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To better describe the genetic diversity of hantaviruses associated with human illness in South America, we screened blood samples from febrile patients in Chapare Province in central Bolivia during 2008-2009 for recent hantavirus infection. Hantavirus RNA was detected in 3 patients, including 1 who died. Partial RNA sequences of small and medium segments from the 3 patients were most closely related to Andes virus lineages but distinct (<90% nt identity) from reported strains. A survey for IgG against hantaviruses among residents of Chapare Province indicated that 12.2% of the population had past exposure to ≥1 hantaviruses; the highest prevalence was among agricultural workers. Because of the high level of human exposure to hantavirus strains and the severity of resulting disease, additional studies are warranted to determine the reservoirs, ecologic range, and public health effect of this novel strain of hantavirus. [ABSTRACT FROM AUTHOR] more...

Background: Arthropod-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/Findings: A 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/Significance: Our 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. Author Summary: Over recent decades, the variety and quantity of diseases caused by viruses transmitted to humans by mosquitoes and other arthropods (also known as arboviruses) have increased around the world. One difficulty in studying these diseases is the fact that the symptoms are often non-descript, with patients reporting such symptoms as low-grade fever and headache. Our goal in this study was to use laboratory tests to determine the causes of such non-descript illnesses in sites in four countries in South America, focusing on arboviruses. We established a surveillance network in 13 locations in Ecuador, Peru, Bolivia, and Paraguay, where patient samples were collected and then sent to a central laboratory for testing. Between May 2000 and December 2007, blood serum samples were collected from more than 20,000 participants with fever, and recent arbovirus infection was detected for nearly one third of them. The most common viruses were dengue viruses (genera Flavivirus). We also detected infection by viruses from other genera, including Alphavirus and Orthobunyavirus. This data is important for understanding how such viruses might emerge as significant human pathogens. [ABSTRACT FROM AUTHOR] more...

Venezuelan equine encephalitis virus (VEEV) has been responsible for hundreds of thousands of human and equine cases of severe disease in the Americas. A passive surveillance study was conducted in Peru, Bolivia and Ecuador to determine the arboviral etiology of febrile illness. Patients with suspected viral-associated, acute, undifferentiated febrile illness of <7 days duration were enrolled in the study and blood samples were obtained from each patient and assayed by virus isolation. Demographic and clinical information from each patient was also obtained at the time of voluntary enrollment. In 2005–2007, cases of Venezuelan equine encephalitis (VEE) were diagnosed for the first time in residents of Bolivia; the patients did not report traveling, suggesting endemic circulation of VEEV in Bolivia. In 2001 and 2003, VEE cases were also identified in Ecuador. Since 1993, VEEV has been continuously isolated from patients in Loreto, Peru, and more recently (2005), in Madre de Dios, Peru. We performed phylogenetic analyses with VEEV from Bolivia, Ecuador and Peru and compared their relationships to strains from other parts of South America. We found that VEEV subtype ID Panama/Peru genotype is the predominant one circulating in Peru. We also demonstrated that VEEV subtype ID strains circulating in Ecuador belong to the Colombia/Venezuela genotype and VEEV from Madre de Dios, Peru and Cochabamba, Bolivia belong to a new ID genotype. In summary, we identified a new major lineage of enzootic VEEV subtype ID, information that could aid in the understanding of the emergence and evolution of VEEV in South America. Author Summary: Venezuelan equine encephalitis virus (VEEV) has been responsible for hundreds of thousands of human and equine cases of severe disease in the Americas. In 2005–2007, cases of Venezuelan equine encephalitis (VEE) were diagnosed for the first time in residents of Bolivia; the patients did not report traveling, suggesting endemic circulation of VEEV in Bolivia. In 2001 and 2003, VEE cases were also identified in Ecuador. We characterize recent VEEV from Bolivia, Ecuador and Peru and compared their relationships to strains from other parts of South America. We found that most VEEV from Peru grouped within a particular genetic lineage known to circulate in Panama and Peru whereas the VEEV circulating in Ecuador belong to a genetic lineage that circulates in Colombia and Venezuela. Importantly, the VEEV from Madre de Dios, Peru and Cochabamba, Bolivia belong to a new genetic lineage. This finding could aid in the understanding of the emergence and evolution of VEEV in South America and underscores the need for continuous monitoring for VEEV activity. [ABSTRACT FROM AUTHOR] more...

A small focus of hemorrhagic fever (HF) cases occurred near Cochabamba, Bolivia, in December 2003 and January 2004. Specimens were available from only one fatal case, which had a clinical course that included fever, headache, arthralgia, myalgia, and vomiting with subsequent deterioration and multiple hemorrhagic signs. A non-cytopathic virus was isolated from two of the patient serum samples, and identified as an arenavirus by IFA staining with a rabbit polyvalent antiserum raised against South American arenaviruses known to be associated with HF (Guanarito, Machupo, and Sabiá). RT-PCR analysis and subsequent analysis of the complete virus S and L RNA segment sequences identified the virus as a member of the New World Clade B arenaviruses, which includes all the pathogenic South American arenaviruses. The virus was shown to be most closely related to Sabiá virus, but with 26% and 30% nucleotide difference in the S and L segments, and 26%, 28%, 15% and 22% amino acid differences for the L, Z, N, and GP proteins, respectively, indicating the virus represents a newly discovered arenavirus, for which we propose the name Chapare virus. In conclusion, two different arenaviruses, Machupo and Chapare, can be associated with severe HF cases in Bolivia. [ABSTRACT FROM AUTHOR] more...

The article discusses the case of a 15-year-old boy in Magdalena, Bolivia who developed hay fever for five days. His symptoms were malaise, asthenia, conjunctival injection, vesicular rash, facial edema, arthralgia, myalgias, bone pain, abdominal pain, headache and earache. A 64-fold immunoglobulin M seroconversion was detected via serologic analyses. A reverse transcription polymerase chain reaction (PCR) method was employed for the extraction of viral ribonucleic acid (RNA) from the acute-phase sample. Barriers to the diagnosis of ilheus virus (ILVH) in disease-endemic areas are mild unspecific symptoms, short viremic period and lack of advanced confirmatory laboratory techniques. more...

Background: In the context of a rapid increase of dengue cases in the Americas, a monitoring system based on systematic serological control (IgM) of patients consulting for suspected dengue was developed in Bolivia at the end of the 1990s. In the most affected city of Santa Cruz, this system was complemented by an entomological surveillance program based on periodical search for immature stages of Aedes aegypti in dwelling water-holding containers. Here, we analyze these data and describe dengue patterns over 6 years (2002-2008), highlighting the spatial distribution of patients and vectors., Methodology /principal Findings: Data mining concerned six annual epidemic cycles (2002-2008), with continuous serological and clinical results and entomological data from 16 surveys, examined at the scales of 36 urban areas and four concentric areas covering the entire city. Annual incidence varied from 0.28‰ to 0.95‰; overall incidence was higher in women and adults, and dengue dynamics followed successive periods of high (January-June) and low (July-December) transmission. Lower numbers of cases from the city center to the periphery were observed, poorly related to the more homogeneous and permanent distribution of A. aegypti. "Plant pots" were a major vector source in the city center, and "Tires" and "Odds and ends" beyond the second ring of the city., Conclusions/significance: Over the years, the increasing trend of dengue cases has been highlighted as well as its widespread distribution over the entire city, but an underestimation of the number of cases is strongly suspected. Contrary to popular belief, the city center appears more affected than the periphery, and dengue is not particularly related to waste. Interestingly, the clinical diagnosis of dengue by physicians improved over the years, whatever the gender, age and residential area of suspected cases. more...

Guaroa virus (GROV) was first isolated from humans in Colombia in 1959. Subsequent isolates of the virus have been recovered from febrile patients and mosquitoes in Brazil, Colombia, and Panama; however, association of the virus with human disease has been unclear. As part of a study on the etiology of febrile illnesses in Peru and Bolivia, 14 GROV strains were isolated from patients with febrile illnesses, and 3 additional cases were confirmed by IgM seroconversion. The prevalence rate of GROV antibodies among Iquitos residents was 13%; the highest rates were among persons with occupations such as woodcutters, fisherman, and oil-field workers. Genetic characterization of representative GROV isolates indicated that strains from Peru and Bolivia form a monophyletic group that can be distinguished from strains isolated earlier in Brazil and Colombia. This study confirms GROV as a cause of febrile illness in tropical regions of Central and South America. more...