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Wilder-Smith, Annelies
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Publications (10 of 111) Show all publications
Tozan, Y., Headley, T. Y., Sewe, M. O., Schwartz, E., Shemesh, T., Cramer, J. P., . . . Wilder-Smith, A. (2019). A Prospective Study on the Impact and Out-of-Pocket Costs of Dengue Illness in International Travelers. American Journal of Tropical Medicine and Hygiene, 100(6), 1525-1533
Open this publication in new window or tab >>A Prospective Study on the Impact and Out-of-Pocket Costs of Dengue Illness in International Travelers
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2019 (English)In: American Journal of Tropical Medicine and Hygiene, ISSN 0002-9637, E-ISSN 1476-1645, Vol. 100, no 6, p. 1525-1533Article in journal (Refereed) Published
Abstract [en]

Although the costs of dengue illness to patients and households have been extensively studied in endemic populations, international travelers have not been the focus of costing studies. As globalization and humantravel activities intensify, travelers are increasingly at risk for emerging and reemerging infectious diseases, such as dengue. This exploratory study aims to investigate the impact and out-of-pocket costs of dengue illness among travelers. We conducted a prospective study in adult travelers with laboratory-confirmed dengue and recruited patients at travel medicine clinics in eight different countries from December 2013 to December 2015. Using a structured questionnaire, we collected information on patients and their health-care utilization and out-of-pocket expenditures, as well as income and other financial losses they incurred because of dengue illness. A total of 90 patients participated in the study, most of whom traveled for tourism (74%) and visited countries in Asia (82%). Although 22% reported hospitalization and 32% receiving ambulatory care while traveling, these percentages were higher at 39% and 71%, respectively, after returning home. The out-of-pocket direct and indirect costs of dengue illness were US$421 (SD 744) and US$571 (SD 1,913) per episode, respectively, averaging to a total out-of-pocket cost of US$992 (SD 2,052) per episode. The study findings suggest that international travelers incur important direct and indirect costs because of dengue-related illness. This study is the first to date to investigate the impact and out-of-pocket costs of travel-related dengue illness from the patient's perspective and paves the way for future economic burden studies in this population.

Place, publisher, year, edition, pages
AMER SOC TROP MED & HYGIENE, 2019
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-162029 (URN)10.4269/ajtmh.18-0780 (DOI)000476674600034 ()30994088 (PubMedID)
Available from: 2019-08-08 Created: 2019-08-08 Last updated: 2019-08-08Bibliographically approved
Liyanage, P., Rocklöv, J., Tissera, H., Palihawadana, P., Wilder-Smith, A. & Tozan, Y. (2019). Evaluation of intensified dengue control measures with interrupted time series analysis in the Panadura Medical Officer of Health division in Sri Lanka: a case study and cost-effectiveness analysis. The Lancet Planetary Health, 3(5), e211-e218
Open this publication in new window or tab >>Evaluation of intensified dengue control measures with interrupted time series analysis in the Panadura Medical Officer of Health division in Sri Lanka: a case study and cost-effectiveness analysis
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2019 (English)In: The Lancet Planetary Health, ISSN 2542-5196, Vol. 3, no 5, p. e211-e218Article in journal (Refereed) Published
Abstract [en]

Background: Dengue has become a major public health problem in Sri Lanka with a considerable economic burden. As a response, in June, 2014, the Ministry of Health initiated a proactive vector control programme in partnership with military and police forces, known as the Civil-Military Cooperation (CIMIC) programme, that was targeted at high-risk Medical Officer of Health (MOH) divisions in the country. Evaluating the effectiveness and cost-effectiveness of population-level interventions is essential to guide public health planning and resource allocation decisions, particularly in resource-limited health-care settings.

Methods: Using an interrupted time series design with a non-linear extension, we evaluated the impact of vector control interventions from June 22, 2014, to Dec 29, 2016, in Panadura, a high-risk MOH division in Western Province, Sri Lanka. We used dengue notification and larval survey data to estimate the reduction in Breteau index and dengue incidence before and after the intervention using two separate models, adjusting for time-varying confounding variables (ie, rainfall, temperature, and the Oceanic Niño Index). We also assessed the cost and cost-effectiveness of the CIMIC programme from the perspective of the National Dengue Control Unit under the scenarios of different levels of hospitalisation of dengue cases (low [25%], medium [50%], and high [75%]) in terms of cost per disability-adjusted life-year averted (DALY).

Findings: Vector control interventions had a significant impact on combined Breteau index (relative risk reduction 0·43, 95% CI 0·26 to 0·70) and on dengue incidence (0·43, 0·28 to 0·67), the latter becoming prominent 2 months after the intervention onset. The mean number of averted dengue cases was estimated at 2192 (95% CI 1741 to 2643), and the total cost of the CIMIC programme at 2016 US$271 615. Personnel costs accounted for about 89% of the total cost. In the base-case scenario of moderate level of hospitalisation, the CIMIC programme was cost-saving with a probability of 70% under both the lowest ($453) and highest ($1686) cost-effectiveness thresholds, resulting in a net saving of $20 247 (95% CI −57 266 to 97 790) and averting 176 DALYs (133 to 226), leading to a cost of −$98 (−497 to 395) per DALY averted. This was also the case for the scenario with high hospitalisation levels (cost per DALY averted −$512, 95% CI −872 to −115) but with a higher probability of 99%. In the scenario with low hospitalisation levels (cost per DALY averted $690, 143 to 1379), although the CIMIC programme was cost-ineffective at the lowest threshold with a probability of 77%, it was cost-effective at the highest threshold with a probability of 99%.

Interpretation: This study suggests that communities affected by dengue can benefit from investments in vector control if interventions are implemented rigorously and coordinated well across sectors. By doing so, it is possible to reduce the disease and economic burden of dengue in endemic settings.

Funding: None.

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-163272 (URN)10.1016/S2542-5196(19)30057-9 (DOI)31128766 (PubMedID)2-s2.0-85065896383 (Scopus ID)
Available from: 2019-09-12 Created: 2019-09-12 Last updated: 2019-09-16Bibliographically approved
Massad, E., Bezerra Coutinhol, F. A. & Wilder-Smith, A. (2019). Modelling an optimum vaccination strategy against ZIKA virus for outbreak use. Epidemiology and Infection, 147, Article ID UNSP e196.
Open this publication in new window or tab >>Modelling an optimum vaccination strategy against ZIKA virus for outbreak use
2019 (English)In: Epidemiology and Infection, ISSN 0950-2688, E-ISSN 1469-4409, Vol. 147, article id UNSP e196Article in journal (Refereed) Published
Abstract [en]

We present a model to optimise a vaccination campaign aiming to prevent or to curb a Zika virus outbreak. We show that the optimum vaccination strategy to reduce the number of cases by a mass vaccination campaign should start when the Aedes mosquitoes' density reaches the threshold of 1.5 mosquitoes per humans, the moment the reproduction number crosses one. The maximum time it is advisable to wait for the introduction of a vaccination campaign is when the first ZIKV case is identified, although this would not be as effective to minimise the number of infections as when the mosquitoes' density crosses the critical threshold. This suboptimum strategy, however, would still curb the outbreak. In both cases, the catch up strategy should aim to vaccinate at least 25% of the target population during a concentrated effort of 1 month immediately after identifying the threshold. This is the time taken to accumulate the herd immunity threshold of 56.5%. These calculations were done based on theoretical assumptions that vaccine implementation would be feasible within a very short time frame.

Place, publisher, year, edition, pages
CAMBRIDGE UNIV PRESS, 2019
Keywords
Control strategies, mathematical models, vaccines, Zika virus
National Category
Infectious Medicine
Identifiers
urn:nbn:se:umu:diva-162026 (URN)10.1017/S0950268819000712 (DOI)000475912200127 ()31364534 (PubMedID)
Available from: 2019-08-09 Created: 2019-08-09 Last updated: 2019-08-09Bibliographically approved
Paixao, E. S., Leong, W.-Y., Rodrigues, L. C. & Wilder-Smith, A. (2018). Asymptomatic Prenatal Zika Virus Infection and Congenital Zika Syndrome. Open Forum Infectious Diseases, 5(4)
Open this publication in new window or tab >>Asymptomatic Prenatal Zika Virus Infection and Congenital Zika Syndrome
2018 (English)In: Open Forum Infectious Diseases, ISSN 2328-8957, Vol. 5, no 4Article in journal (Refereed) Published
Abstract [en]

To investigate to what extent asymptomatic vs symptomatic prenatal Zika virus infections contribute to birth defects, we identified 3 prospective and 8 retrospective studies. The ratio varied greatly in the retrospective studies, most likely due to recruitment and recall bias. The prospective studies revealed a ratio of 1: 1 for asymptomatic vs symptomatic maternal Zika infections resulting in adverse fetal outcomes.

Place, publisher, year, edition, pages
Oxford University Press, 2018
Keywords
asymptomatic prenatal infection, congenital Zika syndrome, maternal infection, microcephaly, Zika
National Category
Infectious Medicine
Identifiers
urn:nbn:se:umu:diva-147829 (URN)10.1093/ofid/ofy073 (DOI)000431146000025 ()29732381 (PubMedID)
Available from: 2018-05-21 Created: 2018-05-21 Last updated: 2019-04-24Bibliographically approved
Massad, E., Amaku, M., Coutinho, F. A., Struchiner, C. J., Burattini, M. N., Khan, K., . . . Wilder-Smith, A. (2018). Estimating the probability of dengue virus introduction and secondary autochthonous cases in Europe. Scientific Reports, 8(1), Article ID 4629.
Open this publication in new window or tab >>Estimating the probability of dengue virus introduction and secondary autochthonous cases in Europe
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2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, no 1, article id 4629Article in journal (Refereed) Published
Abstract [en]

Given the speed of air travel, diseases even with a short viremia such as dengue can be easily exported to dengue naïve areas within 24 hours. We set out to estimate the risk of dengue virus introductions via travelers into Europe and number of secondary autochthonous cases as a result of the introduction. We applied mathematical modeling to estimate the number of dengue-viremic air passengers from 16 dengue-endemic countries to 27 European countries, taking into account the incidence of dengue in the exporting countries, travel volume and the probability of being viremic at the time of travel. Our models estimate a range from zero to 167 air passengers who are dengue-viremic at the time of travel from dengue endemic countries to each of the 27 receiving countries in one year. Germany receives the highest number of imported dengue-viremic air passengers followed by France and the United Kingdom. Our findings estimate 10 autochthonous secondary asymptomatic and symptomatic dengue infections, caused by the expected 124 infected travelers who arrived in Italy in 2012. The risk of onward transmission in Europe is reassuringly low, except where Aedes aegypti is present.

National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-147390 (URN)10.1038/s41598-018-22590-5 (DOI)000427465800009 ()29545610 (PubMedID)
Available from: 2018-05-02 Created: 2018-05-02 Last updated: 2018-06-09Bibliographically approved
Wilder-Smith, A., Tissera, H., AbuBakar, S., Kittayapong, P., Logan, J., Neumayr, A., . . . Preet, R. (2018). Novel tools for the surveillance and control of dengue: findings by the dengueTools research consortium. Global Health Action, 11(1), Article ID 1549930.
Open this publication in new window or tab >>Novel tools for the surveillance and control of dengue: findings by the dengueTools research consortium
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2018 (English)In: Global Health Action, ISSN 1654-9716, E-ISSN 1654-9880, Vol. 11, no 1, article id 1549930Article, review/survey (Refereed) Published
Abstract [en]

Background: Dengue fever persists as a major global disease burden, and may increase as a consequence of climate change. Along with other measures, research actions to improve diagnosis, surveillance, prevention, and predictive models are highly relevant. The European Commission funded the DengueTools consortium to lead a major initiative in these areas, and this review synthesises the outputs and findings of this work conducted from 2011 to 2016. Research areas: DengueTools organised its work into three research areas, namely [1] Early warning and surveillance systems; [2] Strategies to prevent dengue in children; and [3] Predictive models for the global spread of dengue. Research area 1 focused on case-studies undertaken in Sri Lanka, including developing laboratory-based sentinel surveillance, evaluating economic impact, identifying drivers of transmission intensity, evaluating outbreak prediction capacity and developing diagnostic capacity. Research area 2 addressed preventing dengue transmission in school children, with case-studies undertaken in Thailand. Insecticide-treated school uniforms represented an intriguing potential approach, with some encouraging results, but which were overshadowed by a lack of persistence of insecticide on the uniforms with repeated washing. Research area 3 evaluated potential global spread of dengue, particularly into dengue-naive areas such as Europe. The role of international travel, changing boundaries of vectors, developing models of vectorial capacity under different climate change scenarios and strategies for vector control in outbreaks was all evaluated. Concluding remarks: DengueTools was able to make significant advances in methods for understanding and controlling dengue transmission in a range of settings. These will have implications for public health agendas to counteract dengue, including vaccination programmes. Outlook: Towards the end of the DengueTools project, Zika virus emerged as an unexpected epidemic in the central and southern America. Given the similarities between the dengue and Zika viruses, with vectors in common, some of the DengueTools thinking translated readily into the Zika situation.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2018
Keywords
Dengue, DengueTools, surveillance, impregnated clothing, schools, Aedes, vectorial capacity, edictive modelling, importation, travel, Zika, reverse transcription-recombinase polymerase plification
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-154333 (URN)10.1080/16549716.2018.1549930 (DOI)000451847300001 ()
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2018-12-27Bibliographically approved
O'Reilly, K. M., Lowe, R., Edmunds, W. J., Mayaud, P., Kucharski, A., Eggo, R. M., . . . Yakob, L. (2018). Projecting the end of the Zika virus epidemic in Latin America: a modelling analysis. BMC Medicine, 16, Article ID 180.
Open this publication in new window or tab >>Projecting the end of the Zika virus epidemic in Latin America: a modelling analysis
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2018 (English)In: BMC Medicine, ISSN 1741-7015, E-ISSN 1741-7015, Vol. 16, article id 180Article in journal (Refereed) Published
Abstract [en]

Background: Zika virus (ZIKV) emerged in Latin America and the Caribbean (LAC) region in 2013, with serious implications for population health in the region. In 2016, the World Health Organization declared the ZIKV outbreak a Public Health Emergency of International Concern following a cluster of associated neurological disorders and neonatal malformations. In 2017, Zika cases declined, but future incidence in LAC remains uncertain due to gaps in our understanding, considerable variation in surveillance and the lack of a comprehensive collation of data from affected countries.

Methods: Our analysis combines information on confirmed and suspected Zika cases across LAC countries and a spatio-temporal dynamic transmission model for ZIKV infection to determine key transmission parameters and projected incidence in 90 major cities within 35 countries. Seasonality was determined by spatio-temporal estimates of Aedes aegypti vectorial capacity. We used country and state-level data from 2015 to mid-2017 to infer key model parameters, country-specific disease reporting rates, and the 2018 projected incidence. A 10-fold cross-validation approach was used to validate parameter estimates to out-of-sample epidemic trajectories.

Results: There was limited transmission in 2015, but in 2016 and 2017 there was sufficient opportunity for wide-spread ZIKV transmission in most cities, resulting in the depletion of susceptible individuals. We predict that the highest number of cases in 2018 would present within some Brazilian States (Sao Paulo and Rio de Janeiro), Colombia and French Guiana, but the estimated number of cases were no more than a few hundred. Model estimates of the timing of the peak in incidence were correlated (p < 0.05) with the reported peak in incidence. The reporting rate varied across countries, with lower reporting rates for those with only confirmed cases compared to those who reported both confirmed and suspected cases.

Conclusions: The findings suggest that the ZIKV epidemic is by and large over within LAC, with incidence projected to be low in most cities in 2018. Local low levels of transmission are probable, but the estimated rate of infection suggests that most cities have a population with high levels of herd immunity.

Place, publisher, year, edition, pages
BioMed Central, 2018
Keywords
Zika virus, Epidemic, Mathematical modelling, Latin America and the Caribbean, Connectivity
National Category
Public Health, Global Health, Social Medicine and Epidemiology Infectious Medicine
Identifiers
urn:nbn:se:umu:diva-152869 (URN)10.1186/s12916-018-1158-8 (DOI)000446198400001 ()30285863 (PubMedID)
Funder
EU, Horizon 2020, 734548
Available from: 2018-10-31 Created: 2018-10-31 Last updated: 2018-10-31Bibliographically approved
Wilder-Smith, A., Chang, C. R. & Leong, W. Y. (2018). Zika in travellers 1947-2017: a systematic review. Journal of Travel Medicine, 25, Article ID tay044.
Open this publication in new window or tab >>Zika in travellers 1947-2017: a systematic review
2018 (English)In: Journal of Travel Medicine, ISSN 1195-1982, E-ISSN 1708-8305, Vol. 25, article id tay044Article in journal (Refereed) Published
Abstract [en]

Introduction: Travellers contributed substantially to the rapid spread of Zika virus (ZIKV). They act as sentinel and may unmask ongoing ZIKV transmission in countries where outbreaks have not yet been reported. Our objectives were to (i) describe the burden of ZIKV infections in international travellers over time; (ii) estimate the proportion of birth defects as a result of maternal ZIKV infection in travellers; (iii) track the extent of sexual transmission; (iv) summarize ZIKV infections in returning travellers as reported by the GeoSentinel network; and (v) identify countries without reports on local ZIKV transmission where travellers served as sentinel.

Methods: We performed a systematic review from 1947 to April 2017 on travel-associated ZIKV infections. We also compared published reports on autochthonous ZIKV transmission in Asia with published reports on exportations from travellers in Asia.

Results: Of 314 papers that fit the inclusion criteria, 61 were eligible for final analysis. There was an exponential increase in the number of reported ZIKV infected travellers from the years 2013 to 2016, which declined in 2017. Amongst pregnant women with ZIKV infection, (5%) resulted in a fetus or infant with ZIKV-associated birth defects. An estimated 1% of the total number of ZIKV cases reported in the USA and Europe were acquired through sexual transmission. Through the GeoSentinel network, five countries (Indonesia, Philippines, Thailand, Vietnam, Cameroon) were identified as sentinel markers where ZIKV was exported despite the absence of reported local transmission.

Conclusions: Mobility patterns and travel volumes can help to identify the most likely origin of importation, and also in predicting further propagation. Studies on pregnant returning travellers have contributed to a better understanding of the risk estimates of congenital Zika syndrome/microcephaly as a result of maternal ZIKV infection, and the relative contribution of sexual transmission.

Place, publisher, year, edition, pages
Oxford University Press, 2018
Keywords
Zika, flavivirus, travellers, mobility patterns, GeoSentinel, sexual transmission
National Category
Public Health, Global Health, Social Medicine and Epidemiology Infectious Medicine
Identifiers
urn:nbn:se:umu:diva-150620 (URN)10.1093/jtm/tay044 (DOI)000451511000001 ()30016469 (PubMedID)
Available from: 2018-08-14 Created: 2018-08-14 Last updated: 2018-12-19Bibliographically approved
Wilder-Smith, A., Vannice, K., Durbin, A., Hombach, J., Thomas, S. J., Thevarjan, I. & Simmons, C. P. (2018). Zika vaccines and therapeutics: landscape analysis and challenges ahead. BMC Medicine, 16, Article ID 84.
Open this publication in new window or tab >>Zika vaccines and therapeutics: landscape analysis and challenges ahead
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2018 (English)In: BMC Medicine, ISSN 1741-7015, E-ISSN 1741-7015, Vol. 16, article id 84Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Various Zika virus (ZIKV) vaccine candidates are currently in development. Nevertheless, unique challenges in clinical development and regulatory pathways may hinder the licensure of high-quality, safe, and effective ZIKV vaccines.

DISCUSSION: Implementing phase 3 efficacy trials will be difficult given the challenges of the spatio-temporal heterogeneity of ZIKV transmission, the unpredictability of ZIKV epidemics, the broad spectrum of clinical manifestations making a single definite endpoint difficult, a lack of sensitive and specific diagnostic assays, and the need for inclusion of vulnerable target populations. In addition to a vaccine, drugs for primary prophylaxis, post-exposure prophylaxis, or treatment should also be developed to prevent or mitigate the severity of congenital Zika syndrome.

CONCLUSION: Establishing the feasibility of immune correlates and/or surrogates are a priority. Given the challenges in conducting phase 3 trials at a time of waning incidence, human challenge trials should be considered to evaluate efficacy. Continued financial support and engagement of industry partners will be essential to the successful development, licensure, and accessibility of Zika vaccines or therapeutics.

Place, publisher, year, edition, pages
BioMed Central, 2018
Keywords
Anti-virals, Clinical endpoints, Efficacy trials, Flavivirus, Human controlled infections, Immune correlates, Immune surrogates, Monoclonal antibodies, Prophylaxis, Therapeutics, Zika, Zika diagnostics, Zika vaccines
National Category
Infectious Medicine
Identifiers
urn:nbn:se:umu:diva-150619 (URN)10.1186/s12916-018-1067-x (DOI)000435012000001 ()29871628 (PubMedID)2-s2.0-85048075716 (Scopus ID)
Available from: 2018-08-14 Created: 2018-08-14 Last updated: 2018-08-16Bibliographically approved
Leonhard, S. E., Lant, S., Jacobs, B. C., Wilder-Smith, A., Ferreira, M. L., Solomon, T. & Willison, H. J. (2018). Zika virus infection in the returning traveller: what every neurologist should know. Practical Neurology, 18(4), 271-277
Open this publication in new window or tab >>Zika virus infection in the returning traveller: what every neurologist should know
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2018 (English)In: Practical Neurology, ISSN 1474-7758, E-ISSN 1474-7766, Vol. 18, no 4, p. 271-277Article in journal (Refereed) Published
Abstract [en]

Zika virus has been associated with a wide range of neurological complications. Neurologists in areas without current active transmission of the virus may be confronted with Zika-associated neurological disease, as a large number of returning travellers with Zika virus infection have been reported and the virus continues to spread to previously unaffected regions. This review provides an overview of Zika virus-associated neurological disease and aims to support neurologists who may encounter patients returning from endemic areas.

Place, publisher, year, edition, pages
BMJ Publishing Group Ltd, 2018
Keywords
Guillain-Barré syndrome, clinical neurology, neuroimmunology, neurovirology, zika virus
National Category
Public Health, Global Health, Social Medicine and Epidemiology Infectious Medicine
Identifiers
urn:nbn:se:umu:diva-150618 (URN)10.1136/practneurol-2017-001789 (DOI)29618586 (PubMedID)2-s2.0-8505096790 (Scopus ID)
Available from: 2018-08-14 Created: 2018-08-14 Last updated: 2018-08-15Bibliographically approved
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