Via the PLOS blog Translational Global Health: El Niño predictions signal urgent need to prepare for epidemic in eastern Africa. Excerpt:
Recent climate predictions suggest East Africa may be in line for an epidemic of Rift Valley fever – an infectious disease which can hit people, their livestock and livelihoods, and national economies hard.
Data from the Climate Prediction Centre and International Research Institute for Climate and Society suggest there is a 99.9% chance there will be an El Niño occurrence this year, with a 90% chance it will last until March/April 2016.
At least two of the most recent Rift Valley fever epidemics in East Africa – those in 1997/98 and 2006/2007 – were associated with El Niño weather patterns, with Kenya suffering losses amounting to US$32 million in the most recent.
Given the strong predictions of an El Niño occurrence, and the established association between El Niño and Rift Valley fever risk, countries in the Horn of Africa need to start laying out measures to manage the developing risk. In particular, public education on the linkages between the expected weather patterns and disease risk is vital to minimise human exposure to the disease should an epidemic occur.
Disease and climate change
El Niño – the warm phase of El Niño Southern Oscillation (ENSO) – is a warming of sea surface temperatures in central and eastern equatorial Pacific Ocean which occurs every three to seven years, triggering a chain of atmospheric changes throughout the world. In the Horn of Africa it results in heavy rainfall, particularly when there is a simultaneous increase in the sea surface temperatures in the western Indian Ocean. The current predictions give a strong indication that sea surface temperatures in the Indian Ocean are indeed also on an upward trend.
Questions are often raised on whether there are linkages between ENSO and global warming. ENSO is not considered a driver of climate change, but it is the strongest naturally occurring source of climate variability globally. As such, global warming is likely to double the frequency of ‘super’ El Niños.
Epidemics of malaria, Rift Valley fever and foot rot in animals have all been reported in eastern Africa during past El Niño events.
Rift Valley fever is a zoonotic disease, i.e. one that is passed to humans from a vertebrate animal ‘host’. It is caused by the Rift Valley fever virus which is carried by mosquitoes. Intense and persistent rain provides perfect breeding conditions for the mosquito vectors which initiate and intensify the virus’s transmission.