Genetic Characterization of Venezuelan Equine Encephalitis Virus from Bolivia, Ecuador and Peru: Identification of a New Subtype ID Lineage

Abstract

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.

Arboviral Etiologies of Acute Febrile Illnesses in Western South America, 2000–2007

“…This data is corroborated by a previous study of healthy participants, in which we found that nearly 25% of the urban population carries VEEV-neutralizing antibodies [24]. In addition, based on data collected through this program the geographic range of MAYV and VEEV is wider than had been previously demonstrated, extending to southern Peru and Bolivia [14], [19]. Taken together these factors suggest that the potential establishment of the neotropical alphaviruses as urban pathogens should be closely monitored.…”

Genetic and Anatomic Determinants of Enzootic Venezuelan Equine Encephalitis Virus Infection of Culex (Melanoconion) taeniopus

“…This has already been observed with other arboviral viruses, such as chikungunya, dengue, yellow fever, and Japanese encephalitis viruses [51]. Similar trends have also been observed with enzootic strains of VEEV that have caused endemic disease as well as outbreaks in Peru, Central America, and Mexico [16], [17]. Historically, studies of VEEV emergence have focused on epidemic strains within subtypes IAB and IC; however, enzootic ID and IE strains can also cause a large burden of endemic disease, which can often be misdiagnosed as dengue fever [52].…”

Endemic Venezuelan Equine Encephalitis in the Americas: Hidden Under The Dengue Umbrella

“…Surveillance conducted in Cochabamba revealed that VEEV causes a similar number of febrile cases to dengue virus (7 vs 6.6%, respectively, of dengue-like illness) [41], providing evidence that VEE represents a serious public health concern in the area and that its impact has been greatly underestimated. Moreover, an adult Bolivian patient developed neurological disease after infection with this Bolivia/Peru VEEV subtype ID genotype, confirming the severe disease potential of enzootic VEEV from this region [40]. Ecological studies are still needed to identify reservoir hosts and mosquito vectors involved in enzootic transmission in Bolivia, as well as to determine whether VEEV circulates in other areas of the country that are not sampled by current surveillance activities.…”

“…The circulation of VEEV subtype ID in Bolivia was first reported in 2005, when the virus was isolated from febrile patients residing in Eterazama, Cochabamba [40,41]. Since this initial report, VEEV has been almost continuously isolated in Bolivia from patients with no history of travel within 30 days of their illness, suggesting that VEE is endemic in Bolivia.…”

“…Genetic analyses of the VEEV strains from Pastaza, Ecuador, demonstrate that these isolates cluster within the Colombia/Venezuela ID genotype, which includes the progenitors of epizootic IAB and IC viruses (Figure 4) [40]. Field studies conducted in the coastal region from 1975 to 1977 detected the presence of VEEV subtype ID of the southwestern Colombia/Ecuador genotype [44,45].…”