Molecular characterization of dengue viruses isolated from patients in Central Java, Indonesia

Unraveling Dengue Virus Diversity in Asia: An Epidemiological Study through Genetic Sequences and Phylogenetic Analysis

Dengue virus (DENV) is the causative agent of dengue. Although most infected individuals are asymptomatic or present with only mild symptoms, severe manifestations could potentially devastate human populations in tropical and subtropical regions. In hyperendemic regions such as South Asia and Southeast Asia (SEA), all four DENV serotypes (DENV-1, DENV-2, DENV-3, and DENV-4) have been prevalent for several decades. Each DENV serotype is further divided into multiple genotypes, reflecting the extensive diversity of DENV. Historically, specific DENV genotypes were associated with particular geographical distributions within endemic regions. However, this epidemiological pattern has changed due to urbanization, globalization, and climate change. This review comprehensively traces the historical and recent genetic epidemiology of DENV in Asia from the first time DENV was identified in the 1950s to the present. We analyzed envelope sequences from a database covering 16 endemic countries across three distinct geographic regions in Asia. These countries included Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka from South Asia; Cambodia, Laos, Myanmar, Thailand, and Vietnam from Mainland SEA; and Indonesia, the Philippines, Malaysia, and Singapore from Maritime SEA. Additionally, we describe the phylogenetic relationships among DENV genotypes within each serotype, along with their geographic distribution, to enhance the understanding of DENV dynamics.

Relationship between the Number of Repeats in the Neck Regions of L-SIGN and Augmented Virus Replication and Immune Responses in Dengue Hemorrhagic Fever

C-type lectins play a crucial role as pathogen-recognition receptors for the dengue virus, which is responsible for causing both dengue fever (DF) and dengue hemorrhagic fever (DHF). DHF is a serious illness caused by the dengue virus, which exists in four different serotypes: DEN-1, DEN-2, DEN-3, and DEN-4. We conducted a genetic association study, during a significant DEN-2 outbreak in southern Taiwan, to explore how variations in the neck-region length of L-SIGN (also known as CD209L, CD299, or CLEC4M) impact the severity of dengue infection. PCR genotyping was utilized to identify polymorphisms in variable-number tandem repeats. We constructed L-SIGN variants containing either 7- or 9-tandem repeats and transfected these constructs into K562 and U937 cells, and cytokine and chemokine levels were evaluated using enzyme-linked immunosorbent assays (ELISAs) following DEN-2 virus infection. The L-SIGN allele 9 was observed to correlate with a heightened risk of developing DHF. Subsequent results revealed that the 9-tandem repeat was linked to elevated viral load alongside predominant T-helper 2 (Th2) cell responses (IL-4 and IL-10) in K562 and U937 cells. Transfecting K562 cells in vitro with L-SIGN variants containing 7- and 9-tandem repeats confirmed that the 9-tandem repeat transfectants facilitated a higher dengue viral load accompanied by increased cytokine production (MCP-1, IL-6, and IL-8). Considering the higher prevalence of DHF and an increased frequency of the L-SIGN neck's 9-tandem repeat in the Taiwanese population, individuals with the 9-tandem repeat may necessitate more stringent protection against mosquito bites during dengue outbreaks in Taiwan.

Comparative phylogenetic analysis and transcriptomic profiling of Dengue (DENV-3 genotype I) outbreak in 2021 in Bangladesh

Background

The next-generation sequencing (NGS) technology facilitates in-depth study of host-pathogen metatranscriptome. We, therefore, implicated phylodynamic and transcriptomic approaches through NGS technology to know/understand the dengue virus (DENV) origin and host response with dengue fever.

Methods

In this study, blood serum RNA was extracted from 21 dengue patients and 3 healthy individuals. Total transcriptomic data were analyzed for phylogenetic, phylodynamic, differential express gene (DEG), and gene ontology (GO) using respective bioinformatics tools.

Results

The viral genome sequence revealed dengue viral genome size ranges 10647 to 10707 nucleotide. Phylogenetic and phylodynamic analysis showed that the 2021 epidemic isolates were DENV-3 genotype-I and maintained as a new clade in compared to 2019 epidemic. Transcriptome analysis showed a total of 2686 genes were DEG in dengue patients compared to control with a q-value < 0.05. DESeq2 plot counts function of the top 24 genes with the smallest q-values of differential gene expression of RNA-seq data showed that 11 genes were upregulated, whereas 13 genes were downregulated. GO analysis showed a significant upregulation (p = < 0.001) in a process of multicellular organismal, nervous system, sensory perception of chemical stimulus, and G protein-coupled receptor signaling pathways in the dengue patients. However, there were a significant downregulation (p = < 0.001) of intracellular component, cellular anatomical entity, and protein-containing complex in dengue patients. Most importantly, there was a significant increase of a class of immunoregulatory proteins in dengue patients in compared to the controls, with increased GO of immune system process. In addition, upregulation of toll receptor (TLR) signaling pathways were found in dengue patients. These TLR pathways were particularly involved for the activation of innate system coupled with adaptive immune system that probably involved the rapid elimination of dengue virus infected cells. These differentially expressed genes could be further investigated for target based prophylactic interventions for dengue.

Conclusion

This is a first report describing DENV complete genomic features and differentially expressed genes in patients in Bangladesh. These genes may have diagnostic and therapeutic values for dengue infection. Continual genomic surveillance is required to further investigate the shift in dominant genotypes in relation to viral pathogenesis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-023-02030-1.

Hyperendemic Dengue and Possible Zika Circulation in the Westernmost Region of the Indonesian Archipelago

The transmission of dengue and other medically important mosquito-borne viruses in the westernmost region of Indonesia is not well described. We assessed dengue and Zika virus seroprevalence in Aceh province, the westernmost area of the Indonesian archipelago. Serum samples collected from 199 randomly sampled healthy residents of Aceh Jaya in 2017 were analyzed for neutralizing antibodies by plaque reduction neutralization test (PRNT). Almost all study participants (198/199; 99.5%) presented with multitypic profiles of neutralizing antibodies to two or more DENV serotypes, indicating transmission of multiple DENV in the region prior to 2017. All residents were exposed to one or more DENV serotypes by the age of 30 years. The highest geometric mean titers were measured for DENV-4, followed by DENV-1, DENV-2 and DENV-3. Among a subset of 116 sera, 27 neutralized ZIKV with a high stringency (20 with PRNT90 > 10 and 7 with PRNT90 > 40). This study showed that DENV is hyperendemic in the westernmost region of the Indonesian archipelago and suggested that ZIKV may have circulated prior to 2017.

Co-Circulation of Chikungunya and Multiple DENV Serotypes and Genotypes, Western Indonesia 2015-2016

Dengue is a mosquito-borne disease of public health concern affecting tropical and subtropical countries, including Indonesia. Although studies on dengue epidemiology have been undertaken in Indonesia, data are lacking in many areas of the country. The aim of this study was to determine dengue virus (DENV) and chikungunya virus (CHIKV) molecular epidemiology in western regions of the Indonesian archipelago. A one-year prospective study was conducted in Aceh and Jambi in 2015 and 2016, respectively, where patients with dengue-like illness were enrolled. Of 205 patients recruited, 29 and 27 were confirmed with dengue in Aceh and Jambi, respectively, and three from Jambi were confirmed with chikungunya. DENV-1 was the predominant serotype identified in Aceh while DENV-2 was predominant in Jambi. All DENV-1 and DENV-2 from both regions were classified as Genotype I and Cosmopolitan genotype, respectively, and all DENV-3 viruses from Jambi were Genotype I. Some viruses, in particular DENV-1, displayed a distinct lineage distribution, where two DENV-1 lineages from Aceh were more closely related to viruses from China instead of Jambi highlighting the role of travel and flight patterns on DENV transmission in the region. DENV-2 from both Aceh and Jambi and DENV-3 from Jambi were all closely related to Indonesian local strains. All three CHIKV belonged to Asian genotype and clustered closely with Indonesian CHIKV strains including those previously circulating in Jambi in 2015, confirming continuous and sustainable transmission of CHIKV in the region. The study results emphasize the importance of continuous epidemiological surveillance of arboviruses in Indonesia and simultaneous testing for CHIKV among dengue-suspected patients.

Comparative cytokine profiling identifies common and unique serum cytokine responses in acute chikungunya and dengue virus infection

Background

Infection by chikungunya (CHIKV) and dengue virus (DENV) can cause a wide spectrum of clinical features, many of which are undifferentiated. Cytokines, which broadly also include chemokines and growth factors, have been shown to play a role in protective immunity as well as DENV and CHIKV pathogenesis. However, differences in cytokine response to both viruses remain poorly understood, especially in patients from countries where both viruses are endemic. Our study is therefore aimed to provide a comparative profiling of cytokine response induced by acute DENV and CHIKV infections in patients with similar disease stages and in experimental in vitro infections.

Methods

By using multiplex immunoassay, we compared host cytokine profiles between acute CHIKV and DENV infections by analysing serum cytokine levels of IL-1α, IL-4, IL-5, IL-8, IL-13, RANTES, MCP-3, eotaxin, PDGF-AB/BB, and FGF-2 from the sera of acute chikungunya and dengue fever patients. We further investigated the cytokine profile responses using experimental in vitro CHIKV and DENV infections of peripheral blood mononuclear cells (PBMCs).

Results

We found that both CHIKV and DENV-infected patients had an upregulated level of IL-8 and IL-4, with the highest IL-4 level observed in DENV-2 infected patients. Higher IL-8 level was also correlated with lower platelet count in dengue patients. IL-13 and MCP-3 downregulation was observed only in chikungunya patients, while conversely PDGF-AB/BB and FGF-2 downregulation was unique in dengue patients. Age-associated differential expression of IL-13, MCP-3, and IL-5 was also observed, while distinct kinetics of IL-4, IL-8, and FGF-2 expression between CHIKV and DENV-infected patients were identified. Furthermore, the unique pattern of IL-8, IL-13 and MCP-3, but not IL-4 expression was also recapitulated using experimental in vitro infection in PBMCs.

Conclusions

Taken together, our study identified common cytokine response profile characterized by upregulation of IL-8 and IL-4 between CHIKV and DENV infection. Downregulation of IL-13 and MCP-3 was identified as a unique cytokine response profile of acute CHIKV infection, while distinct downregulation of PDGF-AB/BB and FGF-2 characterized the response from acute DENV infection. Our study provides an important overview of the host cytokine responses between CHIKV and DENV infection, which is important to further understand the mechanism and pathology of these diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06339-6.

Evolution, heterogeneity and global dispersal of cosmopolitan genotype of Dengue virus type 2

Dengue virus type 2 (DENV-2) contributes substantially to the dengue burden and dengue-related mortality in the tropics and sub-tropics. DENV-2 includes six genotypes, among which cosmopolitan genotype is the most widespread. The present study investigated the evolution, intra-genotype heterogeneity and dispersal of cosmopolitan genotype to understand unique genetic characteristics that have shaped the molecular epidemiology and distribution of cosmopolitan lineages. The spatial analysis demonstrated a wide geo-distribution of cosmopolitan genotype through an extensive inter-continental network, anchored in Southeast Asia and Indian sub-continent. Intra-genotype analyses using 3367 envelope gene sequences revealed six distinct lineages within the cosmopolitan genotype, namely the Indian sub-continent lineage and five other lineages. Indian sub-continent lineage was the most diverged among six lineages and has almost reached the nucleotide divergence threshold of 6% within E gene to qualify as a separate genotype. Genome wide amino acid signatures and selection pressure analyses further suggested differences in evolutionary characteristics between the Indian sub-continent lineage and other lineages. The present study narrates a comprehensive genomic analysis of cosmopolitan genotype and presents notable genetic characteristics that occurred during its evolution and global expansion. Whether those characteristics conferred a fitness advantage to cosmopolitan genotype in different geographies warrant further investigations.

Epidemiology and challenges of dengue surveillance in the WHO South-East Asia Region

Dengue poses a significant health and economic burden in the WHO South-East Asia Region. Approaches for control need to be aligned with current knowledge on the epidemiology of dengue in the region. Such knowledge will ensure improved targeting of interventions to reduce dengue incidence and its socioeconomic impact. This review was undertaken to describe the contemporary epidemiology of dengue and critically analyse the existing surveillance strategies in the region. Over recent decades, dengue incidence has continued to increase with geographical expansion. The region has now become hyper-endemic for multiple dengue virus serotypes/genotypes. Every epidemic cycle was associated with a change of predominant serotype/genotype and this was often associated with severe disease with intense transmission. Classical larval indices are widely used in vector surveillance and adult mosquito samplings are not implemented as a part of routine surveillance. Further, there is a lack of integration of entomological and disease surveillance systems, often leading to inaction or delays in dengue prevention and control. Disease surveillance does not capture all cases, resulting in under-reporting, and has thus failed to adequately represent the true burden of disease in the region. Possible solutions include incorporating adult mosquito sampling into routine vector surveillance, the establishment of laboratory-based sentinel surveillance, integrated vector and dengue disease surveillance and climate-based early warning systems using available technologies like mobile apps.

Outbreak of severe dengue associated with DENV-3 in the city of Manado, North Sulawesi, Indonesia

BACKGROUND

In early 2019, an outbreak of severe dengue was reported in Manado, North Sulawesi Province, Indonesia. This epidemic raised public concern and recorded the highest number of cases in the last 10 years. This study aimed to determine the clinical spectrum, disease aetiology and virological characteristics associated with this outbreak of severe dengue.

METHODS

Dengue was diagnosed using non-structural protein 1 detection, reverse transcription polymerase chain reaction and immunoglobulin (Ig)G/IgM serology. Envelope gene sequencing was conducted to determine the phylogeny of the dengue virus (DENV).

RESULTS

In total, 146 patients with a median age of 8 years (interquartile range IQR 5-11 years) were recruited. Most patients experienced expanded dengue syndrome, characterized by severe organ involvement including liver enlargement, stomach ache and coagulation problems. During the outbreak, DENV-3 was the dominant serotype (75.9%). Smaller numbers of DENV-1, -2 and -4 were also detected. Phylogenetically, the dominant DENV-3 strains were grouped in multiple clusters and were related to other Indonesian strains, suggesting the emergence of heterogenous local viruses.

CONCLUSION

The occurrence of an outbreak of severe dengue in Manado was confirmed, and DENV-3 was found to be the dominant serotype during the outbreak. This study shows the benefits of virological surveillance in understanding the aetiological agents responsible for outbreaks of severe dengue.

Dengue Virus Serotype 4 Is Responsible for the Outbreak of Dengue in East Java City of Jember, Indonesia

Outbreaks of dengue virus (DENV) in Indonesia have been mainly caused by the DENV serotype-1; -2; or -3. The DENV-4 was the least-reported serotype in Indonesia during the last five decades. We recently conducted a molecular epidemiology study of dengue in the Jember regency, East Java province, Indonesia. Dengue is endemic in the region and outbreaks occur annually. We investigated the clinical characteristics and etiology of dengue-like febrile illness in this regency to understand the disease dynamics. A total of 191 patients with clinical symptoms similar to dengue were recruited during an 11-month study in 2019-2020. Children accounted for the majority of cases and dengue burden was estimated in 41.4% of the cases based on NS1 antigen, viral RNA, and IgG/IgM antibody detection with the majority (73.4%) being primary infections. Secondary infection was significantly associated with a higher risk of severe dengue manifestation. All four DENV serotypes were detected in Jember. Strikingly, we observed the predominance of DENV-4, followed by DENV-3, DENV-1, and DENV-2. Genotype determination using Envelope gene sequence revealed the classification into Genotype I, Cosmopolitan Genotype, Genotype I, and Genotype II for DENV-1, -2, -3, and -4, respectively. The predominance of DENV-4 in Jember may be associated with a new wave of DENV infections and spread in a non-immune population lacking a herd-immunity to this particular serotype.

Circulation of Various Dengue Serotypes in a Community-Based Study in Jakarta, Indonesia

Dengue virus (DENV) infection remains to be a serious health problem in Indonesia. Community-based dengue studies to determine circulating DENV serotypes based on the geography and season are limited owing to the expensive cost and significant effort required. Many patients with DENV infection are not hospitalized and many visit the hospital in the later phase of the disease. In this study, we performed active DENV surveillance in a community in Jakarta to study the circulating dengue serotypes; adult febrile patients with fever less than 48 hours were recruited. Disease severity was defined using the World Health Organization (WHO) 1997 guidelines. Rapid NS1 dengue antigen detection was used to screen patients with DENV in the community. Viral culture using the C6/36 cell line, an increased antibody titer on hemagglutination inhibition test and enzyme linked immunosorbent assay, or detection of the viral genome on reverse transcription-polymerase chain reaction was used to confirm DENV infection. Of the 102 patients, 68 (66.7%) were confirmed to have DENV infection, with DENV-2 being the most dominant serotype, followed by DENV-3, DENV-1, and DENV-4, in concordance with several reports of mixed DENV infection. Interestingly, in terms of disease severity, although DENV-3 infection was not the predominant circulating serotype, infection with it tended to cause a more severe disease than infection with DENV-2.

Dengue viral infection in Indonesia: Epidemiology, diagnostic challenges, and mutations from an observational cohort study

BACKGROUND

Dengue virus (DENV) infection is a major cause of acute febrile illness in Indonesia. Diagnostic inaccuracy may occur due to its varied and non-specific presentation. Characterization of DENV epidemiology, clinical presentation, and virology will facilitate appropriate clinical management and public health policy.

METHODOLOGY/PRINCIPAL FINDINGS

A multicenter observational cohort study was conducted in Indonesia to assess causes of acute fever requiring hospitalization. Clinical information and specimens were collected at enrollment, 14-28 days, and 3 months from 1,486 children and adults. Total of 468 (31.9%) cases of DENV infection were confirmed by reference laboratory assays. Of these, 414 (88.5%) were accurately diagnosed and 54 had been misdiagnosed as another infection by sites. One hundred initially suspected dengue cases were finally classified as 'non-dengue'; other pathogens were identified in 58 of those cases. Mortality of DENV infection was low (0.6%). Prior DENV exposure was found in 92.3% of subjects >12 years. DENV circulated year-round in all cities, with higher incidence from January to March. DENV-3 and DENV-1 were the predominant serotypes. This study identified DENV-1 with TS119(C→T) substitution in the serotyping primer annealing site, leading to failure of serotype determination.

CONCLUSIONS/SIGNIFICANCE

DENV is a common etiology of acute febrile illness requiring hospitalization in Indonesia. Diagnostic accuracy at clinical sites merits optimization since misdiagnosis of DENV infection and over-estimation of dengue can negatively impact management and outcomes. Mutation at the annealing site of the serotyping primer may confound diagnosis. Clinicians should consider following diagnostic algorithms that include DENV confirmatory testing. Policy-makers should prioritize development of laboratory capacity for diagnosis of DENV.

Multiple introductions of dengue virus strains contribute to dengue outbreaks in East Kalimantan, Indonesia, in 2015-2016

BACKGROUND

Dengue fever is a febrile disease caused by dengue virus (DENV), which affects people throughout the tropical and subtropical regions of the world, including Indonesia. East Kalimantan (Borneo) province suffered a dramatic increase in dengue cases in 2015 and 2016, making it the province with the second highest incidence of dengue in Indonesia. Despite this, dengue in East Kalimantan is understudied; leaving transmission dynamics of the disease in the area are mostly unknown. In this study, we investigate the factors contributing to the outbreaks in East Kalimantan.

METHODS

Prospective clinical and molecular virology study was conducted in two main cities in the province, namely Samarinda and Balikpapan, in 2015-2016. Patients' clinical, hematological, and demographic data were recorded. Dengue detection and confirmation was performed using NS1-antigen and IgG/IgM antibody detection. RT-PCR was conducted to determine the serotypes of the virus. Phylogenetic analysis was performed based on envelope gene sequences.

RESULTS

Three hundred patients with suspected dengue were recruited. Among these, 132 (44%) were diagnosed with dengue by NS1 antigen and/or nucleic acid detection. The majority of the infections (60%) were primary, with dengue hemorrhagic fever (DHF) the predominant manifestation (71.9%). Serotyping detected all four DENV serotypes in 112 (37.3%) cases, with the majority of patients (58.9%) infected by DENV-3. Phylogenetic analysis based on envelope gene sequences revealed the genotypes of the viruses as DENV-1 Genotype I, DENV-2 Cosmopolitan, and DENV-3 Genotype I. Most virus strains were closely-related to strains from cities in Indonesia.

CONCLUSIONS

Our observations indicate that multiple introductions of endemic DENV from surrounding cities in Indonesia, coupled with relatively low herd immunity, were likely responsible for the outbreak of the dominant viruses. The study provides information on the clinical spectrum of the disease, together with serology, viral genetics, and demographic data, which will be useful for better understanding of dengue disease in Borneo.

Molecular characterization and phylogenetic analysis of dengue viruses imported into Taiwan during 2011-2016

A total of 1,596 laboratory-confirmed imported dengue cases were identified in Taiwan during 2011–2016. Most of the imported cases arrived from Southeast Asia as well as the Indian subcontinent, the Pacific region, Latin America, Australia and Africa. Phylogenetic analyses of the complete envelope protein gene sequences from 784 imported dengue virus (DENV) isolates were conducted, and the results suggest that the DENV-1 genotype I and DENV-2 Cosmopolitan genotype comprise the predominant serotype/genotype of DENV strains circulating in Southeast Asia. The DENV-1 genotype III, DENV-3 genotype III and DENV-4 genotype I and II strains were found to be newly emerging in several Southeast Asian countries. Our results also showed that geographical restrictions of DENV-1 genotype I, DENV-1 genotype III and DENV-2 Cosmopolitan genotype are becoming blurred, indicating the extensive introductions and continuous expansions of DENV strains between nations in Southeast Asia. In this study, we present the geographic distribution and dynamic transmission of DENV strains circulating in Southeast Asian countries. In addition, we demonstrated local dengue epidemics caused by several imported DENV strains in Taiwan during 2011–2016.

Dengue is the most prevalent mosquito-borne viral disease in the world. The expansion of dengue viruses to different parts of the world has been accelerated by the increase in worldwide travel and trade. In this study, we present the results of a laboratory-based dengue surveillance in Taiwan during 2011–2016. A total of 1,596 laboratory-confirmed imported dengue cases were identified. The travelers were infected in 29 countries in Southeast Asia, the Indian subcontinent, the Pacific region, Latin America, Australia and Africa. Phylogenetic analyses of the envelope gene sequences of 784 imported dengue virus isolates suggest that the DENV-1 genotype I and DENV-2 Cosmopolitan genotype comprise the predominant serotype/genotype DENV strains circulating in Southeast Asia. Our results also showed that geographical restrictions of some of the DENV genotypes are becoming blurred, indicating the extensive introductions and continuous expansions of DENV strains between countries in Southeast Asia. In addition, we demonstrated dengue outbreaks in Taiwan caused by viruses imported from Asia and the Americas. The DENV envelope gene sequences from this study will contribute to a better understanding of the genetic evolution, dynamic transmission and global expansion of dengue viruses.

Dengue virus serotype distribution based on serological evidence in pediatric urban population in Indonesia

BACKGROUND

Dengue is a febrile illness transmitted by mosquitoes, causing disease across the tropical and sub-tropical world. Antibody prevalence data and serotype distributions describe population-level risk and inform public health decision-making.

METHODOLOGY/PRINCIPAL FINDINGS

In this cross-sectional study we used data from a pediatric dengue seroprevalence study to describe historical dengue serotype circulation, according to age and geographic location. A sub-sample of 780 dengue IgG-positive sera, collected from 30 sites across urban Indonesia in 2014, were tested by the plaque reduction neutralization test (PRNT) to measure the prevalence and concentration of serotype-specific neutralizing antibodies according to subject age and geography. PRNT results were obtained from 776 subjects with mean age of 9.6 years. 765 (98.6%) neutralized one or more dengue serotype at a threshold of >10 (1/dil). Multitypic profiles were observed in 50.9% of the samples; a proportion which increased to 63.1% in subjects aged 15-18 years. Amongst monotypic samples, the highest proportion was reactive against DENV-2, followed by DENV-1, and DENV-3, with some variation across the country. DENV-4 was the least common serotype. The highest anti-dengue antibody titers were recorded against DENV-2, and increased with age to a geometric mean of 516.5 [1/dil] in the oldest age group.

CONCLUSIONS/SIGNIFICANCE

We found that all four dengue serotypes have been widely circulating in most of urban Indonesia, and more than half of children had already been exposed to >1 dengue serotype, demonstrating intense transmission often associated with more severe clinical episodes. These data will help inform policymakers and highlight the importance of dengue surveillance, prevention and control.

Clinical Features and Laboratory Findings of Travelers Returning to South Australia with Dengue Virus Infection

Reported cases of dengue are rising in South Australia (SA) in travellers returning from dengue-endemic regions. We have undertaken a retrospective analysis to identify the clinical and laboratory characteristics of patients returning to SA with suspected dengue virus (DENV) infection. From 488 requests, 49 (10%) were defined by serology as acute dengue, with the majority of patients (75%) testing as non-structural protein 1 (NS1) and/or IgM positive. Dengue was most commonly acquired in Indonesia (42.9%) with clinical features of fever (95%), headache (41%) and myalgia/arthralgia (56%). The presence of rash (36%) and laboratory findings of neutropenia, leukopenia, thrombocytopenia, but not elevated C-reactive protein, were distinct from findings in DENV-seronegative patients. Available dengue seropositive samples were analysed by RT-PCR, with 14/32 (43.8%) positive by a serotype non-specific DENV assay, but 28/32 positive (87.5%) when also assessed by serotype-specific RT-PCR. Serotype analysis revealed the predominance of DENV-1 and DENV-2 and the presence of DENV-3, but not DENV-4 or Zika virus (ZIKV). Thus, dengue in returned travellers in SA presents in a manner consistent with World Health Organization (WHO) definitions, with symptoms, travel history and laboratory results useful in prioritising the likelihood of dengue. This definition will assist the future management in DENV-non-endemic regions, such as SA.