Dengue virus infection: predictors for severe dengue

Dengue virus (DENV) infection is a mosquito born disease that is endemic in all WHO regions, except European region, and may present a broad range of severity. It may appear as an asymptomatic condition, dengue fever (DF), or life threatening forms, such as dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), or the currently defined severe dengue. Currently there are means to diagnose DENV infection, but there is no accurate means to early predict the progress into severe manifestations. Therefore, this article addresses the factors that might be used to predict the progress into severe dengue. Predictors for severe dengue are the previously established warning signs, and coexisting conditions, as is recommended by the WHO, in addition to Caucasian race, and people with AB blood group. In the future, viral load assessment, viral serotype testing, NS1, cytokine, elastase, hyaluronan, soluble thrombomodulin, and NO level, and circulating endothelial cell detection test are promising to be studied and developed as early predictors of severe dengue.     

Outlook of dengue in Malaysia: a century later

Dengue continues to be a major health threat to Malaysia a century after its first reported outbreak in 1902. Examination of the available outbreak data suggested that a major DF/DHF outbreak occurred in Malaysia in a cyclical pattern of approximately every 8 years. All four dengue virus serotypes are found co-circulating in Malaysia, but after the first and only major outbreak involving DEN-4 in 1960's, only DEN-1, DEN-2 and DEN-3 were associated with DF/DHF outbreaks. It is argued that perhaps the spread of the later dengue virus serotypes followed the pattern of spread of the mosquito vector Aedes aegypti, whereas the former was associated with Aedes albopictus, the outdoor and rural area dwelling mosquito. Estimating from the trend and pattern of dengue and the associated dengue virus serotypes, unless there is a major breakthrough in dengue vaccine development, it is likely that dengue outbreaks will continue to occur in Malaysia throughout the 21st century.     

The differences of clinical manifestations and laboratory findings in children and adults with dengue virus infection.

BACKGROUND: Dengue haemorrhagic fever is an important public health problem and mainly occurs in children less than 15 years of age. Recently, the incidence of the disease have increased in adults but data on clinical and laboratory presentations of those affected are limited. OBJECTIVES: To assess and compare clinical manifestations and laboratory findings of dengue virus infected children and adults in Thailand. STUDY DESIGN: A 1-year study was conducted from September 2003 to August 2004 for dengue virus infected patients admitted to Phetchabun Provincial Hospital, Thailand. Physical signs, symptoms, and laboratory features were recorded. All dengue patients were confirmed using immunochromatographic test on convalescent sera. RESULTS: Based on serology-confirmed dengue virus infection, there was 286 dengue patients including 15 (5.3%) dengue fever and 271 (94.7%) dengue haemorrhagic fever (DHF). Among DHF cases, clinical classifications were DHF I, 40.9%; DHF II, 43%; and DHF III or dengue shock syndrome (DSS), 10.8%. Of all dengue patients, 231 cases (80.8%) were children aged less than 15 years and 55 cases (19.2%) were adults. The highest proportion of child cases was DHF I (42.9%), whereas that of adults was DHF II (51%). Some clinical manifestations were more common in adult patients, such as petechiae, melena, headache, retro-orbital pain, joint pain, myalgia, nausea and vomiting (p-value<0.05). Signs found commonly in children were epistaxis, oliguria, and liver enlargement (p-value<0.05). Haemoconcentration, thrombocytopenia, increased alanine aminotransferase, and longer prothrombin time were found to be significantly higher in adults than in children (p-value<0.05). CONCLUSIONS: Some clinical presentations of dengue disease and laboratory findings in adults are different from those in children. Therefore, adults as well as pediatric cases of DHF need appropriate and prompt case management to reduce the mortality rate of DHF.     

Chikungunya virus of Asian and Central/East African genotypes in Malaysia

BackgroundChikungunya virus (CHIKV) of the Central/East African genotype has caused large outbreaks worldwide in recent years. In Malaysia, limited CHIKV outbreaks of the endemic Asian and imported Central/East African genotypes were reported in 1998 and 2006. Since April 2008, an unprecedented nationwide outbreak has affected Malaysia.ObjectiveTo study the molecular epidemiology of the current Malaysian CHIKV outbreak, and to evaluate cross-neutralisation activity of serum from infected patients against isolates of Asian and Central/East African genotypes.Study designSerum samples were collected from 83 patients presenting in 2008, and tested with PCR for the E1 gene, virus isolation, and for IgM. Phylogenetic analysis was performed on partial E1 gene sequences of 837 bp length. Convalescent serum from the current outbreak and Bagan Panchor outbreak (Asian genotype, 2006) were tested for cross-neutralising activity against representative strains from each outbreak.ResultsCHIKV was confirmed in 34 patients (41.0%). The current outbreak strain has the A226V mutation in the E1 structural protein, and grouped with Central/East African isolates from recent global outbreaks. Serum cross-neutralisation activity against both Central/East African and Asian genotypes was observed at titres from 40 to 1280.ConclusionsThe CHIKV strain causing the largest Malaysian outbreak is of the Central/East African genotype. The presence of the A226V mutation, which enhances transmissibility of CHIKV by Aedes albopictus, may explain the extensive spread especially in rural areas. Serum cross-neutralisation of different genotypes may aid potential vaccines and limit the effect of future outbreaks.     

Randomized controlled trial of zinc supplementation for persistent diarrhea in adults with HIV-1 infection

BACKGROUND: In children, zinc supplementation reduces the incidence and severity of diarrhea. METHODS: HIV-infected adults with > or =7 days of diarrhea recruited at 3 tertiary hospitals in Lima, Peru, received a zinc sulfate capsule containing 50 mg of elemental zinc twice daily or an identical placebo for 14 days. Outcomes included persistence of diarrhea at day 14 and time until cessation of diarrhea. RESULTS: The 81 subjects randomized to zinc and 78 randomized to placebo were comparable at baseline, except for higher prevalences of certain enteric pathogens in the zinc group; complete follow-up rates were 62% and 69%, respectively. Zinc concentrations were consistent with zinc deficiency at follow-up in 94% of placebo recipients and 66% of zinc recipients (P = 0.01). Persistence of diarrhea at day 14 according to follow-up interview (60% for zinc-treated patients and 57.4% for placebo-treated patients) or to patient diary (42.2% vs. 31.9%) did not differ significantly. Adjusting for enteric pathogens and CD4 count, the hazard ratio (HR) for zinc supplementation and cessation of diarrhea (according to the diaries) was 0.91 (95% confidence interval [CI]: 0.50 to 1.64). CONCLUSION: Supplemental zinc had no significant effect on the duration or remission of diarrhea in HIV-infected adults.     

Cross-reactive T-cell responses to the nonstructural regions of dengue viruses among dengue fever and dengue hemorrhagic fever patients in Malaysia

Dengue virus infections are a major cause of morbidity and mortality in tropical and subtropical areas in the world. Attempts to develop effective vaccines have been hampered by the lack of understanding of the pathogenesis of the disease and the absence of suitable experimental models for dengue viral infection. The magnitude of T-cell responses has been reported to correlate with dengue disease severity. Sixty Malaysian adults with dengue viral infections were investigated for their dengue virus-specific T-cell responses to 32 peptides antigens from the structural and nonstructural regions from a dengue virus isolate. Seventeen different peptides from the C, E, NS2B, NS3, NS4A, NS4B, and NS5 regions were found to evoke significant responses in a gamma interferon enzyme-linked immunospot (ELISPOT) assay of samples from 13 selected patients with dengue fever (DF) and dengue hemorrhagic fever (DHF). NS3 and predominantly NS3(422-431) were found to be important T-cell targets. The highest peaks of T-cell responses observed were in responses to NS3(422-431) and NS5(563-571) in DHF patients. We also found almost a sevenfold increase in T-cell response in three DHF patients compared to three DF patient responses to peptide NS3(422-431). A large number of patients' T cells also responded to the NS2B(97-106) region. The ELISPOT analyses also revealed high frequencies of T cells that recognize both serotype-specific and cross-reactive dengue virus antigens in patients with DHF.     

Thin-basement-membrane nephropathy in adults with persistent hematuria

Thin-basement-membrane nephropathy, also called benign recurrent hematuria, is characterized by diffuse thinning of the glomerular basement membrane and by hematuria. To determine the incidence of thin-basement-membrane nephropathy among patients with idiopathic hematuria, we conducted a prospective study in the nephrology units of three large hospitals in the Netherlands. Eighty normotensive adults without azotemia underwent renal biopsy because of recurrent macroscopic hematuria (n = 26) or persistent microscopic hematuria (n = 54). Idiopathic IgA nephropathy was found in 27 of the 80 patients. Light microscopical examination showed that 42 patients had normal renal tissue. The remaining 11 patients had mesangioproliferative glomerulonephritis (n = 5), interstitial nephritis (n = 3), or focal global glomerulosclerosis (n = 3). Tissue from the 42 patients whose renal biopsy specimens were normal when examined with light microscopy was analyzed morphometrically with electron microscopy to determine the thickness of the glomerular basement membrane. Two subsets of patients were identified by this analysis. In 18, thin-basement-membrane nephropathy was found (mean basement-membrane thickness [+/- SE], 191 +/- 28 nm; normal, 350 +/- 43 nm); all but one of these 18 patients had microscopic hematuria, which persisted during follow-up (median duration, 50 months). (Of the 54 patients who presented with microscopic hematuria, 17 [31 percent] had thin-basement-membrane nephropathy.) The thickness of the glomerular basement membrane was normal in the other 24 patients (361 +/- 69 nm); during follow-up, hematuria disappeared in all 13 of these patients who had macroscopic hematuria, and hematuria resolved in 5 of the 11 patients who had microscopic hematuria. We conclude that in patients with persistent microscopic hematuria, the incidence of thin-basement-membrane nephropathy is similar to that of idiopathic IgA nephropathy. Morphometric analysis of the thickness of the glomerular basement membrane should be included in the workup of adults with persistent microscopic hematuria that is not of urologic origin.     

Molecular and serological diagnosis of Chikungunya virus infection

INTRODUCTION: In 2005-2006, during the Chikungunya virus outbreak in La Réunion (Indian Ocean), we urgently established the molecular and serological methods for the diagnosis of Chikungunya virus (CHIKV) from various types of samples. METHODS: CHIKV RNA was detected using a highly sensitive real-time RT PCR assay. A co-extracted and co-amplified internal control RNA was used to identify RT PCR inhibitors. Depending on their nature samples were pretreated before nucleic acid extraction. Viral loads were measured using a synthetic RNA calibrator. CHIKV immunoglobulin (Ig) G and M antibodies were detected by ELISA either from sera or from blood absorbed on filter paper. RESULTS: CHIKV RNA was found in various types of samples such as plasma, cerebrospinal fluid, and placenta, but was not found in some samples including maternal milk and synovial samples. Detection of IgG from filter paper absorbed blood is specific and sensitive. Routine data showed that maternally transferred IgG and naturally acquired IgM persist at least 12 and 18 months, respectively. DISCUSSION: The techniques enabled the diagnosis of chikungunya in known and newly described forms of the disease. They are used for routine diagnosis and large scale surveys.     

Serum nitric oxide in children with dengue infection

One hundred and ten patients (M/F = 67/43) from King Chulalongkorn Memorial Hospital and the provincial hospitals of Uttaradit, Ayudhaya, and Sakonnakorn, who were clinically diagnosed with dengue infection and serologically confirmed by ELISA anti-Dengue IgM and IgG were recruited. Their serum NO level was measured using commercially available assay kits to investigate its correlation with the severity of the dengue infection: dengue fever (DF), DHF I/II, and DHF III/IV or dengue shock syndrome (DSS). Serum NO levels were also measured in 38 healthy controls (M/F = 19/19). Serum NO levels in dengue patients were lower than those of the controls (control = 168.18 +/- 24.10 micromol/l, DF = 124.94 +/- 36.79 micromol/l, DHF I/II = 99.69 +/- 33.42 micromol/l, and DHF III/IV = 120.63 +/- 46.26 micromol/l; p < 0.05). Serum NO levels in patients with DHF I/II were significantly lower than in those with DHF III/IV. These preliminary data revealed that levels of serum NO in dengue patients were significantly lower than those of normal controls. Patients with DSS had higher NO levels than those with DHF I/II. The decreased NO in dengue patients could be due to endothelial damage rendering the endothelium incapable of producing NO. Endothelial function seems to play a role in the pathogenesis of dengue infection. Further studies are required to see whether serum NO levels could play a role in the course of the disease and could help predict the severity of dengue infection.     

Report of a fatal case of dengue infection with hepatitis: demonstration of dengue antigens in hepatocytes and liver apoptosis.

A fatal case of dengue (DEN) infection associated with a spleen rupture and with hepatitis is reported here. Microscopic studies showed numerous areas of spleen rupture with hematomas and revealed necrotic foci in liver samples obtained at autopsy. Although hepatitis was reported in several cases of DEN fever, the mechanism of liver injury remains poorly understood. In this case, immunohistochemistry showed that DEN viral antigens were mostly detected in hepatocytes surrounding the necrotic foci. By in situ detection of DNA fragmentation, apoptotic hepatocytes were found to be colocated with DEN virus-infected hepatocytes. These findings suggest that hepatocytes are the major sites of DEN virus replication in the liver and that DEN virus induces apoptosis of hepatocytes in vivo.     

Bloodstream infections in hospitalized adults with dengue fever: Clinical characteristics and recommended empirical therapy

Background

Dengue is an important mosquito-borne tropical viral disease and dual infection, though rare, has been regarded as a risk factor for severe disease and mortality. However, few studies focused on bloodstream infections (BSIs) and empirical antibiotic therapy rarely addressed.

Common variants of chemokine receptor gene CXCR3 and its ligands CXCL10 and CXCL11 associated with vascular permeability of dengue infection in peninsular Malaysia

Dengue causes significantly more human disease than any other arboviruses. It causes a spectrum of illness, ranging from mild self-limited fever, to severe and fatal dengue hemorrhagic fever, as evidenced by vascular leakage and multifactorial hemostatic abnormalities. There is no specific treatment available till date. Evidence shows that chemokines CXCL10, CXCL11 and their receptor CXCR3 are involved in severity of dengue, but their genetic association with the susceptibility of vascular leakage during dengue infection has not been reported. We genotyped 14 common variants of these candidate genes in 176 patients infected with dengue. rs4859584 and rs8878 (CXCL10) were significantly associated with vascular permeability of dengue infection (P < 0.05); while variants of CXCL11 showed moderate significance of association (P = 0.0527). Haplotype blocks were constructed for genes CXCL10 and CXCL11 (5 and 7 common variants respectively). Haplotype association tests performed revealed that, “CCCCA” of gene CXCL10 and “AGTTTAC” of CXCL11 were found to be significantly associated with vascular leakage (P = 0.0154 and 0.0366 respectively). In summary, our association study further strengthens the evidence of the involvement of CXCL10 and CXCL11 in the pathogenesis of dengue infection.