During the 1990s, epidemic cholera emerged along the coast of Peru and then spread to neighboring countries in Central and South America. Subsequently, more than 1.2 million cases were reported during the 1990s in the region. Today, the source of emergence remains unknown. Although the onset of the epidemic was initially attributed to a cargo ship, it was later suggested that El Niño, the warm phase of El Niño–Southern Oscillation (ENSO), may have been a key driver, via ecosystem changes along the coast of Peru.
Recently, the El Niño link has been challenged by Iván J. Ramírez, CCB adjunct scientist, and assistant professor of environmental health at The New School in New York City. According to a recent study published by Ramirez and coauthors in Weather, Climate and Society, the El Niño event of 1991 could not have triggered the initiation of the epidemic since El Niño developed well after the epidemic began in January 1991. Rather, El Niño was likely a contributor (along with social factors) to epidemics in early 1992 at the peak of the 1991-92 event. Preliminary evidence presented by the authors was based on the definition of El Niño, which previous studies had not considered. The definition is important because it affects how one characterizes the temporal relationship between El Niño and disease, which is dependent on whether the two events coincide in time. Although it has been fifteen years since the epidemic, understanding the climate link to cholera in Peru remains important today, as it may provide insights to understanding the recent emergence of cholera in the region, which began in Haiti in 2010.
For more information and to learn about the “multiple pathways” approach to understanding climate impacts on health and society (based on the CCB approach, “Climate Affairs”), please see the links below.
Ramírez, I.J., S. Grady, and M.H. Glantz, 2013: Reexamining El Niño and cholera in Peru: a climate affairs approach. Weather, Climate and Society, 5, 148–161. doi: http://dx.doi.org/10.
Ramírez, I.J., 2014: Cholera resurgence in Piura, Peru: examining climate associations during the 1997-98 El Niño. GeoJournal. (online March 2014).http://link.springer.
Iván J. Ramírez. http://newschool.