Dengue fever is one of the fatal hemorrhagic fevers which is induced by the dengue virus (DENV) and transmitted through the bite of an infected Aedes species mosquito Ae. aegypti or Ae. albopictus [1]. There are four known serotypes of the dengue virus: DENV-1, DENV-2, DENV 3, DENV-4. The reported fifth serotype (DENV-5) has yet to be confirmed [2]. Viruses of all serotypes cause severe and fatal health consequences in the affected individuals. This deadly viral disease is known since the XVIII century. In 1779, outbreaks of this disease described as joint fever were recorded in Batavia (Indonesia) and in 1780 in California, in the United States of America (USA), and it is termed a famous re-emerging disease caused by mosquitoes in the world [3]. Several parts of Asian countries, such as Bangladesh and India, as well as American countries, including Brazil, have been identified as dengue-prone regions. Historically, the number of dengue cases reported in the countries of the Americas during the first half of 2024 has surpassed the total annual cases reported in previous years (as of June 18, 2024) [4]. According to a recent report by the Pan American Health Organization, 9,386,082 cases of dengue were recorded across 43 countries and territories in the Americas, which is double the 4,617,108 cases reported in 2023.
Brazil, a South American country faced another surge in dengue fever in 2024. In Brazil, the number of reported cases of dengue in 2024 is 10,060,163, which corresponds to a geometric spike of 328% compared with the number of cases in 2023 [5]. The overall incidence rate in 2024 was 4,701 cases per 100,000 population, with a total of 5,898 fatal cases reported, and the case fatality rate (CFR) was approximately 0.059%
Due to the frequent outbreaks of dengue fever in Brazil, the disease is a threat to public health, and it is necessary to develop adequate and well-implemented surveillance strategies, such as a national health surveillance system and epidemiological surveillance, to combat this disease [6].
A study conducted in 2020 revealed a lack of human and technological resources in healthcare units and surveillance departments in the country, which retarded the notification process and data analysis, leading to failure to detect the socioeconomic profile of patients with dengue [7].
The lack of these resources causes significant irregularities in the dengue surveillance system in Brazil. A proper surveillance system for the dengue virus in Brazil must be implemented as it is an important and necessary step for the prevention and control of this disease. This is an urgent task because it is relevant to the global response to emerging dengue in the country [8].
Despite several strategies, such as the use of standard vector control measures (strengthening mosquito control with high-vector density) to combat dengue in Brazil [9], the disease still prevails in the country due to inadequate multi-pronged surveillance measures.
The aim of this article was to examine the multifaceted surveillance strategies employed to address the unprecedented surge in dengue cases in Brazil. It focuses on the integration of genomic, wastewater, traveler-based, and digital health surveillance, as well as molecular surveillance and traditional public health methods, to effectively monitor and combat dengue outbreaks. Owing to the increasing threat of dengue, there is a need for effective prevention and management programs that work in hand with the population [10]. Previous efforts to combat dengue fever in Brazil included the Aedes aegypti Eradication Program (PEAa) in 1996 and the National Dengue Control Program (PNCD) in 2002 [11]. Unfortunately, these efforts either failed to be implemented because of unfavorable social and environmental conditions (PEAa) or did not significantly contribute to the prevention of dengue outbreaks in Brazil (PNCD) [11]. In 2024, the Brazilian government created the Emergency Operations Center (COE) to fight dengue and other arboviruses. This action aims to significantly enhance efforts to monitor and analyze the situation to curtail the spread of the virus in the country. To strengthen this action, there is a need for the Brazilian government to adopt an intense multifaceted approach, including surveillance such as waste-water system monitoring, which has been effectively used in Nepal where DENV was detected using quantitative reverse transcription polymerase chain reaction (RT-qPCR) and digital PCR (RT-dPCR) during the analysis of 34 water samples from two functioning wastewater treatment plants (WWTPs), a non-functioning WWTP, and two untreated and treated aeration hospital tanks [12]. This study from Nepal showed that an endogenous biomarker, known as pepper mild mottle virus, was effective against DENV. [12]. The Brazilian government could also strengthen its traveler surveillance system to tackle the spread of dengue in the country. This system should involve the collection of samples from travelers from other countries or states in Brazil, who volunteered to provide the necessary data for the detection of dengue. These travelers will answer surveys that contain metadata to accommodate the samples and inform the public health authorities in Brazil. All the collected samples should be sent to the CDC [13]. If the Brazilian government adopts this surveillance system, an early warning system to detect dengue in near real-time would be possible. Countries such as Cuba, Haiti, Jamaica, and the US have successfully adopted this system [14]. Certain genetic methods, such as gene expression profiling analyses, utilization of the midgut microbiota of mosquito species against DENV, and RNAi defense mechanisms, particularly through the sequencing of small RNAs from infected Ae. aegypti [15], should be integrated into Brazil’s dengue surveillance and control efforts. In addition, vaccines such as Sanofi-Pasteur’s tetravalent vaccine Dengvaxia (CYD-TDV) can be tried to combat dengue in Brazil, as it was tested in Mexico [15]. Other genomic approaches that could be used to combat dengue in Brazil include the massive release of Ae. aegypti, which carries the wMel strain of Wolbachia as a biological control [16, 17], as well as the release of vectors that carry a dominant lethal allele (RIDL), which significantly reduces the viability of offspring, thereby eliminating the vector populations by releasing males carrying a transgene [15]. Traditional strategies to combat dengue in Brazil should involve intense awareness campaigns regarding the mode of transmission, clinical features, and management of the disease among Brazilians. These awareness campaigns should be conducted by the healthcare providers in Brazil. For example, emphasis should be placed on discarding plastic containers and flowerpots, which serve as breeding sites for mosquitoes [18]. Research collaboration with experts on neglected tropical diseases, including dengue, should be taken seriously by the Brazilian government, especially in developing a digital health approach that should implement Information and Communication Technology (ICT) to support surveillance programs that in turn can aid in predicting and combating outbreaks of dengue [19]. Digital health encompasses the use of mobile health (mHealth) applications, electronic health records (EHRs), electronic medical records (EMRs), wearable devices, telehealth and telemedicine, and personalized medicine that support hybrid dengue surveillance [19]. Challenges identified in [20], such as lack of proper synergy between epidemiological and environmental surveillance, where areas prone to dengue do not tally with areas with large volumes of infections due to a lack of multi-centered data analysis, communication barriers among institutions, far distance of the offices, and a disengaged database system, should be addressed through the One Health approach and public-private partnership (PPP). In particular, there is an urgent need to develop and maintain a well-coordinated database and surveillance system for dengue detection. Brazil is prone to dengue and, therefore, needs urgent and holistic interventions, especially through multi-pronged strategies that should be taken into action by the authorities and stakeholders involved.