Latin America's Dengue Outbreak Poses a Global Health Threat

Abstract

Dengue fever, caused by the dengue virus (DENV), poses a significant global health challenge, particularly in tropical and subtropical regions. Recent increases in indigenous DENV cases in Europe are concerning, reflecting rising incidence linked to climate change and the spread of Aedes albopictus mosquitoes. These vectors thrive under environmental conditions like temperature and humidity, which are increasingly influenced by climate change. Additionally, global travel accelerates the cross-border spread of mosquito-borne diseases. DENV manifests clinically in a spectrum from asymptomatic cases to severe conditions like dengue hemorrhagic fever and dengue shock syndrome, influenced by viral serotype and host factors. In 2024, Brazil experienced a fourfold increase in dengue cases compared to 2023, accompanied by higher mortality. Conventional control measures, such as vector control, community engagement, and vaccination, proved insufficient as climate change exacerbated mosquito proliferation, challenging containment efforts. In this regard, our review analyzes prevention measures and therapeutic protocols during the outbreak while addressing DENV transmission dynamics, clinical presentations, and epidemiological shifts. It also evaluates diagnostic strategies combining clinical assessment with serological and molecular testing, providing information to improve diagnostic and preventive measures. The global expansion of dengue-endemic regions, including outbreaks in Europe, highlights the urgent need for enhanced surveillance, proactive interventions, and international collaboration to mitigate the growing threat of Dengue and other arboviruses like West Nile, Zika, Chikungunya, Oropouche, and Yellow Fever viruses.

Keywords: Dengue; epidemiology; outbreak; pandemic; vaccines.

Figure 3

Geographic distribution of serotypes and dengue cases in different regions of the Americas and Brazil, 2024. (a) Distribution of the serotypes by country in Latin America from 2016 to November 2024 [57,58]. Latin America comprises 20 countries: Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Ecuador, El Salvador, Guatemala, Haiti, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, the Dominican Republic, Uruguay, and Venezuela. Twenty-five countries and territories reported the circulation of Dengue serotypes in the Americas. Brazil, Costa Rica, Guatemala, Honduras, Mexico, and Panama reported the simultaneous circulation of DENV-1, DENV-2, DENV-3, and DENV-4 [59,60]. In Brazil, Minas Gerais state reported the simultaneous circulation of DENV-1, DENV-2, DENV-3, and DENV-4 [61]. ND = Not divulged. (b) Number of probable (under investigation) and confirmed dengue cases in Brazil from January to June 2023 (blue) and 2024 (orange). Values above each column represent the combined total of cases in thousands [57]. The maps display the number of probable (panel (c)) and confirmed (panel (d)). Dengue cases across Brazilian states in 2024 [57]. (e) Number of deaths caused by dengue in Brazil in 2024. Confirmed DENV cases in Brazil are determined through laboratory testing and clinical–epidemiological criteria. In 2024, 37% of cases were confirmed via laboratory tests, while 63% were based on clinical–epidemiological assessment. The number of confirmed deaths was determined based on laboratory and/or clinical–epidemiological criteria. The number of dengue cases under investigation refers to those that have been officially reported.

Figure 4

Development and evolution of Dengue symptoms in humans. Dengue progresses through three distinct clinical phases. (1) Febrile phase, which begins after the incubation period and is characterized by classic symptoms such as high fever, rash, myalgia, retro-orbital pain, nausea, and diarrhea (depicted on the left side of the figure). (2) Critical phase, which occurs as the fever starts to subside. During this period, symptoms may worsen, indicating a potential progression to a more severe condition. Symptoms include plasma leakage through capillaries, hemorrhages, shock, and liver or kidney impairment (depicted on the right side of the figure). (3) Recovery phase, where the extravasated fluid is reabsorbed, and gastrointestinal symptoms gradually reduce. This image was created based on data from references [85,86] and designed with BioRender.

Figure 5

Tissue tropism of Dengue (DENV) and Zika (ZIKV) viruses detected in humans. The organs and body fluids where Dengue virus (DENV, left side) and Zika virus (ZIKV, right side) have been detected in humans bitten by Ae. aegypti mosquitoes carrying these viruses. The figure is based on data obtained from references [87,88,89,90] and designed with BioRender.

Figure 1

Reproduction cycle of Aedes spp. and dengue transmission cycle. The reproduction cycle of Aedes spp. mosquitoes and the dengue transmission cycle involve several stages. Male and female mosquitoes mate (step 1), and female mosquitoes go for blood feeding for egg development (step 2). A female mosquito then bites an infected individual, acquiring the Dengue virus (step 3 and 4). This infected mosquito subsequently bites multiple healthy individuals, transmitting the virus to them (step 5). These newly infected individuals then transmit the virus to additional mosquitoes that bite them. The female mosquito lays her eggs in stagnant water sources (step 6), where the eggs hatch into larvae and develop into new mosquitoes, perpetuating the cycle (step 7). Two types of vertical DENV transmission may occur: from an infected pregnant woman to her baby, which is rare [41], and natural vertical transmission of DENV in Ae. aegypti and Ae. albopictus mosquito populations, which serves as a mechanism for viral persistence in the environment during periods unfavorable for horizontal transmission [22,43,44,45]. This last process is an important maintenance strategy for DENV circulation, ensuring the virus remains within mosquito populations even when conditions limit transmission between mosquitoes and human hosts. The figure was designed with BioRender.

Figure 2

Distribution of the total number of dengue cases, including both confirmed cases and cases under investigation, in Latin American countries (2023–2024) and average temperature anomalies (2022–2024). (a) Dengue cases in Latin America exhibited significant regional variation in 2023 and from January to May 2024, with marked increases in several countries. Brazil presented a largest proportion of cases, with a notable escalation from 3,064,739 cases in 2023 to 7,253,599 cases until May of 2024. Similarly, Argentina reported an increase of dengue cases from 146,876 in 2023 to 498,091 in 2024, while Paraguay experienced an increase from 63,216 to 278,827. Nicaragua showed substantial decrease in case numbers. This figure was performed using data obtained from the Pan American Health Organization (PAHO). Graph colored based on the dengue fever cases shown in Table 1. (b) Temperature anomalies in South America in the period of 2022–2024.

Figure 2

Distribution of the total number of dengue cases, including both confirmed cases and cases under investigation, in Latin American countries (2023–2024) and average temperature anomalies (2022–2024). (a) Dengue cases in Latin America exhibited significant regional variation in 2023 and from January to May 2024, with marked increases in several countries. Brazil presented a largest proportion of cases, with a notable escalation from 3,064,739 cases in 2023 to 7,253,599 cases until May of 2024. Similarly, Argentina reported an increase of dengue cases from 146,876 in 2023 to 498,091 in 2024, while Paraguay experienced an increase from 63,216 to 278,827. Nicaragua showed substantial decrease in case numbers. This figure was performed using data obtained from the Pan American Health Organization (PAHO). Graph colored based on the dengue fever cases shown in Table 1. (b) Temperature anomalies in South America in the period of 2022–2024.

Figure 6

Aedes albopictus distribution in Europe. Established populations in the Mediterranean region highlight potential endemic hotspots for Dengue transmission, driven by increasingly favorable climate conditions for the proliferation of Aedes species [155].

Figure 7

Annual count of total autochthonous dengue cases in Europe. (a) Annual count of total dengue autochthonous cases in Europe. The curve represents the exponential regression, showing an increase in total autochthonous cases in Europe as a function of time (in year). (b) Temperature anomalies in Europe in the period of 2023 to 2024.