Dengue fever continues to spread at unprecedented rates throughout Latin America and the Caribbean. So far this year, almost five million people have been infected, almost two-thirds of them in Brazil, the epicenter of the epidemic.
The second worst-hit country in the hemisphere is Argentina, which has reported over 233,000 cases in the summer, eight times as many as last year. Other countries reporting high numbers include Colombia, Costa Rica, Guatemala, Guadeloupe, French Guiana, Martinique, Mexico, Paraguay and Peru. At the end of March, even Puerto Rico declared a public health emergency as the number of cases exceeded the highs of the entire previous year.
Brazil has recorded a record 3.14 million cases so far, and health experts soberly note dengue cases could rise to over 4.2 million, close to the total number of cases in North and South America in 2023. According to the Brazilian Health Ministry’s dengue fever dashboard, 1,344 people have died and another 1,872 are under investigation for the cause of death. For comparison: In 2023, 1,094 people died of dengue fever.
There are four serotypes of dengue viruses (DENV 1-4) that cause the mosquito-borne disease known as dengue (or bonebreaker) fever, which is currently rampant in North and South America.
About half of the world’s population (in 129 countries) lives in tropical and subtropical areas that are at risk of dengue fever. According to an estimate by Health professionals Up to 400 million people are infected with dengue fever every year. More than 100 million have symptomatic infections and 40,000 die from complications caused by severe infections, including hemorrhagic shock.
A similar dramatic increase in dengue cases has been reported in the South and Southeast Asian regions, including Bangladesh and Thailand. In November 2023, health authorities reported World Health Organization (WHO) that the number of cases rose from just 62,400 in 2022 to almost 310,000. In Thailand, they tripled to 136,655 in 2023 compared to the previous year. According to the WHO, India, Indonesia, Myanmar, Sri Lanka and Thailand are among the 30 countries in the world most affected by endemic dengue.
In the WHO Western Pacific region, Vietnam (150,000 cases and 36 deaths) and the Philippines (167,000 infections and 575 deaths) were hardest hit by the disease. Australia, Cambodia, China, Lao People’s Democratic Republic, Malaysia and Singapore also report impacts from dengue fever. The report states: “Member States with endemic transmission continue to report prolonged seasonal dengue epidemics with increasing size and geographical spread. However, the incidence of the disease is less reliable because not all cases are reported, particularly in Pacific island countries and territories…”
As a rule, winter prevents year-round infections with diseases transmitted by mosquitoes. But rising global temperatures have made temperate climates more vulnerable to transmission of the dengue virus, as higher rainfall rates from torrential rains lead to flooding and standing water – conditions that favor these mosquitoes.
The WHO report on the global dengue situation of December 21, 2023 stated: “The global incidence of dengue virus has increased significantly over the last two decades and poses a significant threat to public health. The WHO has from 2000 documented a tenfold increase in cases reported worldwide by 2019, an increase from 500,000 to 5.2 million. The year 2019 marked an unprecedented peak with cases reported in 129 countries.”
After a slight decline at the beginning of the corona pandemic, dengue fever spread even further in 2023, and the outbreak on the American continent this year dwarfs all previous epidemics.
In its assessment of the unprecedented development, the WHO points to various factors, including changes in weather patterns caused by climate change, the spread and adaptation of mosquitoes, unplanned urbanization and human activities, fragile health systems in the face of political and financial instability, the simultaneous spread of multiple strains of the Dengue virus, lack of specific treatments and “long-lasting, simultaneous outbreaks, including Covid-19”.
The disease is not contagious. Mosquitoes that carry the virus transmit the pathogen to humans. Symptoms typically begin after a few days to two weeks. These include high fever, severe headache, vomiting, muscle and joint pain, and a characteristic rash and itching. They usually last up to seven days and treatment is supportive. In rare cases, the disease can progress to a condition known as dengue hemorrhagic shock, with a mortality rate of 10 to 25 percent, even with intensive medical care.
There are currently two vaccines that offer protection against dengue fever infections. Dengavaxia from Sanofi Pasteur is based on a weakened form of live viruses, is suitable for all four serotypes and has been available since 2015. The vaccine is administered in three doses, six months apart. It is approved for people between the ages of six and 45 who have a previous laboratory-confirmed dengue infection and who live in endemic areas. Because of a antibody-dependent enhancement the vaccine may worsen future infections in dengue-naïve recipients.
A second dengue vaccine, Qdenga, is manufactured by Takeda Pharmaceuticals Vaccine and completed clinical testing in 2022. It is recommended by the WHO for the prevention of dengue fever in people aged four and over without a previous infection. This is also a live, attenuated vaccine against all four serotypes of the dengue virus, which is administered in two doses three months apart.
But the Vaccine is only available to a limited extent and is unaffordable. In Europe it can be purchased for $115 per dose. In Indonesia it costs $40. According to the New York Times purchased the entire global supply of Qdenga for $19 per dose in January. Nevertheless, it only has enough vaccine for 3.3 million of Brazil’s 220 million inhabitants. Children aged six to 16 are given priority.
The increasing prevalence of dengue fever and its spread towards the poles is an indication of the massive redistribution of global biodiversity caused by climate change. 2023 was the warmest year since global weather records began in 1850, and was 1.35 degrees Celsius above the pre-industrial averages from 1850 to 1900. Continued and accelerating global processes can only exacerbate these processes for human populations.
In one report the Royal Society February 2023 states: “A basic meta-analysis estimated that terrestrial species moved uphill at a rate of 1.1 meters per year and to higher latitudes at a rate of 1.7 kilometers per year. Among the millions of species on the move are some of the most important pathogens, disease vectors and wildlife reservoirs affecting human health and economic development.”
They continued: “In recent years, mosquito-borne diseases such as malaria, dengue and the Zika virus have and will continue to spread to new latitudes and altitudes as their ectothermic vectors impose thermal limits on transmission. Part of this spread was facilitated by parallel global invasions of Aedes aegypti and Aedes albopictus, which have spread at an estimated rate of 250 and 150 kilometers per year, respectively.”
The magazine Nature published another scientific paper in 2022 report, in which the authors attempted to quantify the full extent of climate change on human pathogenic diseases. The authors wrote in the comprehensive paper: “The assemblage of pathogenic diseases exacerbated by climate hazards comprises 58 percent of all infectious diseases reported to have affected humanity worldwide. This means that out of an authoritative list of 375 documented infectious diseases that have affected humanity, 218 were made worse by climate hazards.”
They warn in their summary: “The human pathogenic diseases and transmission routes that are exacerbated by climatic hazards are too numerous for comprehensive social adaptation. This highlights the urgent need to address the root cause 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 profits over the broader problems that are making the planet uninhabitable. It is exacerbating the already criminal levels of inequality that are amassing obscene fortunes at one end of society while impoverishing billions of people at the other. Abject poverty, inadequate housing and nutrition, and lack of access to quality health services exacerbate the threats posed by these diseases, which are becoming increasingly common and virulent.