Spatial dynamics and the basic reproduction number of the 1991 –1997 Cholera epidemic in Peru

by Alexandra Smirnova, Natalie Sterrett, Oscar J. Mujica, C ésar Munayco, Luis Suárez, Cécile Viboud, Gerardo Chowell After being cholera free for over 100 years, Peru experienced an unprecedented epidemic ofVibrio cholerae O1 that began in 1991 and generated multiple waves of disease over several years. We developed a mechanistic transmission model that accounts for seasonal variation in temperature to estimate spatial variability in the basic reproduction number (R0), the initial concentration of vibrios in the environment, and cholera reporting rates. From 1991-1997, cholera spread following a multi-wave pattern, with weekly incidence concentrated during warm seasons. The epidemic first hit the coastal departments of Peru and subsequently spread through the highlands and jungle regions. The correlation between model predictions and observations was high (range inR2: 58% to 97%). Department-level population size and elevation explained significant variation in spatial-temporal transmission patterns. The overallR0 across departments was estimated at 2.1 (95% CI: 0.8,7.3), high enough for sustained transmission. Geographic-region level R0s varied substantially from 2.4 (95% CI: 1.1, 7.3) for the coastal region, 1.9 (0.7, 6.4) for the jungle region, and 1.5 (0.9, 2.2) for the highlands region. At the department level, mean R0 ranged from 0.8 to 6.9. Department-level R0s were correlated with overall observed attack rates (Spearmanρ = 0.59,P = 0.002), elevation (ρ = −0.4...
Source: PLoS Neglected Tropical Diseases - Category: Tropical Medicine Authors: Source Type: research