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.)

Abstract. Chikungunya virus (CHIKV) is a mosquito-borne pathogen that was only endemic in Africa and south Asia until 2005 and, when the virus spread into the Indian Ocean islands, Europe, and Asia. Autochthonous CHIKV transmission in the Caribbean islands was reported in December of 2013. In Panama, two febrile cases were detected in May of 2014: one traveling from Haiti, and the other traveling from the Dominican Republic. After other imported cases were detected, the first autochthonous case was reported in August of the same year. We detected CHIKV viral RNA and isolated the virus from serum samples. The phylogenetic analysis of the two imported isolates and one autochthonous CHIKV isolate indicated that the viruses belong to the Asian lineage in the Caribbean clade and are related to viruses recently identified in Saint Martin island, British Virgin Islands, China, and the Philippines. Although the circulating CHIKV lineages in the Americas have not yet been described, our results suggest that the Asian lineage is circulating in most American countries reporting autochthonous infection.Chikungunya virus (CHIKV; Alphavirus, Togaviridae) is a mosquito-borne pathogen that is endemic in Africa and some countries in Asia. In 2004, a CHIKV epidemic in costal Kenya was reported, and by 2005 and 2006, CHIKV had spread to the Indian Ocean island of La Reunion as well as Asia, where it caused major epidemics. Several imported cases were reported in Europe and the Americas.1 Three mayor lineages of CHIKV have been described: the east, central and south African (ECSA) lineage, the west African lineage, and the Asian lineage.2 A single mutation in the ECSA strain allowed the emergence of the Indian Ocean outbreak lineage (IOL) because of the increase of viral infectivity, dissemination, and transmission of CHIKV in Aedes albopictus.3,4 The IOL has been related to the explosive CHIKV epidemics in the Indian Ocean and Asia and autochthonous infections in Italy and the south of France as well as several imported cases into the Americas.2,5 Therefore, it was believed that the IOL of CHIKV would reach the Americas, 6 where the two vectors Ae. aegypti and Ae. albopictus have an overlapping distribution 7 and adapt to cause autochthonous infection. Autochthonous CHIKV infections caused by the Asian lineage were reported in December of 2013 on the French island of Saint Martin and spread to several others Caribbean islands and Latin American countries in 2014. 8,9 Here, we report the detection of imported cases of CHIKV in Panama and the establishment of autochthonous infections as well as the results of the genetic characterization of the CHIKV viral strains.On May 13 and 14, 2014, two suspected cases of Chikungunya fever were detected in two public medical facilities in Panama City, Panama. The first patient (256114) was a 23-yearold male with the following travel history: Brazil to Haiti to Panama to Brazil. The day before his travel to Haiti from Rio de Janeiro (May 6), he presented fever, myalgia, and general malaise; he ...

Dengue virus (DENV) is the most prevalent arbovirus in terms of human public health importance globally. In addition to DENV epidemiological surveillance, genomic surveillance may help investigators understand the epidemiological dynamics, geographic distribution, and temporal patterns of DENV circulation. Herein, we aimed to reconstruct the molecular epidemiology and phylogeny of DENV in Panama to connect the epidemiological history of DENV dispersal and circulation in Latin America. We retrospectively analyzed the epidemiological data obtained during 25 years of DENV surveillance in Panama. DENV was reintroduced in Panama in 1993 after a 35 year absence of autochthonous transmission. The increase in the number of total dengue cases has been accompanied by an increase in severe and fatal cases, with the highest case fatality rate recorded in 2011. All four serotypes were detected in Panama, which is characterized by serotype replacement and/or co-circulation of multiple serotypes. Phylogenetic analysis of datasets collected from envelope (E) gene sequences obtained from viruses isolated from human sera demonstrated that circulating viruses were highly diverse and clustered in distinct clades, with co-circulation of clades from the same genotype. Our analyses also suggest that Panamanian strains were related to viruses from different regions of the Americas, suggesting a continuous exchange of viruses within the Americas.

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We report an epidemiologic analysis of 4,210 cases of infection with severe acute respiratory syndrome coronavirus 2 and genetic analysis of 313 new near-complete virus genomes in Panama during March 9–April 16, 2020. Although containment measures reduced R 0 and R t , they did not interrupt virus spread in the country.

Background With more than 50000 accumulated cases, Panama has one of the highest incidences of SARS-CoV-2 in Central America, despite the fast implementation of disease control strategies. We investigated the early transmission patterns of the virus and the outcomes of mitigation measures in the country. Methods We collected information from epidemiological surveillance, including contact tracing, and genetic data from SARS-CoV-2 whole genomes, of the first five weeks of the outbreak. These data were used to estimate the exponential growth rate, doubling time and the time-varying effective reproductive number (Rt) using date of symptom onset in a Bayesian framework. The time of most recent ancestor for the introduced and circulating lineages was estimated by Bayesian analysis. Findings A total of 4210 subjects were SARS-CoV-2 positive during the period evaluated, of them we sequenced 313 cases, detecting the circulation of 10 SARS-CoV-2 lineages. Whole genomes analysis identified the local transmission of one cryptic lineage as early as 2 weeks before it was detected by surveillance systems. Analysis of transmission dynamics showed that lockdown reduced Rt and increased the doubling time, however, these measures did not stop the circulation of this lineage in the country. Interpretation These results demonstrate the value of epidemiological modeling and genome surveillance to assess mitigation strategies. At the same time, an active search for cryptic transmission clusters is crucial to interrupt local transmission of SARS-CoV-2 in a region.

BackgroundChikungunya virus (CHIKV) typically causes explosive epidemics of fever, rash and polyarthralgia after its introduction into naïve populations. Since its introduction in Panama in May of 2014, few autochthonous cases have been reported; most of them were found within limited outbreaks in Panama City in 2014 and Puerto Obaldia town, near the Caribbean border with Colombia in 2015. In order to confirm that Panama had few CHIKV cases compared with neighboring countries, we perform an epidemiological analysis of chikungunya cases reported from May 2014 to July 2015. Moreover, to understand this paucity of confirmed CHIKV cases, a vectorial analysis in the counties where these cases were reported was performed.MethodsChikungunya cases were identified at medical centers and notified to health authorities. Sera samples were analyzed at Gorgas Memorial Institute for viral RNA and CHIKV-specific antibody detection.ResultsA total of 413 suspected cases of CHIKV infections were reported, with incidence rates of 0.5 and 0.7 per 100,000 inhabitants in 2014 and 2015, respectively. During this period, 38.6% of CHIKV cases were autochthonous with rash and polyarthralgia as predominant symptoms. CHIKV and DENV incidence ratios were 1:306 and 1:34, respectively. A phylogenetic analysis of E1/E2 genomic segment indicates that the outbreak strains belong to the Asian genotype and cluster together with CHIKV isolates from other American countries during the same period. Statistical analysis of the National Vector Control program at the district level shows low and medium vector infestation level for most of the counties with CHIKV cases. This index was lower than for neighboring countries.ConclusionsPrevious training of clinical, laboratory and vector workers allowed a good caption and detection of the chikungunya cases and fast intervention. It is possible that low/medium vector infestation level could explain in part the paucity of chikungunya infections in Panama.

An investigation in Panama found that Punta Toro virus species complex (PTVs) may contribute to febrile illnesses with symptoms mirroring those of dengue fever. However, further studies are needed to determine if PTV infection causes only a mild disease or if it can have more serious manifestations in some patients.