Economic impact of dengue illness in the Americas

Effectiveness of mass dengue vaccination with CYD-TDV (Dengvaxia®) in the state of Paraná, Brazil: integrating case-cohort and case-control designs

Background

CYD-TDV (Dengvaxia®) was the first dengue vaccine approved, launched in Brazil in 2015 for individuals aged 9-44 years. We aimed to estimate the effectiveness of CYD-TDV in preventing symptomatic dengue cases during a campaign targeting individuals aged 15-27 years in selected municipalities in Paraná, Brazil. Additionally, we examined whether a history of dengue, as recorded by the surveillance system, modified the vaccine's effectiveness.

Methods

We conducted a case-cohort analysis comparing the frequency of vaccination, with at least one dose of CYD-TDV, in individuals with dengue confirmed by RT-PCR, identified by the surveillance system during 2019 and 2020, with the vaccination coverage in the target population. Moreover, in a case-control design using weighted controls, we assessed the documented history of dengue as a modifier of the vaccine's effectiveness. We used a logistic random-effects regression model, with data clustered in municipalities and incorporating covariates such as the incidence of dengue before the campaign, age, and sex. We calculated vaccine effectiveness (VE) as (1-relative risk) x 100%.

Findings

1869 dengue cases were identified, which had a vaccination frequency significantly lower than the overall vaccination coverage in the target population (50.3% vs. 57.2%, respectively; overall VE: 21.3%; 95% confidence interval [CI]: 13.4%-28.4%). In individuals with a documented history of dengue, vaccination had a VE of 71% (95% CI: 58%-80%) in reducing the incidence of dengue. However, vaccination was not associated with a significant reduction in the overall dengue case risk in individuals without a documented history of dengue (VE: 12%; 95% CI: -21% to 36%). In this last stratum, vaccination was associated with reduced cases due to DENV-1 and DENV-4, but an excess of DENV-2 cases.

Interpretation

Vaccination led to a significant reduction in reported dengue cases within the target population. The case-control design suggested that this reduction was primarily driven by the benefits observed in individuals with a documented history of dengue. In endemic regions with limited serological testing facilities, a previous history of dengue diagnosis recorded by epidemiological surveillance could be used to triage candidates for CYD-TDV vaccination.

Funding

Research supported by Sanofi.

A multimodal framework for extraction and fusion of satellite images and public health data

In low- and middle-income countries, the substantial costs associated with traditional data collection pose an obstacle to facilitating decision-making in the field of public health. Satellite imagery offers a potential solution, but the image extraction and analysis can be costly and requires specialized expertise. We introduce SatelliteBench, a scalable framework for satellite image extraction and vector embeddings generation. We also propose a novel multimodal fusion pipeline that utilizes a series of satellite imagery and metadata. The framework was evaluated generating a dataset with a collection of 12,636 images and embeddings accompanied by comprehensive metadata, from 81 municipalities in Colombia between 2016 and 2018. The dataset was then evaluated in 3 tasks: including dengue case prediction, poverty assessment, and access to education. The performance showcases the versatility and practicality of SatelliteBench, offering a reproducible, accessible and open tool to enhance decision-making in public health.

Discovery of Potent Degraders of the Dengue Virus Envelope Protein

Targeted protein degradation has been widely adopted as a new approach to eliminate both established and previously recalcitrant therapeutic targets. Here we report the development of small molecule degraders of the envelope (E) protein of dengue virus. We developed two classes of bivalent E-degraders, linking two previously reported E-binding small molecules, GNF-2 and CVM-2-12-2, to a glutarimide-based recruiter of the CRL4CRBN ligase to effect proteosome-mediated degradation of the E protein. ZXH-2-107 (based on GNF-2) is an E degrader with ABL inhibition while ZXH-8-004 (based on CVM-2-12-2) is a selective and potent E-degrader. These two compounds provide proof-of-concept that difficult-to-drug targets such as a viral envelope protein can be effectively eliminated using a bivalent degrader and provide starting points for the future development of a new class antiviral drugs.

The macroeconomic impact of a dengue outbreak: Case studies from Thailand and Brazil

BACKGROUND

Dengue is spreading in (sub)tropical areas, and half of the global population is at risk. The macroeconomic impact of dengue extends beyond healthcare costs. This study evaluated the impact of dengue on gross domestic product (GDP) based on approaches tailored to two dengue-endemic countries, Thailand and Brazil, from the tourism and workforce perspectives, respectively.

FINDINGS

Because the tourism industry is a critical economic sector for Thailand, lost tourism revenues were estimated to analyze the impact of a dengue outbreak. An input-output model estimated that the direct effects (on international tourism) and indirect effects (on suppliers) of dengue on tourism reduced overall GDP by 1.43 billion US dollars (USD) (0.26%) in the outbreak year 2019. The induced effect (reduced employee income/spending) reduced Thailand's GDP by 375 million USD (0.07%). Overall, lost tourism revenues reduced Thailand's GDP by an estimated 1.81 billion USD (0.33%) in 2019 (3% of annual tourism revenue). An inoperability input-output model was used to analyze the effect of workforce absenteeism on GDP due to a dengue outbreak in Brazil. This model calculates the number of lost workdays associated with ambulatory and hospitalized dengue. Input was collected from state-level epidemiological and economic data for 2019. An estimated 22.4 million workdays were lost in the employed population; 39% associated with the informal sector. Lost workdays due to dengue reduced Brazil's GDP by 876 million USD (0.05%).

CONCLUSIONS

The economic costs of dengue outbreaks far surpass the direct medical costs. Dengue reduces overall GDP and inflicts national economic losses. With a high proportion of the population lacking formal employment in both countries and low income being a barrier to seeking care, dengue also poses an equity challenge. A combination of public health measures, like vector control and vaccination, against dengue is recommended to mitigate the broader economic impact of dengue.

The influence of gender and temephos exposure on community participation in dengue prevention: a compartmental mathematical model

BACKGROUND

The use of temephos, the most common intervention for the chemical control of Aedes aegypti over the last half century, has disappointing results in control of the infection. The footprint of Aedes and the diseases it carries have spread relentlessly despite massive volumes of temephos. Recent advances in community participation show this might be more effective and sustainable for the control of the dengue vector.

METHODS

Using data from the Camino Verde cluster randomized controlled trial, a compartmental mathematical model examines the dynamics of dengue infection with different levels of community participation, taking account of gender of respondent and exposure to temephos.

RESULTS

Simulation of dengue endemicity showed community participation affected the basic reproductive number of infected people. The greatest short-term effect, in terms of people infected with the virus, was the combination of temephos intervention and community participation. There was no evidence of a protective effect of temephos 220 days after the onset of the spread of dengue.

CONCLUSIONS

Male responses about community participation did not significantly affect modelled numbers of infected people and infectious mosquitoes. Our model suggests that, in the long term, community participation alone may have the best results. Adding temephos to community participation does not improve the effect of community participation alone.

Low-dose dengue virus 3 human challenge model: a phase 1 open-label study

Dengue human infection models present an opportunity to explore the potential of a vaccine, anti-viral or immuno-compound for clinical benefit in a controlled setting. Here we report the outcome of a phase 1 open-label assessment of a low-dose dengue virus 3 (DENV-3) challenge model (NCT04298138), in which nine participants received a subcutaneous inoculation with 0.5 ml of a 1.4 × 103 plaque-forming unit per ml suspension of the attenuated DENV-3 strain CH53489. The primary and secondary endpoints of the study were to assess the safety of this DENV-3 strain in healthy flavivirus-seronegative individuals. All participants developed RNAaemia within 7 days after inoculation with peak titre ranging from 3.13 × 104 to 7.02 × 108 genome equivalents per ml. Solicited symptoms such as fever and rash, clinical laboratory abnormalities such as lymphopenia and thrombocytopenia, and self-reported symptoms such as myalgia were consistent with mild-to-moderate dengue in all volunteers. DENV-3-specific seroconversion and memory T cell responses were observed within 14 days after inoculation as assessed by enzyme-linked immunosorbent assay and interferon-gamma-based enzyme-linked immunospot. RNA sequencing and serum cytokine analysis revealed anti-viral responses that overlapped with the period of viraemia. The magnitude and frequency of clinical and immunologic endpoints correlated with an individual's peak viral titre.

Bamboo stumps that are artificially in use put pressure on dengue and chikungunya vector control in Dhaka city, Bangladesh

BACKGROUND OBJECTIVES

Aedes aegypti and Ae. albopictus mosquitoes breed in natural and artificial containers, and they transmit dengue and chikungunya. A study was conducted to identify the contribution of bamboo stumps to these disease vectors that were used in the flower garden as pillars to hold the bamboo flex fence.

METHODS

Two sizes of whole bamboo were used to hold fences around gardens at Dhaka University, Bangladesh, and were painted red and green. Mosquito larvae and pupae were collected from bamboo stumps between July and August, and vectors were identified up to the species level. The data were analyzed using the STATA/MP 14.2 version.

RESULTS

83.5% and 0.2% were Ae. albopictus and Ae. aegypti, respectively, and the remaining were Culex and Ar-migeres species. Ae. albopictus, Ae. aegypti, and both species-positive bamboo stumps were 46.9, 0.7, and 47.1%, respectively. 54.5% of the bamboo stumps had at least one mosquito species. The average stump depth for Aedes positive stumps (mean=11.7 cm, SE = 0.5) was significantly (p <0.001) higher than the Aedes negative stumps (mean = 9.5 cm, SE = 0.4). 53.8% and 38.0% stumps were found Aedes positive on the ground and upper sides of fences, respectively, and found significant (p<0.01) differences between both sides. A zero-inflated negative binomial count model is significant at a 5% level of significance, χ2(4) = 11.8, p = 0.019 (<0.05) for Ae. albopictus. Stump depth is found to have a significant positive effect on the number of Aedes-positive stumps.

INTERPRETATION CONCLUSION

Artificially used natural containers are adding pressure to current mosquito control activities as mosquitoes are breeding on them, which needs additional attention.

Demographic history and the efficacy of selection in the globally invasive mosquito Aedes aegypti

Aedes aegypti is the main vector species of yellow fever, dengue, zika and chikungunya. The species is originally from Africa but has experienced a spectacular expansion in its geographic range to a large swath of the world, the demographic effects of which have remained largely understudied. In this report, we examine whole-genome sequences from 6 countries in Africa, North America, and South America to investigate the demographic history of the spread of Ae. aegypti into the Americas its impact on genomic diversity. In the Americas, we observe patterns of strong population structure consistent with relatively low (but probably non-zero) levels of gene flow but occasional long-range dispersal and/or recolonization events. We also find evidence that the colonization of the Americas has resulted in introduction bottlenecks. However, while each sampling location shows evidence of a past population contraction and subsequent recovery, our results suggest that the bottlenecks in America have led to a reduction in genetic diversity of only ~35% relative to African populations, and the American samples have retained high levels of genetic diversity (expected heterozygosity of ~0.02 at synonymous sites) and have experienced only a minor reduction in the efficacy of selection. These results evoke the image of an invasive species that has expanded its range with remarkable genetic resilience in the face of strong eradication pressure.

Epidemiology and burden of dengue fever in the United States: a systematic review

BACKGROUND

Dengue is currently a global concern. The range of dengue vectors is expanding with climate change, yet United States of America (USA) studies on dengue epidemiology and burden are limited. This systematic review sought to characterize the epidemiology and disease burden of dengue within the USA.

METHODS

Studies evaluating travel-related and endemic dengue in US states and territories were identified and qualitatively summarized. Commentaries and studies on ex-US cases were excluded. MEDLINE, Embase, Cochrane Library, Latin American and Caribbean Center of Health Sciences Information, Centre for Reviews and Dissemination and Clinicaltrials.gov were searched through January 2022.

RESULTS

116 studies were included. In US states, dengue incidence was generally low, with spikes occurring in recent years in 2013-16 (0.17-0.31 cases/100,000) and peaking in 2019 (0.35 cases/100,000). Most cases (94%, n = 7895, 2010-21) were travel related. Dengue was more common in Puerto Rico (cumulative average: 200 cases/100,000, 1980-2015); in 2010-21, 99.9% of cases were locally acquired. There were <50 severe cases in US states (2010-17); fatal cases were even rarer. Severe cases in Puerto Rico peaked in 1998 (n = 173) and 2021 (n = 76). Besides lower income, risk factors in US states included having birds in residence, suggesting unspecified environmental characteristics favourable to dengue vectors. Commonly reported symptoms included fever, headache and rash; median disease duration was 3.5-11 days. Hospitalization rates increased following 2009 World Health Organization disease classification changes (pre-2009: 0-54%; post-2009: 14-75%); median length of stay was 2.7-8 days (Puerto Rico) and 2-3 days (US states). Hospitalization costs/case (2010 USD) were$14 350 (US states),$1764-$5497 (Puerto Rico) and$4207 (US Virgin Islands). In Puerto Rico, average days missed were 0.2-5.3 (work) and 2.5 (school).

CONCLUSIONS

Though dengue risk is ongoing, treatments are limited, and dengue's economic burden is high. There is an urgent need for additional preventive and therapeutic interventions.

Common patterns between dengue cases, climate, and local environmental variables in Costa Rica: A wavelet approach

Dengue transmission poses significant challenges for public health authorities worldwide due to its susceptibility to various factors, including environmental and climate variability, affecting its incidence and geographic spread. This study focuses on Costa Rica, a country characterized by diverse microclimates nearby, where dengue has been endemic since its introduction in 1993. Using wavelet coherence and clustering analysis, we performed a time-series analysis to uncover the intricate connections between climate, local environmental factors, and dengue occurrences. The findings indicate that multiannual dengue frequency (3 yr) is correlated with the Oceanic Niño Index and the Tropical North Atlantic Index. This association is particularly prominent in cantons located along the North and South Pacific Coast, as well as in the Central cantons of the country. Furthermore, the time series of these climate indices exhibit a leading phase of approximately nine months ahead of dengue cases. Additionally, the clustering analysis uncovers non-contiguous groups of cantons that exhibit similar correlation patterns, irrespective of their proximity or adjacency. This highlights the significance of climate factors in influencing dengue dynamics across diverse regions, regardless of spatial closeness or distance between them. On the other hand, the annual dengue frequency was correlated with local environmental indices. A persistent correlation between dengue cases and local environmental variables is observed over time in the North Pacific and the Central Region of the country's Northwest, with environmental factors leading by less than three months. These findings contribute to understanding dengue transmission's spatial and temporal dynamics in Costa Rica, highlighting the importance of climate and local environmental factors in dengue surveillance and control efforts.

Knowledge, attitude, and practice of healthcare workers regarding dengue fever in Mazandaran Province, northern Iran

Background

Dengue fever is a rapidly emerging infection worldwide with a high public health burden. Adequate training of healthcare workers is essential to warrant the timely provision of health services to improve the outcome of dengue management.

Methods

This is an analytical cross-sectional study, conducted to assess the knowledge, attitudes and practice (KAP) of healthcare workers regarding dengue from April 2021 to March 2022 in Mazandaran Province, northern Iran. Data was collected using a researcher-made structured questionnaire, prepared as Google Forms, and sent to target groups through social media and email. Data analysis was performed by SPSS 22 software using descriptive and inferential statistics (Chi-square) at a significant level of 5%.

Results

Most of the respondents had heard about dengue (83.8%); media (32.7%) and academic education (25%) were the main sources of information. Respondents had less knowledge associated with dengue symptoms (52%) than prevention and control (69%), transmission (72.2%) and clinical management (81%). Based on the 70% cut-off point, the majority of the participants had a good attitude (81%) and practice (73%). However, only 49.6% of the respondents showed good practice regarding dengue local transmission. A significant difference was observed between participants knowledge on clinical management with occupation; attitude with gender and occupation; and practice with gender (p < 0.05).

Conclusion

The results of this study revealed gaps in some dimensions of KAP in healthcare workers, therefore, a greater focus should be placed on future training programs to raise knowledge and attitude leading to sound practice and behavior for adequate management of dengue.

Dengue vaccine acceptability before and after the availability of COVID-19 vaccines in Puerto Rico

Dengue is a growing public health threat, causing approximately 400 million infections annually. In June 2021, the Advisory Committee on Immunization Practices recommended the first dengue vaccine (CYD-TDV) for children aged 9-16 years with a previous dengue infection, living in endemic areas, such as Puerto Rico (PR). As the COVID-19 pandemic affected vaccine intention worldwide, we assessed dengue vaccine intention before (pre-COVID) and after (post-COVID) COVID-19 vaccine availability among participants enrolled in the Communities Organized to Prevent Arboviruses (COPA) cohort to prepare for dengue vaccine implementation in PR. We used logistic regression models to evaluate changes in dengue vaccine intention by interview timing and participant characteristics. Among 2,513 participants pre-COVID, 2,512 answered the dengue vaccine intention question for themselves, and 1,564 answered relative to their children. Post-COVID, dengue vaccine intention in adults increased for themselves from 73.4% to 84.5% (adjusted odds ratio (aOR) = 2.27, 95%CI: 1.90-2.71) and relative to their children from 75.6% to 85.5% (aOR = 2.21, 95%CI: 1.75-2.78). Among all participants, groups with higher dengue vaccine intention included those who reported previous year influenza vaccine uptake and those who reported being frequently bitten by mosquitos, compared to those who did not. Adult males were also more likely to intend to vaccinate themselves than females. Respondents who were employed or in school were less likely to intend to vaccinate compared to those who were not working. The primary reasons for vaccine hesitancy were concerns with side effects and not believing in vaccines, which should be considered during educational strategies prior to dengue vaccine implementation. In general, dengue vaccine intention is high in PR and has increased after COVID-19 vaccine availability, potentially due to increased awareness of vaccine importance during the COVID-19 pandemic.

Dengue as a Disease Threatening Global Health: A Narrative Review Focusing on Latin America and Brazil

Arboviruses constitute the largest known group of viruses. These viruses are the etiological agents of pathologies known as arboviruses, with dengue being one of the most prevalent. Dengue has resulted in important socioeconomic burdens placed on different countries around the world, including those in Latin America, especially Brazil. Thus, this work intends to carry out a narrative-based review of the literature, conducted using a study of the secondary data developed through a survey of scientific literature databases, and to present the situation of dengue, particularly its distribution in these localities. Our findings from the literature demonstrate the difficulties that managers face in controlling the spread of and planning a response against dengue, pointing to the high cost of the disease for public coffers, rendering the resources that are already limited even scarcer. This can be associated with the different factors that affect the spread of the disease, including ecological, environmental, and social factors. Thus, in order to combat the disease, it is expected that targeted and properly coordinated public policies need to be adopted not only in specific localities, but also globally.

How can the copepod Mesocyclops longisetus (Thiébaud, 1912) be used to control mosquito production effectively in pots, plates, and slabs?

We tested the effectiveness of predation by the cyclopoid copepod Mesocyclops longisetus (Thiébaud, 1912) in Culicidae and Chironomidae larvae, aiming to test if (i) the introduction of copepods effectively controls mosquito larvae and (ii) the density of copepods is important for ensuring control. We conducted two semi-field experiments: the first involved 14 experimental runs over 75 consecutive days, compared in a randomized block design, four repetitions per treatment in each experimental run (block); and the second experiment involved a total of five experimental runs, lasting 25 and 33 days each. In the first experiment, culicid larvae were preyed on by copepods, especially at high copepod densities (15 copepods per litre), which reduced culicid densities by approximately 61% and 64% for different containers, considering that the environmental temperature declined linearly by about 10ºC from February (summer) to May (autumn) (32ºC to 22ºC). Even the lowest copepod density (5 per liter) produced a substantial reduction in the abundance of culicid larvae when chironomid larvae were abundant. On the other hand, there was no effective control of chironomid larvae. In the second experiment, increases in Culicidae and Chironomidae were concomitant with decreases in copepods. Thus, when the copepods were in high densities, there was no increase in insects, although the larvae of culicids were not eliminated from the experimental units. We conclude that the introduction of copepods in small containers and ponds can be useful for the control of culicid larvae without harming chironomid populations, and densities up to 15 per litre are recommended, although even low densities cause substantial reduction.

Public health impact and cost-effectiveness of implementing a 'pre-vaccination screening' strategy with the dengue vaccine in Puerto Rico

BACKGROUND

The World Health Organization (WHO) recommended 'pre-vaccination screening' as its preferred implementation strategy when using the licensed dengue vaccine (CYD-TDV; Dengvaxia, Sanofi), so that only individuals with previous dengue infection are vaccinated. The US Centers for Disease Control and Prevention (CDC) recommended use of CYD-TDV to prevent dengue in children with previous laboratory-confirmed dengue infection in regions where dengue is endemic. Here, we evaluate the public health impact and cost-effectiveness of a 'pre-vaccination screening' strategy in Puerto Rico.

METHODS

The current analysis builds upon a previously published transmission model used to assess the benefits/risks associated with dengue vaccination. For 'pre-vaccination screening', three alternative testing methods were assessed: one using an immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) dengue serotest, another with dengue serotesting using a rapid diagnostic test (RDT), and one using both sequentially (as recommended in Puerto Rico). The time horizon considered was 10 years.

RESULTS

In Puerto Rico, the disability-adjusted life years (DALYs) averted for 'pre-vaccination screening' with an ELISA-based program, RDT-based program, and both sequentially would be a median 1,192 (95% CI: 716-2,232), 2,812 (95% CI: 1,579-5,019), and 1,017 (95% CI: 561-1,738), respectively. These benefits would arise from the reduction in cases: median 24,961 (95% CI: 17,480-36,782), 58,273 (95% CI: 40,729-84,796), 20,775 (95% CI: 14,637-30,374) fewer cases, respectively. The cost per DALY averted from a payer perspective would be US$12,518 (95 %CI: US$4,749-26,922), US$10,047 (95% CI: US$3,350-23,852), and US$12,334 (95% CI: US$4,965-26,444), respectively. All three strategies would be cost saving from a societal perspective.

CONCLUSIONS

Our study supports the WHO and CDC 'pre-vaccination screening' guidance for CYD-TDV implementation. In Puerto Rico, regardless of the testing strategy and even with a relatively low rate of testing, it would be cost-effective from a payer perspective and cost saving from a societal perspective.

The one health perspective to improve environmental surveillance of zoonotic viruses: lessons from COVID-19 and outlook beyond

The human population has doubled in the last 50 years from about 3.7 billion to approximately 7.8 billion. With this rapid expansion, more people live in close contact with wildlife, livestock, and pets, which in turn creates increasing opportunities for zoonotic diseases to pass between animals and people. At present an estimated 75% of all emerging virus-associated infectious diseases possess a zoonotic origin, and outbreaks of Zika, Ebola and COVID-19 in the past decade showed their huge disruptive potential on the global economy. Here, we describe how One Health inspired environmental surveillance campaigns have emerged as the preferred tools to monitor human-adjacent environments for known and yet to be discovered infectious diseases, and how they can complement classical clinical diagnostics. We highlight the importance of environmental factors concerning interactions between animals, pathogens and/or humans that drive the emergence of zoonoses, and the methodologies currently proposed to monitor them-the surveillance of wastewater, for example, was identified as one of the main tools to assess the spread of SARS-CoV-2 by public health professionals and policy makers during the COVID-19 pandemic. One-Health driven approaches that facilitate surveillance, thus harbour the potential of preparing humanity for future pandemics caused by aetiological agents with environmental reservoirs. Via the example of COVID-19 and other viral diseases, we propose that wastewater surveillance is a useful complement to clinical diagnosis as it is centralized, robust, cost-effective, and relatively easy to implement.

Evolution of inflammation and immunity in a dengue virus 1 human infection model

Dengue virus (DENV) infections are major causes of morbidity and mortality throughout the tropics and subtropics. More than 400 million infections are estimated to occur every year, resulting in nearly 100 million symptomatic infections and more than 20,000 deaths. Early immune response kinetics to infection remain unclear, in large part due to the variable incubation period exhibited by the DENVs after introduction into a susceptible host. To fill this knowledge gap, we performed a comprehensive virologic and immunologic analysis of individuals experimentally infected with the underattenuated DENV-1 strain 45AZ5. This analysis captured both the kinetics and composition of the innate, humoral, and cellular immune responses elicited by experimental DENV-1 infection, as well as virologic and clinical features. We observed a robust DENV-specific immunoglobulin A (IgA) antibody response that manifested between the appearance of DENV-specific IgM and IgG in all challenged individuals, as well as the presence of a non-neutralizing/NS1-specific antibody response that was delayed relative to the appearance of DENV virion–specific humoral immunity. RNA sequencing analysis revealed discrete and temporally restricted gene modules that correlated with acute viremia and the induction of adaptive immunity. Our analysis provides a detailed description, in time and space, of the evolving matrix of DENV-elicited human inflammation and immunity and reveals several previously unappreciated immunological aspects of primary DENV-1 infection that can inform countermeasure development and evaluation.

Risk Factors Associated with Passengers with Imported Dengue Fever at International Airports in Taiwan

Dengue fever (DF) is a mosquito-borne disease prevalent in the tropics (e.g., sub-Saharan Africa, Asia, and Central and South America) and a common cause of febrile illness in travelers. The high incidence of imported DF in Taiwan has led to a domestic outbreak. This study explored the risk factors associated with individuals given diagnoses of imported DF at international airports in Taiwan. The results may serve as a reference for DF prevention. In this retrospective study, data from the symptom notification system database of the Taiwan Centers for Disease Control (TCDC) were used. These data concerned travelers who returned to Taiwan from DF-endemic areas with suspected DF symptoms. The epidemiological characteristics of the cases were analyzed, and 28 variables related to DF infection were included in the multivariate logistic regression analysis. In 2018-2019, there were 8656 cases (451 positive and 8205 negative cases). The results revealed DF symptoms and a 16-30-day stay in endemic areas to be independent risk factors and the presence of three respiratory symptoms and <10 days of short-term travel to be protective factors. These results may enable the accurate assessment of symptoms in travelers with DF as well as the risk factors associated with imported DF, lowering the risk of indigenous DF outbreaks caused by imported DF.

Economic burden estimation associated with dengue and chikungunya in Gujarat, India

Background

Dengue and chikungunya have been emerging as major vector-borne diseases. The global burden of the diseases is rising as a public health problem. The complexity of disease is governed by multiple constraints including only symptomatic treatment and inflicts heavy social and economic burden on society. The present study is designed to assess the economic burden of dengue and chikungunya infection by calculating cost per patient in Gujarat, India.

Methods

A total of 210 patients were enrolled in the study from Ahmedabad and Kheda district of Gujarat from May 2018 to December 2019 of which 150 had dengue and 60 chikungunya infections, subject to the willingness of participation in the survey. Information on wage loss days, cost associated with medicines, diagnosis, special food and travel cost, etc., for the calculation of the direct and indirect costs associated with dengue and chikungunya were collected from these participants using a structured questionnaire. Informed consent was taken before including any participant in the study.

Results

In the dengue sample, 86 were males (57.3%) and the rest were females, and in the chikungunya sample, 31 were males (51.7%) and the rest females. The median age of the participants with dengue and chikungunya was 18 (p25 to p75: 8 to 26) and 30 (p25 to p75: 21 to 45) years respectively. Median family income was recorded as Rs 15,000 (p25 to p75: 9000 to 25500) and Rs 12,000 (p25 to p75: 9000 to 18500) for the dengue and chikungunya cases, respectively. The average duration of the illness was observed to be higher in chikungunya (median days (P25 to p75): 15 (7-45)) than dengue (median days (P25 to p75): 10 (5-15)). The median indirect cost in the case of dengue was Rs 1,931 (p25 to p75: 300 to 4500) while Rs 2,550 (p25 to p75: 0 to 5250) was observed for chikungunya cases. Two types of direct cost, namely, direct cost related to medical expenses and direct cost related to other expenses were calculated. Direct cost related to medical expenses was observed to be higher in dengue (Md (P25 to p75): Rs 2,450 (400-5000)) than chikungunya (Md (P25 to p75): Rs 1,500 (150-5200)) while indirect cost related to other expenses were comparable between dengue (Md (P25 to p75): Rs 1,575 (1300-2600)) and chikungunya (Md (P25 to p75): Rs 1500 (850-2850)). The average total cost for one dengue episode was estimated to be Rs 6,860 (3700-12525) whereas it was Rs 7,000 (2550-14000) for one episode of Chikungunya.

Conclusions

Overall, patients have to bear high costs while suffering from dengue and chikungunya infections. Furthermore, the duration of illness while suffering from viral diseases also contributes to the substantial economic burden. Improved knowledge about the impact of the cost and the economic burden associated with dengue and chikungunya will help policymakers allocate and appropriate resources accordingly.

Dengue Incidence Trends and Its Burden in Major Endemic Regions from 1990 to 2019

BACKGROUND

Dengue has become one of the major vector-borne diseases, which has been an important public health concern. We aimed to estimate the disease burden of dengue in major endemic regions from 1990 to 2019, and explore the impact pattern of the socioeconomic factors on the burden of dengue based on the global burden of diseases, injuries, and risk factors study 2019 (GBD 2019).

METHODS

Using the analytical strategies and data from the GBD 2019, we described the incidence and disability-adjusted life years (DALYs) of dengue in major endemic regions from 1990 to 2019. Furthermore, we estimated the correlation between dengue burden and socioeconomic factors, and then established an autoregressive integrated moving average (ARIMA) model to predict the epidemic trends of dengue in endemic regions. All estimates were proposed as numbers and age-standardized rates (ASR) per 100,000 population, with uncertainty intervals (UIs). The ASRs of dengue incidence were compared geographically and five regions were stratified by a sociodemographic index (SDI).

RESULTS

A significant rise was observed on a global scale between 1990 and 2019, with the overall age-standardized rate (ASR) increasing from 557.15 (95% UI 243.32-1212.53) per 100,000 in 1990 to 740.4 (95% UI 478.2-1323.1) per 100,000 in 2019. In 2019, the Oceania region had the highest age-standardized incidence rates per 100,000 population (3173.48 (95% UI 762.33-6161.18)), followed by the South Asia region (1740.79 (95% UI 660.93-4287.12)), and then the Southeast Asia region (1153.57 (95% UI 1049.49-1281.59)). In Oceania, South Asia, and Southeast Asia, increase trends were found in the burden of dengue fever measured by ASRs of DALY which were consistent with ASRs of dengue incidence at the national level. Most of the countries with the heaviest burden of dengue fever occurred in areas with low and medium SDI regions. However, the burden in high-middle and high-SDI countries is relatively low, especially the Solomon Islands and Tonga in Oceania, the Maldives in South Asia and Indonesia in Southeast Asia. The age distribution results of the incidence rate and disease burden of dengue fever of major endemic regions showed that the higher risk and disease burden are mainly concentrated in people under 14 or over 70 years old. The prediction by ARIMA showed that the risk of dengue fever in South and Southeast Asia is on the rise, and further prevention and control is warranted.

CONCLUSIONS

In view of the rapid population growth and urbanization in many dengue-endemic countries, our research results are of great significance for presenting the future trend in dengue fever. It is recommended to policy makers that specific attention needs to be paid to the negative impact of urbanization on dengue incidence and allocate more resources to the low-SDI areas and people under 14 or over 70 years old to reduce the burden of dengue fever.

Trypsin-like Inhibitor Domain (TIL)-Harboring Protein Is Essential for Aedes aegypti Reproduction

Cysteine-rich trypsin inhibitor-like domain (TIL)-harboring proteins are broadly distributed in nature but remain understudied in vector mosquitoes. Here we have explored the biology of a TIL domain-containing protein of the arbovirus vector Aedes aegypti, cysteine-rich venom protein 379 (CRVP379). CRVP379 was previously shown to be essential for dengue virus infection in Ae. aegypti mosquitoes. Gene expression analysis showed CRVP379 to be highly expressed in pupal stages, male testes, and female ovaries. CRVP379 expression is also increased in the ovaries at 48 h post-blood feeding. We used CRISPR-Cas9 genome editing to generate two mutant lines of CRVP379 with mutations inside or outside the TIL domain. Female mosquitoes from both mutant lines showed severe defects in their reproductive capability; mutant females also showed differences in their follicular cell morphology. However, the CRVP379 line with a mutation outside the TIL domain did not affect male reproductive performance, suggesting that some CRVP379 residues may have sexually dimorphic functions. In contrast to previous reports, we did not observe a noticeable difference in dengue virus infection between the wild-type and any of the mutant lines. The importance of CRVP379 in Ae. aegypti reproductive biology makes it an interesting candidate for the development of Ae. aegypti population control methods.

Knowledge, Attitudes, and Practices in Relation to Mosquito-Borne Diseases in Bangladesh

Mosquito-borne diseases (MBDs) such as dengue, malaria, and chikungunya are common in Bangladesh, with frequent outbreaks in the rainy season. Analysis of the knowledge, attitudes, and practices of people toward any crisis is fundamental to addressing any gap. Here, we conducted a cross-sectional study mainly focusing on the northern, southern and central parts of Bangladesh to understand the level of knowledge, attitudes, and practices of people regarding MBDs, mosquito habitats, or control measures. A total of 1720 participants were involved in the study from 33 out of 64 districts of Bangladesh, of which 56.9% were male. While most of them knew about dengue (97.1%), chikungunya (81.4%), and malaria (85.2%), only half of them were aware of filaria (53.3%), which is endemic to the northern region. A knowledge score (0−8, low), (9−16, moderate), (17−24, high), and attitude score (0−4, poor), (5−8, moderate), and (9−13, high) were assigned. While poor and moderate attitudes were considered negative, good attitudes were considered positive. About 45% of the respondents had a moderate knowledge score (50−70); however, about 67.9% of participants showed a good attitude score (>70) towards the control of MBDs. It was found that the knowledge and attitude of the responders were related to their profession (knowledge p < 0.001; attitude, p = 0.002), residential area (knowledge p < 0.001; attitude, p < 0.001), and education level (knowledge p < 0.001; attitude p = 0.004). A mosquito is a kind of nuisance bug, and about 79.8% of responders admitted that they kill mosquitoes as soon as they notice them. They also use bed nets (93.7%) followed by mosquito coils (85.7%) as a preventive method. Interestingly, 73.2% of the responders were reluctant to contact the local government during an increase in mosquito numbers. Overall, the people of Bangladesh have a positive attitude towards the prevention of mosquito-borne diseases. It is highly recommended that the government creates more knowledge regarding this issue and develops collaborative approaches with local people to implement robust preventive measures against mosquito-borne diseases.

Cost-effectiveness of a Dengue Vector Control Intervention in Colombia

Dengue is a public health problem in Colombia and in the municipality of Girardot, an area of high risk for dengue transmission. We present the results of an economic evaluation from the societal perspective and 1-year time horizon comparing the regular control program for dengue prevention versus an intervention that comprised an environmental management strategy by covering the most Aedes aegypti productive breeding sites with insecticide covers, community actions, and educational activities. The effectiveness of the intervention was measured as the reduction in probability of dengue infection obtained from a community trial. Resource use was estimated from clinical records that were validated by clinical experts; unit costs were taken from national tariffs. Patient costs were obtained from a household survey. We found that the intervention generated an additional cost of USD20.9 per household and an incremental effectiveness of 0.00173 (reduction in the probability of reported dengue cases). Overall, both alternatives generate similar effectiveness, but the new intervention was associated with increasing costs. We conclude the new intervention is a potentially cost-effective option in areas where high prevalence of dengue exists.

ATP-sensitive inward rectifier potassium channels reveal functional linkage between salivary gland function and blood feeding in the mosquito, Aedes aegypti

Reducing saliva secretions into the vertebrate host reduces feeding efficacy by most hematophagous arthropods. However, seminal studies suggested saliva is not a prerequisite for blood feeding in Aedes aegypti. To test this paradigm, we manually transected the salivary duct of female A. aegypti and an inability to salivate was correlated to an inability to imbibe blood. These data justified testing the relevance of inwardly rectifying potassium (Kir) channels in the A. aegypti salivary gland as an antifeedant target site. Pharmacological activation of ATP-gated Kir (K_ATP) channels reduced the secretory activity of the salivary gland by 15-fold that led to near elimination of blood ingestion during feeding. The reduced salivation and feeding success nearly eliminated horizontal transmission and acquisition of Dengue virus-2 (DENV2). These data suggest mosquito salivation is a prerequisite for blood feeding and provide evidence that K_ATP channels are critical for salivation, feeding, and vector competency.

The salivary gland of Aedes aegypti is needed for efficient blood feeding, and disruption of ATP-gated Kir channels prevents salivation and blood feeding in A. aegypti as well as horizontal transmission and acquisition of Dengue virus2.

Managing biological invasions: the cost of inaction

Ecological and socioeconomic impacts from biological invasions are rapidly escalating worldwide. While effective management underpins impact mitigation, such actions are often delayed, insufficient or entirely absent. Presently, management delays emanate from a lack of monetary rationale to invest at early invasion stages, which precludes effective prevention and eradication. Here, we provide such rationale by developing a conceptual model to quantify the cost of inaction, i.e., the additional expenditure due to delayed management, under varying time delays and management efficiencies. Further, we apply the model to management and damage cost data from a relatively data-rich genus (Aedes mosquitoes). Our model demonstrates that rapid management interventions following invasion drastically minimise costs. We also identify key points in time that differentiate among scenarios of timely, delayed and severely delayed management intervention. Any management action during the severely delayed phase results in substantial losses $$( > 50\%$$ ( > 50 % of the potential maximum loss). For Aedes spp., we estimate that the existing management delay of 55 years led to an additional total cost of approximately $ 4.57 billion (14% of the maximum cost), compared to a scenario with management action only seven years prior (< 1% of the maximum cost). Moreover, we estimate that in the absence of management action, long-term losses would have accumulated to US$ 32.31 billion, or more than seven times the observed inaction cost. These results highlight the need for more timely management of invasive alien species—either pre-invasion, or as soon as possible after detection—by demonstrating how early investments rapidly reduce long-term economic impacts.

Traditional Knowledge to Contemporary Medication in the Treatment of Infectious Disease Dengue: A Review

Dengue has become a worldwide affliction despite incessant efforts to search for a cure for this long-lived disease. Optimistic consequences for dengue vaccine are implausible as the efficiency is tied to previous dengue virus (DENV) exposure and a very high cost is required for large-scale production of vaccine. Medicinal plants are idyllic substitutes to fight DENV infection since they constitute important components of traditional medicine and show antiviral properties, although the mechanism behind the action of bioactive compounds to obstruct viral replication is less explored and yet to be discovered. This review includes the existing traditional knowledge on how DENV infects and multiplies in the host cells, conscripting different medicinal plants that obtained bioactive compounds with anti-dengue properties, and the probable mechanism on how bioactive compounds modulate the host immune system during DENV infection. Moreover, different plant species having such bioactive compounds reported for anti-DENV efficiency should be validated scientifically via different in vitro and in vivo studies.

Solving Patient Allocation Problem during an Epidemic Dengue Fever Outbreak by Mathematical Modelling

Dengue fever is a mosquito-borne disease that has rapidly spread throughout the last few decades. Most preventive mechanisms to deal with the disease focus on the eradication of the vector mosquito and vaccination campaigns. However, appropriate mechanisms of response are indispensable to face the consequent events when an outbreak takes place. This study applied single and multiple objective linear programming models to optimize the allocation of patients and additional resources during an epidemic dengue fever outbreak, minimizing the summation of the distance travelled by all patients. An empirical study was set in Ciudad del Este, Paraguay. Data provided by a privately run health insurance cooperative was used to verify the applicability of the models in this study. The results can be used by analysts and decision makers to solve patient allocation problems for providing essential medical care during an epidemic dengue fever outbreak.

Influence of climate variables on dengue fever occurrence in the southern region of Thailand

The 3-5year epidemic cycle of dengue fever in Thailand makes it a major re-emerging public health problem resulting in being a burden in endemic areas. Although the Thai Ministry of Public Health adopted the WHO dengue control strategy, all dengue virus serotypes continue to circulate. Health officers and village health volunteers implement some intervention options but there is a need to ascertain most appropriate (or a combination of) interventions regarding the environment and contextual factors that may undermine the effectiveness of such interventions. This study aims to understand the dengue-climate relationship patterns at the district level in the southern region of Thailand from 2002 to 2018 by examining the statistical association between dengue incidence rate and eight environmental patterns, testing the hypothesis of equal incidence of these. Data on environmental variables and dengue reported cases in Nakhon Si Thammarat province situated in the south of Thailand from 2002 to 2018 were analysed to (1) detect the environmental factors that affect the risk of dengue infectious disease; to (2) determine if disease risk is increasing or decreasing over time; and to (3) identify the high-risk district areas for dengue cases that need to be targeted for interventions. To identify the predictors that have a high and significant impact on reported dengue infection, three steps of analysis were used. First, we used Partial Least Squares (PLS) Regression and Poisson Regression, a variant of the Generalized Linear Model (GLM). Negative co-efficient in correspondence with the PLS components suggests that sea-level pressure, wind speed, and pan evaporation are associated with dengue occurrence rate, while other variables were positively associated. Using the Akaike information criterion in the stepwise GLM, the filtered predictors were temperature, precipitation, cloudiness, and sea level pressure with the standardized coefficients showing that the most influential variable is cloud cover (three times more than temperature and precipitation). Also, dengue occurrence showed a constant negative response to the average increase in sea-level pressure values. In southern Thailand, the predictors that have been locally determined to drive dengue occurrence are temperature, rainfall, cloud cover, and sea-level pressure. These explanatory variables should have important future implications for epidemiological studies of mosquito-borne diseases, particularly at the district level. Predictive indicators guide effective and dynamic risk assessments, targeting pre-emptive interventions.

Monomeric IgA Antagonizes IgG-Mediated Enhancement of DENV Infection

Dengue virus (DENV) is a prevalent human pathogen, infecting approximately 400 million individuals per year and causing symptomatic disease in approximately 100 million. A distinct feature of dengue is the increased risk for severe disease in some individuals with preexisting DENV-specific immunity. One proposed mechanism for this phenomenon is antibody-dependent enhancement (ADE), in which poorly-neutralizing IgG antibodies from a prior infection opsonize DENV to increase infection of F_c gamma receptor-bearing cells. While IgM and IgG are the most commonly studied DENV-reactive antibody isotypes, our group and others have described the induction of DENV-specific serum IgA responses during dengue. We hypothesized that monomeric IgA would be able to neutralize DENV without the possibility of ADE. To test this, we synthesized IgG and IgA versions of two different DENV-reactive monoclonal antibodies. We demonstrate that isotype-switching does not affect the antigen binding and neutralization properties of the two mAbs. We show that DENV-reactive IgG, but not IgA, mediates ADE in F_c gamma receptor-positive K562 cells. Furthermore, we show that IgA potently antagonizes the ADE activity of IgG. These results suggest that levels of DENV-reactive IgA induced by DENV infection might regulate the overall IgG mediated ADE activity of DENV-immune plasma in vivo, and may serve as a predictor of disease risk.

Novel inhibitors of the renal inward rectifier potassium channel of the mosquito vector Aedes aegypti

The mosquito continues to be the most lethal animal to humans due to the devastating diseases that it carries and transmits. Controlling mosquito-borne diseases relies heavily on vector management using neurotoxic insecticides with limited modes of action. This has led to the emergence of resistance to pyrethroids and other neurotoxic insecticides in mosquitoes, which has reduced the efficacy of chemical control agents. Moreover, many neurotoxic insecticides are not selective for mosquitoes and negatively impact beneficial insects such as honeybees. Developing new mosquitocides with novel mechanisms of action is a clear unmet medical need; this review covers the efforts made toward this end by targeting the renal inward rectifier potassium channel (Kir) of the mosquito.

Economic costs of biological invasions within North America

Invasive species can have severe impacts on ecosystems, economies, and human health. Though the economic impacts of invasions provide important foundations for management and policy, up-to-date syntheses of these impacts are lacking. To produce the most comprehensive estimate of invasive species costs within North America (including the Greater Antilles) to date, we synthesized economic impact data from the recently published InvaCost database. Here, we report that invasions have cost the North American economy at least US$ 1.26 trillion between 1960 and 2017. Economic costs have climbed over recent decades, averaging US$ 2 billion per year in the early 1960s to over US$ 26 billion per year in the 2010s. Of the countries within North America, the United States (US) had the highest recorded costs, even after controlling for research effort within each country ($5.81 billion per cost source in the US). Of the taxa and habitats that could be classified in our database, invasive vertebrates were associated with the greatest costs, with terrestrial habitats incurring the highest monetary impacts. In particular, invasive species cumulatively (from 1960–2017) cost the agriculture and forestry sectors US$ 527.07 billion and US$ 34.93 billion, respectively. Reporting issues (e.g., data quality or taxonomic granularity) prevented us from synthesizing data from all available studies. Furthermore, very few of the known invasive species in North America had reported economic costs. Therefore, while the costs to the North American economy are massive, our US$ 1.26 trillion estimate is likely very conservative. Accordingly, expanded and more rigorous economic cost reports are necessary to provide more comprehensive invasion impact estimates, and then support data-based management decisions and actions towards species invasions.

Biological invasions in France: Alarming costs and even more alarming knowledge gaps

The ever-increasing number of introduced species profoundly threatens global biodiversity. While the ecological and evolutionary consequences of invasive alien species are receiving increasing attention, their economic impacts have largely remained understudied, especially in France. Here, we aimed at providing a general overview of the monetary losses (damages caused by) and expenditures (management of) associated with invasive alien species in France. This country has a long history of alien species presence, partly due to its long-standing global trade activities, highly developed tourism, and presence of overseas territories in different regions of the globe, resulting in a conservative minimum of 2,750 introduced and invasive alien species. By synthesizing for the first time the monetary losses and expenditures incurred by invasive alien species in Metropolitan France and French overseas territories, we obtained 1,583 cost records for 98 invasive alien species. We found that they caused a conservative total amount ranging between US$ 1,280 million and 11,535 million in costs over the period 1993–2018. We extrapolated costs for species invading France, for which costs were reported in other countries but not in France, which yielded an additional cost ranging from US$ 151 to 3,030 millions. Damage costs were nearly eight times higher than management expenditure. Insects, and in particular the Asian tiger mosquito Aedes albopictus and the yellow fever mosquito Ae. aegypti, totalled very high economic costs, followed by non-graminoid terrestrial flowering and aquatic plants (Ambrosia artemisiifolia, Ludwigia sp. and Lagarosiphon major). Over 90% of alien species currently recorded in France had no costs reported in the literature, resulting in high biases in taxonomic, regional and activity sector coverages. To conclude, we report alarming costs and even more alarming knowledge gaps. Our results should raise awareness of the importance of biosecurity and biosurveillance in France, and beyond, as well as the crucial need for better reporting and documentation of cost data.

The economic costs of biological invasions in Brazil: a first assessment

Biological invasions are one of the leading causes of global environmental change and their impacts can affect biodiversity, ecosystem services, human health and the economy. Yet, the understanding on the impacts of invasive alien species is still limited and mostly related to alien species outbreaks and losses in agricultural yield, followed by the understanding of the ecological impacts on natural systems. Notably, the economic impacts of biological invasions have rarely been quantified. Brazil has at least 1214 known alien species from which 460 are recognized as invasive alien species. Still, there are no comprehensive estimates of the cost of their impact and management. Here, we aimed at filling this gap by providing a comprehensive estimate of the economic cost of biological invasions in Brazil. In order to quantify these costs for species, ecosystems and human well-being we used the InvaCost database which is the first global compilation of the economic costs of biological invasions. We found that Brazil reportedly spent a minimum of USD 105.53 billions over 35 years (1984–2019), with an average spent of USD 3.02 (± 9.8) billions per year. Furthermore, USD 104.33 billion were due to damages and losses caused by invaders, whereas only USD 1.19 billion were invested in their management (prevention, control or eradication). We also found that recorded costs were unevenly distributed across ecosystems, and socio-economic sectors, and were rarely evaluated and published. We found that the economic costs with losses and damages were substantially greater than those used for prevention, control or eradication of IAS. Since our data show costs reported in Brazil for only 16 invasive alien species, our estimates are likely a conservative minimum of the actual economic costs of biological invasions in Brazil. Taken together, they indicate that invasive alien species are an important cause of economic losses and that Brazil has mostly opted for paying for the damage incurred by biological invasions rather than investing in preventing them from happening.

Economic costs of biological invasions in Ecuador: the importance of the Galapagos Islands

Biological invasions, as a result of human intervention through trade and mobility, are the second biggest cause of biodiversity loss. The impacts of invasive alien species (IAS) on the environment are well known, however, economic impacts are poorly estimated, especially in mega-diverse countries where both economic and ecological consequences of these effects can be catastrophic. Ecuador, one of the smallest mega-diverse countries, lacks a comprehensive description of the economic costs of IAS within its territory. Here, using "InvaCost", a public database that compiles all recorded monetary costs associated with IAS from English and Non-English sources, we investigated the economic costs of biological invasions. We found that between 1983 and 2017, the reported costs associated with biological invasions ranged between US$86.17 million (when considering only the most robust data) and US$626 million (when including all cost data) belonging to 37 species and 27 genera. Furthermore, 99% of the recorded cost entries were from the Galapagos Islands. From only robust data, the costliest identified taxonomic group was feral goats (Capra hircus; US$20 million), followed by Aedes mosquitoes (US$2.14 million) while organisms like plant species from the genus Rubus, a parasitic fly (Philornis downsi), black rats (Rattus rattus) and terrestrial gastropods (Achatina fulica) represented less than US$2 million each. Costs of "mixed-taxa" (i.e. plants and animals) represented the highest (61% of total robust costs; US$52.44 million). The most impacted activity sector was the national park authorities, which spent about US$84 million. Results from robust data also revealed that management expenditures were the major type of costs recorded in the Galapagos Islands; however, costs reported for medical losses related to Aedes mosquitoes causing dengue fever in mainland Ecuador would have ranked first if more detailed information had allowed us to categorize them as robust data. Over 70% of the IAS reported for Ecuador did not have reported costs. These results suggest that costs reported here are a massive underestimate of the actual economic toll of invasions in the country.

Analysis of Neutralizing Antibodies as a Correlate of Instantaneous Risk of Hospitalized Dengue in Placebo Recipients of Dengue Vaccine Efficacy Trials

BACKGROUND

In the CYD14 (NCT01373281) and CYD15 (NCT01374516) dengue vaccine efficacy trials, Month 13 neutralizing antibody (nAb) titers correlated inversely with risk of symptomatic, virologically confirmed dengue (VCD) between Month 13 (one month post-final-dose) and Month 25. We assessed nAb titer as a correlate of instantaneous risk of hospitalized VCD (HVCD), for which participants were continually surveilled for 72 months.

METHODS

Using longitudinal nAb titers from the per-protocol immunogenicity subsets, we estimated hazard ratios (HRs) of HVCD by current nAb titer value for three correlate/endpoint pairs: average titer across all four serotypes/HVCD of any serotype (HVCD-Any), serotype-specific titer/homologous HVCD, and serotype-specific titer/heterologous HVCD.

RESULTS

Baseline-seropositive placebo recipients with higher average titer had lower instantaneous risk of HVCD-Any in 2-16-year-olds and in 9-16-year-olds (HR 0.26 or 0.15 per 10-fold increase in average titer by two methods, 95% CIs 0.14 to 0.45 and 0.07 to 0.34, respectively) pooled across both trials. Results were similar for homologous HVCD. There was evidence suggesting increased HVCD-Any risk in participants with low average titer (1:10 to 1:100) compared to seronegative participants (HR 1.85, 95% CI 0.93 to 3.68).

CONCLUSIONS

Natural infection-induced nAbs were inversely associated with hospitalized dengue, upon exceeding a relatively low threshold.

Persistence of symptoms in dengue patients: a clinical cohort study

BACKGROUND

Dengue is commonly considered an acute illness and follows three phases: febrile, critical in some cases and recovery. However, a number of studies have described a continuation of dengue symptoms for weeks or months, extending the recovery phase. Here we evaluate this persistence of dengue symptoms during convalescence.

METHODS

Our clinical cohort study included patients who sought medical services 48 to 144 h from the onset of fever at seven hospitals or ambulatory centers in Morelos, Mexico. Seventy-nine laboratory-confirmed dengue patients were followed up regularly using clinic and/or home visits and telephone calls for as long as symptoms persisted or up to 6 mo.

RESULTS

In total, 55.7% of patients had dengue-related symptoms 1 mo after the onset of fever; pain and dermatological manifestations were the most common persistent symptoms. Prognostic factors for symptom persistence were: ≥4 d of fever (RR 1.72; 95% CI 1.35 to 2.19), platelet count ≤100 000/mm3 (RR 1.20; 95% CI 1.20 to 2.20), petechiae/bruises (RR 1.97; 95% CI 1.56 to 2.48) and abdominal pain/hepatomegaly (RR 1.79; 95% CI 1.41 to 2.28).

CONCLUSIONS

Persistence of dengue symptoms were common in laboratory-confirmed dengue patients. Manifestations related to tissue damage were associated with persistence after 30 d; host characteristics, such as age and health status before infection, were associated with prolonged persistence (>60 d). The burden of dengue may be higher than previously estimated.

Temperature, traveling, slums, and housing drive dengue transmission in a non-endemic metropolis

Dengue is steadily increasing worldwide and expanding into higher latitudes. Current non-endemic areas are prone to become endemic soon. To improve understanding of dengue transmission in these settings, we assessed the spatiotemporal dynamics of the hitherto largest outbreak in the non-endemic metropolis of Buenos Aires, Argentina, based on detailed information on the 5,104 georeferenced cases registered during summer-autumn of 2016. The highly seasonal dengue transmission in Buenos Aires was modulated by temperature and triggered by imported cases coming from regions with ongoing outbreaks. However, local transmission was made possible and consolidated heterogeneously in the city due to housing and socioeconomic characteristics of the population, with 32.8% of autochthonous cases occurring in slums, which held only 6.4% of the city population. A hierarchical spatiotemporal model accounting for imperfect detection of cases showed that, outside slums, less-affluent neighborhoods of houses (vs. apartments) favored transmission. Global and local spatiotemporal point-pattern analyses demonstrated that most transmission occurred at or close to home. Additionally, based on these results, a point-pattern analysis was assessed for early identification of transmission foci during the outbreak while accounting for population spatial distribution. Altogether, our results reveal how social, physical, and biological processes shape dengue transmission in Buenos Aires and, likely, other non-endemic cities, and suggest multiple opportunities for control interventions.

Dengue fever is mainly transmitted by a mosquito species that is highly urbanized, and lays eggs and develops mostly in artificial water containers. Dengue transmission is sustained year-round in most tropical regions of the world, but in many subtropical/temperate regions it occurs only in the warmest months. To improve understanding of dengue transmission in these regions, we analyzed one of the largest outbreaks in Buenos Aires city, a subtropical metropolis. Based on information on 5,104 georeferenced cases during summer-autumn 2016, we found that most transmission occurred in or near home, that slums had the highest risk of transmission, and that, outside slums, less-affluent neighborhoods of houses (vs. apartments) favored transmission. We showed that the cumulative effects of temperature over the previous few weeks set the temporal limits for transmission to occur, and that the outbreak was sparked by infected people arriving from regions with ongoing outbreaks. Additionally, we implemented a statistical method to identify transmission foci in real-time that improves targeting control interventions. Our results deepen the understanding of dengue transmission as a result of social, physical, and biological processes, and pose multiple opportunities for improving control of dengue and other mosquito-borne viruses such as Zika, chikungunya, and yellow fever.

Exploring the utility of social-ecological and entomological risk factors for dengue infection as surveillance indicators in the dengue hyper-endemic city of Machala, Ecuador

The management of mosquito-borne diseases is a challenge in southern coastal Ecuador, where dengue is hyper-endemic and co-circulates with other arboviral diseases. Prior work in the region has explored social-ecological factors, dengue case data, and entomological indices. In this study, we bring together entomological and epidemiological data to describe links between social-ecological factors associated with risk of dengue transmission at the household level in Machala, Ecuador. Households surveys were conducted from 2014-2017 to assess the presence of adult Aedes aegypti (collected via aspiration) and to enumerate housing conditions, demographics, and mosquito prevention behaviors. Household-level dengue infection status was determined by laboratory diagnostics in 2014-2015. Bivariate analyses and multivariate logistic regression models were used to identify social-ecological variables associated with household presence of female Ae. aegypti and household dengue infection status, respectively. Aedes aegypti presence was associated with interruptions in water service and weekly trash collection, and household air conditioning was protective against mosquito presence. Presence of female Ae. aegypti was not associated with household dengue infections. We identified shaded patios and head of household employment status as risk factors for household-level dengue infection, while window screening in good condition was identified as protective against dengue infection. These findings add to our understanding of the systems of mosquito-borne disease transmission in Machala, and in the larger region of southern Ecuador, aiding in the development of improved vector surveillance efforts, and targeted interventions.

Temporally integrated single cell RNA sequencing analysis of PBMC from experimental and natural primary human DENV-1 infections

Dengue human infection studies present an opportunity to address many longstanding questions in the field of flavivirus biology. However, limited data are available on how the immunological and transcriptional response elicited by an attenuated challenge virus compares to that associated with a wild-type DENV infection. To determine the kinetic transcriptional signature associated with experimental primary DENV-1 infection and to assess how closely this profile correlates with the transcriptional signature accompanying natural primary DENV-1 infection, we utilized scRNAseq to analyze PBMC from individuals enrolled in a DENV-1 human challenge study and from individuals experiencing a natural primary DENV-1 infection. While both experimental and natural primary DENV-1 infection resulted in overlapping patterns of inflammatory gene upregulation, natural primary DENV-1 infection was accompanied with a more pronounced suppression in gene products associated with protein translation and mitochondrial function, principally in monocytes. This suggests that the immune response elicited by experimental and natural primary DENV infection are similar, but that natural primary DENV-1 infection has a more pronounced impact on basic cellular processes to induce a multi-layered anti-viral state.

Dengue Human Challenge Models allow for the analysis of host/virus interactions under highly controlled experimental conditions. However, it is unclear how close the immune response generated by an attenuated challenge virus compares to that generated by a naturally acquired DENV infection. In this study, we utilized single cell RNA sequencing to assess the immune response generated by both experimental and natural primary DENV-1 infections. This analysis suggests that the immune response elicited by experiential and natural primary DENV-1 infections are similar, but that natural DENV-1 infection has a more pronounced impact on basic cellular processes to induce a multi-layered anti-viral state.

Economic impact of dengue in Singapore from 2010 to 2020 and the cost-effectiveness of Wolbachia interventions

The release of Wolbachia-infected mosquitoes is a promising disease intervention strategy that aims to control dengue and other arboviral infections. While early field trials and modelling studies suggest promising epidemiological and entomological outcomes, the overall cost effectiveness of the technology is not well studied in a resource rich setting nor under the suppression approach that aims to suppress the wild-type mosquito population through the release of Wolbachia-infected males. We used economical and epidemiological data from 2010 to 2020 to first ascertain the economic and health costs of dengue in Singapore, a high income nation where dengue is hyper-endemic. The hypothetical cost effectiveness of a national Wolbachia suppression program was then evaluated historically from 2010 to 2020. We estimated that the average economic impact of dengue in Singapore from 2010 to 2020 in constant 2010US$ ranged from $1.014 to $2.265 Billion. Using empirically derived disability weights, we estimated a disease burden of 7,645-21,262 DALYs from 2010-2020. Under an assumed steady-state running cost of a national Wolbachia suppression program in Singapore, we conservatively estimate that Wolbachia would cost an estimated $50,453-$100,907 per DALYs averted and would lead to an estimated $329.40 Million saved in economic costs over 2010 to 2020 under 40% intervention efficacy. Wolbachia releases in Singapore are expected to be highly cost-effective and its rollout must be prioritised to reduce the onward spread of dengue.

Modeling the competitive diffusions of rumor and knowledge and the impacts on epidemic spreading

The interaction between epidemic spreading and information diffusion is an interdisciplinary research problem. During an epidemic, people tend to take self-protective measures to reduce the infection risk. However, with the diffusion of rumor, people may be difficult to make an appropriate choice. How to reduce the negative impact of rumor and to control epidemic has become a critical issue in the social network. Elaborate mathematical model is instructive to understand such complex dynamics. In this paper, we develop a two-layer network to model the interaction between the spread of epidemic and the competitive diffusions of information. The results show that knowledge diffusion can eradicate both rumor and epidemic, where the penetration intensity of knowledge into rumor plays a vital role. Specifically, the penetration intensity of knowledge significantly increases the thresholds for rumor and epidemic to break out, even when the self-protective measure is not perfectly effective. But eradicating rumor shouldn't be equated with eradicating epidemic. The epidemic can be eradicated with rumor still diffusing, and the epidemic may keep spreading with rumor being eradicated. Moreover, the communication-layer network structure greatly affects the spread of epidemic in the contact-layer network. When people have more connections in the communication-layer network, the knowledge is more likely to diffuse widely, and the rumor and epidemic can be eradicated more efficiently. When the communication-layer network is sparse, a larger penetration intensity of knowledge into rumor is required to promote the diffusion of knowledge.

Alzahrani M, Azhar EI, Amir A, Aljiffri AM, Althaqafi AO. The economic burden of dengue fever in the Kingdom of Saudi Arabia

Rapid urbanization, global trade, and the exceptionally great numbers of worldwide visitors during Hajj and Umrah have all placed the Kingdom of Saudi Arabia at a significant risk of introducing several vector-borne tropical diseases, such as dengue fever virus (DENV) infection. In this study we estimated DENV infection cost of illness (COI) in Saudi Arabia in the period 2013–2017, by processing national data including all declared cases recorded in referral centers in the western region, being the endemic region of the country. Using a statistically validated predictive model that was built on a representative sample of 717 laboratory-confirmed cases of DENV infection, direct costs, due to care-related expenditures, were estimated by applying the predictive equation to national data. However, indirect costs, which are due to productivity loss, were estimated using the human capital model based on gross domestic product adjusted for invalidity duration. Further, under-reporting was adjusted by using an expansion factor EF = 3. We observed highest estimated costs in 2016 with over US$168.5 Million total costs, including direct (US$29.0 Million) and indirect (US$139.5 Million) costs, for a total 4415 confirmed cases. The total DENV COI for the five years was estimated as US$551.0 Million for a total 15,369 patients (59.7%) out of 25,745 declared cases, resulting in an average cost of US$11 947.6 by patient. Depending on the year, productivity years loss costs accounted for 63.3% to 83.8% of the estimated total costs. Dengue has a substantial local economic burden that costs US$110.2 Million per year, stressing the urgent need for an effective national prevention strategy to perform considerable cost-savings besides reducing morbidity.

The global incidence of DENV infection has evidenced a dramatic increase in the recent two decades with a great number of cases that are misclassified or underreported. These epidemiological characteristics generate high economic costs, especially in endemic regions and countries such as Saudi Arabia. This two-phase study aimed at providing economic data that helps political efficiency and resource prioritization for dengue prevention programs, by assessing the economic burden of disease over the last five years 2013–2017. A double-method used to estimate direct costs due to care expenses and indirect costs due to productivity loss, by using a predictive and an economic model, respectively. Assuming an expansion factor of 3 to correct under-reporting, the average estimated costs of dengue illness per year in the current study was US$117.87 million. Comparison of these findings with international reports emphasized the substantial disease burden of dengue fever in Saudi Arabia. Despite some limitations, this study provided the first economic data of dengue fever infection burden in Saudi Arabia.

Serosurvey for dengue virus infection among pregnant women in the West Nile virus enzootic community of El Paso Texas

All 4 dengue viruses (DENV) cause sporadic outbreaks of human disease in the Rio Grande Valley along the US-Mexico border. In addition, West Nile virus (WNV) is enzootic in most border communities, and is the only arbovirus known to cause human disease in the El Paso, Texas community. In an effort to determine if DENV were also endemic in the El Paso community, a serosurvey was conducted among mothers at the time of delivery of their babies in selected hospitals. Cord-blood plasma samples obtained from mothers were tested for DENV antibody by an enzyme-linked immuno-sorbent assay (ELISA), plaque reduction neutralization test (PRNT) and a multiplex microsphere immunoassay. All DENV antibody positive plasma samples were also tested for WNV antibody by the same assays to consider the possibility that DENV antibody positive samples reflected WNV cross reactive antibody. The results indicated that 0.74% (11/1,472) of the mothers had a previous DENV infection and that 3.3% (48/1,472) had a previous WNV infection. Of these mothers, 0.20% (3/1,472) had antibody to both DENV and WNV as evidence of infection by both viruses. The results indicated that 0.2% (3/1472) of the mothers were positive for antibody to only WNV envelope, thus suggesting an undetermined flavivirus infection. Although 6 of the 11 DENV antibody positive mothers did not have a history of travel to a DENV endemic country, the findings of this survey provided further evidence of local transmission of WNV and suggested the possibility of focal autochthonous transmission of DENV in the El Paso community.

Burden of disease due to microcephaly associated with the Zika virus in Colombia

In 2015, the Zika virus was introduced in Colombia. The emergence of this arbovirus is a public health challenge for the country, considering the association between the infection and congenital disorders such as microcephaly. Thus, we estimated the burden of disease due to microcephaly associated with Zika in Colombia and its administrative subdivisions for the period 2015-2016. We conducted an exploratory ecological study, using as unit of measurement disability-adjusted life years (DALYs). The cases of microcephaly were obtained from the Zika national and departmental databases built by the National Public Health Surveillance System (SIVIGILA). Deaths attributed to microcephaly were estimated from previous studies. Finally, we calculated mortality rates and incidences, then we performed a sensitivity analysis under three scenarios (conservative, medium, and extreme) to estimate the DALYs. In the 2015-2016 period, 10,609.4 DALYs were caused by microcephaly associated with Zika in Colombia. 71% of the total DALYs were years of life lost and 29% were years lived with disability. Five out of 32 departments (Meta, Córdoba, Tolima, Valle del Cauca, and Norte de Santander) contributed 71% of total DALYs. The burden of microcephaly associated with Zika outweighed the burden of other congenital anomalies such as neural tube defects and Down syndrome in children aged between 0 and 4 years in Colombia. Public health efforts must be made to prevent and monitor these cases.

Further SAR on the (Phenylsulfonyl)piperazine Scaffold as Inhibitors of the Aedes aegypti Kir1 (AeKir) Channel and Larvicides

Zika virus (ZIKV), dengue fever (DENV) and chikungunya (CHIKV) are arboviruses that are spread to humans from the bite of an infected adult female Aedes aegypti mosquito. As there are no effective vaccines or therapeutics for these diseases, the primary strategy for controlling the spread of these viruses is to prevent the mosquito from biting humans through the use of insecticides. Unfortunately, the commonly used classes of insecticides have seen a significant increase in resistance, thus complicating control efforts. Inhibiting the renal inward rectifier potassium (Kir) channel of the mosquito vector Aedes aegypti has been shown to be a promising target for the development of novel mosquitocides. We have shown that Kir1 channels play key roles in mosquito diuresis, hemolymph potassium homeostasis, flight, and reproduction. Previous work from our laboratories identified a novel (phenylsulfonyl)piperazine scaffold as potent AeKir channel inhibitors with activity against both adult and larval mosquitoes. Herein, we report further SAR work around this scaffold and have identified additional compounds with improved in vitro potency and mosquito larvae toxicity.

The economic impact and cost-effectiveness of combined vector-control and dengue vaccination strategies in Thailand: results from a dynamic transmission model

BACKGROUND AND AIMS

Dengue fever is a major public health problem in tropical/subtropical regions. Prior economic analyses have predominantly evaluated either vaccination or vector-control programmes in isolation and do not really consider the incremental benefits and cost-effectiveness of mixed strategies and combination control. We estimated the cost-effectiveness of single and combined approaches in Thailand.

METHODS

The impacts of different control interventions were analysed using a previously published mathematical model of dengue epidemiology and control incorporating seasonality, age structure, consecutive infection, cross protection, immune enhancement and combined vector-host transmission. An economic model was applied to simulation results to estimate the cost-effectiveness of 4 interventions and their various combinations (6 strategies): i) routine vaccination of 1-year olds; ii) chemical vector control strategies targeting adult and larval stages separately; iii) environmental management/ public health education and awareness [EM/ PHEA]). Payer and societal perspectives were considered. The health burden of dengue fever was assessed using disability-adjusted life-years (DALYs) lost. Costs and effects were assessed for 10 years. Costs were discounted at 3% annually and updated to 2013 United States Dollars. Incremental cost-effectiveness analysis was carried out after strategies were rank-ordered by cost, with results presented in a table of incremental analysis. Sensitivity and scenario analyses were undertaken; and the impact and cost-effectiveness of Wolbachia was evaluated in exploratory scenario analyses.

RESULTS

From the payer and societal perspectives, 2 combination strategies were considered optimal, as all other control strategies were dominated. Vaccination plus adulticide plus EM/ PHEA was deemed cost-effective according to multiple cost-effectiveness criteria. From the societal perspective, incremental differences vs. adulticide and EM/ PHEA resulted in costs of $157.6 million and DALYs lost of 12,599, giving an expected ICER of $12,508 per DALY averted. Exploratory scenario analyses showed Wolbachia to be highly cost-effective ($343 per DALY averted) vs. other single control measures.

CONCLUSIONS

Our model shows that individual interventions can be cost-effective, but that important epidemiological reductions and economic impacts are demonstrated when interventions are combined as part of an integrated approach to combating dengue fever. Exploratory scenario analyses demonstrated the potential epidemiological and cost-effective impact of Wolbachia when deployed at scale on a nationwide basis. Our findings were robust in the face of sensitivity analyses.

Epidemiological Impact and Hospitalization costs applied to dengue in the Midwest region of Minas Gerais state, Brazil, from SUS perspective

BACKGROUND & OBJECTIVES

Dengue is considered one of the greatest public health challenges in the world, especially, for tropical and subtropical countries. Brazil highlights with considerable number of registers associated with this arbovirus, with emphasis on the state of Minas Gerais and its municipalities in regions such as the midwest. We aimed to evaluate the economic and epidemiological impact of dengue in the midwest region of minas Gerais, from SUS perspective.

METHODS

Our study evaluated the epidemiological impact of dengue fever in the midwest region of Minas Gerais using data applied to Divinópolis city from SUS perspective between 2000 to 2015 considering SIH/SUS database (hospitalization registers) and 2007 to 2017 using the SINAN database (notification cases). We analyzed the number of notification registers and hospital services, as well as their costs, from a SUS perspective associated with this infection.

RESULTS

There were 26,516 notifications associated with dengue, with 21,953 cases being confirmed by SEMUSA, with a median incidence of 211 cases/100,000 inhabitants of dengue notifications between 2007 and 2017. The southeast and southwest regions in the municipality are highlighted with high number of cases. Additionally, 160 hospitalizations were recorded with 33.79% in individuals between 15 and 34 years old and expenses of USD 53,737.21 for SUS between 2000 and 2015.

INTERPRETATION & CONCLUSION

Divinópolis is the reference (social and economic) municipality of the midwest region in Minas Gerais state. Our study is the first conducted involving a long period of follow up applied to dengue context in this locality, especially, including the costs associated with hospitalization services. We hope to contribute to the discussions regarding the coping strategies of the disease, considering the impact in its different regions, highlighting the need for continued efforts and initiatives aimed at combating the vector of this and other arboviruses such as Zika and chikungunya.

Factors associated with thrombocytopenia in patients with dengue fever: a retrospective cohort study

OBJECTIVE

Some patients with dengue fever tend to develop thrombocytopenia during the course of infection and are thus vulnerable to haemorrhagic manifestations and other complications. However, the factors associated with the development of thrombocytopenia are unknown. We aimed to identify factors associated with an increased risk of thrombocytopenia and haematological changes in patients with confirmed dengue fever.

DESIGN

Retrospective cohort study.

SETTING

Brazilian multicentre primary care databases.

PARTICIPANTS

387 patients had positive laboratory serological confirmation of dengue infection during 2014. The data were identified from two databases: Notification of Injury Information System (SINAN) and Municipal Laboratory.

MAIN OUTCOME MEASURE

The presence of thrombocytopenia (platelet count <1 50×10⁹/L). The associations of factors that predisposed patients to thrombocytopenia and haematological changes were analysed using logistic regression. ORs and 95% CIs were calculated.

RESULTS

Among 387 patients, 156 had both dengue and thrombocytopenia. The risk factors associated with thrombocytopenia included male sex (OR: 1.77, 95% CI: 1.16 to 2.71, p=0.007), age of 46-64 years (OR: 2.20, 95% CI: 1.15 to 4.21, p=0.009) or ≥65 years (OR: 3.02, 95% CI: 1.40 to 6.50, p=0.002), presence of leucopenia (OR: 6.85, 95% CI: 4.27 to 10.99, p<0.001) and high mean corpuscular haemoglobin (MCH) levels (OR: 2.00, 95% CI: 1.29 to 3.12, p=0.005).

CONCLUSION

Older age, male sex, presence of leucopenia and high MCH levels were identified as risk factors associated with the development of thrombocytopenia in this population.

Epidemiological characteristics of dengue in mainland China from 1990 to 2019: A descriptive analysis

In the past 30 years, dengue has undergone dramatic changes in China every year. This study explores the epidemiological trend of dengue in China during this period to identify high-risk seasons, regions, ages, susceptible populations, and provide information for dengue prevention and control activities.Dengue data from 1990 to 2019 were derived from the Public Health Science Data Center, Web of Science, China National Knowledge Infrastructure, PubMed, and Centers for Disease Control and Prevention of the corresponding province. GraphPad Prism 7 was conducted to generate disease evolution maps, occupational heat maps, and monthly heat maps of dengue cases and deaths in mainland China and Guangdong Province. Excel 2016 was used to create a cyclone map of age and gender distribution. Powerpoint 2016 was performed to create geographic maps.From 1990 to 2019, the annual number of dengue cases showed an increasing trend and reaching a peak in 2014, with 46,864 dengue cases (incidence rate: 3.4582/100,000), mainly contributed by Guangdong Province (45,189 cases, accounting for 96.43%). Dengue pandemics occurred every 4 to 6 years. The prevalence of dengue fever was Autumn, which was generally prevalent from June to December and reached its peak from September to November. The provinces reporting dengue cases each year have expanded from the southeastern coastal region to the southwest, central, northeast, and northwest regions, and the provinces with a high incidence were Guangdong, Guangxi, Yunnan, Fujian, and Zhejiang. People aged 25 to 44 years were more susceptible to dengue virus infection. And most of them were male patients. Dengue mainly occurs in the following groups: students, business service staffs, workers, farmers, retired staffs, housewives, and the unemployed. Four provinces reported deaths from dengue, namely Guangdong Province, Zhejiang Province, Henan Province, and Hunan Province.The dengue fever epidemic occurred every 4 to 6 years, mostly in autumn. The endemic areas were Guangdong, Guangxi, Yunnan, Fujian, and Zhejiang provinces. People aged 25 to 44 years, men, students, business service staffs, workers, farmers, retired staffs, housewives, and the unemployed were more susceptible to dengue fever. These findings help to develop targeted public health prevention and control measures.

Epidemiology of dengue fever in Guatemala

Dengue fever occurs worldwide and about 1% of cases progress to severe haemorrhage and shock. Dengue is endemic in Guatemala and its surveillance system could document long term trends. We analysed 17 years of country-wide dengue surveillance data in Guatemala to describe epidemiological trends from 2000 to 2016.Data from the national dengue surveillance database were analysed to describe dengue serotype frequency, seasonality, and outbreaks. We used Poisson regression models to compare the number of cases each year with subsequent years and to estimate incidence ratios within serotype adjusted by age and gender. 91,554 samples were tested. Dengue was confirmed by RT-qPCR, culture or NS1-ELISA in 7097 (7.8%) cases and was IgM ELISA-positive in 19,290 (21.1%) cases. DENV1, DENV2, DENV3, and DENV4 were detected in 2218 (39.5%), 2580 (45.9%), 591 (10.5%), and 230 (4.1%) cases. DENV1 and DENV2 were the predominant serotypes, but all serotypes caused epidemics. The largest outbreak occurred in 2010 with 1080 DENV2 cases reported. The incidence was higher among adults during epidemic years, with significant increases in 2005, 2007, and 2013 DENV1 outbreaks, the 2010 DENV2 and 2003 DENV3 outbreaks. Adults had a lower incidence immediately after epidemics, which is likely linked to increased immunity.

Dengue is the most common mosquito-borne virus, and a major cause of fever, with an estimated 390 million infections annually. Guatemala, in Central America, has had ongoing dengue transmission since the 1990s. Its national surveillance system monitors outbreaks and seasonal trends of infections to inform public health responses. We have analysed 17 years of surveillance data collected from 2000 to 2016, to describe seasonal trends, outbreak years, and the fluctuating prevalence of the four dengue serotypes. Laboratory data from 91,554 individual serum samples were included, of which 7.8% were positive for dengue. All four dengue serotypes circulate in the country, with dengue 1 and 2 being the predominant serotypes. This is important, as it increases the likelihood of dengue infections being followed by a new infection with a different serotype, which can lead to severe dengue. We also report that adults in Guatemala have a lower likelihood of infection the year after an epidemic, which might be linked to an increased immunity in the population.