Eastern Equine Encephalitis in Latin America

Abstract

BACKGROUND The eastern equine encephalitis (EEE) and Venezuelan equine encephalitis (VEE) viruses are pathogens that infect humans and horses in the Americas. Outbreaks of neurologic disease in humans and horses were reported in Panama from May through early August 2010. METHODS We performed antibody assays and tests to detect viral RNA and isolate the viruses in serum samples from hospitalized patients. Additional cases were identified with enhanced surveillance. RESULTS A total of 19 patients were hospitalized for encephalitis. Among them, 7 had confirmed EEE, 3 had VEE, and 1 was infected with both viruses; 3 patients died, 1 of whom had confirmed VEE. The clinical findings for patients with EEE included brain lesions, seizures that evolved to status epilepticus, and neurologic sequelae. An additional 99 suspected or probable cases of alphavirus infection were detected during active surveillance. In total, 13 cases were confirmed as EEE, along with 11 cases of VEE and 1 case of dual infection. A total of 50 cases in horses were confirmed as EEE and 8 as VEE; mixed etiologic factors were associated with 11 cases in horses. Phylogenetic analyses of isolates from 2 cases of equine infection with the EEE virus and 1 case of human infection with the VEE virus indicated that the viruses were of enzootic lineages previously identified in Panama rather than new introductions. CONCLUSIONS Cases of EEE in humans in Latin America may be the result of ecologic changes that increased human contact with enzootic transmission cycles, genetic changes in EEE viral strains that resulted in increased human virulence, or an altered host range. (Funded by the National Institutes of Health and the Secretaría Nacional de Ciencia, Tecnología e Innovación, Panama.)

Current Strategic Thinking for the Development of a Trivalent Alphavirus Vaccine for Human Use

“…However, recent analyses of a 2010 outbreak in Panama have challenged that paradigm. 49 Given that these strains caused severe disease in humans, additional studies in animal models may be warranted to determine Figure 1. Multiple sequence alignment (MSA) was used to generate maximum likelihood tree and tanglegram of whole genome versus E1 gene of VEEV genomes.…”

Madariaga Virus Infection Associated with a Case of Acute Disseminated Encephalomyelitis

“…Cross IgM or IgG reaction due to heterologous antibodies can be observed; in this case, PRNT is an invaluable tool for laboratory confirmation. 1 In this patient, we observed seroconversion from positive to negative IgM and neutralizing antibodies against only MADV.…”

“…During his hospitalization, 10 other children from the same geographical region were admitted, with clinical signs of encephalitis, six of them were confirmed as MADV infections, three had venezuelan equine encephalitis virus (VEEV) infection, and one was dual infected with both viruses; all these cases were confirmed by immunoglobulin M (IgM) serology. 1 The National Veterinary Epidemiological Surveillance System reported equine deaths in the region, and Gorgas Memorial Institute or the University of Texas Medical Branch confirmed equine MADV infections. of the basal nuclei and the right thalamic mesencephalic region.…”

Mercadeo Virus: A Novel Mosquito-Specific Flavivirus from Panama

“…Mosquito collections were conducted in 2011 in Darien Province (7°38′0″ N to 76°57′0″ W), in eastern Panama, close to the border with Colombia, in the same region where a human and equine outbreak of alphaviral encephalitis had occurred during 2010. 10 The collection localities were El Real de Santa Maria, Santa Librada, and Los Pavitos, in the municipality of Chepigana. There are two major wetland habitats at these sites.…”

“…mosquitoes collected in Panama in 2011 during retrospective field studies in a region where an arbovirus encephalitis outbreak had occurred the year before. 10 …”