In recent days, the world has witnessed extreme weather events. Costa Rica has been hit by low pressure systems, with unprecedented rainfall throughout the national territory. Also, regions of Spain such as Valencia, Catalonia and Malaga have been impacted by the catastrophic DANA, which has already claimed the lives of at least 216 people.
And while some regions of the world are covered with water, the opposite is true in others. Just a few weeks ago we witnessed forest fires in Peru and Colombia and the worst droughts in the Brazilian Amazon. All these weather events cause material losses, damage to homes, roads, bridges and buildings, economic and livelihood losses and even direct deaths. However, there is another consequence of which little is said: the proliferation of communicable diseases because of climate change.
Proliferation of diseases
According to the Pan American Health Organization (PAHO), climate change exacerbates some threats to public health and creates new challenges. It is estimated that in the future, because of climate change, around 250,000 additional deaths per year will occur worldwide.
With rising global temperatures, certain insects, such as mosquitoes, are expanding their habitats to regions where they could not previously survive. This has led to an increased spread of diseases transmitted by these vectors, such as dengue fever, Zika, chikungunya and malaria.
Areas that were once too cold for these insects now allow them to survive and reproduce, increasing the risk of outbreaks in previously safe places. In Latin America, for example, Aedes aegypti mosquitoes have colonized new, higher altitude areas, exposing millions of people to diseases that were limited to tropical regions.
Floods such as those that have occurred in Guanacaste during the last week also cause septic tanks and other wastewater treatment systems to overflow, resulting in contamination of the drinking water supply. This leads to outbreaks of waterborne diseases such as hepatitis A and leptospirosis, among other diarrheal diseases.
Additionally, the effects of climate change force many people to remain in temporary shelters, in a state of overcrowding that leads to the transmission of respiratory diseases and limited access to optimal hygiene conditions.
Brain-eating amoeba
Beyond the proliferation of common diseases, climate change also leads to the emergence of diseases caused by infectious agents that are difficult to diagnose, such as viruses, bacteria and parasites.
Such is the case of free-living amoebae such as Naegleria fowleri, popularly known as the “brain-eating amoeba”. This amoeba is a protozoan capable of living and replicating in the environment without the need of a host. Infection with this microorganism causes a severe infection called primary amebic meningoencephalitis (PAM), with a mortality rate of approximately 97%.
The amoeba enters through the nose, crosses the nasal membrane and follows the olfactory nerve to the brain, where it incubates in an average time of five days. Symptoms begin with a rapid onset of a severe frontal headache, fever, vomiting and nausea that worsen to stiff neck, altered mental status, hallucinations, coma and finally death.
Infection with this amoeba is associated with immersions in natural fresh water contaminated with the amoeba. These are usually warm bodies of water such as hot springs, or pools of water in warm areas.
Climate change has caused a high variability of these natural environments and today the distribution of this pathogen is highly variable. According to a National Geographic study, the presence of this amoeba in bodies of water has increasingly moved northward from the tropics and to higher and higher elevations. This is associated with the fact that areas where it was previously absent have become warmer.
Diagnosis and professional updating
Investment in professional updating is undoubtedly a measure of adaptation to climate change. Increasingly, there is a need for professionals who consider climate change and variability in their day-to-day work, so that they can offer solutions in line with our times.
In the case of communicable diseases, epidemiological analyses must increasingly consider climatic factors. We have left behind the times when it was known for certain which diseases belonged to which region. An example of this dates back to February 2020, when thanks to the quick action and above all to the application of updated knowledge in epidemiology, considering climatic variables of different professionals of the Costa Rican Social Security Fund and the University of Costa Rica, they saved the life of a 4 year old girl who had been infected with Naegleria fowleri, in the province of Cartago .
In addition to being an environmental issue, climate change is a public health crisis. Its impact on the increase in the prevalence and distribution of diseases is a wake-up call for governments, organizations and civil society to act. Applying climate change mitigation and adaptation measures not only protects the environment, but also protects and promotes the health and integrity of all people.