Infectious Disease And The Climate Crisis: Dengue Fever In Honduras

Honduras in 2019 saw a shocking spread of Dengue Fever, totalling 175 out of 400 deaths last year in an epidemic that swept across Central America. In fact, according to the Pan American Health Organization, there were thirteen times the number of cases compared to 2018 of the disease which can cause fever, internal bleeding and death if not treated. Extreme weather events, climate change, political unrest and gang culture all play a part in why Honduras was at the epicentre of such a large outbreak.

The New York Times (NYT) reported, “the nation’s poorly supplied and understaffed medical facilities lacked the capacity to adequately handle even the nation’s normal demands, much less an epidemic of historic proportions”. The lack of resources was compounded by gang-controlled areas blocking health officials, with NYT revealing that “one worker for the health ministry has had to pay bribes to gang members – in small amounts of cash or marijuana – to do her work”. Delays in accessing at-risk areas have allowed the growth of hotspots in some of the most vulnerable regions of the country. There is also public unrest and dissatisfaction with the current President Juan Orlando Hernandez. According to the Associated Press, Hernandez “won another term in spite of a constitutional ban on his re-election in 2017”. There have been nationwide protests with a backdrop of fear over potential privatization of healthcare and education. Paraguay may be the next area to be hit by a Dengue epidemic, with the President having already been struck by the disease. He is expected to make a full recovery, but there have already been over 7,000 confirmed cases this year, which is akin to 2013 levels in an outbreak which was responsible for 250 deaths in Paraguay.

Health officials are working tirelessly to try and halt the disease in the face of political tensions, poverty and being under-resourced themselves. The adviser on sustainable development and environmental health from the Pan American Health Organization in Honduras, Eduardo Ortiz, spoke on this matter, stating that “in another country, there would be many sick but not as many deaths[…] the cure for dengue is political”. The cure being political is pivotal to this whole story. Whilst climate change, as will be explored, is going to exacerbate the spread of disease and put millions at risk in the short and long-term, with the correct funding and some degree of stability or trust of local officials, lives can be saved.

One non-political reason that Dengue was able to flourish in Honduras was weather-related. September 2019 saw a drought in Honduras that led to an emergency government declaration. Drought itself leads to people collecting water in their homes; the stagnant water ideal breeding ground for mosquitos. However, this was followed by “unexpectedly intense rainfall” with flooded areas subsequently also becoming ideal mosquito habitat, providing the springboard for an epidemic to take hold. The NYT contextualizes this as “part of increasing weather variability that climate scientists say is most likely related to climate change”. More extreme drought and rainfall can, therefore, provide conditions for more severe outbreaks of the disease. The Aedes mosquito that carries Dengue is also the carrier for Zika and chikungunya. One study published in Nature Microbiology journal in 2019 explains that warmer temperatures mean a greater range for the Aedes mosquito, but also that they become biting adults faster. The report predicts that over 2 billion people could be at risk of Aedes related diseases by 2080 due to climate factors and increasing urbanization.

Climate change is widely expected to increase levels of infectious disease globally. The WHO estimates five times the number of cases of malaria following “El Nino events”, which involves extreme weather (like the droughts or flooding in Honduras that allowed dengue to spread). Climate change will exacerbate extreme weather globally. They estimate that two to three degrees increase in temperature would equate to “hundreds of millions” more people being at risk of malaria alone. Climate change-based migration could easily lead to the growth of informal settlements too if not politically managed in an adequate manner and areas with poor sanitation, lack of health professionals and poverty will also amplify the ability for pathogens to spread.  Whilst bodies of water in flooded areas are ideal for malaria, drought is perfect for diseases like the West-Nile virus, as it means that both the mosquitoes and birds needed to carry the disease are forced more frequently into closer proximity to each other around a scarce water supply, according to Dr. Emily Shukman’s report in the New England Journal of Medicine.

Arturo Casadevall, professor of microbiology and immunology at Johns Hopkins University warns specifically about heat resistant mutations in fungi, explaining that “global warming will select for with higher heat tolerance that can defeat our endothermy defences and bring new infectious diseases”. Essentially, human body temperature is too high and natural defences too strong for roughly 95% of all fungal diseases presently. However, if climate change forces fungi to adapt to higher temperatures, Casadevall theorizes that “some with pathogenic potential for humans will break through the thermal defensive barrier”, i.e. not be killed off by our body’s natural defences. “If these threats materialize, medicine will need to confront new infectious diseases for which it has no experience… effective responses take time, and countless lives are lost in the process”. Climate change will force pathogens, not just humans, to adapt to new a new climate reality, which could have deadly consequences.

To move forward effectively in the context of climate change and infectious disease, there has to be both short and long term thinking employed. It is outrageous that anywhere in the world, there should be people dying of preventable diseases right now. This crisis is quite clearly also not going to play out neutrally, with those in poorer countries and especially in and around tropical regions, the most likely to be affected. Poor areas with inadequate sanitation are again likely to be the worst affected. Climate change is driven by consumption of transport, agricultural products, non-reusable plastics, non-renewable energy and so many other things used particularly by the richest people in the world, but the poorest areas will once again see the worst effects. The cure is political; a sharp realignment of global priorities to avert the worst of climate change and to treat the lives currently being lost as the top priority is the only acceptable way forward.

Matthew Gold