Is climate change making the Ebola outbreak worse?

Monday, 10 November 2014 10:26 GMT

Fruit bats are seen resting on tree branches in a forested area of Subic Bay, Olongapo province, north of Manila, Philippines, March 6, 2009. REUTERS/John Javellana

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Extreme weather, forest loss and malnutrition may play a role in spreading the virus and weakening immune systems

Ebola is an extremely infectious disease, with no specific treatment or vaccine. It has a fatality rate that can be as high as 90 percent, and an average case fatality rate of 50 percent. West Africa has been hard hit. The current outbreak there has been recorded as the largest and most complex in history, with more cases and deaths than all previous outbreaks combined.   

This has caused a humanitarian crisis that has exposed the weaknesses in affected countries’ health systems. While it may not be a top priority for those rushing to stem the outbreak, has climate change made things worse?

In a 2008 article published by Scientific American, Ebola was noted as one of 12 infectious diseases most likely to spread and worsen as a result of climate change. The researchers observed that Ebola outbreaks tended to follow unusual downpours or droughts, made more likely by climate change.

Considering predictions from both UNEP’s Africa Adaptation Gap report and the IPCC’s latest assessment report of worsening climate change impacts, which include under-nutrition and disease, responding to the climate change-driven components of infections becomes an imperative.

Degradation of ecosystems through activities like deforestation has been linked to infections, specifically Ebola. It has been reported that three countries hardest-hit by Ebola - Liberia, Sierra Leone, and Guinea - have also experienced increased logging operations in recent years.  

A 2012 article published in the Onderstepoort Journal of Veterinary Research found a considerable overlap between deforested regions and Ebola outbreaks.

In a September 2014 fact sheet, the World Health Organization (WHO) explains this possible linkage by noting that deforestation typically disrupts natural ecosystems, and puts humans in greater contact with wild creatures, including bats and primates that are known hosts of the virus. Hence the likelihood of humans acquiring the infection is greatly increased.

In a 2009 publication, Yale Environment 360 noted that deforestation results in the dislocation of hosts like fruit bats, increasing encounters with humans who are exposed to the pathogens the bats carry.

For instance, the 2007 outbreak in the Congo, which resulted in 260 infections and 186 fatalities, has been traced by scientists to massive migration of fruit bats into stricken villages just prior to the epidemic .

Other than dislocation of Ebola host species, loss of biodiversity and habitats devastates otherwise ‘safe’ species traditionally hunted for game meat, leaving impoverished villagers with no choice but to eat survivor species such as fruit bats, increasing chances of transmission of the virus to humans.

BUILDING IMMUNITY

Medically speaking, impaired immunity opens the way for infectious diseases, which typically raise bodily nutrient needs but reduce food intake through loss of appetite, for instance. Disease and under-nutrition create a synergistic downward spiral that must be broken for recovery to occur.

In other words, a sick person who can only ingest small amounts of food but needs more nutrients to boost their chances of recovery must receive nutritious-enough food. The U.N. FAO argues that the twin problems of infection and nutrition should be tackled together.

The importance of nutrients in fighting infections is paramount.  Zinc supplementation was found in a 2006 study published in the American Journal of Tropical Medicine and Hygiene to reduce diarrhoea morbidity by 23 percent in children. Diarrhoea is one of symptom of Ebola known to cause death.

The FAO records that six African countries are among those who receive 60 percent of their dietary requirements of iron and zinc from grains and legumes - and Sierra Leone is one of them.

Yet in a warming climate, food is likely become less nutritious, according to a 2014 study published in nature.com that examined the impact of higher carbon dioxide levels.

A 2001 study found that immune-system boosting compounds were more prevalent in ecologically grown crops than conventionally produced crops.

It is imperative for Africa to ensure that its entire food system is resilient and robust enough to provide nutritious food to its citizens - and hence help to control some disease symptoms.

The application of ecosystems-based adaptation approaches to climate change could improve agricultural productivity in rural communities, and hence reduce their need to encroach on animal habitats to supplement their food needs.

That would lower their chances of being infected with the Ebola virus, as well boosting the restoration of habitats and ecosystems, keeping carrier species like fruit bats away from human settlements.   

In fostering a more comprehensive response to Ebola, it will be important to start looking at how climate change may be contributing to its spread, and finding of ways of tackling any climate-linked drivers of infection and barriers to patients’ recovery.

Richard Munang is UNEP’s Africa Regional Climate Change Programme Co-ordinator, tweeting as @mtingem. Robert Mgendi is an Ecosystem-based Adaptation Officer with the UNEP’s Regional Office for Africa Climate Change Programme.

The views expressed here are those of the authors and do not necessarily represent those of the institution with which they are affiliated.