Dengue is an acute illness caused by the positive-strand RNA dengue virus (DENV). There are four genetically distinct DENVs (DENV-1-4) that cause disease in tropical and subtropical countries. Most ...patients are viremic when they present with symptoms; therefore, RT-PCR has been increasingly used in dengue diagnosis. The CDC DENV-1-4 RT-PCR Assay has been developed as an in-vitro diagnostic platform and was recently approved by the US Food and Drug Administration (FDA) for detection of dengue in patients with signs or symptoms of mild or severe dengue. The primers and probes of this test have been designed to detect currently circulating strains of DENV-1-4 from around the world at comparable sensitivity. In a retrospective study with 102 dengue cases confirmed by IgM anti-DENV seroconversion in the convalescent sample, the RT-PCR Assay detected DENV RNA in 98.04% of the paired acute samples. Using sequencing as a positive indicator, the RT-PCR Assay had a 97.92% positive agreement in 86 suspected dengue patients with a single acute serum sample. After extensive validations, the RT-PCR Assay performance was highly reproducible when evaluated across three independent testing sites, did not produce false positive results for etiologic agents of other febrile illnesses, and was not affected by pathological levels of potentially interfering biomolecules. These results indicate that the CDC DENV-1-4 RT-PCR Assay provides a reliable diagnostic platform capable for confirming dengue in suspected cases.
BACKGROUND: In 2007, a total of 10,508 suspected dengue cases were reported in Puerto Rico. Blood donations were tested for dengue virus (DENV) RNA and recipients of RNA‐positive donations traced to ...assess transfusion transmission.
STUDY DESIGN AND METHODS: Blood donation samples from 2007 were maintained in a repository and tested individually for DENV RNA by transcription‐mediated amplification (TMA); a subset was further tested by an enhanced TMA (eTMA) assay. TMA‐reactive samples were considered confirmed if TMA (including eTMA) was repeat reactive (RR). All TMA‐RR samples were tested by quantitative, DENV type–specific reverse transcriptase–polymerase chain reaction (RT‐PCR) and for anti‐DENV immunoglobulin (Ig)M by enzyme‐linked immunosorbent assay. Samples positive by RT‐PCR were further tested for infectivity in mosquito cell culture. Patients receiving components from TMA‐RR donations were followed.
RESULTS: Of 15,350 donation samples tested, 29 were TMA‐RR for a prevalence of 1 per 529 (0.19%). DENV Types 1, 2, and 3 with viral titers of 105 to 109 copies/mL were detected by RT‐PCR in 12 samples of which all were infectious in mosquito culture. Six TMA‐RR samples were IgM positive. Three of the 29 recipients receiving TMA‐RR donations were tested. One recipient in Puerto Rico transfused with red blood cells containing 108 copies/mL DENV‐2 became febrile 3 days posttransfusion and developed dengue hemorrhagic fever. The recipient was DENV‐2 RNA positive by RT‐PCR; both the donor and the recipient viruses had identical envelope sequences.
CONCLUSIONS: High rates of viremia were detected in blood donors in Puerto Rico coupled with the first documented transfusion transmission of severe dengue disease, suggesting that further research on interventions is needed.
The emergence and spread of Zika virus (ZIKV) presented a challenge to the diagnosis of ZIKV infections in areas with transmission of dengue (DENV) and chikungunya (CHIKV) viruses. To facilitate ...detection of ZIKV infections, and differentiate these infections from DENV and CHIKV, we developed the Trioplex real-time RT-PCR assay (Trioplex assay). Here, we describe the optimization of multiplex and singleplex formats of the assay for a variety of chemistries and instruments to facilitate global standardization and implementation. We evaluated the analytical performance of all Trioplex modalities for detection of these three pathogens in serum and whole blood, and for ZIKV in urine. The limit of detection for the three viruses and in different RNA-extraction modalities is near 10
genome copy equivalents per milliliter (GCE/mL). Simultaneous testing of more than one specimen type from each patient provides a 6.4% additional diagnostic sensitivity. Overall, the high sensitivity of the Trioplex assay demonstrates the utility of this assay ascertaining Zika cases.
The flaviviruses dengue, West Nile, and Japanese encephalitis represent three major mosquito-borne viruses worldwide. These pathogens impact the lives of millions of individuals and potentially could ...affect non-endemic areas already colonized by mosquito vectors. Unintentional transport of infected vectors (
Aedes
and
Culex
spp.), traveling within endemic areas, rapid adaptation of the insects into new geographic locations, climate change, and lack of medical surveillance have greatly contributed to the increase in flaviviral infections worldwide. The mechanisms by which flaviviruses alter the immune and the central nervous system have only recently been examined despite the alarming number of infections, related deaths, and increasing global distribution. In this review, we will discuss the expansion of the geographic areas affected by flaviviruses, the potential threats to previously unaffected countries, the mechanisms of pathogenesis, and the potential therapeutic interventions to limit the devastating consequences of these viruses.
We reconstructed the SARS-CoV-2 epidemic caused by Omicron variant in Puerto Rico by sampling genomes collected during October 2021-May 2022. Our study revealed that Omicron BA.1 emerged and replaced ...Delta as the predominant variant in December 2021. Increased transmission rates and a dynamic landscape of Omicron sublineage infections followed.
The four genetically divergent dengue virus (DENV) types are traditionally classified as serotypes. Antigenic and genetic differences among the DENV types influence disease outcome, vaccine-induced ...protection, epidemic magnitude, and viral evolution. We characterized antigenic diversity in the DENV types by antigenic maps constructed from neutralizing antibody titers obtained from African green monkeys and after human vaccination and natural infections. Genetically, geographically, and temporally, diverse DENV isolates clustered loosely by type, but we found that many are as similar antigenically to a virus of a different type as to some viruses of the same type. Primary infection antisera did not neutralize all viruses of the same DENV type any better than other types did up to 2 years after infection and did not show improved neutralization to homologous type isolates. That the canonical DENV types are not antigenically homogeneous has implications for vaccination and research on the dynamics of immunity, disease, and the evolution of DENV.
Chikungunya virus (CHIKV) caused a large outbreak in Puerto Rico in 2014, followed by a Zika virus (ZIKV) outbreak in 2016. Communities Organized for the Prevention of Arboviruses (COPA) is a cohort ...study in southern Puerto Rico, initiated in 2018 to measure arboviral disease risk and provide a platform to evaluate interventions. To identify risk factors for infection, we assessed prevalence of previous CHIKV infection and recent ZIKV and DENV infection in a cross-sectional study among COPA participants. Participants aged 1-50 years (y) were recruited from randomly selected households in study clusters. Each participant completed an interview and provided a blood specimen, which was tested by anti-CHIKV IgG ELISA assay and anti-ZIKV and anti-DENV IgM MAC-ELISA assays. We assessed individual, household, and community factors associated with a positive result for CHIKV or ZIKV after adjusting for confounders. During 2018-2019, 4,090 participants were enrolled; 61% were female and median age was 28y (interquartile range IQR: 16-41). Among 4,035 participants tested for CHIKV, 1,268 (31.4%) had evidence of previous infection. CHIKV infection prevalence was lower among children 1-10 years old compared to people 11 and older (adjusted odds ratio aOR 2.30; 95% CI 1.71-3.08). Lower CHIKV infection prevalence was associated with home screens (aOR 0.51; 95% CI 0.42-0.61) and air conditioning (aOR 0.64; 95% CI 0.54-0.77). CHIKV infection prevalence also varied by study cluster of residence and insurance type. Few participants (16; 0.4%) had evidence of recent DENV infection by IgM. Among 4,035 participants tested for ZIKV, 651 (16%) had evidence of recent infection. Infection prevalence increased with older age, from 7% among 1-10y olds up to 19% among 41-50y olds (aOR 3.23; 95% CI 2.16-4.84). Males had an increased risk of Zika infection prevalence compared with females (aOR 1.31; 95% CI 1.09-1.57). ZIKV infection prevalence also decreased with the presence of home screens (aOR 0.66; 95% CI 0.54-0.82) and air conditioning (aOR 0.69; 95% CI 0.57-0.84). Similar infection patterns were observed for recent ZIKV infection prevalence and previous CHIKV infection prevalence by age, and the presence of screens and air conditioners in the home decreased infection risk from both viruses by as much as 50%.
We reconstructed the 2016-2017 Zika virus epidemic in Puerto Rico by using complete genomes to uncover the epidemic's origin, spread, and evolutionary dynamics. Our study revealed that the epidemic ...was propelled by multiple introductions that spread across the island, intricate evolutionary patterns, and ≈10 months of cryptic transmission.
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