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Epidemiological challenges in Dengue outbreak: DENV-5 emergence and public health strategies

2024; Wolters Kluwer; Volume: 62; Issue: 1 Linguagem: Inglês

10.1097/io9.0000000000000017

2405-8572

Farzana Yesmin, Rehnuma Nasim, Ramisa Anjum, Syed Masudur Rahman Dewan,

Malaria Research and Control

Dear Editor, Epidemics caused by dengue have been a serious hazard to public health throughout America, Africa, Southeast Asia, Europe, the Western Pacific, and the Eastern Mediterranean1. With between 100 and 400 million cases reported yearly, it presently poses a threat to almost half of the world's population2. In Southeast Asia, dengue became a problem for public health after the Second World War, and it was for the postwar urbanization that created the optimum circumstances for the virus to spread in tropical and sub-tropical regions3. As of August 2023, there have been more than three million cases of dengue recorded worldwide, with more than 2000 fatalities. The largest number of dengue cases ever reported globally was in 2019. All regions were affected, and dengue transmission was recorded in Afghanistan for the first time. The American Region reported 3.1 million cases, with more than 25 000 classified as severe. A high number of cases were reported in Bangladesh (101 000), Malaysia (131 000), Philippines (420 000), Vietnam (320 000) in Asia2. Since the start of the year, the majority of cases have been documented in the region of the Americas, with the greatest number of cases. Additionally, Asian countries like Afghanistan, Bangladesh, Cambodia, China, India, and Malaysia also reported dengue cases4. Aedes aegypti and A. albopictus are frequently used in the transmission of dengue, a Flavivirus infection carried by mosquitoes5. The four serotypes of the dengue virus (DENV) are DENV-1, DENV-2, DENV-3, and DENV-4. In 2007, a 37-year-old patient in the Sarawak State of Malaysia had a sample in 2013 identified as a novel serotype of DENV-54,6. DENV-5 circulates mostly among nonhuman primates, and in contrast to the other serotypes it follows the sylvatic spreading cycle7. Previous ecological and clinical studies on sylvatic DENV suggest that human movement into the forest and land-use changes that improve human-forest interaction could facilitate DENV spillover into humans and possibly introduce new strains or serotypes into a human-endemic cycle8. Since no new viral serotype had been found in the preceding 50 years, the initial hypothesis was that the new virus might be a variant of the dengue 4 serotype. But after being exposed to DENV-5, rhesus macaque monkeys that had already recovered from the sickness and had been preinfected with the other four serotypes acquired a distinctly different set of antibodies. This proved beyond a reasonable doubt that the new virus was a novel serotype rather than a variant of DENV-49. Although the precise cause of DENV-5 transmission is still unknown, genetic changes from sylvatic to human strains, a high frequency of DENV mutations, and extensive deforestation may have contributed to the virus's emergence7,10. Because infection with sylvatic DENV might result in a clinical presentation identical to that caused by infection with strains from the human transmission cycle, it is likely that sylvatic dengue cases are under-reported11. Because jungle canopies are home to sylvatic DENV reservoirs, vaccination programs may only be able to temporarily suppress dengue, making the long-term goal of eliminating the disease unlikely7. Furthermore, the problem of cross-reactivity caused by infection with different flaviviruses and DENV serotypes remains unresolved. The cross-reactivity of flaviviruses in clinical settings may result in a delay in adequate intervention management. As a result, precise diagnostics with high specificity and sensitivity are critical for providing quick diagnosis and early treatment for DENV-infected people. Furthermore, there is a greater probability of antibody-dependent enhancement occurring and worsening the illness situation10. Recent clinical trials with the promising Chimerivax tetravalent vaccine suffered a setback. The discovery of DENV-5 and more such sylvatic strains in the future may further impede the Dengue Vaccine Initiative. Therefore, it is critical to consider the development of the dengue vaccine as an adjunctive tool to other public health measures, such as vector control, community engagement, and political will7. There is currently a critical need for an efficient vector control method and an integrated vector management strategy due to the absence of widely effective antiviral medicine or immunization12,13. Given the lack of knowledge on the relationship between sylvatic strains and human populations, more investigation into the epidemiology of sylvatic DENV has become imperative. Ecological study as well as molecular epidemiological studies are badly needed to determine the role that vectors play in the spread of dengue, as well as any additional sylvatic variants of the virus that may exist among nonhuman primates and their mode of transmission to humans7,14,15. The prevalence of dengue fever has been steadily increasing and is now a major health concern for people. In addition, the introduction of the novel serotype DENV-5 poses a new risk to dengue control efforts. Future research is needed into the genetics of the host and proteins like cytokines that influence the degree of defense the virus of dengue. Another concern is the emergence of multiple serotypes specially DENV-5. The development of the dengue vaccines can be hampered for DENV-5 due to its sylvatic type. Preventive measures such as modifying populations of mosquitoes should be implemented. Further research is recommended to obtain a better understanding of the disease's epidemiology through the DENV-5 serotype at present, as well as the likelihood of its spread in the future. Ethical approval Not applicable. Consent Not applicable. Sources of funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Author contribution F.Y. and R.N.: conceptualized and wrote the draft; R.A.: revised the manuscript; S.M.R.D.: conceptualized, revised the manuscript, and supervised the project. All the authors agreed to submit the manuscript in its current form. Conflicts of interest disclosures None. Research registration unique identification number (UIN) Not applicable. Guarantor SMRD, the author for correspondence. Data availability statement Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.