Diseases that may increase with climate change – 12/11/2023 – Balance and Health

Saying that the day is hotter or that the rain is heavier should become more common in the coming years in Brazil, due to climate change.

And, according to researchers interviewed by BBC News Brasil, the strong social inequality that exists in the country should have a direct impact on who will suffer most from the effects of climate change on public health — whether through the emergence of new diseases or the growth in the number of arbovirus cases. (diseases transmitted mainly by mosquitoes) already known, such as dengue, malaria and yellow fever.

Cassia Lemos, a researcher at the National Institute for Space Research (Inpe), is one of the Brazilians who has dedicated herself to predicting how climate change will impact Brazil’s healthcare system.

The coordinator of AdaptaBrasil, a platform that shows the potential risks of climate change in the country in different areas, states that studies already show that the diseases that are expected to increase most with climate change are arboviruses.

“In addition to dengue fever, which is already a problem, our projections show that malaria is expected to spread even further across the North region and reach the Northeast coast intensively by 2050.”

The projections of the platform created by the federal government, in partnership with research educational institutions in Brazil, also point to an increase in cases of American cutaneous leishmaniasis and visceral leishmaniasis.

To arrive at the predictions, the researchers analyzed the epidemiological profile of infections, the specificities of each disease and data on the development of the health condition, for example, hospitalization or death.

Next, the socioeconomic and demographic aspects of each municipality were considered, as well as the organization and quality of the health system on a municipal scale to respond to the health demands of diseases and to promote surveillance and control of vectors.

“With this, we realize that it is not only the increase in temperature or extreme weather events that will cause diseases, but the socio-ecological characteristics of the Brazilian population must favor the proliferation of these pathologies”, says Cassia.

More resistant vectors

For Leandro Gurgel, researcher at the Oswaldo Cruz Foundation (Fiocruz), another fact that should contribute to arboviruses becoming a bigger problem in the future is that mosquitoes and mosquitoes take Charles Darwin’s Theory of Natural Selection literally.

“We all have a temperature tolerance limit, whether higher or lower, but what we have noticed is that vectors adapt increasingly better to these climatic extremes. This makes them an increasingly greater problem for public health in the world, because they are more resistant, [os mosquitos] they have more specimens and are consequently able to reach more people by transmitting diseases”, points out Gurgel.

As an example, the Fiocruz researcher cites the reproduction capacity of Aedes aegypti —one of the best-known vectors for Brazilians for transmitting dengue, chikungunya and zika viruses.

“O Aedes aegypti It is a mosquito that is increasingly adapted to climate change. In the past, we heard that it only reproduced in clean, still water. Nowadays, for example, we know that it reproduces in garbage, dirty water and that the mosquito egg can remain viable for more than a year without water”, he says.

“But the worst thing is that, nowadays, it is not just by biting an infected person that the vector becomes infected and transmits the disease. The simple act of a female ‘pregnant’ with the Aedes aegypti Sting a person with dengue automatically causes them to infect up to 50% of their ‘children’. In other words, they are new Aedes that already have the capacity to transmit diseases at their origin”, explains Gurgel.

Higher risk of death

It is not just arbovirus diseases that are expected to increase in the future.

Studies show that respiratory, cardiovascular and even kidney diseases are expected to increase in Brazil following an increase of 1.5ºC to 4ºC in the average temperature by the end of this century, according to projections by the United Nations Intergovernmental Panel on Climate Change (IPCC).

To give you an idea, a survey that evaluated the health records of 1,816 Brazilian cities between 2000 and 2015 suggests that an increase of 1ºC in the average temperature may have increased the risk of hospitalizations for diseases that affect the kidneys by almost 1%. The research was carried out by the University of São Paulo (USP) and Monash University, in Australia.

According to researchers, most kidney diseases occur due to dehydration, which is expected to worsen as temperatures rise in the coming years.

At the same time, another study by Salud Urbana en América Latina (Salurbal), published in the journal Nature Medicine, found that the higher the temperature, the greater the risk of death from cardiovascular and respiratory diseases.

To reach their conclusion, the researchers analyzed the relationship between temperatures that are too high or too low and mortality in 326 cities in nine countries in Latin America, between 2002 and 2015.

“What we noticed is that for both extreme temperatures and low [frio]as for extreme temperatures upwards [calor], increases the risk of death from diseases. However, when the temperature is higher, [calor]this risk of dying increases”, explains Waleska Teixeira Caiaffa, a Brazilian doctor who participated in the study and coordinator of the Urban Health Observatory at the Federal University of Minas Gerais (UFMG).

This is because long-term exposure to high temperatures decreases the body’s ability to maintain a constant temperature, leading to heatstroke, syncope and heat exhaustion — which causes a greater chance of a person having a stroke, for example.

“The data only highlights how climate change is not an issue that should only be linked to the environment, but to all sectors, as everyone will in some way be affected by rising temperatures or extreme weather events”, points out Waleska Caiaffa.

Other diseases

The incidence of infectious and parasitic diseases due to flooding caused by natural disasters or extreme weather events in large urban centers is also expected to increase in Brazil.

This is because rain, difficulty in water drainage and failures in garbage and sewage collection create favorable scenarios for leptospirosis outbreaks.

Likewise, the lack of water due to high temperatures can cause more cases of schistosomiasis and diarrhea, problems resulting from the consumption of contaminated water.

Snails of the genus Biomphalaria, which are hosts of the parasite that causes schistosomiasis, are favored by water points with little current.

“It could be, for example, that we have more of a malaria problem in the North and Northeast, but dengue in the Southeast. The increase in diseases will depend a lot on what the climate changes will be for each region and what the socioeconomic situation of the population is like. “, says James Venturi, coordinator of the postgraduate program in infectious and parasitic diseases at the Federal University of Mato Grosso do Sul (UFMS).

The researcher also highlights that society’s own response can favor the proliferation of certain parasites.

“So, for example, when I have an increase in temperature and need to use even more pesticides and fungicides, we already notice natural selection, making these parasites more resistant and prone to contaminating [no sentido de infectar] human beings in the future.”

Action and reaction

For Leandro Gurgel, a researcher at Fiocruz, more than ever commitment is needed from governments and civil society to mitigate climate change.

“Just like diseases, which are the result of an attack on the environment, the same thing is happening to the environment. We are attacking it and eventually the bill arrives, whether with an increase in temperature, a change in the rainfall regime or even extreme weather events”, he states.

Waleska Teixeira Caiaffa, from UFMG, highlights that the situation needs to be discussed more by society.

“People need to understand that what we expected to happen in 2030 is already happening. We need to organize our health service for these new demands, and this also includes urban planning.”

“An elderly person in the favela who lives in a house without running water or basic sanitation could be a potential victim of climate change. Just like a child without access to basic health services. We need to understand the seriousness of climate change”, says the doctor.

The text was originally published here.