RESUMEN
UNLABELLED: Phylodynamic analysis of genome-wide single-nucleotide polymorphism (SNP) data is a powerful tool to investigate underlying evolutionary processes of bacterial epidemics. The method was applied to investigate a collection of 65 clinical and environmental isolates of Vibrio cholerae from Haiti collected between 2010 and 2012. Characterization of isolates recovered from environmental samples identified a total of four toxigenic V. cholerae O1 isolates, four non-O1/O139 isolates, and a novel nontoxigenic V. cholerae O1 isolate with the classical tcpA gene. Phylogenies of strains were inferred from genome-wide SNPs using coalescent-based demographic models within a Bayesian framework. A close phylogenetic relationship between clinical and environmental toxigenic V. cholerae O1 strains was observed. As cholera spread throughout Haiti between October 2010 and August 2012, the population size initially increased and then fluctuated over time. Selection analysis along internal branches of the phylogeny showed a steady accumulation of synonymous substitutions and a progressive increase of nonsynonymous substitutions over time, suggesting diversification likely was driven by positive selection. Short-term accumulation of nonsynonymous substitutions driven by selection may have significant implications for virulence, transmission dynamics, and even vaccine efficacy. IMPORTANCE: Cholera, a dehydrating diarrheal disease caused by toxigenic strains of the bacterium Vibrio cholerae, emerged in 2010 in Haiti, a country where there were no available records on cholera over the past 100 years. While devastating in terms of morbidity and mortality, the outbreak provided a unique opportunity to study the evolutionary dynamics of V. cholerae and its environmental presence. The present study expands on previous work and provides an in-depth phylodynamic analysis inferred from genome-wide single nucleotide polymorphisms of clinical and environmental strains from dispersed geographic settings in Haiti over a 2-year period. Our results indicate that even during such a short time scale, V. cholerae in Haiti has undergone evolution and diversification driven by positive selection, which may have implications for understanding the global clinical and epidemiological patterns of the disease. Furthermore, the continued presence of the epidemic strain in Haitian aquatic environments has implications for transmission.
Asunto(s)
Cólera/epidemiología , Cólera/microbiología , Microbiología Ambiental , Variación Genética , Selección Genética , Vibrio cholerae O139/clasificación , Vibrio cholerae O1/clasificación , ADN Bacteriano/química , ADN Bacteriano/genética , Evolución Molecular , Haití/epidemiología , Mutación Missense , Mutación Puntual , Polimorfismo de Nucleótido Simple , Análisis de Secuencia de ADN , Vibrio cholerae O1/genética , Vibrio cholerae O1/aislamiento & purificación , Vibrio cholerae O139/genética , Vibrio cholerae O139/aislamiento & purificaciónRESUMEN
Response to the 2010 Haitian earthquake included an array of diverse yet critical actions. This paper will briefly review the evacuation of a small group of patients with burns to burn centers in the southeastern United States (US). This particular evacuation brought together for the first time plans, groups, and organizations that had previously only exercised this process. The response to the Haitian earthquake was a glimpse at what the international community working together can do to help others, and relieve suffering following a catastrophic disaster. The international response was substantial. This paper will trace one evacuation, one day for one unique group of patients with burns to burn centers in the US and review the lessons learned from this process. The patient population with burns being evacuated from Haiti was very small compared to the overall operation. Nevertheless, the outcomes included a better understanding of how a larger event could challenge the limited resources for all involved. This paper includes aspects of the patient movement, the logistics needed, and briefly discusses reimbursement for the care provided.