Genetic Studies of Vibrio cholerae in South West Cameroon —A Phylogenetic Analysis of Isolates from the 2010-2011 Epidemic

Conclusions This study provides data on whole genome sequence analysis of V. cholerae isolates from the South West Region-Cameroon. While the epidemic curve shows multiple peaks, there was no evidence of seasonality, nor has there been major recurrence of illness in subsequent years: i.e., we did not see the annual seasonal epidemics described in Asia and other regions of the world. Movement of strains through local environmental reservoirs might be expected to show correlation between genetic distance and geographic distance of sampling locations, with genetic heterogeneity generally increasing with progressively more distant locations from the initial epicenter of epidemic. Moreover, phylogenetic relationships among sampled strains would show highly supported monophyletic clades, corresponding to different transmission chains. On the contrary, the star-like topology of the tree and the lack of correlation between genetic and geographic distance seen with the South West Region outbreak are highly consistent with an exponential outbreak localized around a relatively restricted area (i.e., the city of Buea) with occasional spillover to other parts of the region likely mediated by occasional human-to-human contact. Intriguingly, one of the earliest sampled strains from the epicenter of the epidemic was significantly separated from all other strains, and appeared to be a natural outgroup for the tree; and thus, this phylogenetic analysis suggests this natural outgroup as the ori...
Source: PLOS Currents Outbreaks - Category: Epidemiology Authors: Source Type: research