Dengue fever

About: Dengue fever is a research topic. Over the lifetime, 17463 publications have been published within this topic receiving 485745 citations. The topic is also known as: Dengue & dengue disease.

Immature Dengue Virus: A Veiled Pathogen?

Abstract: Cells infected with dengue virus release a high proportion of immature prM-containing virions. In accordance, substantial levels of prM antibodies are found in sera of infected humans. Furthermore, it has been recently described that the rates of prM antibody responses are significantly higher in patients with secondary infection compared to those with primary infection. This suggests that immature dengue virus may play a role in disease pathogenesis. Interestingly, however, numerous functional studies have revealed that immature particles lack the ability to infect cells. In this report, we show that fully immature dengue particles become highly infectious upon interaction with prM antibodies. We demonstrate that prM antibodies facilitate efficient binding and cell entry of immature particles into Fc-receptor-expressing cells. In addition, enzymatic activity of furin is critical to render the internalized immature virus infectious. Together, these data suggest that during a secondary infection or primary infection of infants born to dengue-immune mothers, immature particles have the potential to be highly infectious and hence may contribute to the development of severe disease.

Evaluation of an Enzyme Immunoassay for Detection of Dengue Virus NS1 Antigen in Human Serum

Abstract: We evaluated a one-step sandwich-format microplate enzyme immunoassay for detecting dengue virus NS1 antigen (Ag) in human serum by use of Platelia Dengue NS1 Ag kits (Bio-Rad Laboratories, Marnes La Coquette, France). We collected 299 serum samples from patients with dengue disease and 50 serum samples from patients not infected with dengue virus. For the 239 serum samples from patients with acute infections testing positive by reverse transcription-PCR and/or virus isolation for one of the four dengue virus serotypes, the sensitivity of the Platelia Dengue NS1 Ag kit was 88.7% (95% confidence interval, 84.0% to 92.4%). None of the serum samples from patients not infected with dengue virus tested positive with the Platelia Dengue NS1 Ag kit. A diagnostic strategy combining the Platelia Dengue NS1 Ag test for acute-phase sera and immunoglobulin M capture enzyme-linked immunosorbent assay for early-convalescent-phase sera increased sensitivity only from 88.7% to 91.9%. Thus, NS1 antigen detection with the Platelia Dengue NS1 Ag kit could be used for first-line testing for acute dengue virus infection in clinical diagnostic laboratories.

Zika virus infection, Cambodia, 2010.

Abstract: To the Editor: Zika virus (ZIKV), a member of the family Flaviviridae, genus Flavivirus, was first isolated from the blood of a sentinel rhesus monkey from the Zika Forest of Uganda in 1948 (1). Since that time, serologic studies and virus isolations have demonstrated that the virus has a wide geographic distribution, including eastern and western Africa; the Indian subcontinent; Southeast Asia; and most recently, Micronesia (2–5). The virus is transmitted primarily through the bite of infected mosquitoes and most likely is maintained in a zoonotic cycle involving nonhuman primates (1), although recent evidence suggests the possibility of occasional sexual transmission in humans (4). Few case reports have described the clinical characteristics of ZIKV infection in humans. Most reports describe a self-limiting febrile illness that could easily be mistaken for another arboviral infection, such as dengue or chikungunya fever. We report a confirmed case of ZIKV infection in Cambodia. Since 2006, the US Naval Medical Research Unit No. 2 (NAMRU-2) has conducted surveillance for acute fever to determine causes of the infection among patients who seek health care at local clinics in Cambodia. Patients were enrolled by the health clinic physician after they gave informed consent in accordance with an institutional review board protocol approved by NAMRU-2 and the National Ethics Committee for Human Research of Cambodia. At enrollment, the physician administered a questionnaire and collected specimens (blood and throat swabs). All items were transported to the NAMRU-2 laboratory in Phnom Penh, where testing was conducted for a variety of viral, bacterial, and parasitic pathogens. In August 2010, a blood specimen was collected from a 3-year-old boy at a health clinic in Kampong Speu Province, Cambodia. The child’s reported clinical symptoms included 4 days of fever and sore throat and cough and a headache for 3 days. A maculopapular rash was not observed, and the boy was not hospitalized. The clinic staff conducted a follow-up interview and reported that the patient recovered fully. ZIKV infection was confirmed in this patient by using PCR, sequencing, and serology and through virus isolation. ELISA for chikungunya and dengue virus IgM and IgG antibodies on acute- and convalescent-phase serum was negative. A universal flavivirus real-time PCR screen that targets the nonstructural (NS) 5 gene (6) determined that the patient’s serum was positive for flavivirus RNA, but subsequent species-specific PCR ruled out 2 other flaviviruses that are highly endemic to the region (dengue and Japanese encephalitis viruses) (7–9). This result was the first nondengue, non–Japanese encephalitis virus flavivirus detected after samples from ≈10,000 enrolled patients were tested. Nucleic acid sequencing of the amplicon isolated by gel purification produced a 100-bp fragment with 100% sequence identity to ZIKV (nucleotide position 8,969 of the NS5 gene of the isolate GenBank accession no. {"type":"entrez-nucleotide","attrs":{"text":"EU545988","term_id":"189092757"}}EU545988). ZIKV infection subsequently was serologically confirmed by hemagglutination-inhibition tests on paired serum samples. The patient’s acute-phase sample was negative, but a convalescent-phase sample gave a positive reaction with ZIKV antigen to a serum dilution of 1:320 and was negative to antigens for the 4 dengue serotypes and yellow fever and West Nile viruses. These results demonstrate that the patient had a clear monotypic flavivirus immune response with seroconversion against ZIKV, indicating a recent primary infection. The most common signs and symptoms reported in confirmed ZIKV infections are fever, headache, malaise, maculopapular rash, fatigue or myalgia, and arthritis and arthralgia (Table). In addition to fever and headache, the patient in this study had a sore throat and cough. Because of the patient’s age, additional information about symptoms was difficult to obtain. Table Reported or observed clinical signs and symptoms in persons with Zika virus infection, 1962–2010 The clinical characteristics exhibited by this case-patient are similar to those of shown in a small cluster of ZIKV infections described in Indonesia during 1977–1978 in which maculopapular rash was not observed (5). Maculopapular rash was reported as a common sign in case-patients from the recent Yap Island outbreak (3), as well as in case reports from Uganda (2), Senegal, and the United States (4), A case report of laboratory-acquired ZIKV infection also noted the lack of maculopapular rash (10). The clinical features of ZIKV infection are similar to those of dengue virus and chikungunya virus infections, and both arboviruses are found in Southeast Asia. In this region, laboratory-based confirmation is essential. The extent of ZIKV infections in Cambodia is unknown; further studies are needed to clarify the prevalence and geographic distribution of ZIKV infection in the country.

Global Epidemiology of Dengue Outbreaks in 1990-2015: A Systematic Review and Meta-Analysis.

Abstract: Dengue is an arthropod-borne infectious disease caused by dengue virus (DENV) infection and transmitted by Aedes mosquitoes. Approximately 50-100 million people are infected with DENV each year, resulting in a high economic burden on both governments and individuals. Here, we conducted a systematic review and meta-analysis to summarize information regarding the epidemiology, clinical characteristics, and serotype distribution and risk factors for global dengue outbreaks occurring from 1990 to 2015. We searched the PubMed, Embase and Web of Science databases through December 2016 using the term “dengue outbreak”. In total, 3853 studies were identified, of which 243 studies describing 262 dengue outbreaks met our inclusion criteria. The majority of outbreak-associated dengue cases were reported in the Western Pacific Region, particularly after the year 2010; these cases were primarily identified in China, Singapore and Malaysia. The pooled mean age of dengue-infected individuals was 30.1 years; of the included patients, 54.5% were male, 23.2% had DHF, 62.0% had secondary infections, and 1.3% died. The mean age of dengue patients reported after 2010 was older than that of patients reported before 2010 (34.0 vs 27.2 yrs); however, the proportions of patients who had DHF, had secondary infections and died significantly decreased after 2010. Fever, malaise and asthenia were the most frequently reported clinical symptoms and signs among dengue patients. In addition, among the identified clinical symptoms and signs, positive tourniquet test (OR = 4.86), ascites (OR = 13.91) and shock (OR = 308.09) were identified as the best predictors of dengue infection, DHF and mortality, respectively (both P < 0.05). The main risk factors for dengue infection, DHF and mortality were living with uncovered water container (OR = 1.65), suffering from hypotension (OR = 6.18) and suffering from diabetes mellitus (OR = 2.53), respectively (all P < 0.05). The serotype distribution varied with time and across WHO regions. Overall, co-infections were reported in 46.8% of the evaluated outbreaks, and the highest pooled mortality rate (2.0%) was identified in DENV-2 dominated outbreaks. Our study emphasizes the necessity of implementing programs focused on targeted prevention, early identification, and effective treatment.