BackgroundArthropod-borne viruses (arboviruses) are among the most common agents of human febrile illness worldwide and the most important emerging pathogens, causing multiple notable epidemics of human disease over recent decades. Despite the public health relevance, little is know about the geographic distribution, relative impact, and risk factors for arbovirus infection in many regions of the world. Our objectives were to describe the arboviruses associated with acute undifferentiated febrile illness in participating clinics in four countries in South America and to provide detailed epidemiological analysis of arbovirus infection in Iquitos, Peru, where more extensive monitoring was conducted.Methodology/FindingsA clinic-based syndromic surveillance system was implemented in 13 locations in Ecuador, Peru, Bolivia, and Paraguay. Serum samples and demographic information were collected from febrile participants reporting to local health clinics or hospitals. Acute-phase sera were tested for viral infection by immunofluorescence assay or RT-PCR, while acute- and convalescent-phase sera were tested for pathogen-specific IgM by ELISA. Between May 2000 and December 2007, 20,880 participants were included in the study, with evidence for recent arbovirus infection detected for 6,793 (32.5%). Dengue viruses (Flavivirus) were the most common arbovirus infections, totaling 26.0% of febrile episodes, with DENV-3 as the most common serotype. Alphavirus (Venezuelan equine encephalitis virus [VEEV] and Mayaro virus [MAYV]) and Orthobunyavirus (Oropouche virus [OROV], Group C viruses, and Guaroa virus) infections were both observed in approximately 3% of febrile episodes. In Iquitos, risk factors for VEEV and MAYV infection included being male and reporting to a rural (vs urban) clinic. In contrast, OROV infection was similar between sexes and type of clinic.Conclusions/SignificanceOur data provide a better understanding of the geographic range of arboviruses in South America and highlight the diversity of pathogens in circulation. These arboviruses are currently significant causes of human illness in endemic regions but also have potential for further expansion. Our data provide a basis for analyzing changes in their ecology and epidemiology.

The effect of physiological concentrations of different chlorides on the structure of a dipalmitoyl phosphatidylcholine (DPPC) bilayer has been investigated through atomistic molecular dynamics simulations. These calculations provide support to the concept that Li+, Na+, Ca2+, Mg2+, Sr2+, Ba2+, and Ac3+, but not K+, bind to the lipid-head oxygens. Ion binding exhibits an influence on lipid order, area per lipid, orientation of the lipid head dipole, the charge distribution in the system, and therefore the electrostatic potential across the head-group region of the bilayer. These structural effects are sensitive to the specific characteristics of each cation, i.e., radius, charge, and coordination properties. These results provide evidence aimed at shedding some light into the apparent contradictions among different studies reported recently regarding the ordering effect of ions on zwitterionic phosphatidylcholine lipid bilayers.

BackgroundAcute respiratory illnesses and influenza-like illnesses (ILI) are a significant source of morbidity and mortality worldwide. Despite the public health importance, little is known about the etiology of these acute respiratory illnesses in many regions of South America. In 2006, the Peruvian Ministry of Health (MoH) and the US Naval Medical Research Center Detachment (NMRCD) initiated a collaboration to characterize the viral agents associated with ILI and to describe the clinical and epidemiological presentation of the affected population.Methodology/Principal FindingsPatients with ILI (fever ≥38°C and cough or sore throat) were evaluated in clinics and hospitals in 13 Peruvian cities representative of the four main regions of the country. Nasal and oropharyngeal swabs, as well as epidemiological and demographic data, were collected from each patient. During the two years of this study (June 2006 through May 2008), a total of 6,835 patients, with a median age of 13 years, were recruited from 31 clinics and hospitals; 6,308 were enrolled by regular passive surveillance and 527 were enrolled as part of outbreak investigations. At least one respiratory virus was isolated from the specimens of 2,688 (42.6%) patients, with etiologies varying by age and geographical region. Overall the most common viral agents isolated were influenza A virus (25.1%), influenza B virus (9.7%), parainfluenza viruses 1, 2, and 3, (HPIV-1,-2,-3; 3.2%), herpes simplex virus (HSV; 2.6%), and adenoviruses (1.8%). Genetic analyses of influenza virus isolates demonstrated that three lineages of influenza A H1N1, one lineage of influenza A H3N2, and two lineages of influenza B were circulating in Peru during the course of this study.ConclusionsTo our knowledge this is the most comprehensive study to date of the etiologic agents associated with ILI in Peru. These results demonstrate that a wide range of respiratory pathogens are circulating in Peru and this fact needs to be considered by clinicians when treating patients reporting with ILI. Furthermore, these data have implications for influenza vaccine design and implementation in South America.

OBJECTIVE Our goal was to estimate the impact of a Shigella vaccine in an area where shigellosis is endemic by characterizing the disease burden and antibiotic-resistance profiles of isolates and by determining the prevalence of Shigella flexneri serotypes. PATIENTS AND METHODS We conducted a 43-month-long prospective, community-based diarrheal disease surveillance in 442 children <72 months of age in the Peruvian Amazon between October 1, 2002, and April 15, 2006. RESULTS The incidence of diarrheal disease was 4.38 episodes per child-year. The incidence rate for shigellosis was 0.34 episodes per child-year in children <72 months of age and peaked in children between 12 and 23 months at 0.43 episodes per child-year. Maternal education at or beyond the primary grade level, piped water supply, weight-for-age z score, and improved water-storage practices were the most significant determinants of disease in this community with living conditions comparable to many rural areas in the developing world. CONCLUSIONS Children living in this region had a 20-fold higher rate of disease incidence detected by active surveillance as those recently estimated by passive detection. Most symptomatic disease was caused by S flexneri, although the diversity of serotypes will require a multivalent vaccine to have a significant impact on the burden of disease caused by shigellosis. Several other public health disease-control interventions targeted at water source and improved storage, nutritional interventions, and improved maternal education seem to have a greater impact than a univalent S flexneri 2a vaccine.