitalization in children or from subtropical regions. METHODS: We conducted a test-negative year-round study between October 2009 and September 2013, recruiting children 6 months to 17 years of age admitted to two hospitals in Hong Kong with a febrile acute respiratory infection. Cases were tested for influenza A and B and conditional logistic regression was used to estimate vaccine effectiveness comparing influenza vaccination history of the trivalent influenza vaccine (TIV) among patients testing positive versus negative for influenza, adjusting for age and sex and matching by calendar week of recruitment. RESULTS: Overall vaccine effectiveness against hospitalization with laboratory-confirmed influenza A and B was estimated to be 61.7% (95% CI: 43.0%, 74.2%). The estimated vaccine effectiveness against A(H3N2) was 36.6% (95% CI: -25.5%, 67.9%) compared to 71.5% (95% CI: 39.4%, 86.6%) for A(H1N1)pdm09 and 68.8% (95% CI: 41.6%, 83.3%) for B. CONCLUSIONS: Vaccine effectiveness against hospitalization in children varied from year to year, but was moderate to high overall even in an area with influenza activity throughout the year.

Population-based hospitalization burden of influenza a virus subtypes and antigenic drift variants in children in Hong Kong (2004-2011).

OBJECTIVES: We aim to document and analyze influenza hospitalization burden in light of antigenic changes in circulating influenza viruses in Hong Kong. METHODS: The pediatric age-specific rates of influenza A hospitalization in Hong Kong for 2004-2011 which encompassed the emergence of H1N1pdm09 were extrapolated from admissions to 2 hospitals that together catered for 72.5% of all pediatric admissions on Hong Kong Island. Influenza A was detected by immunofluorescence, culture and/or PCR on nasopharyngeal aspirates. RESULTS: Influenza A caused high rates of hospitalization in children with year to year fluctuations. The highest hospitalization burden was seen with H1N1pdm09 in 2009. Additional factors affecting hospitalization were the proportion of viral circulation among different subtypes, and antigenic drifts. Taking these into effect, an H3N2 dominated year was not always associated with more hospitalizations than a 'seasonal' H1N1 year. Hospitalization burden was higher in seasons when drifted viruses of H1N1 or H3N2 dominated. No hospitalization was documented in infants <6 months of age during years when an undrifted virus circulated (2006 for H1N1 and 2008 for H3N2) but significant hospitalization was observed with a drifted or shifted virus (2004, 2005, 2007 and 2010 for H3N2, and 2009 for H1N1pdm09). CONCLUSIONS: We documented a consistently high pediatric hospitalization burden of influenza A. Knowledge of antigenic changes and their proportion of circulation aids in the interpretation of impact of the subtypes. Year-to-year variation in hospitalization rates in young infants appeared to correlate with antigenic variation, lending support to the role of protection from maternal antibodies.

A novel psittacine adenovirus identified during an outbreak of avian chlamydiosis and human psittacosis: zoonosis associated with virus-bacterium coinfection in birds.

Chlamydophila psittaci is found worldwide, but is particularly common among psittacine birds in tropical and subtropical regions. While investigating a human psittacosis outbreak that was associated with avian chlamydiosis in Hong Kong, we identified a novel adenovirus in epidemiologically linked Mealy Parrots, which was not present in healthy birds unrelated to the outbreak or in other animals. The novel adenovirus (tentatively named Psittacine adenovirus HKU1) was most closely related to Duck adenovirus A in the Atadenovirus genus. Sequencing showed that the Psittacine adenovirus HKU1 genome consists of 31,735 nucleotides. Comparative genome analysis showed that the Psittacine adenovirus HKU1 genome contains 23 open reading frames (ORFs) with sequence similarity to known adenoviral genes, and six additional ORFs at the 3' end of the genome. Similar to Duck adenovirus A, the novel adenovirus lacks LH1, LH2 and LH3, which distinguishes it from other viruses in the Atadenovirus genus. Notably, fiber-2 protein, which is present in Aviadenovirus but not Atadenovirus, is also present in Psittacine adenovirus HKU1. Psittacine adenovirus HKU1 had pairwise amino acid sequence identities of 50.3-54.0% for the DNA polymerase, 64.6-70.7% for the penton protein, and 66.1-74.0% for the hexon protein with other Atadenovirus. The C. psittaci bacterial load was positively correlated with adenovirus viral load in the lung. Immunostaining for fiber protein expression was positive in lung and liver tissue cells of affected parrots, confirming active viral replication. No other viruses were found. This is the first documentation of an adenovirus-C. psittaci co-infection in an avian species that was associated with a human outbreak of psittacosis. Viral-bacterial co-infection often increases disease severity in both humans and animals. The role of viral-bacterial co-infection in animal-to-human transmission of infectious agents has not received sufficient attention and should be emphasized in the investigation of disease outbreaks in human and animals.