An unprecedented wave of dengue continues to sweep Latin America and the Caribbean, with nearly five million people infected in 2024, nearly two-thirds of them in Brazil, the epicenter of the epidemic.
Argentina, the second worst-hit country in the hemisphere, recorded more than 233,000 cases over the summer, eight times higher than last year. Other countries with high numbers include Colombia, Costa Rica, Guatemala, Guadeloupe, French Guiana, Martinique, Mexico, Paraguay and Peru. In late March, Puerto Rico even declared a public health emergency as the number of cases surpassed the highest level of the entire previous year.
Brazil now has a record 3.14 million dengue cases, and health experts soberly note that the number of cases could reach 4.2 million, roughly the same as the total number of dengue cases in America in 2023. The dengue dashboard states that 1,344 people have already died and another 1,872 deaths are under investigation. In comparison, dengue caused 1,094 deaths in 2023.
Four serotypes of dengue virus (DENV 1–4) cause the mosquito-borne disease known as dengue, which is currently circulating in the continental United States this year.
About half the world’s population (in 129 countries) lives in tropical and subtropical areas at risk of dengue. Health experts estimate that up to 400 million people become infected with dengue every year. More than 100 million of them have symptomatic infections, and 40,000 die from complications caused by serious infections, including hemorrhagic shock.
In the South and Southeast Asian regions, Bangladesh and Thailand, among others, have reported similar increases in dengue cases. In November 2023, health authorities reportedWorld Health Organization (WHO) that the number of cases for the year has reached almost 310,000, compared with just 62,400 in 2022. In Thailand, the number of cases has tripled compared to the previous year, with 136,655 dengue cases reported in 2023. As noted by WHO, India Indonesia, Myanmar, Sri Lanka and Thailand are among the 30 countries most affected by endemic dengue.
In the WHO Western Pacific region, the worst affected countries are Vietnam (150,000 cases and 36 deaths) and the Philippines (167,000 cases and 575 deaths). Other countries reporting the effects of dengue include Australia, Cambodia, China, Laos, Malaysia and Singapore. As the report states, “Member States with endemic transmission continue to report longer seasonal outbreaks of dengue fever that are increasing in size and geographic scope. However, incidence rates are less reliable due to under-reporting of cases, especially in island countries and Pacific territories. […]»
Winter tends to prevent mosquito-borne infections throughout the year. However, rising global temperatures have made temperate climates more favorable for dengue virus transmission, as higher rainfall from heavy rains leads to flooding and pools of stagnant water, which are favorable conditions for these mosquitoes.
As WHO’s December 21, 2023 report on the global dengue situation highlights, “The incidence of dengue worldwide has increased significantly over the past two decades, representing a major public health challenge. Between 2000 and 2019, the number of reported cases worldwide increased tenfold, from 500,000 to 5.2 million, according to WHO. 2019 marked an unprecedented peak, with cases reported in 129 countries.”
After a slight decline at the start of the COVID pandemic, dengue began to spread even more widely in 2023, and the 2024 outbreak in America eclipsed all previous outbreaks.
In its assessment of this unprecedented development, WHO highlighted several factors, including changes in weather patterns caused by climate change, the spread and adaptation of mosquitoes, uncontrolled urbanization and human activities, the fragility of health systems in the context of political and financial instability, the simultaneous spread of several dengue virus strains, the lack of specific treatments and “long-term concurrent epidemics, including COVID-19.”
The disease is not contagious. Mosquitoes that carry the virus transmit the pathogen to humans. Symptoms usually appear within a few days to two weeks. These include high fever, severe headaches, vomiting, muscle and joint pain, and a characteristic rash and itching. These symptoms usually last up to seven days and supportive care is offered. In rare cases, the disease can progress to a condition known as dengue hemorrhagic shock, with a mortality rate of 10 to 25%, even with intensive medical support.
There are currently two vaccines available to protect against dengue infection. Dengavaxia, a live attenuated viral vaccine against four serotypes of dengue fever, produced by Sanofi Pasteur, was launched on the market in 2015. The vaccine is administered in three doses at six-month intervals. It is approved for use in people aged 6 to 45 years with previous laboratory-confirmed dengue infection and living in endemic areas. Because of antibody-dependent enhancement, the vaccine may make future dengue infections more severe in people who have never been infected with dengue.
A second dengue vaccine, Qdenga, produced by Takeda Pharmaceuticals Vaccine, which will complete clinical trials in 2022, is recommended by WHO for the prevention of dengue in people aged four years and older who have never been infected with dengue. It is also a live attenuated vaccine against four serotypes of dengue virus, which is administered in two doses at an interval of three months.
However, limited supply and cost of the vaccine have made it prohibitive. In Europe, the vaccine can be purchased for $115 per dose. In Indonesia it costs 40 dollars. In January, according to the report The newspaper “New York TimesBrazil acquired the world’s entire supply of Qdenga, paying $19 per dose for bulk purchases. However, there are only enough vaccines left to treat 3.3 million of Brazil’s 220 million people. Priority is given to children from 6 to 16 years old.
The increase in the prevalence of dengue fever and its spread towards the poles is significant and indicates a massive redistribution of global biodiversity caused by climate change. 2023 was the warmest year since global records began in 1850 and exceeds the pre-industrial average from 1850 to 1900 by 1.35 degrees Celsius. The continued acceleration of global processes can only worsen these processes for the human population.
According to a report published in February 2023 by the Royal Society, “a fundamental meta-analysis found that terrestrial species are currently increasing in height at a rate of 1.1 meters per year, and towards higher latitudes at a rate of 1.7 kilometers per year.” . year. Among the millions of species on the move are some of the most important pathogens, disease vectors, and wildlife reservoirs that impact human health and economic development.
In recent years, mosquito-borne diseases such as malaria, dengue and Zika virus have also spread to new latitudes and altitudes and will continue to do so in the future, following thermal transmission limits set by their ectothermic vectors. This expansion was facilitated in part by parallel global invasions of Aedes aegypti and Aedes albopictus, which spread approximately 250 and 150 kilometers per year, respectively.
In another scientific report published in 2022 in the journal NatureThe authors attempted to quantify the extent of the impact of climate change on human pathogenic diseases. In their comprehensive work, they write: “The totality of pathogenic diseases aggravated by climate hazards represents 58% of all infectious diseases reported to have affected humanity worldwide, that is, in only a list of 375 infectious diseases documented to have affected humanity, 218 they have been found to be exacerbated by climate hazards.
In their summary, they warn: “Human pathogens and transmission routes exacerbated by climate hazards are too numerous to support comprehensive social adaptation, highlighting the urgent need to work at the source of the problem: reducing greenhouse gas emissions.”
However, greenhouse gas emissions and ongoing climate change are a byproduct of the anarchy of capitalist production, which prioritizes the immediate accumulation of profit over the broader problems that make life on the planet inhospitable. This exacerbates already criminal levels of inequality, which have led to the accumulation of obscene wealth on the one hand and the impoverishment of billions of people on the other. Extreme poverty, inadequate housing and nutrition, and lack of access to quality health services add to the threat posed by these diseases, which continue to increase in incidence and virulence.
(Article published in English on April 15, 2024)
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