Evaluation of eight commercial Zika virus IgM and IgG serology assays for diagnostics and research.

Several commercial Zika virus (ZIKV) serology assays have been developed since the recognition of ZIKV outbreaks as a Public Health Emergency of International Concern in 2016. However, test interpretation for ZIKV serology can be challenging due to antibody cross-reactivity with other flaviviruses like dengue virus (DENV). Therefore, we sought to evaluate the performance of eight commercially available ZIKV IgM and IgG assays across three testing platforms, namely, immunochromatographic tests (ICT), ELISAs and immunofluorescence tests (IIFT). The test panel comprised of 278 samples, including acute and convalescent sera or plasma from ZIKV-confirmed, DENV-confirmed, non-ZIKV and non-DENV patients, and residual sera from healthy blood donors. The ZIKV IgM and IgG serology assays yielded higher test sensitivities of 23.5% - 97.1% among ZIKV convalescent samples as compared to 5.6% - 27.8% among ZIKV acute samples; the test specificities were 63.3% - 100% among acute and convalescent DENV, non-DENV samples. Among the ELISAs and IIFTs, the Diapro ZIKV IgM ELISA demonstrated high test sensitivity (96%) and specificity (80%) when tested on early convalescent samples, while the Euroimmun ZIKV IgG ELISA yielded the highest test specificity of 97% - 100% on samples from non-ZIKV patients and healthy blood donors. For rapid ICTs, the LumiQuick IgM rapid ICT yielded low test sensitivity, suggesting its limited utility. We showed that commercial ZIKV IgM and IgG serology assays have differing test performances, with some having moderate to high test sensitivities and specificities when used in a dengue endemic setting, although there were limitations in IgG serology.

Force of Infection and True Infection Rate of Dengue in Singapore: Implications for Dengue Control and Management.

National data on dengue notifications do not capture all dengue infections and do not reflect the true intensity of disease transmission. To assess the true dengue infection rate and disease control efforts in Singapore, we conducted age-stratified serosurveys among residents after a 2013 outbreak that was the largest dengue outbreak on record. The age-weighted prevalence of dengue immunoglobulin G among residents was 49.8% (95% confidence interval: 48.4, 51.1) in 2013 and 48.6% (95% confidence interval: 47.0, 50.0) in 2017; prevalence increased with age. Combining these data with those from previous serosurveys, the year-on-year estimates of the dengue force of infection from 1930 to 2017 revealed a significant decrease from the late 1960s to the mid-1990s, after which the force of infection remained stable at approximately 10 per 1,000 persons per year. The reproduction number (R0) had also declined since the 1960s. The reduction in dengue transmission may be attributed to the sustained national vector program and partly to a change in the age structure of the population. The improved estimated ratio of notified cases to true infections, from 1:14 in 2005-2009 to 1:6 in 2014-2017, signifies that the national notification system, which relies on diagnosed cases, has improved over time. The data also suggest that the magnitudes of dengue epidemics cannot be fairly compared across calendar years and that the current disease control program remains applicable.

Ex vivo haemostatic capacity of plasma upon thawing and beyond: a comparison between fresh frozen plasma (FFP) and frozen plasma prepared from whole blood stored at room temperature up to 24 hours postcollection (RTFP24).

BACKGROUND/OBJECTIVES: We compared the ex vivo haemostatic capacity of RTFP24 with FFP upon thawing and >24 h post-thaw. We included thrombin generation (TG) as few studies had compared global haemostatic function, and most did not directly compare RTFP24 with FFP >24 h post-thaw. MATERIALS/METHODS: Twenty units each of RTFP24 and FFP were measured for coagulation factors and thrombin generation upon thawing (D0) and 4 days post-thaw (D4). Labile factors were also measured from D1 to D3. 10 single cryoprecipitate units were each prepared from FFP and RTFP24, and measured for FXIII, FVIII and fibrinogen at D0. RESULTS: At D0, RTFP24 was comparable to FFP except for lower FV, protein S, endogenous thrombin potential (ETP) and higher FXIII. These differences were likely clinically insignificant since 95% and 80% of RTFP24 met our laboratory's reference ranges for FV/protein S and ETP, respectively. There were no differences between RTFP24- and FFP-derived cryoprecipitate. At D4, RTFP24 was comparable to FFP except for lower FV, ETP, and higher FXI and FXIII. More RTFP24 than FFP had ETP lower than our laboratory's reference range (45% vs 15%). Multiple coagulation factors and all TG parameters declined from their respective baselines. The percentage declines were comparable or less in RTFP24, except for protein C, fibrinogen and time to peak. CONCLUSION: RTFP24 and FFP, and their derived cryoprecipitate have comparable haemostatic capacity upon thawing. RTFP24 has poorer TG potential than FFP >24 h post-thaw, not supporting universal extension of RTFP24's shelf life except to facilitate urgent transfusions for massive haemorrhage.

Hidden Drug Abuse in Hong Kong: From Social Acquaintance to Social Isolation.

The present paper examines the issue of hidden drug abuse in Hong Kong. Although official statistics show that the reported number of drug-abuse cases has been in decline in recent years, it has been reported that drug abusers tend to hide themselves at home to take drugs; thus, they are not discovered easily by the law enforcement and social control agents who report drug abuse cases to the Central Registry of Drug Abuse, resulting in the decrease in the reported number of drug-abuse cases. This "dark figure" phenomenon is a reflection of the official figure and reporting behavior, not the actual situation of drug abuse in Hong Kong. Through in-depth interviews of 30 ex-drug addicts, the majority of them started drug taking in early youth, the present paper identifies five stages of drug taking from social acquaintance to social isolation. It argues that although drug taking among abusers is a kind of social activity in their initial stage of drug use, they become socially isolated when their drug use is prolonged. Several reasons are identified, including users' easy accessibility to drugs and changes in the popularity of drugs and use of drug equipment. Most importantly, the hidden process is triggered and aggravated by numerous negative drug effects, such as decline in physical health, weak physical appearance leading to self-perceived discrimination, co-occurrence of psychiatric symptoms of increased anxiety and suspicion, and decline of trust among peers due to prolonged drug abuse. Possible solutions associated with clinical interventions, legislative policies, and law-enforcement operations are proposed.

Dengue seroprevalence of healthy adults in Singapore: serosurvey among blood donors, 2009.

Routine national notifications of dengue cases typically do not reflect the true dengue situation due to large proportion of unreported cases. Serosurveys, when conducted periodically, could shed light on the true dengue infections in the population. To determine the magnitude of dengue infections of the adult population in Singapore following the outbreak in 2007, we performed a cross-sectional study on blood donor samples from December 2009 to February 2010. The residual blood of 3,995 donors (aged 16-60 years) was screened for the presence of dengue-specific immunoglobulin G (IgG) and IgM using enzyme-linked immunosorbent assay (ELISA) kits. The age-weighted IgG prevalence of residents was 50.8% (N = 3,627, 95% confidence interval [CI] = 49.4-52.3%). Dengue IgG prevalence increased with age, with the lowest in 16-20 years age group (16.1%) and the highest in 56-60 years age group (86.6%). Plaque reduction neutralization test (PRNT) on samples of young resident adults (aged 16-30 years) revealed lower prevalence of neutralizing antibodies to each serotype, ranging from 5.4% to 20.3% compared with the older age groups. The level of exposure to dengue among the young adults is relatively low despite the endemicity of the disease in Singapore. It partially explains the population's susceptibility to explosive outbreaks and the high incidence rate among young adults.

Electroswitchable photoluminescence activity: synthesis, spectroscopy, electrochemistry, photophysics, and X-ray crystal and electronic structures of [Re(bpy)(CO)3(C[triple bond]C[bond]C6H4[bond]C[triple bond]C)Fe(C5Me5)(dppe)][PF6](n) (n = 0, 1).

A novel heterobimetallic alkynyl-bridged complex, [Re(bpy)(CO)(3)(C[triple bond]C[bond]C(6)H(4)[bond]C[triple bond]C)Fe(C(5)Me(5))(dppe)], 1, and its oxidized species, [Re(bpy)(CO)(3)(C[triple bond]C[bond]C(6)H(4)[bond]C[triple bond]C)Fe(C(5)Me(5))(dppe)][PF(6)], 2, have been synthesized and their X-ray crystal structures determined. A related vinylidene complex, [Re(bpy)(CO)(3)(C[triple bond]C[bond]C(6)H(4)[bond](H)C[double bond]C)Fe(C(5)Me(5))(dppe)][PF(6)], 3, has also been synthesized and characterized. The cyclic voltammogram of 1 shows a quasireversible reduction couple at -1.49 V (vs SCE), a fully reversible oxidation at -0.19 V, and a quasireversible oxidation at +0.88 V. In accord with the electrochemical results, density-functional theory calculations on the hydrogen-substituted model complex Re(bpy)(CO)(3)(C[triple bond]C[bond]C(6)H(4)[bond]C[triple bond]C)Fe(C(5)H(5))(dHpe) (Cp = C(5)H(5), dHpe = H(2)P[bond](CH(2))(2)[bond]PH(2)) (1-H) show that the LUMO is mainly bipyridine ligand pi* in character while the HOMO is largely iron(II) d orbital in character. The electronic absorption spectrum of 1 shows low-energy absorption at 390 nm with a 420 nm shoulder in CH(2)Cl(2), while that of 2 exhibits less intense low-energy bands at 432 and 474 nm and additional low-energy bands in the NIR at ca. 830, 1389, and 1773 nm. Unlike the related luminescent rhenium(I)-alkynyl complex [Re(bpy)(CO)(3)(C[triple bond]C[bond]C(6)H(4)[bond]C[triple bond]C[bond]H)], 4, complex 1 is found to be nonemissive, and such a phenomenon is attributed to an intramolecular quenching of the emissive d pi(Re) --> pi*(bpy) (3)MLCT state by the low-lying MLCT and LF excited states of the iron moiety. Interestingly, switching on of the luminescence property derived from the d pi(Re) --> pi*(bpy) (3)MLCT state can be demonstrated in the oxidized species 2 and the related vinylidene analogue 3 due to the absence of the quenching pathway.