No abstract

No abstract

An epidemic of Zika virus (ZIKV) illness that occurred in July 2007 on Yap Island in the Federated States of Micronesia prompted entomological studies to identify both the primary vector(s) involved in transmission and the ecological parameters contributing to the outbreak. Larval and pupal surveys were performed to identify the major containers serving as oviposition habitat for the likely vector(s). Adult mosquitoes were also collected by backpack aspiration, light trap, and gravid traps at select sites around the capital city. The predominant species found on the island was Aedes (Stegomyia) hensilli. No virus isolates were obtained from the adult field material collected, nor did any of the immature mosquitoes that were allowed to emerge to adulthood contain viable virus or nucleic acid. Therefore, laboratory studies of the probable vector, Ae. hensilli, were undertaken to determine the likelihood of this species serving as a vector for Zika virus and other arboviruses. Infection rates of up to 86%, 62%, and 20% and dissemination rates of 23%, 80%, and 17% for Zika, chikungunya, and dengue-2 viruses respectively, were found supporting the possibility that this species served as a vector during the Zika outbreak and that it could play a role in transmitting other medically important arboviruses.

Cross-reactivity within flavivirus antibody assays, produced by shared epitopes in the envelope proteins, can complicate the serological diagnosis of Zika virus (ZIKAV) infection. We assessed the utility of the plaque reduction neutralization test (PRNT) to confirm recent ZIKAV infections and rule out misleading positive immunoglobulin M (IgM) results in areas with various levels of past dengue virus (DENV) infection incidence. We reviewed PRNT results of sera collected for diagnosis of ZIKAV infection from 1 January through 31 August 2016 with positive ZIKAV IgM results, and ZIKAV and DENV PRNTs were performed. PRNT result interpretations included ZIKAV, unspecified flavivirus, DENV infection, or negative. For this analysis, ZIKAV IgM was considered false positive for samples interpreted as a DENV infection or negative. In U.S. states, 208 (27%) of 759 IgM-positive results were confirmed to be ZIKAV compared to 11 (21%) of 52 in the U.S. Virgin Islands (USVI), 15 (15%) of 103 in American Samoa, and 13 (11%) of 123 in Puerto Rico. In American Samoa and Puerto Rico, more than 80% of IgM-positive results were unspecified flavivirus infections. The false-positivity rate was 27% in U.S. states, 18% in the USVI, 2% in American Samoa, and 6% in Puerto Rico. In U.S. states, the PRNT provided a virus-specific diagnosis or ruled out infection in the majority of IgM-positive samples. Almost a third of ZIKAV IgM-positive results were not confirmed; therefore, providers and patients must understand that IgM results are preliminary. In territories with historically higher rates of DENV transmission, the PRNT usually could not differentiate between ZIKAV and DENV infections.

G lobally, over 2.5 billion people are estimated to be at risk of dengue virus (DENV) infection with an estimated 96 million symptomatic cases of dengue occurring annually (1). Despite ongoing research efforts, there are no sustainable vector control approaches or effective antiviral drugs to prevent or treat dengue, and vaccines have only recently been licensed by few countries and with suboptimal efficacy (2, 3, 4, 5). However, improvements in patient clinical management has been shown to reduce mortality among patients with severe dengue from 5% to Ͻ0.5% (6-9).Delayed dengue case identification often occurs in areas with limited diagnostics or surveillance resources, especially where dengue outbreaks are episodic or have been under-recognized (e.g., Africa and Oceania) (10, 11). These factors decrease health care provider awareness to include dengue in the differential diagnosis with other acute febrile illnesses (AFIs) such as malaria, leptospirosis, and influenza (12). Lastly, minimal or no laboratory infrastructure to conduct standard dengue diagnostic assays or perform them in a timely manner limits their utility for case management (13).Laboratory diagnosis of dengue can be achieved with a single serum specimen obtained during the febrile phase of the illness by testing for DENV analytes (e.g., nucleic acid, nonstructural protein 1 [NS1], and anti-DENV IgM) (14). DENV viremia occurs for up to 7 days after the onset of fever, and anti-DENV IgM begins to appear around 3 days after fever onset (15, 16). Although detection of DENV nucleic acid by real-time reverse transcriptase PCR (rRT-PCR) is the most sensitive and specific means to detect DENV viremia (17), immunoassays to detect DENV NS1 antigen provide acceptable levels of detection sensitivity and specificity (18,19). Immunoassays with good sensitivities and specificities to detect anti-DENV IgM are also widely available (20). However, both of these diagnostic approaches are instrument dependent and require facilities capable of performing complex diagnostic tests.The availability of dengue rapid diagnostic tests (RDTs) has the potential to change the current situation in resource-limited areas and improve dengue clinical management. We evaluated an RDT that detected both DENV NS1 antigen and anti-DENV IgM for its ability to provide accurate information for detecting dengue from outbreaks as the main cause of febrile illness in areas without ongoing laboratory testing. In all settings, a suspected dengue case was defined as a person with an AFI presenting for medical care. Serum specimens were collected from all suspected dengue cases upon initial presentation along with patient demographics, days post onset of illness (DPO), and specimen collection date (Table 1). Second convalescent specimens were not collected for patients, and only specimens collected upon patient presentation to hospital or clinic were used in this study. MATERIALS AND METHODS Study design. The Centers for Disease Control and PreventionDiagnostic testing. The RDT used during each ...

On 23 May 2011, CDC identified a multistate cluster of Salmonella Heidelberg infections and two multidrug-resistant (MDR) isolates from ground turkey retail samples with indistinguishable pulsed-field gel electrophoresis patterns. We defined cases as isolation of outbreak strains in persons with illness onset between 27 February 2011 and 10 November 2011. Investigators collected hypothesis-generating questionnaires and shopper-card information. Food samples from homes and retail outlets were collected and cultured. We identified 136 cases of S. Heidelberg infection in 34 states. Shopper-card information, leftover ground turkey from a patient's home containing the outbreak strain and identical antimicrobial resistance profiles of clinical and retail samples pointed to plant A as the source. On 3 August, plant A recalled 36 million pounds of ground turkey. This outbreak increased consumer interest in MDR Salmonella infections acquired through United States-produced poultry and played a vital role in strengthening food safety policies related to Salmonella and raw ground poultry.

No abstract

No abstract