El Niño may help spread dangerous diseases across oceans

Dangerous bacteria may ‘piggyback’ from Asia to Latin America

April 2
A new study tracks potential public health impacts of El Niño.

Staff Report

Along with causing weather-related disasters like flooding or drought, El Niño may be a factor in spreading waterborne diseases like cholera thousands of miles across oceans, according to a new study published in the journal Nature Microbiology.

The findings by U.S. and UK researchers suggest that the arrival of new diseases in Latin America is linked with the spread of warmer El Niño waters. Examples include a 1990 cholera outbreak in Peru that killed 13,000 people, and two instances (1997 and 2010) when  new variants the bacterium Vibrio parahaemolyticus led to widespread human illness through contaminated shellfish. The study explored how those outbreaks concurred in both time and space with significant El Niño events.

“The effects of El Niño events and their impacts on local weather, fisheries and the risk of more extreme meteorological events are already well-documented. Now understanding the role the ocean currents are also playing in transporting these disease has huge significance for public health campaigns in those countries,” said lead author Dr Jaime Martinez-Urtaza, with the University of Bath’s Milner Centre for Evolution and Department of Biology & Biochemistry.

“Through our findings we suggest that so-called vibrios — microscopic bacteria commonly found in seawater — can attach to larger organisms such as zooplankton to travel oceans. Numerous previous studies have shown how such vibrios bind to and use these larger organisms as a source of energy and through this mechanism, we suggest, they are essentially able to piggyback to travel such enormous diseases, driven by ocean currents,” Martinez-Urtaza said in a press release describing the findings.

El Niño describes the unusual warming of surface waters along the tropical west coast of South America. These events tend to occur every 3 – 7 years; something many suggest have become more regular and extreme in recent years, as a result of climate change.

Through genome sequencing, the researchers also tracked possible links between organisms that are causing illnesses in Asia with those that emerge in Latin America.

Co-author, Dr Craig Baker-Austin from the UK Cefas Weymouth laboratory added: “An El Niño event could represent an efficient long-distance ‘biological corridor’, allowing the displacement of marine organisms from distant areas. This process could provide both a periodic and unique source of new pathogens into America with serious implications for the spread and control of disease.”

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