Trends in patterns of dengue transmission over 4 years in a pediatric cohort study in Nicaragua.

BACKGROUND: Dengue is the most prevalent mosquito-borne viral disease in humans and a major urban public health problem worldwide. METHODS: A prospective cohort study of approximately 3800 children initially aged 2-9 years was established in Managua, Nicaragua, in 2004 to study the natural history of dengue transmission in an urban pediatric population. Blood samples from healthy subjects were collected annually prior to the dengue season, and identification of dengue cases occurred via enhanced passive surveillance at the study health center. RESULTS: Over the first four years of the study, seroprevalence of anti-dengue virus (DENV) antibodies increased from 22%-40% in the 2-year-old cohort and 90%-95% in the 9-year-old cohort. The incidence of symptomatic dengue cases and the ratio of inapparent to symptomatic DENV infection varied substantially from year to year. The switch in dominant transmission from DENV-1 to DENV-2 was accompanied by an increase in disease severity but, paradoxically, a decrease in transmission. Phylogeographic analysis of full-length DENV-2 sequences revealed strong geographic clustering of dengue cases. CONCLUSIONS: This large-scale cohort study of dengue in the Americas demonstrates year-to-year variation of dengue within a pediatric population, revealing expected patterns in transmission while highlighting the impact of interventions, climate, and viral evolution.

Repurposing leflunomide for relapsed/refractory multiple myeloma: a phase 1 study.

The inexpensive, well-tolerated, immunomodulatory agent leflunomide, used extensively for the treatment of rheumatoid arthritis, has been shown to produce significant activity against multiple myeloma (MM) in pre-clinical studies. We conducted a phase 1 study (clinicaltrials.gov: NCT02509052) of single agent leflunomide in patients with relapsed/refractory MM (≥3 prior therapies). At dose levels 1 and 2 (20 and 40 mg), no dose-limiting toxicities (DLTs) were observed. At dose level 3 (60 mg), one patient experienced elevated alanine aminotransferase; an additional three patients were enrolled at this dose level without further DLTs. Overall, toxicities were infrequent and manageable. Nine out of 11 patients achieved stable disease (SD), two subjects experiencing SD for nearly one year or longer. The tolerable safety profile of leflunomide, combined with a potential disease stabilization, is motivating future studies of leflunomide, in combination with other MM drugs, or as an approach to delay progression of smoldering MM.

The Nicaraguan pediatric dengue cohort study: study design, methods, use of information technology, and extension to other infectious diseases.

Dengue is a mosquito-borne viral disease that is a major public health problem worldwide. In 2004, the Pediatric Dengue Cohort Study was established in Managua, Nicaragua, to study the natural history and transmission of dengue in children. Here, the authors describe the study design, methods, and results from 2004 to 2008. Initially, 3,721 children 2-9 years of age were recruited through door-to-door visits. Each year, new children aged 2 years are enrolled in the study to maintain the age structure. Children are provided with medical care through the study, and data from each medical visit are recorded on systematic study forms. All participants presenting with suspected dengue or undifferentiated fever are tested for dengue by virologic, serologic, and molecular biologic assays. Yearly blood samples are collected to detect inapparent dengue virus infections. Numerous information and communications technologies are used to manage study data, track samples, and maintain quality control, including personal data assistants, barcodes, global information systems, and fingerprint scans. Close collaboration with the Nicaraguan Ministry of Health and use of almost entirely local staff are essential components for success. This study is providing critical data on the epidemiology and transmission of dengue in the Americas needed for future vaccine trials.

Evaluation of immunological markers in serum, filter-paper blood spots, and saliva for dengue diagnosis and epidemiological studies.

BACKGROUND: Numerous immunological approaches exist to diagnose dengue or detect dengue virus (DENV) infections. OBJECTIVES: To determine the best immunological markers and specimen types for dengue diagnosis and for measuring incidence of DENV infection in community-based studies. STUDY DESIGN: In one study, acute- and convalescent-phase samples were collected from hospitalized suspected pediatric dengue cases in Managua, Nicaragua, from September 2003 to February 2004. A second study examined specimens collected in a community setting in Managua before and after the 2003-2004 dengue season to measure incidence of DENV infection. In both studies, detection of anti-DENV IgM, IgA, and IgG in serum, filter-paper blood spots, and saliva was compared to a gold standard performed on serum samples. RESULTS: For dengue diagnosis, the highest sensitivity and specificity was obtained by measuring IgM or IgA in serum or filter-paper blood spots; intermediate and poor results were obtained in saliva for IgM and IgA, respectively. Detection of IgG alone in serum, filter-paper blood spots, or saliva functioned best for measuring DENV infection. CONCLUSIONS: Detection of IgM and IgA in serum and filter-paper blood spots yielded optimal results for diagnosis of dengue cases, whereas IgG was the best marker for measuring incidence of DENV infection.

Characterization of Aedes aegypti (Diptera: Culcidae) production sites in urban Nicaragua.

To characterize the production patterns of the dengue virus vector Aedes aegypti (L.) (Diptera: Culcidae), pupal surveys were conducted in selected neighborhoods of two major cities in Nicaragua. In León, 833 houses were visited in July and September 2003, corresponding to the beginning and middle of the dengue season; in Managua, 1,365 homes were visited in July 2003. In total, 7,607 containers were characterized, of which 11% were positive for Ae. aegypti larvae and 4% for pupae. In addition to barrels, potted plants and superficial water on tarps and in puddles were identified as highly productive sites. Univariate and multivariate analysis revealed frequency of container use, use of a lid, and rainwater filling as key variables affecting pupal positivity. Importantly, this survey demonstrated the risk associated with the presence of lids, the limited temporal efficacy of temephos, and the lack of association of water availability with risky water storage practices. Finally, we introduce the concept of an efficiency value and an accompanying graphical display system that can facilitate development of targeted pupal control strategies. These data underscore the importance of entomological surveillance of pupal productivity to gather information from which to derive streamlined, efficient, and effective vector control measures to reduce the density of Aedes mosquito larvae and pupae and thus the risk for dengue.

Serotype-specific differences in clinical manifestations of dengue.

Dengue, the most prevalent arthropod-borne viral disease of humans, is caused by four serotypes of dengue virus (DENV 1-4). Although all four DENV serotypes cause a range of illness, defining precisely which clinical characteristics are associated with the distinct serotypes has been elusive. A cross-sectional study was conducted on 984 and 313 hospitalized children with confirmed DENV infections during two time periods, respectively, in the same hospitals in Nicaragua: a 3-year period (1999-2001) when DENV-2 accounted for 96% of the viruses identified, and the 2003 dengue season when DENV-1 predominated (87% of identified serotypes). When the two periods were compared, more shock (OR 1.91, 95% CI 1.35-2.71) and internal hemorrhage (OR 2.05, CI 1.16-3.78) were observed in the period when DENV-2 predominated, whereas increased vascular permeability was associated to a greater degree with the DENV-1 period (OR 2.36, CI 1.80-3.09). Compared with the DENV-2 period, the DENV-1 season was associated with more hospitalized primary dengue cases (OR 3.86, CI 2.72-5.48) and more primary DENV infections with severe manifestations (OR 2.93, CI 2.00-4.28). These findings provide new data to characterize the pathogenic potential of distinct DENV serotypes in human populations.

Identification of Aedes albopictus in urban Nicaragua.

Larvae of Aedes albopictus, a mosquito known for transmitting dengue virus, were identified in the city of León, Nicaragua, in 2003. Mosquito larvae were collected from a total of 2,225 residences in the 2 largest cities in Nicaragua during the period from June to September of 2003, and larval Ae. albopictus were identified in 4 homes in León. This represents the 1st detection of Ae. albopictus in a major Nicaraguan urban center, and increased control efforts appear to have eliminated the mosquito subsequently from León. The presence of Ae. albopictus in urban Nicaragua highlights the need for surveillance of areas thought to be free of the mosquito so that early detection and control activities can prevent its spread.

Phase II study of monthly pasireotide LAR (SOM230C) for recurrent or progressive meningioma.

OBJECTIVE: A subset of meningiomas recur after surgery and radiation therapy, but no medical therapy for recurrent meningioma has proven effective. METHODS: Pasireotide LAR is a long-acting somatostatin analog that may inhibit meningioma growth. This was a phase II trial in patients with histologically confirmed recurrent or progressive meningioma designed to evaluate whether pasireotide LAR prolongs progression-free survival at 6 months (PFS6). Patients were stratified by histology (atypical [World Health Organization grade 2] and malignant [grade 3] meningiomas in cohort A and benign [grade 3] in cohort B). RESULTS: Eighteen patients were accrued in cohort A and 16 in cohort B. Cohort A had median age 59 years, median Karnofsky performance status 80, 17 (94%) had previous radiation therapy, and 11 (61%) showed high octreotide uptake. Cohort B had median age 52 years, median Karnofsky performance status 90, 11 (69%) had previous radiation therapy, and 12 (75%) showed high octreotide uptake. There were no radiographic responses to pasireotide LAR therapy in either cohort. Twelve patients (67%) in cohort A and 13 (81%) in cohort B achieved stable disease. In cohort A, PFS6 was 17% and median PFS 15 weeks (95% confidence interval: 8-20). In cohort B, PFS6 was 50% and median PFS 26 weeks (12-43). Treatment was well tolerated. Octreotide uptake and insulin-like growth factor-1 levels did not predict outcome. Expression of somatostatin receptor 3 predicted favorable PFS and overall survival. CONCLUSIONS: Pasireotide LAR has limited activity in recurrent meningiomas. The finding that somatostatin receptor 3 is associated with favorable outcomes warrants further investigation. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that in patients with recurrent or progressive meningioma, pasireotide LAR does not significantly increase the proportion of patients with PFS at 6 months.

Phase 2 study of dose-intense temozolomide in recurrent glioblastoma.

BACKGROUND: Among patients with glioblastoma (GBM) who progress on standard temozolomide, the optimal therapy is unknown. Resistance to temozolomide is partially mediated by O(6)-methylguanine-DNA methyltransferase (MGMT). Because MGMT may be depleted by prolonged temozolomide administration, dose-intense schedules may overcome resistance. METHODS: This was a multicenter, phase 2, single-arm study of temozolomide (75-100 mg/m(2)/day) for 21 days of each 28-day cycle. Patients had GBM in first recurrence after standard therapy. The primary end point was 6-month progression-free survival (PFS6). RESULTS: Fifty-eight participants were accrued, 3 of whom were ineligible for analysis; one withdrew before response assessment. There were 33 men (61%), with a median age of 57 years (range, 25-79 years) and a median Karnofsky performance score of 90 (range, 60-100). Of 47 patients with MGMT methylation results, 36 (65%) had methylated tumors. There were 7 (13%) partial responses, and PFS6 was only 11%. Response and PFS did not depend on MGMT status; MSH2, MLH1, or ERCC1 expression; the number of prior temozolomide cycles; or the time off temozolomide. Treatment was well tolerated, with limited grade 3 neutropenia (n = 2) or thrombocytopenia (n = 2). CONCLUSIONS: Dose-intense temozolomide on this schedule is safe in recurrent GBM. However, efficacy is marginal and predictive biomarkers are needed.

Gene expression patterns of dengue virus-infected children from nicaragua reveal a distinct signature of increased metabolism.

BACKGROUND: Infection with dengue viruses (DENV) leads to a spectrum of disease outcomes. The pathophysiology of severe versus non-severe manifestations of DENV infection may be driven by host responses, which could be reflected in the transcriptional profiles of peripheral blood immune cells. METHODOLOGY/PRINCIPAL FINDINGS: We conducted genome-wide microarray analysis of whole blood RNA from 34 DENV-infected children in Nicaragua collected on days 3-6 of illness, with different disease manifestations. Gene expression analysis identified genes that are differentially regulated between clinical subgroups. The most striking transcriptional differences were observed between dengue patients with and without shock, especially in the expression of mitochondrial ribosomal proteins associated with protein biosynthesis. In the dengue hemorrhagic fever patients, one subset of differentially expressed genes encode neutrophil-derived anti-microbial peptides associated with innate immunity. By performing a meta-analysis of our dataset in conjunction with previously published datasets, we confirmed that DENV infection in vivo is associated with large changes to protein and nucleic acid metabolism. Additionally, whereas in vitro infection leads to an increased interferon signature, this was not consistently observed from in vivo patient samples, suggesting that the interferon response in vivo is relatively transient and was no longer observed by days 3-6 of illness. CONCLUSIONS/SIGNIFICANCE: These data highlight important differences between different manifestations of severity during DENV infection as well as identify some commonalities. Compilation of larger datasets in the future across multiple studies, as we have initiated in this report, may well lead to better prediction of disease manifestation via a systems biology approach.

Improvement in hospital indicators after changes in dengue case management in Nicaragua.

Dengue is a major problem worldwide, and improving case management is a significant priority. In consultation with colleagues in Thailand, changes in management of hospitalized dengue cases were introduced in Nicaragua, including oral rather than intravenous (IV) fluids upon admission, continuous monitoring of clinical and laboratory signs, and use of IV fluids principally during the critical phase and colloids in management of shock. Two periods were compared, before (2003) and after (2005) their implementation, to assess impact. In 2003, 182 hospitalized laboratory-confirmed dengue cases 0-14 years of age who presented < or = 5 days post-symptom onset were included in the study; 46 were enrolled in 2005. Outcomes included significant reductions in days of IV fluid administration ( P = 0.0001), number of patients receiving IV fluids ( P < 0.0001), and duration of hospitalization ( P < 0.0001), and a non-significant reduction in the number of admissions to the intensive care unit from 8 in 2003 to 0 in 2005 ( P = 0.36). This study demonstrates concrete gains in dengue patient care and case management.

Phenotyping of peripheral blood mononuclear cells during acute dengue illness demonstrates infection and increased activation of monocytes in severe cases compared to classic dengue fever.

In vitro studies have attempted to identify dengue virus (DEN) target cells in peripheral blood; however, extensive phenotyping of peripheral blood mononuclear cells (PBMCs) from dengue patients has not been reported. PBMCs collected from hospitalized children suspected of acute dengue were analyzed for DEN prM, CD32, CD86, CD14, CD11c, CD16, CD209, CCR7, CD4, and CD8 by flow cytometry to detect DEN antigen in PBMCs and to phenotype DEN-positive cells. DEN prM was detected primarily in activated monocytes (CD14(+), CD32(+), CD86(+), CD11c(+)). A subset of samples analyzed for DEN nonstructural protein 3 (NS3) confirmed that approximately half of DEN antigen-positive cells contained replicating virus. A higher percentage of PBMCs from DHF patients expressed prM, CD86, CD32, and CD11c than did those from DF patients. Increased activation of monocytes and greater numbers of DEN-infected cells were associated with more severe dengue, implicating a role for monocyte activation in dengue immunopathogenesis.

High seroprevalence of antibodies against dengue virus in a prospective study of schoolchildren in Managua, Nicaragua.

To investigate the incidence of dengue virus (DENV) infection in Nicaragua, a 2-year prospective study was conducted in schoolchildren 4-16 years old in the capital city of Managua. Blood samples were collected before the rainy season in 2001, 2002 and 2003, and were assayed for DENV-specific antibodies. Participants were monitored for dengue-like illness, and acute and convalescent blood samples were collected from suspected dengue cases. In 2001 and 2002, 602 and 397 students were recruited, respectively, and paired annual serum samples were available from 467 and 719 participants in 2001-2002 and 2002-2003, respectively. The overall seroprevalence of anti-DENV antibodies was 91%, increasing from 75% at age 4 to 100% at age 16. The incidence of DENV infection was 12% in Year 1 and 6% in Year 2 (P < 0.001). During Year 1, four laboratory-confirmed dengue cases were detected, with one DENV2 isolate; during Year 2, there were six confirmed dengue cases, with one DENV1 isolate. These and additional circulating serotypes were confirmed by plaque reduction neutralisation test. This study demonstrates surprisingly high transmission of DENV in urban Nicaragua.

Sequential immunization with vesicles prepared from heterologous Neisseria meningitidis strains elicits broadly protective serum antibodies to group B strains.

The capsular polysaccharide of Neisseria meningitidis group B is an autoantigen, whereas noncapsular antigens are highly variable. These factors present formidable challenges for development of a broadly protective and safe group B vaccine. Mice and guinea pigs were sequentially immunized with three doses of micovesicles or outer membrane vesicles prepared from three meningococcal strains that were each antigenically heterologous with respect to the two major porin proteins, PorA and PorB, and the group capsular polysaccharide. The resulting antisera conferred passive protection against meningococcal group B bacteremia in infant rats and elicited complement-mediated bactericidal activity against genetically diverse group B strains that were either homologous or heterologous with respect to PorA of the strains used to prepare the vaccine. By using knockout strains, a portion of the bactericidal antibody was directed against the highly conserved protein, neisserial surface protein A (NspA). Further, an anti-NspA monoclonal antibody elicited by the sequential immunization was highly bactericidal against strains that were previously shown to be resistant to bacteriolysis by anti-NspA antibodies produced by immunization with recombinant NspA. Sequential immunization with heterologous vesicle preparations offers a novel approach to eliciting broadly protective immunity against N. meningitidis strains. An NspA-based vaccine prepared from protein expressed by Neisseria also may be more effective than the corresponding recombinant protein made in Escherichia coli.