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

摘要

After being cholera free for over 100 years and in the absence of an effective vaccine against the disease, Peru experienced one of the worst multi-wave epidemics in South American history from 1991-1997. Here we applied statistical and mathematical modeling to a weekly spatio-temporal dataset of cholera cases to investigate transmission patterns and variation in the basic reproduction number. Our findings indicate that the epidemic first hit the coastal departments of Peru and subsequently spread through the highlands and jungle regions. There were 3 4 consecutive well-defined waves concentrated during the warm seasons. Cholera transmission potential and the initial concentration of vibrios were higher in coastal departments compared to other departments. Moreover, reporting rate estimates were low, consistent with the significant fraction of asymptomatic or mild cases that is associated with the El Tor cholera biotype. Our results suggest that cholera vibrios, autochthonous to plankton in the natural aquatic environment, may have been present in multiple coastal locations, possibly leading to multiple disease introductions along the Pacific coast of Peru.