Introduction

Arthropod-borne viruses (Arboviruses) are a diverse group of RNA viruses primarily transmitted to humans and other vertebrates through the bites of infected arthropods, such as mosquitoes, ticks, and sandflies. They are unique in infecting both vertebrates and blood-sucking arthropods. Arboviruses have a devastating impact on human health, with the dengue virus being of greatest medical significance, with global estimates of 390 million cases annually1. Other arboviruses that cause major human diseases include chikungunya, yellow fever, Japanese encephalitis (JE), West Nile, Zika, and tick-borne encephalitis viruses. The worldwide impact of arboviruses is substantial, contributing to as many as 700,000 deaths each year due to diseases associated with arboviral infections2. The arbovirus group encompasses a wide range of viruses from different families, including Flaviviridae, Togaviridae, Bunyaviridae, and Reoviridae3. Due to their complex transmission cycles involving vectors and reservoir hosts, arboviruses pose significant challenges for public health.

India is endemic to several arboviral diseases, including dengue fever, JE and chikungunya. Its diverse climate and geography create favourable conditions for the proliferation of arthropod vectors, facilitating the transmission of arboviruses throughout the country4. Additionally, factors such as urbanisation, population growth, and environmental changes further exacerbate the risk of arboviral outbreaks in India. Between 2018 and 20235, India experienced the occurrence of dengue, affecting 823,786 individuals and resulting in 1134 deaths. Simultaneously, JE impacted 7945 individuals during this period, causing 786 deaths. Chikungunya affected 51,953 individuals with no reported fatalities, highlighting its ongoing impact on public health infrastructure in India, albeit with a lower burden compared to dengue and JE. These reported case numbers may underestimate the true incidence, particularly for dengue, due to underreporting, asymptomatic cases and limitations in surveillance systems, as highlighted by previous studies6,7. In addition, Zika, Kyasanur forest disease (KFD), and Crimean-Congo haemorrhagic fever (CCHF) viruses pose new emerging threats in India5. An increasing number of cases related to these viruses have started to be reported from various parts of the country. Thus, it is crucial to understand the arboviruses, their epidemiology, transmission dynamics, clinical features, and other factors contributing to re-emergence, existing prevention and control measures, and to identify research gaps and priorities. This understanding is essential for developing effective prevention and control strategies tailored to the Indian context, thereby mitigating the burden of these diseases and fostering socioeconomic development.

In this review, we provide an in-depth discussion of the epidemiology, transmission dynamics, clinical manifestations, and therapeutic strategies of major arboviral diseases, including dengue, chikungunya, Japanese encephalitis, Zika, KFD, and CCHF. Despite ongoing public health efforts, critical challenges persist in India’s response to arboviral diseases, including gaps in surveillance, inconsistencies in policy implementation, and limited community engagement. The manuscript highlights advancements in arbovirus diagnostics, including molecular and serological techniques, as well as emerging technologies such as CRISPR-based assays and portable point-of-care diagnostics. Additionally, we discuss novel vector control measures, including genetic modifications of mosquito populations and AI-driven surveillance systems, as promising avenues for arbovirus containment. Emphasising a One Health approach, this review calls for integrated efforts in surveillance, vector management, healthcare infrastructure, and research to strengthen arbovirus control in India.

Arboviruses in India: unravelling the origins and contributing factors

The arboviruses and their vectors spread worldwide through the slave trade, establishing a local transmission cycle wherever environmental conditions were suitable. The origins of dengue fever trace back to the Jin Dynasty (265–420 AD) in China, with epidemics simultaneously emerging across Asia, Africa, and North America during the 1780s8,9. JE was identified in Japan in 187110, and Chikungunya virus was detected in 1952 during an outbreak in south-eastern Tanzania9. The KFD virus was isolated in 1957 from the forests of the Shimoga district of Karnataka, India11. The Zika and the CCHF viruses, the most recent arboviruses detected in India, were identified in Uganda in 1947 and the Crimean Peninsula on the banks of the Congo River in 1944, respectively12,13.

In India, in 1780, an epidemic of dengue-like illness was recorded in Madras; however, the first confirmed dengue case was reported from Calcutta in 1944 from serum samples of US soldiers who returned from India. By 1965, all four serotypes of the dengue virus were detected circulating in India. In subsequent years, molecular studies showed that they belong to different genotypes14. The serotype and genotype are known to influence transmission, vector competence and clinical outcomes. The JE virus was detected in Nagpur, Maharashtra, in 1952 and has subsequently been reported in more than 24 states of the country15. Genotype I and Genotype III, with a dominance of Genotype I, are known to be circulating in the country15. Chikungunya was detected in 1963, and several outbreaks were reported until 1973; however, the virus disappeared and was only detected again in 2005 in a large epidemic affecting more than 1.6 million people16. Chikungunya has a single serotype and three major genotypes (East Central South African, West African, and the Asian). The Asian genotype was circulating till 1973 in India; however, the ECSA genotype was found responsible for the 2005–2006 outbreak in India16.

The origin and emergence of arboviruses are shaped by a complex interplay of multiple factors. Arboviruses have the capacity to undergo genetic mutations that improve their ability to infect vectors and hosts, evade immune responses, and spread more effectively. These evolutionary changes may result in the emergence of strains that are more virulent or easily transmissible17. Mosquitoes and ticks can acclimate to new habitats and hosts, potentially increasing their effectiveness in transmitting viruses. Alterations in vector genetics can additionally prompt the development of novel virus strains18. Inadequate surveillance, prevention, and control measures can allow arboviruses to spread unchecked. Limited access to healthcare and vector control resources can exacerbate outbreaks19. Enhanced travel and trade facilitate the introduction of arboviruses to new regions, while human activities such as agriculture and urbanisation heighten the proximity of people to vector habitats, thereby escalating transmission risks20. Temperature, precipitation, and humidity are essential for the breeding and survival of arthropod vectors. Climate change can extend the geographic range and activity periods of these vectors, thereby increasing the potential for arbovirus transmission21. Deforestation, urbanisation, and land use changes transform the habitats of vectors like mosquitoes and ticks, increasing human-vector contact and facilitating the spill over of viruses from wildlife reservoirs to human populations22. Greater biodiversity often hosts a wide range of arboviruses, with wildlife, particularly birds and mammals, frequently acting as reservoirs, sustaining and amplifying these viruses in natural settings23. Conflict, population movements, and economic instability can disrupt public health systems, resulting in inadequate sanitation and living conditions that foster the proliferation of vectors and facilitate virus transmission24.

Key arbovirus vectors in India

Indian weather conditions favour the establishment of insect/arthropod vectors, and factors such as urbanization, deforestation, unplanned development, rapid travel, migrations, changing climate and human behaviour, and the adoption of new practices help in their spread, establishment, and proliferation into new areas, playing a crucial role the disease transmission. Dengue, chikungunya, and Zika viruses are transmitted by Aedes spp. mosquitoes, whereas mosquitoes of Culex spp. are vectors for JE. The CCHF and KFD viruses are vectored by hard ticks belonging to the order Ixodid. Ticks of Hyalomma spp. are mainly responsible for transmitting and maintaining CCHF in bovines and humans, whereas Haemaphysalis spp. ticks play an important role in maintaining and transmitting the KFD virus in monkeys and humans25.

In India, Aedes aegypti is incriminated as the principal vector; however, Aedes albopictus is also documented as a vector, especially in the southern part of the country5. Furthermore, the dengue and chikungunya viruses are also detected in Aedes vittatus26, which is known to be present in India.

A. aegypti, a day-biting mosquito, has domesticated itself in both rural and urban settings and is known to be highly anthropophilic and endophilic. On the other hand, A. albopictus mainly uses tree holes for egg-laying, feeds on both humans and animals, and is primarily found in areas adjacent to forested or rural areas, with a few instances of detection in urban areas27.

Different populations of Aedes have been shown to have varying vectorial capacities to transmit specific viruses28. Factors such as temperature, humidity, insecticide resistance, etc., are also known to affect the vector competence of Aedes mosquitoes. Similarly, mutations in the virus genome are known to affect vector competence.

The JE virus has been isolated from 16 species of mosquitoes in India; however, the presence of the virus does not necessarily indicate their ability to cause the disease5. The vishnui subgroup of mosquitoes, consisting of Culex tritaeniorhynchus, Culex vishnui, and Culex pseudovishnui, is considered a major vector of JE in India. Several studies have reported many secondary vectors, such as Mansonia indiana, Culex gelidus, Culex pipiens, Anopheles subpictus, and Mansonia uniformis5. The JE virus vectors are mainly exophilic and zoophilic, preferring to feed on pigs and cows, with humans being accidental hosts29.

The KFD virus is primarily transmitted by Hemaphysalis spinigera ticks; additionally, the virus has been isolated from Ixodes species such as Hemaphysalis turturis, Hemaphysalis bispinosa, Hemaphysalis cuspidata, and Hemaphysalis wellingtoni30. The tick larvae feed to repletion on a single host, typically monkeys, then drop to the ground to moult into nymphs. The nymphs seek out another host to attach to and feed on before dropping back to the ground to moult into adults. After copulation, female ticks seek humid and warm locations to lay thousands of eggs, which hatch under favourable conditions. The larvae then travel on shrubs and timber, seeking blood meals from small mammals like monkeys31.

In India, Hyalomma anatolicum is considered the main vector of CCHF, although Hyalomma marginatum and H. marginatum rufipes are also known to transmit the disease32. Hyalomma ticks lay larvae on the bodies of animals, primarily bovines. After feeding, the larvae drop from the cattle’s body while it rests and seek out humid cracks and crevices in cattle sheds, where females lay their eggs. Questing larvae, nymphs, and adults then reattach to livestock in the shed. Thus, humans involved in handling livestock have an increased chance of contracting CCHF infection33.

Burden of arbovirus infections in India

Arboviruses cause a significant global impact, leading to up to 700,000 annual deaths2, profoundly affecting humankind and the socio-economic status of countries endemic to arboviruses (contributing to more than 17% of annual infectious disease burden)34.

Between 2018 and 2023, the majority of combined cases of dengue, chikungunya, and JE in India were reported in 2022 (n = 242,427), with only 51,638 cases reported in 2020. However, in 2023, cases decreased by two-fold. Arboviral disease-associated mortality peaked in the year 2022 (n = 433) but reduced to 147 deaths in 20235.

Over the six-year period, the states of Punjab, Gujarat, Kerala, and Uttar Pradesh reported the maximum number of dengue cases in India (Fig. 1). The highest dengue-associated mortality occurred in Punjab, Kerala, Rajasthan, and Maharashtra. Simultaneously, Assam experienced the highest JE cases (Fig. 2) and associated fatalities during this period. In contrast, chikungunya affected individuals in the states of Gujarat and Karnataka with no reported fatalities (Fig. 3)5. These pieces of evidence indicate that addressing regional variations is crucial for enhancing healthcare outcomes and mitigating socio-economic challenges associated with vector-borne diseases.

Fig. 1: The geo-spatial distribution of dengue cases in Indian states and union territories.
figure 1

This figure illustrates the geo-spatial distribution of dengue for different years A 2018, B 2019, C 2020, D 2021, E 2022, and F 2023, respectively.

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Fig. 2: The geo-spatial distribution of Japanese encephalitis cases in Indian states and union territories.
figure 2

This figure illustrates the geo-spatial distribution of Japanese encephalitis for different years A 2018, B 2019, C 2020, D 2021, E 2022, and F 2023, respectively.

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Fig. 3: The geo-spatial distribution of chikungunya cases in Indian states and union territories.
figure 3

This figure illustrates the geo-spatial distribution of chikungunya for different years A 2018, B 2019, C 2020, D 2021, E 2022, and F 2023, respectively.

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Reports of Zika virus (ZIKV) cases have emerged in several regions of India, including Gujarat, Tamil Nadu, Madhya Pradesh, Rajasthan, Kerala, Maharashtra, Uttar Pradesh, Delhi, Jharkhand, Punjab, and Telangana35,36,37,38. The first case was identified in November 2016, followed by cases in Ahmedabad and Chennai in 2017, indicating potential local transmission. The first outbreak occurred in Jaipur, Rajasthan, in 2018, with 159 confirmed cases. As the outbreak declined, cases emerged in Madhya Pradesh, with 130 positive cases and two fatalities35. In 2021, Uttar Pradesh reported over 100 confirmed cases, and Kerala recorded 19 cases, with one linked to a spontaneous abortion. Genomic analysis showed high similarity with a Rajasthan strain37. Retrospective screening revealed ZIKV presence in Delhi, Jharkhand, Rajasthan, Punjab, and Telangana in 2021, adding to previous reports from Kerala, Maharashtra, and Uttar Pradesh36. In a concerning development, Pune has reported 12 new ZIKV cases in recent months, including 6 among pregnant women, according to The Indian Express on July 9, 2024.

KFD virus was first identified in 195739. Initially endemic in five Karnataka districts (Shimoga, Chikamagalur, Uttara Kannada, Dakshina Kannada, and Udupi) with about 400–500 cases annually40, KFD has also been reported in the Western Ghats, including Kerala, Tamil Nadu, Goa, and Maharashtra41. A significant outbreak occurred in Shimoga in 201442 and in Nilambur, Kerala, the same year43. In 2015, anti-KFD IgG antibodies were found in Wayanad and Palakkad, Kerala44. Another outbreak in 2016 in Sindhudurg, Maharashtra, had a CFR of 2.3%45, which rose to 12.3% in 201744. KFD was reported in the new districts of Hassan and Mysore, Karnataka, in 2018–201946. In 2010, specific IgG antibodies against CCHF were detected in livestock from Gujarat and Rajasthan. This was followed by a confirmed CCHF outbreak in Ahmedabad, Gujarat, in 201147. Retrospective studies showed the virus was present in Gujarat before the outbreak47. The disease has a case fatality rate of 10-50%48. A study found CCHF viral RNA persisting up to 76 days post-onset in a survivor, with high RNA levels linked to fatal cases. Phylogenetic analysis revealed Asian-West African and Asian virus genotypes in humans and ticks, highlighting cross-host transmission risks49. In 2023, a fatal CCHF case was reported in Gujarat48, highlighting ongoing risks and the need for heightened surveillance and prevention.

The economic burden of the disease is not solely on the patient and their family; the government also shoulders the cost by providing free or low-cost treatment facilities. In 2013, India spent $1.51 billion on dengue-related expenses, rising to $5.71 billion in 201650. From 2006 to 2012, the average hospitalisation cost per dengue case was $235.20 USD51. In 2013, the cost per dengue case in Haryana was about 11,563.50 INR52. In Tamil Nadu, from 2016 to 2019, the median cost for paediatric dengue was 5627 INR53. From 2017 to 2018 in Tamil Nadu, median direct costs for paediatric dengue were $179.80 USD, $145.06 USD, and $933.51 USD, and for adults were $312.75 USD, $287.22 USD, and $720.39 USD, depending on severity54. In Gujarat, from 2017 to 2018, the mean hospitalisation cost was $86.9 USD55, and from 2018 to 2019, the average total cost per dengue episode was INR 686056.

For JE in India, median costs were $216.48 (direct), $367.48 (indirect), and $583.96 (total)57. During the 2006 chikungunya epidemic, India lost 25,588 disability adjusted life years (DALYs), with Karnataka contributing 55% of this burden. The epidemic caused productivity losses of at least INR 391 million58. In Orissa, median out-of-pocket healthcare costs were $84, with chikungunya diagnosis costing $7759. In Gujarat, the average cost per episode was INR 700056, and in Andhra Pradesh, the burden was 6600 DALYs, costing $12.4 million60.

Overall, these figures underscore the substantial toll that the arboviral diseases take on both public health and economic well-being.

Clinical features, diagnosis, treatment, and prevention: comprehensive strategies for arbovirus management

Dengue, depending on its severity, the age of the patient, and other biological factors, can present with varied clinical features that are mainly characterised by three phases: febrile, critical, and recovery. For effective clinical management, the WHO, in 2009, classified dengue into dengue with or without warning signs, and severe dengue, thus determining the place of care: home, hospital ward, or under strict observation61. The usefulness and limitations of the WHO’s 2009 dengue classification vs the 1997 classification are debatable62. The guideline recommends hospitalising patients with warning signs and severe dengue, leading to unnecessary hospitalisations in already overburdened health systems63. The warning signs are non-specific and inconsistently defined across studies, necessitating clearer definitions for accurate patient identification64,65. The classification’s adaptability and performance in primary health care require operational research. Dengue is routinely diagnosed by NS1 ELISA and IgM-based ELISA. NS1 ELISA detects primary dengue in 90% of cases and secondary dengue in 60-80% of cases due to the anamnestic immune response, which can result in some false negatives66. IgM-based tests cross-react with other flaviviruses and their levels quickly decrease in secondary infections, posing diagnostic challenges67. The introduction of a future vaccine may render serological methods inadequate. ELISA-based diagnostics are also difficult to implement in peripheral health systems, leading to delays in timely diagnosis. Rapid diagnostic tests have low sensitivity and specificity, making it challenging to rule out infection even with a negative result68. Reliable tests to differentiate between primary and secondary infections are needed. Emerging techniques such as CRISPR/Cas, biosensors, and nanoparticles may address these challenges and are currently under research69,70,71,72. In brief, CRISPR-based genome editing has gained popularity in the past decade for its flexibility and effectiveness, especially in molecular diagnostics. The CRISPR-Cas system uses “programmable guide RNAs” to target specific viral RNA or DNA sequences—Cas12a for DNA and Cas13 for RNA—allowing highly specific and sensitive infection detection69. Similarly, biosensors have also become popular due to their sensitivity, specificity, and portability, providing viable alternatives to traditional lab assays for early-stage infection detection. Advances in multiplexed assays further support applications in identifying and differentiating dengue virus (DENV) from other flaviviruses in endemic areas69. Nanoparticles are often combined with these diagnostic technologies for improved performance. For example, surface plasmon resonance-based sensing uses serotype-specific nanoprobes with CdSeTeS quantum dots and gold nanoparticles to detect DENV serotypes, while electrochemical impedance spectroscopy with gold nanoparticles has been developed to identify DENV strains 1–469. These newer diagnostic techniques are at different stages of research and development. Their practical utility and deployment challenges will become clearer in the near future. Studies suggest additional laboratory tests like complete blood counts, leucocyte counts, haematocrit, ultrasound, and radiographs for effective triaging73,74. Comorbidities predict severe dengue risk. About 2–4% of secondary dengue infections develop severe dengue, which can be fatal. Predicting progression to severe dengue is challenging due to limited understanding of pathogenesis. An acceptable biomarker for predicting severe dengue is still needed; microRNAs show potential75. Additionally, with the increased availability of real-time PCR (RT-PCR) post-COVID-19 at peripheral healthcare setups, its applicability for dengue diagnosis needs to be explored.

Dengue management focuses on providing supportive care. Several drugs, including prednisolone, ivermectin, ribavirin, oseltamivir, and natural medicines like Carica papaya and Eupatorium perfoliatum, are in various stages of clinical trials76,77. Given the lack of effective therapeutics for dengue, incorporating vaccines is crucial in combating the disease. The CYD-TDV vaccine was first authorised in 2015, but its use was limited due to the need for pre-vaccination screening to confirm seropositivity and the increased risk of severe dengue in seronegative individuals. In 2023, WHO’s Strategic Advisory Group of Experts recommended the TAK003 vaccine, administered in two doses three months apart, for use in high transmission areas for children aged 6-16, without requiring pre-vaccination screening (WHO 2023).

Field trials showed TAK003 provided protection against severe dengue in seronegative recipients for serotypes 1 and 2, though data for serotypes 3 and 4 were limited due to fewer infections78,79. TAK003 was introduced in Brazil in 2024, and it is imperative to see the effectiveness of the vaccine in the Indian subcontinent. Remarkably, phase III trials for the TV003/TV005 vaccine have begun in India (https://pib.gov.in/PressReleasePage.aspx?PRID=2045090). The adoption and real-world effectiveness of these vaccines in high-risk countries will become clearer in the near future.

Dengue can lead to long-term morbidity beyond acute symptoms, potentially due to direct viral invasion, excessive cytokine production, autoimmune responses, thrombocytosis, metabolic changes, and altered plasmin activity from cross-reactive antibodies, increasing haemorrhage risk. The exact pathogenesis behind these chronic effects needs further study80,81,82,83.

Common long-term effects include fatigue, joint pain, myalgia, headaches, and impaired vision84,85,86. Less common effects involve neurological issues (cognitive impairment, mood changes, encephalitis, myelitis, Guillain–Barré Syndrome, neuritis), eye problems (floaters, optic neuritis, cataracts, uveitis, and retinal haemorrhages), and cardiovascular complications (myocarditis, pericarditis, and arrhythmias)87,88. These findings emphasise the importance of long-term follow-up studies to clarify morbidity patterns, pathogenesis, and guide public health strategies89.

JE presents as fever, chills, myalgia, convulsions, and headaches after an incubation period of 5-15 days. Symptoms appear in 1 in 250 or more infected patients, with a 30% case fatality rate among those having neurological complications. The disease progresses rapidly, leading to neurological signs like hemiplegia, paraplegia, speech difficulty, and tremors. Long-term neurological impairments affect 30–50% of survivors90. Diagnosis is typically done using IgM ELISA, but other methods include serological tests (a 4-fold rise in IgG titre), virus isolation, and nucleic acid detection. These methods require advanced laboratory and equipment, which is often unavailable in affected areas, leading to an underestimation of the disease burden.

No specific antiviral is licensed for use in JE virus infections. Patients receive symptomatic treatment, and hospitalisations are recommended. Several drugs, including dexamethasone, ribavirin, and minocycline, have been tested91.

India’s national programme uses the SA-14-14-2 vaccine in a two-dose schedule. Studies suggest waning immunity and the potential need for booster doses92,93. The SA-14-14-2 JE vaccine was introduced as a single-dose immunisation in 2006. In 2011, JE vaccination was incorporated into the Universal Immunisation Programme, targeting children aged 16 to 18 months with a single dose. In 2013, a second dose was added as a booster for children at 9 months of age94. JENVAC JE vaccine is used for the adult population (15+) in India. Despite progress in understanding JE pathogenesis, more research is needed to develop early diagnostic tools and prevent disease progression and deaths.

Chikungunya is characterised by fever, joint pains and rash, ranging from mild to severe. Arthralgia, primarily in distal joints, starts 2–5 days after fever onset. Neurological and ocular manifestations like encephalopathy, myeloradiculoneuropathy, retinitis, uveitis, visual defects and conjunctivitis have been reported95. Chronic arthritis persists in 40–80% of patients for over 3 months, and 25% are affected even after a year. The virus in joint spaces likely causes inflammatory responses. Severe cases and fatalities occur in neonates, the elderly, and those with comorbidities.

During the first week, WHO recommends both serological and virological diagnostics, but RT-PCR-based assays for chikungunya are not field-validated. In India, ICMR-NIV supplies IgM ELISA kits, which are recommended for use after 5 days of symptom onset. Consequently, they may miss early infections and are only available in hospitals and programme-recognised laboratories. Accurate, rapid diagnostic tests for early diagnosis are urgently needed.

No specific antivirals exist for chikungunya; however, several are being evaluated for their efficacy and safety. In 2023, the live attenuated vaccine VLA1553, derived from the chikungunya virus-ECSA strain from La Réunion, received FDA approval. In a Phase 3 trial, the vaccine demonstrated the ability to generate protective antibody levels (μPRNT50 titre of ≥150, considered a surrogate marker of protection) in approximately 98% of recipients up to six months after vaccination96,97,98. A study to assess the persistence of antibodies and long-term effects at 1, 2, 3, 4, and 5 years post-vaccination is currently underway. Other vaccines in research include PXVX0317, MV-CHIK-202, ChAdOx1, and VAL-18138899. However, these vaccines are yet to be approved in India.

Only one-fifth of ZIKV infections show symptoms, including fever, rash, conjunctivitis, joint pain, and muscle aches. Diagnosis is primarily done by real-time RT-PCR in serum samples within the first five days100. Serological methods are challenged by cross-reactivity with other flaviviruses, and more studies are needed for non-invasive samples like urine and saliva. Point-of-care tests are currently unavailable. ZIKV can cause neurological complications in foetuses and adults, with congenital Zika syndrome presenting as microcephaly, joint contractures, macular atrophy, and uveitis in infants when mothers are infected during pregnancy101,102. The risk of complications is 1–13% in first-trimester infections103. However, these complications have not been reported from India yet.

There is no specific treatment for ZIKV infection; management includes antipyretics, rest, and hydration. Drugs like hydroxychloroquine, azithromycin, chloroquine, and ivermectin have shown varied preclinical results104. Metformin has shown promise in vitro for inhibiting the virus in trophoblasts105. Non-steroidal anti-inflammatory drugs should be avoided due to the bleeding risk. There are no licensed vaccines against the ZIKV, although various vaccines are in different stages of research106. Challenges such as ensuring safety and efficacy in pregnant women, assessing the impact of trans-placentally transferred IgG on foetal health, and ruling out potential autoimmune side effects through long-term follow-up require careful assessment in future studies106.

KFD has a biphasic clinical presentation after an incubation period of 3-8 days. The acute phase includes high fever, chills, myalgia, headache, diarrhoea, and haemorrhagic symptoms like gum and nose bleeds, hematemesis, and blood in stool, affecting about half of the patients107. Recovery typically occurs after two weeks, but 12-18% of patients enter a second phase after 1–3 weeks, presenting with fever, meningoencephalitis, cerebellitis, and liver dysfunction. Case fatality ranges from 2-20%108. Subclinical infections exist, but their exact proportion is unknown, necessitating serosurveys nationwide.

Diagnosis involves RT-PCR for the NS-5 gene within the first 10 days and IgM ELISA afterwards. With no specific antiviral treatment, supportive care is recommended. The current vaccine’s coverage and effectiveness vary, warranting studies on the genetic divergence of circulating strains from the vaccine strain109.

Research is needed on haemorrhagic manifestations, predictors of the second phase, and mortality. Combining molecular and serological point-of-care tests, using non-invasive samples like urine and throat swabs, and exploring the repurposing of existing antivirals in laboratory conditions using in vitro and in vivo will help in developing interventions.

The formalin-inactivated KFD vaccine was developed by the ICMR-National Institute of Virology, Pune. This vaccine has demonstrated a serological response rate of approximately 93%. The vaccine is administered in two doses, one month apart, to individuals aged 7–65 years, with booster doses given 6–9 months after the initial vaccination. The KFD vaccine has been in use in affected districts since 1990109.

In case of CCHF, the incubation period varies: 1–3 days for tick-borne infections and 5–6 days (up to 13 days) for contact with infected body fluids110. The disease has three phases: a pre-haemorrhagic phase lasting 1–5 days with fever, headache, myalgia, nausea, and vomiting; a haemorrhagic phase lasting 1–3 days marked by petechial rash and progressing to severe bleeding from multiple sites including ecchymoses, bleeding from nose, gastrointestinal or genitourinary tract; and a convalescent phase starting in the second week, with recovery taking up to a year in some cases110. The case-fatality rate, typically 10–40%, peaks in the second week. RT-PCR is used for diagnosis within the first 10 days. Treatment is supportive with fresh frozen plasma, platelet transfusions, and erythrocyte preparations111. No specific antivirals or vaccines are approved for CCHF. Ribavirin’s effectiveness is inconclusive, requiring randomised controlled trials112. Favipiravir shows promise in preclinical studies113. Testing heparin and other anticoagulants for controlling haemorrhagic manifestations is being considered112.

Other emerging arboviruses in India

Chandipura virus (CHPV), a member of the Rhabdoviridae family, was first isolated in 1964 in Chandipura village, central India. In 2003, an acute encephalitis outbreak in Andhra Pradesh was associated with CHPV114. The virus has been detected in sandflies and linked to several encephalitis outbreaks in rural central India. Recently, in July 2024, CHPV cases with high mortality rates were reported in the western Indian states of Gujarat and Rajasthan115, suggesting an expansion of the virus’s geographical range. Although CHPV cases have so far only been reported in India, the presence of potential vectors in tropical regions indicates a risk of emergence in new areas. In addition, viruses such as West Nile, Ganjam, Yellow Fever, and Igawama should be closely monitored, as they could pose a public health threat in the country due to the presence of their vectors and favourable environmental conditions.

Success stories

Despite challenges such as the lack of antiviral drugs, limited trained personnel, diagnostic tools, and operational hurdles, India has demonstrated that a comprehensive approach can effectively manage diseases like JE. This includes robust vaccination campaigns, appropriate clinical interventions, vector control strategies, and the adoption of One Health models. In Uttar Pradesh, the incidence of AES dropped from 18.2 per million (2005–2009) to 15 per million (2015–2019), and the case fatality rate decreased from 33% (1980–1984) to 12.6% (2015–2019), further declining to 5% in 2020116. Additionally, the establishment of the ICMR’s virus research and diagnostic laboratory (VRDL) network has expanded diagnostic facilities across the country, aiding in timely diagnoses and enabling more effective treatment.

Public health policies and interventions

The National Centre for Vector Borne Disease Control (NCVBDC), Govt. of India, has implemented several public health policies and interventions for addressing arboviral diseases. Some of the key interventions and strategies are: (a) Strengthening of surveillance systems to ensure early detection and response to arboviral sporadic cases and outbreaks. This includes routine epidemiological surveillance, serological surveys, and the establishment of sentinel surveillance sites. (b) Comprehensive initiative focusing on the prevention and control of vector-borne diseases, including dengue, chikungunya, JE, and Zika viruses through integrated vector management, involving community participation, biological control, chemical control, and environmental management to reduce mosquito breeding sites. (c) Public education campaigns for promoting preventive measures against arboviral diseases. These campaigns focus on educating communities about the importance of eliminating mosquito breeding sites, using mosquito repellents, and implementing protective measures such as bed nets and window screens. (d) Organising training and refresher courses for healthcare professionals and field workers in disease detection, management, and vector control methods. (e) Promoting ongoing research on arboviral diseases for developing better diagnostic tools, vaccines, and prevention, as well as treatment strategies.

Identified gaps

Despite India’s extensive efforts to manage and control arboviral diseases through various agencies like NCDC, ICMR and NCVBDC and several other initiatives, several gaps and limitations persists.

Surveillance and data management

There is a need for year-round virological, molecular, and entomological surveillance for the early detection of arboviruses, thereby enabling the appropriate case management and outbreak control efforts. Using standardised data collection and dissemination mechanisms among states, districts, and block levels will avoid fragmented and irregular data and facilitate comprehensive analysis and timely intervention.

Inadequate public awareness and community engagement

Despite the existence of public awareness campaigns in the national policy, their reach and impact vary significantly across regions, especially in rural and remote areas. However, continuous community sensitisation regarding necessary preventive measures and the importance of early detection and treatment may prevent outbreaks.

Resource constraints and infrastructural challenges

With the establishment of ICMR's VRDL network with BSL-3 facilities, the key arboviral diseases, such as CCHF and KFD, may benefit from better representation in the national programme guidelines. Adequate funding for arboviral disease control is essential for effective disease surveillance and the implementation of comprehensive vector control measures. Various stakeholders must work together to achieve zero transmission of arboviral diseases. Health infrastructure, particularly in rural areas, is often insufficient to manage and treat arboviral diseases effectively, as supportive management is the mainstay of treatment. This insufficiency includes limited access to diagnostic facilities, trained healthcare personnel, and available treatment options.

Policy implementation and monitoring

Minimise the discrepancies between policy formulation and on-ground implementation, as local variations in policy execution leading to inconsistent results in different regions may hamper the effectiveness of control measures. Robust monitoring and evaluation mechanisms to assess the effectiveness of implemented policies and interventions are much needed. Additionally, engaging community leaders and local stakeholders in programmes like DAMaN and Mandla enhances ownership of interventions, leading to more effective implementation and improved disease control.

One health approach

Arbovirus surveillance systems may adopt a One Health approach, recognising the interconnectedness of human, animal, and environmental health. Collaboration between human health, veterinary, and wildlife agencies facilitates the early detection of emerging arboviruses and the implementation of integrated control strategies to prevent spillover events and zoonotic transmission.

Leveraging artificial intelligence (AI) to combat arboviral diseases

AI enhances arbovirus surveillance on both local and global scales by analysing extensive datasets, including environmental, epidemiological, and entomological data. Integrating these diverse variables into a unified system enhances pattern recognition and develops probabilistic risk models for predicting outbreak spread and severity117. This aids epidemiologists in detecting patterns, forecasting outbreaks, and informing targeted interventions more precisely, utilising advanced techniques like metatranscriptomic sequencing118. Additionally, AI automates data processing, improves data integration, supports modelling, and offers real-time monitoring, enabling public health authorities to identify high-risk areas, efficiently allocate resources, and respond proactively117,118.

In arbovirus surveillance, AI aids in identifying and tracking mosquito vectors, essential for understanding virus transmission dynamics119. Through analysing mosquito population data, AI detects trends indicating increased virus activity or novel virus emergence120. This data guides control measures. For instance, AI utilises satellite imagery, climate data, mosquito surveillance, and human cases to pinpoint vector habitats, high-risk areas, and predict transmission dynamics121. AI also analyses social media and internet searches to develop early warning systems118. Moreover, AI improves disease forecasting and informs targeted interventions through data integration and modelling by public health authorities.

In Burkina Faso, AI has revolutionised surveillance efforts during dengue outbreaks, providing a deeper understanding of arboviral disease impacts122. Moreover, AI has been pivotal in discovering drug and vaccine targets and developing the “anti-dengue” algorithm to identify dengue virus inhibitors123,124. Additionally, automated AI-based peripheral blood smear examination has proven effective in diagnosing dengue among Indian patients125. These advancements underscore AI’s critical role in enhancing arbovirus surveillance and controlling outbreaks. Implementing AI-based surveillance in India could be a crucial step in combating arbovirus outbreaks and reducing associated mortality. With its vast resources, India stands to benefit significantly by addressing neglected public health threats, particularly in rural and underserved areas.

Future research and innovation strategies

Even though research is being conducted, there is a need for more focused and collaborative research on arboviral diseases, particularly in developing new diagnostic tools, vaccines, and innovative vector control methods. The translation of research findings into practical public health interventions needs to ensure the timely adoption of new and effective strategies. Development and deployment of point-of-care diagnostic tests with the capability of distinguishing between different arboviruses that can be used in remote and rural areas. Development and validation of Multiplex PCR assays for the simultaneous detection of multiple arboviruses in a single test. Explore the Biosensors and nanotechnology-based approaches which offer promising avenues for arboviral diagnosis. Antiviral drugs that can effectively treat arboviral infections are limited. Existing treatments are primarily supportive, and there is a significant need for therapeutics that can reduce viral load and disease severity. Repurposing of existing drugs for the treatment of arboviral infections may be another strategy that researchers can explore. RNAi also offer a promising approach for treating arboviral infections by targeting viral RNA and inhibiting viral replication both in vectors and vertebrates, which needs to be tested and validated. An effective vaccine against arboviruses is needed to overcome the challenges, such as achieving long-term immunity. Monoclonal antibodies to target arboviral diseases, by neutralise the virus and prevent its replication in the host, may be explored for future disease management. In addition, research directed towards studying the socio-economic consequences of arboviral diseases, and insights from these studies, can guide and improve policy-making and resource allocation.

Traditional vector control methods have become less effective due to insecticide resistance and logistical challenges. Therefore, an innovative approach, such as genetic modification of mosquitoes, use of biological control agents, and a new class of insecticides, is required. However, these approaches must be implemented with extreme caution to prevent unintended environmental consequences and disruptions to natural ecosystems. To control the vectors of CCHF, vaccinating domestic animals to reduce tick infestations using novel molecules and developing new chemical control methods that are user- and environmentally-friendly can be effective approaches. For the vectors of KFD, focusing on strategies such as community awareness through inter-sectoral coordination with forest, environmental health, and tribal welfare departments, monitoring insecticide resistance among ticks, and evaluating innovative approaches like using drones to spray insecticides on mapped hotspots can be effective approaches.

Research into the adaptation of best practices for integrating different control methods, along with optimising resource use and engaging communities, needs to be tested. AI-based research into predictive modelling, which can help in forecasting outbreaks and understanding the impact of environmental and climatic changes on arboviral disease dynamics required to improve preparedness and response strategies

Future directions and recommendations

An innovative approach to arboviral disease surveillance and case management is the implementation of a Smart Integrated Mosquito Management System (SIMMS), which leverages advanced technology to enhance traditional surveillance methods. Smart traps equipped with IoT sensors can be deployed in strategic locations to count mosquitoes, identify species, and detect viruses in real time, transmitting data wirelessly to a central database. Drones with high-resolution cameras and thermal imaging can be used to monitor mosquito breeding sites, particularly in inaccessible areas. AI and machine learning algorithms can analyse data from these smart traps and drones to predict outbreak hotspots based on environmental factors such as temperature, humidity, and rainfall. A mobile health (mHealth) application can facilitate public engagement by allowing users to report mosquito sightings, bites, and disease symptoms while providing education on prevention and real-time outbreak alerts. Ensuring data security and transparency is crucial for maintaining trust among stakeholders. The collected data can be used for targeted larvicide interventions at identified breeding sites. Integration of the mHealth app with electronic health records can streamline case reporting and management. Additionally, investment in research and development of new diagnostics, vaccines, and treatments is essential for improving disease identification and control. A collaborative online platform can connect public health authorities, researchers, and communities to enhance response strategies. Researching the socio-economic impacts of arboviral diseases can inform policy decisions and resource allocation. Expanding surveillance programmes to include diseases like Zika, KFD, and CCHF is also critical. Finally, leveraging COVID-19 infrastructure, such as RT-PCR and Next-Generation Sequencing capabilities, can strengthen arboviral disease surveillance and management efforts.