The wide-ranging impacts of El Niño on wildlife and animal health

An interview with Dr William B. Karesh (Member of the Working Group on Wildlife and Executive Vice President for Health and Policy at EcoHealth Alliance). 

Briefly, what is El Niño? 

William B. Karesh: El Niño means Little Boy in Spanish. South American fishermen first noticed periods of unusually warm water in the Pacific Ocean in the 1600s. The full name they used was El Niño de Navidad, because El Niño typically peaks around December. During normal conditions in the Pacific Ocean, trade winds blow east to west along the equator, taking warm water from South America towards Asia. To replace that warm water, cold water rises from the depths — a process called upwelling. El Niño and La Niña are two opposing climate patterns that break these normal conditions by weakening trade winds. Scientists call these phenomena the El Niño-Southern Oscillation (ENSO) cycle. El Niño and La Niña can both have  global impacts on weather patterns, causing extreme environmental events, such as wildfires, with strong societal and economic repercussions on our interdependent ecosystems.  Episodes of El Niño and La Niña typically last nine to 12 months but can sometimes last for years. El Niño and La Niña events occur every two to seven years, on average, but they don’t occur on a regular schedule. 

In which direct and indirect ways do weather events prompted by
El Niño–Southern Oscillation (ENSO) affect animal health? Which animals are affected the most?  

W.B.K: Weather conditions affect animal health both directly with temperature extremes/extreme temperatures and water availability (droughts and floods) as well as indirectly with changes in the availability of nutritional and food resources, abundance of vectors, and crowding, dispersal or movement of animals. The weather extremes may result in dehydration and mal-nutrition in both wild and domestic animals and increases in vector-borne diseases such as Rift Valley fever, yellow fever, and malaria. 

Since it occurs on a cyclical basis, should we be able to plan for it? What are the warning signs that ENSO is starting and how much time do we have to prepare? 

W.B.K: Using data collected from ocean buoys and satellite systems such as sea temperature, currents, and atmospheric conditions, climate scientists have developed predictive models that can forecast ENSO events with increasing accuracy several months in advance.  A key predictive indicator is a shift in Pacific trade winds and a lowering in ocean surface temperatures in the equatorial region of the western Pacific Ocean. While the specific degree and time length of the effects may vary a bit, the general pattern of the changes in different locations remain consistent across/in between ENSO events and thus can be used locally for planning purposes. 

What can be done by animal health services and environmental services to be prepared and resilient before an El Niño event? 

W.B.K: The first step is to review the impacts of previous ENSO events at the specific local or region level of concern and tailor preparedness and mitigation plans for the anticipated changes such as increased or decreased rainfall. This understanding of the potential impacts can then be used to develop plans that are locally relevant and engage key agencies and community stakeholders in planning and preparedness, as well as design communication strategies for different audiences.  Activities may include assuring availability of response equipment and supply stockpiles, refresher training of personnel, planning for water availability or flood control, contingency planning for feed/food availability and supply chains, outbreak or mortality event response capabilities, etc. 

How can we support unmanaged wild animal populations during climatic events? 

W.B.K: Where droughts are anticipated, access to water may bring livestock and wildlife into closer proximity. This allows for increased disease transmission from livestock to wildlife or to reduce safe access to water by wildlife. Access to water by people, livestock and wildlife can be discussed and planned by engaging relevant stakeholders and relevant authorities. Anticipated changes in ocean temperatures have predictable effects on fish populations and fisheries, and affect food stocks for marine birds and mammals. Fish harvesting quotas should be adjusted to avoid the depletion of fish stocks, and prevent the starvation of wildlife.

What is the Working Group on Wildlife doing to increase awareness of the impacts that extreme events have on wildlife health? 

W.B.K: The WGW released an early warning for the coming ENSO event for health authorities and the general public. It stands by to advise WOAH, its Members and other interested parties as requested and as the wildlife situation evolves.

You coined the expression “One Health” in 2003 to describe the interdependence of healthy ecosystems, animals and people. How has this concept evolved in the past twenty years, and what are the accomplishments of the One Health approach that underline its significance today? 

W.B.K: The increased attention to ENSO events provides an excellent example of growth of One Health thinking among different sectors that consider how environmental changes can have consequences on health and well-being. The One Health concept has become a starting point for the development of many programs and projects at local, national and international levels to expand cost efficiency and co-benefits. In financial terms, investments in using a One Health approach have exceeded tens of billions (USD) since its inception. 

About Dr William B. Karesh

Dr William B. Karesh is the Executive Vice President for Health and Policy at EcoHealth Alliance. He serves as the Chair of the World Organisation for Animal Health (WOAH) Working Group on Wildlife Diseases and also chairs the International Union for the Conservation of Nature (IUCN) Wildlife Health Specialist Group, a network of wildlife and health experts around the world.

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