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1.
Article in English | MEDLINE | ID: mdl-33761167

ABSTRACT

Yellow fever is a vaccine-preventable acute viral disease that can rapidly spread and cause serious public health impact. Delay in seeking health care from health facilities is a potential risk of prolonged disease spread. Therefore, this study assessed the delay in health-seeking behaviour and implications for yellow fever outcomes in the 2019 outbreak in Nigeria. Furthermore, the study examined the factors associated with delayed yellow fever vaccine uptake. A retrospective study was conducted from January to December 2019 using 137 cases recorded in the WHO database. The data were analysed using descriptive (frequency and percentages) and the Chi-square test. The results were significant at p < 0.05. Results showed a low uptake of yellow fever vaccine (24.1%) among patients and a median total health-seeking delay of 7 [IQR 7, 9] days. The delay was more among the older age ≥40 years (12 [IQR 12, 29]), females (8 [IQR 8, 11], and rural inhabitants 7 [IQR7, 9], particularly in Izzi LGA (9 [IQR 9, 16] than the other subgroups. Patients' location or place of residence was significantly associated with the yellow fever vaccine uptake (p < 0.000*), and delay (p = 0.003*). Conclusively, the low vaccine uptake was due to the delay in health-seeking behaviour. Thus, the healthcare system in Nigeria needs to intensify mass participation in immunisation programmes. Interventions that promote behavioural change towards immunisation are required. Also, health promotion campaigns to educate rural people on desirable health-seeking behaviour are needed.

3.
Pathog Dis ; 79(4)2021 Apr 09.
Article in English | MEDLINE | ID: mdl-33739369

ABSTRACT

The 2019 and 2020 sporadic outbreaks of yellow fever (YF) in Sub-Saharan African countries had raised a lot of global health concerns. This article aims to narratively review the vector biology, YF vaccination program, environmental factors and climatic changes, and to understand how they could facilitate the reemergence of YF. This study comprehensively reviewed articles that focused on the interplay and complexity of YF virus (YFV) vector diversity/competence, YF vaccine immunodynamics and climatic change impacts on YFV transmission as they influence the 2019/2020 sporadic outbreaks in Sub-Saharan Africa (SSA). Based on available reports, vectorial migration, climatic changes and YF immunization level could be reasons for the re-mergence of YF at the community and national levels. Essentially, the drivers of YFV infection due to spillover are moderately constant. However, changes in land use and landscape have been shown to influence sylvan-to-urban spillover. Furthermore, increased precipitation and warmer temperatures due to climate change are likely to broaden the range of mosquitoes' habitat. The 2019/2020 YF outbreaks in SSA is basically a result of inadequate vaccination campaigns, YF surveillance and vector control. Consequently, and most importantly, adequate immunization coverage must be implemented and properly achieved under the responsibility of the public health stakeholders.

4.
Mem Inst Oswaldo Cruz ; 115: e200278, 2021.
Article in English | MEDLINE | ID: mdl-33566939

ABSTRACT

BACKGROUND: The impact of arbovirus cocirculation in Brazil is unknown. Dengue virus (DENV) reinfection may result in more intense viraemia or immunopathology, leading to more severe disease. The Zika virus (ZIKV) epidemic in the Americas provided pathogenicity evidence that had not been previously observed in flavivirus infections. In contrast to other flaviviruses, electron microscopy studies have shown that ZIKV may replicate in viroplasm-like structures. Flaviviruses produce an ensemble of structurally different virions, collectively contributing to tissue tropism and virus dissemination. OBJECTIVES AND METHODS: In this work, the Aedes albopictus mosquito cell lineage (C6/36 cells) and kidney epithelial cells from African green monkeys (Vero cells) were infected with samples of the main circulating arboviruses in Brazil [DENV-1, DENV-2, DENV-3, DENV-4, ZIKV, Yellow Fever virus (YFV) and Chikungunya virus (CHIKV)], and ultrastructural studies by transmission electron microscopy were performed. FINDINGS: We observed that ZIKV, the DENV serotypes, YFV and CHIKV particles are spherical. ZIKV, DENV-1, -2, -3 and -4 presented diameters of 40-50 nm, and CHIKV presented approximate diameters of 50-60 nm. Viroplasm-like structures was observed in ZIKV replication cycle. MAIN CONCLUSIONS: The morphogenesis of these arboviruses is similar to what has been presented in previous studies. However, we understand that further studies are needed to investigate the relationship between viroplasm-like structures and ZIKV replication dynamics.


Subject(s)
Arboviruses , Chikungunya Fever , Dengue , Epidemics , Yellow Fever , Zika Virus Infection , Zika Virus , Animals , Brazil/epidemiology , Chikungunya Fever/epidemiology , Chlorocebus aethiops , Dengue/epidemiology , Vero Cells , Zika Virus Infection/epidemiology
5.
PLoS Med ; 18(2): e1003523, 2021 Feb.
Article in English | MEDLINE | ID: mdl-33600451

ABSTRACT

BACKGROUND: The Eliminate Yellow fever Epidemics (EYE) strategy was launched in 2017 in response to the resurgence of yellow fever in Africa and the Americas. The strategy relies on several vaccination activities, including preventive mass vaccination campaigns (PMVCs). However, to what extent PMVCs are associated with a decreased risk of outbreak has not yet been quantified. METHODS AND FINDINGS: We used the self-controlled case series (SCCS) method to assess the association between the occurrence of yellow fever outbreaks and the implementation of PMVCs at the province level in the African endemic region. As all time-invariant confounders are implicitly controlled for in the SCCS method, this method is an alternative to classical cohort or case-control study designs when the risk of residual confounding is high, in particular confounding by indication. The locations and dates of outbreaks were identified from international epidemiological records, and information on PMVCs was provided by coordinators of vaccination activities and international funders. The study sample consisted of provinces that were both affected by an outbreak and targeted for a PMVC between 2005 and 2018. We compared the incidence of outbreaks before and after the implementation of a PMVC. The sensitivity of our estimates to a range of assumptions was explored, and the results of the SCCS method were compared to those obtained through a retrospective cohort study design. We further derived the number of yellow fever outbreaks that have been prevented by PMVCs. The study sample consisted of 33 provinces from 11 African countries. Among these, the first outbreak occurred during the pre-PMVC period in 26 (79%) provinces, and during the post-PMVC period in 7 (21%) provinces. At the province level, the post-PMVC period was associated with an 86% reduction (95% CI 66% to 94%, p < 0.001) in the risk of outbreak as compared to the pre-PMVC period. This negative association between exposure to PMVCs and outbreak was robustly observed across a range of sensitivity analyses, especially when using quantitative estimates of vaccination coverage as an alternative exposure measure, or when varying the observation period. In contrast, the results of the cohort-style analyses were highly sensitive to the choice of covariates included in the model. Based on the SCCS results, we estimated that PMVCs were associated with a 34% (95% CI 22% to 45%) reduction in the number of outbreaks in Africa from 2005 to 2018. A limitation of our study is the fact that it does not account for potential time-varying confounders, such as changing environmental drivers of yellow fever and possibly improved disease surveillance. CONCLUSIONS: In this study, we provide new empirical evidence of the high preventive impact of PMVCs on yellow fever outbreaks. This study illustrates that the SCCS method can be advantageously applied at the population level in order to evaluate a public health intervention.

6.
Nat Commun ; 12(1): 151, 2021 01 08.
Article in English | MEDLINE | ID: mdl-33420058

ABSTRACT

Mosquito-borne viruses threaten the Caribbean due to the region's tropical climate and seasonal reception of international tourists. Outbreaks of chikungunya and Zika have demonstrated the rapidity with which these viruses can spread. Concurrently, dengue fever cases have climbed over the past decade. Sustainable disease control measures are urgently needed to quell virus transmission and prevent future outbreaks. Here, to improve upon current control methods, we analyze temporal and spatial patterns of chikungunya, Zika, and dengue outbreaks reported in the Dominican Republic between 2012 and 2018. The viruses that cause these outbreaks are transmitted by Aedes mosquitoes, which are sensitive to seasonal climatological variability. We evaluate whether climate and the spatio-temporal dynamics of dengue outbreaks could explain patterns of emerging disease outbreaks. We find that emerging disease outbreaks were robust to the climatological and spatio-temporal constraints defining seasonal dengue outbreak dynamics, indicating that constant surveillance is required to prevent future health crises.


Subject(s)
Chikungunya Fever/epidemiology , Communicable Diseases, Emerging/epidemiology , Dengue/epidemiology , Disease Outbreaks/statistics & numerical data , Endemic Diseases/statistics & numerical data , Zika Virus Infection/epidemiology , Adolescent , Aedes/virology , Animals , Chikungunya Fever/prevention & control , Chikungunya Fever/transmission , Chikungunya Fever/virology , Chikungunya virus/isolation & purification , Child , Child, Preschool , Communicable Diseases, Emerging/prevention & control , Communicable Diseases, Emerging/transmission , Communicable Diseases, Emerging/virology , Dengue/prevention & control , Dengue/transmission , Dengue/virology , Dengue Virus/isolation & purification , Disease Outbreaks/prevention & control , Dominican Republic/epidemiology , Endemic Diseases/prevention & control , Epidemiological Monitoring , Female , Humans , Infant , Infant, Newborn , Male , Mosquito Control , Mosquito Vectors/virology , Spatio-Temporal Analysis , Young Adult , Zika Virus/isolation & purification , Zika Virus Infection/prevention & control , Zika Virus Infection/transmission , Zika Virus Infection/virology
7.
Nat Commun ; 12(1): 595, 2021 01 26.
Article in English | MEDLINE | ID: mdl-33500409

ABSTRACT

Zika virus (ZIKV) emerged from obscurity in 2013 to spread from Asia to the South Pacific and the Americas, where millions of people were infected, accompanied by severe disease including microcephaly following congenital infections. Phylogenetic studies have shown that ZIKV evolved in Africa and later spread to Asia, and that the Asian lineage is responsible for the recent epidemics in the South Pacific and Americas. However, the reasons for the sudden emergence of ZIKV remain enigmatic. Here we report evolutionary analyses that revealed four mutations, which occurred just before ZIKV introduction to the Americas, represent direct reversions of previous mutations that accompanied earlier spread from Africa to Asia and early circulation there. Our experimental infections of Aedes aegypti mosquitoes, human cells, and mice using ZIKV strains with and without these mutations demonstrate that the original mutations reduced fitness for urban, human-amplifed transmission, while the reversions restored fitness, increasing epidemic risk. These findings include characterization of three transmission-adaptive ZIKV mutations, and demonstration that these and one identified previously restored fitness for epidemic transmission soon before introduction into the Americas. The initial mutations may have followed founder effects and/or drift when the virus was introduced decades ago into Asia.


Subject(s)
Epidemics , Evolution, Molecular , Genetic Fitness , Zika Virus Infection/epidemiology , Zika Virus/genetics , Aedes/virology , Africa/epidemiology , Americas/epidemiology , Amino Acid Substitution , Animals , Asia/epidemiology , Cell Line , Disease Models, Animal , Female , Fibroblasts , Humans , Keratinocytes , Mice , Mutation , Phylogeny , Primary Cell Culture , Urban Health/statistics & numerical data , Zika Virus/pathogenicity , Zika Virus Infection/transmission , Zika Virus Infection/virology
8.
Emerg Top Life Sci ; 4(4): 399-410, 2020 12 11.
Article in English | MEDLINE | ID: mdl-33258924

ABSTRACT

Yellow fever virus (YFV) is the etiological agent of yellow fever (YF), an acute hemorrhagic vector-borne disease with a significant impact on public health, is endemic across tropical regions in Africa and South America. The virus is maintained in two ecologically and evolutionary distinct transmission cycles: an enzootic, sylvatic cycle, where the virus circulates between arboreal Aedes species mosquitoes and non-human primates, and a human or urban cycle, between humans and anthropophilic Aedes aegypti mosquitoes. While the urban transmission cycle has been eradicated by a highly efficacious licensed vaccine, the enzootic transmission cycle is not amenable to control interventions, leading to recurrent epizootics and spillover outbreaks into human populations. The nature of YF transmission dynamics is multifactorial and encompasses a complex system of biotic, abiotic, and anthropogenic factors rendering predictions of emergence highly speculative. The recent outbreaks in Africa and Brazil clearly remind us of the significant impact YF emergence events pose on human and animal health. The magnitude of the Brazilian outbreak and spillover in densely populated areas outside the recommended vaccination coverage areas raised the specter of human - to - human transmission and re-establishment of enzootic cycles outside the Amazon basin. Herein, we review the factors that influence the re-emergence potential of YFV in the neotropics and offer insights for a constellation of coordinated approaches to better predict and control future YF emergence events.

10.
Rev Soc Bras Med Trop ; 53: e20200787, 2020.
Article in English | MEDLINE | ID: mdl-33331614

ABSTRACT

INTRODUCTION: Since 2016, Brazil has been in the midst of its largest sylvatic yellow fever epidemic ever, found predominantly outside the Amazon region. Cases originating from Brazil have been reported in France, the Netherlands, Romania, Switzerland, Argentina, and Chile. The epidemic began in the Central-West region of Brazil in 2014, spreading into the Southern region, with significant non-human primate transmission continuing towards Paraguay and Argentina. METHODS: This report is an integrative review of Pan American Health Organization cooperation during a sylvatic yellow fever epidemic. RESULTS: The Pan American Health Organization has played a central role in handling the yellow fever emergency, collaborating with the Ministry of Health and various research groups in supporting interventions of different response areas. The Pan American Health Organization's technical cooperation included: training and workshops to exchange experiences, carrying out technical cooperation in patient management and epidemiological, entomological, laboratory, and epizootic surveillance, organizing the assistance network, and acquiring strategic inputs. The Pan American Health Organization's technical cooperation supported the Ministry of Health's decision to adopt a single-dose vaccine and use fractional doses to support the vaccination needs of more than 39,000,000 people. The coronavirus disease 2019 pandemic contributed to the failure of reaching the yellow fever vaccination goals and made it difficult to integrate the yellow fever vaccine into recommended areas. CONCLUSIONS: Given the ongoing coronavirus disease 2019 pandemic, it is necessary to strengthen measures for the surveillance, prevention, and control of yellow fever with multilateral cooperation between countries.


Subject(s)
Yellow Fever , Argentina , Brazil , Disease Outbreaks , France , Humans , Pan American Health Organization , Pandemics , Paraguay , Yellow Fever/epidemiology , Yellow Fever/prevention & control , Yellow fever virus
11.
PLoS Pathog ; 16(12): e1009068, 2020 12.
Article in English | MEDLINE | ID: mdl-33382858

ABSTRACT

Originating from African forests, Zika virus (ZIKV) has now emerged worldwide in urbanized areas, mainly transmitted by Aedes aegypti mosquitoes. Although Aedes albopictus can transmit ZIKV experimentally and was suspected to be a ZIKV vector in Central Africa, the potential of this species to sustain virus transmission was yet to be uncovered until the end of 2019, when several autochthonous transmissions of the virus vectored by Ae. albopictus occurred in France. Aside from these few locally acquired ZIKV infections, most territories colonized by Ae. albopictus have been spared so far. The risk level of ZIKV emergence in these areas remains however an open question. To assess Ae. albopictus' vector potential for ZIKV and identify key virus outbreak predictors, we built a complete framework using the complementary combination of (i) dose-dependent experimental Ae. albopictus exposure to ZIKV followed by time-dependent assessment of infection and systemic infection rates, (ii) modeling of intra-human ZIKV viremia dynamics, and (iii) in silico epidemiological simulations using an Agent-Based Model. The highest risk of transmission occurred during the pre-symptomatic stage of the disease, at the peak of viremia. At this dose, mosquito infection probability was estimated to be 20%, and 21 days were required to reach the median systemic infection rates. Mosquito population origin, either temperate or tropical, had no impact on infection rates or intra-host virus dynamic. Despite these unfavorable characteristics for transmission, Ae. albopictus was still able to trigger and yield large outbreaks in a simulated environment in the presence of sufficiently high mosquito biting rates. Our results reveal a low but existing epidemic potential of Ae. albopictus for ZIKV, that might explain the absence of large scale ZIKV epidemics so far in territories occupied only by Ae. albopictus. They nevertheless support active surveillance and eradication programs in these territories to maintain the risk of emergence to a low level.


Subject(s)
Mosquito Vectors/metabolism , Mosquito Vectors/virology , Zika Virus Infection/transmission , Aedes/metabolism , Aedes/virology , Animals , Disease Outbreaks , Disease Vectors , Epidemics , Humans , Models, Theoretical , Saliva/virology , Viral Load , Viremia/transmission , Zika Virus/pathogenicity , Zika Virus Infection/epidemiology , Zika Virus Infection/virology
12.
BMC Med ; 18(1): 399, 2020 12 17.
Article in English | MEDLINE | ID: mdl-33327961

ABSTRACT

BACKGROUND: Zika virus (ZIKV) emerged as a global epidemic in 2015-2016 from Latin America with its true geographical extent remaining unclear due to widely presumed underreporting. The identification of locations with potential and unknown spread of ZIKV is a key yet understudied component for outbreak preparedness. Here, we aim to identify locations at a high risk of cryptic ZIKV spread during 2015-2016 to further the understanding of the global ZIKV epidemiology, which is critical for the mitigation of the risk of future epidemics. METHODS: We developed an importation simulation model to estimate the weekly number of ZIKV infections imported in each susceptible spatial unit (i.e. location that did not report any autochthonous Zika cases during 2015-2016), integrating epidemiological, demographic, and travel data as model inputs. Thereafter, a global risk model was applied to estimate the weekly ZIKV transmissibility during 2015-2016 for each location. Finally, we assessed the risk of onward ZIKV spread following importation in each susceptible spatial unit to identify locations with a high potential for cryptic ZIKV spread during 2015-2016. RESULTS: We have found 24 susceptible spatial units that were likely to have experienced cryptic ZIKV spread during 2015-2016, of which 10 continue to have a high risk estimate within a highly conservative scenario, namely, Luanda in Angola, Banten in Indonesia, Maharashtra in India, Lagos in Nigeria, Taiwan and Guangdong in China, Dakar in Senegal, Maputo in Mozambique, Kinshasa in Congo DRC, and Pool in Congo. Notably, among the 24 susceptible spatial units identified, some have reported their first ZIKV outbreaks since 2017, thus adding to the credibility of our results (derived using 2015-2016 data only). CONCLUSION: Our study has provided valuable insights into the potentially high-risk locations for cryptic ZIKV circulation during the 2015-2016 pandemic and has also laid a foundation for future studies that attempt to further narrow this key knowledge gap. Our modelling framework can be adapted to identify areas with likely unknown spread of other emerging vector-borne diseases, which has important implications for public health readiness especially in resource-limited settings.


Subject(s)
Geographic Mapping , Zika Virus Infection/epidemiology , Aedes/physiology , Aedes/virology , Animals , Disease Outbreaks/history , Ecology , Epidemics , Geography , History, 21st Century , Humans , Travel/statistics & numerical data , Zika Virus/physiology , Zika Virus Infection/history
13.
Viruses ; 12(11)2020 10 30.
Article in English | MEDLINE | ID: mdl-33143114

ABSTRACT

Yellow fever (YF) is a re-emerging viral zoonosis caused by the Yellow Fever virus (YFV), affecting humans and non-human primates (NHP). YF is endemic in South America and Africa, being considered a burden for public health worldwide despite the availability of an effective vaccine. Acute infectious disease can progress to severe hemorrhagic conditions and has high rates of morbidity and mortality in endemic countries. In 2016, Brazil started experiencing one of the most significant YF epidemics in its history, with lots of deaths being reported in regions that were previously considered free of the disease. Here, we reviewed the historical aspects of YF in Brazil, the epidemiology of the disease, the challenges that remain in Brazil's public health context, the main lessons learned from the recent outbreaks, and our perspective for facing future YF epidemics.

14.
PLoS Negl Trop Dis ; 14(10): e0008691, 2020 10.
Article in English | MEDLINE | ID: mdl-33001982

ABSTRACT

Optimise control strategies of infectious diseases, identify factors that favour the circulation of pathogens, and propose risk maps are crucial challenges for global health. Ecological niche modelling, once relying on an adequate framework and environmental descriptors can be a helpful tool for such purposes. Despite the existence of a vaccine, yellow fever (YF) is still a public health issue. Brazil faced massive sylvatic YF outbreaks from the end of 2016 up to mid-2018, but cases in human and non-human primates have been recorded until the beginning of 2020. Here we used both human and monkey confirmed YF cases from two epidemic periods (2016/2017 and 2017/2018) to describe the spatial distribution of the cases and explore how biotic and abiotic factors drive their occurrence. The distribution of YF cases largely overlaps for humans and monkeys, and a contraction of the spatial extent associated with a southward displacement is observed during the second period of the epidemics. More contributive variables to the spatiotemporal heterogeneity of cases were related to biotic factors (mammal richness), abiotic factors (temperature and precipitation), and some human-related variables (population density, human footprint, and human vaccination coverage). Both projections of the most favourable conditions showed similar trends with a contraction of the more at-risk areas. Once extrapolated at a large scale, the Amazon basin remains at lower risk, although surrounding forest regions and notably the North-West region, would face a higher risk. Spatial projections of infectious diseases often relied on climatic variables only; here for both models, we instead highlighted the importance of considering local biotic conditions, hosts vulnerability, social and epidemiological factors to run the spatial risk analysis correctly: all YF cases occurring later on, in 2019 and 2020, were observed in the predicted at-risk areas.

15.
PLoS Negl Trop Dis ; 14(10): e0008658, 2020 10.
Article in English | MEDLINE | ID: mdl-33017419

ABSTRACT

BACKGROUND: From the end of 2016 until the beginning of 2019, Brazil faced a massive sylvatic yellow fever (YF) outbreak. The 2016-2019 YF epidemics affected densely populated areas, especially the Southeast region, causing thousands of deaths of humans and non-human primates (NHP). METHODOLOGY/PRINCIPAL FINDINGS: We conducted a molecular investigation of yellow fever virus (YFV) RNA in 781 NHP carcasses collected in the urban, urban-rural interface, and rural areas of Minas Gerais state, from January 2017 to December 2018. Samples were analyzed according to the period of sampling, NHP genera, sampling areas, and sampling areas/NHP genera to compare the proportions of YFV-positive carcasses and the estimated YFV genomic loads. YFV infection was confirmed in 38.1% of NHP carcasses (including specimens of the genera Alouatta, Callicebus, Callithrix, and Sapajus), from the urban, urban-rural interface, and rural areas. YFV RNA detection was positively associated with epidemic periods (especially from December to March) and the rural environment. Higher median viral genomic loads (one million times) were estimated in carcasses collected in rural areas compared to urban ones. CONCLUSIONS/SIGNIFICANCE: The results showed the wide occurrence of YF in Minas Gerais in epidemic and non-epidemic periods. According to the sylvatic pattern of YF, a gradient of viral dissemination from rural towards urban areas was observed. A high YF positivity was observed for NHP carcasses collected in urban areas with a widespread occurrence in 67 municipalities of Minas Gerais, including large urban centers. Although there was no documented case of urban/Aedes YFV transmission to humans in Brazil during the 2016-2019 outbreaks, YFV-infected NHP in urban areas with high infestation by Aedes aegypti poses risks for YFV urban/Aedes transmission and urbanization.

16.
PLoS Pathog ; 16(8): e1008699, 2020 08.
Article in English | MEDLINE | ID: mdl-32764827

ABSTRACT

São Paulo, a densely inhabited state in southeast Brazil that contains the fourth most populated city in the world, recently experienced its largest yellow fever virus (YFV) outbreak in decades. YFV does not normally circulate extensively in São Paulo, so most people were unvaccinated when the outbreak began. Surveillance in non-human primates (NHPs) is important for determining the magnitude and geographic extent of an epizootic, thereby helping to evaluate the risk of YFV spillover to humans. Data from infected NHPs can give more accurate insights into YFV spread than when using data from human cases alone. To contextualise human cases, identify epizootic foci and uncover the rate and direction of YFV spread in São Paulo, we generated and analysed virus genomic data and epizootic case data from NHPs in São Paulo. We report the occurrence of three spatiotemporally distinct phases of the outbreak in São Paulo prior to February 2018. We generated 51 new virus genomes from YFV positive cases identified in 23 different municipalities in São Paulo, mostly sampled from NHPs between October 2016 and January 2018. Although we observe substantial heterogeneity in lineage dispersal velocities between phylogenetic branches, continuous phylogeographic analyses of generated YFV genomes suggest that YFV lineages spread in São Paulo at a mean rate of approximately 1km per day during all phases of the outbreak. Viral lineages from the first epizootic phase in northern São Paulo subsequently dispersed towards the south of the state to cause the second and third epizootic phases there. This alters our understanding of how YFV was introduced into the densely populated south of São Paulo state. Our results shed light on the sylvatic transmission of YFV in highly fragmented forested regions in São Paulo state and highlight the importance of continued surveillance of zoonotic pathogens in sentinel species.


Subject(s)
Genome, Viral , Primate Diseases/virology , Yellow Fever/veterinary , Yellow Fever/virology , Yellow fever virus/genetics , Zoonoses/virology , Animals , Brazil/epidemiology , Disease Outbreaks , Genomics , Humans , Phylogeny , Phylogeography , Primate Diseases/epidemiology , Primate Diseases/transmission , Primates/virology , Yellow Fever/epidemiology , Yellow Fever/transmission , Yellow fever virus/classification , Yellow fever virus/isolation & purification , Zoonoses/epidemiology , Zoonoses/transmission
17.
Article in English | MEDLINE | ID: mdl-32503246

ABSTRACT

The invasion of Aedes albopictus has played a major role in the resurgence of mosquito-borne diseases in Italy, generating the two largest chikungunya outbreaks in Europe (2007, 2017). Knowledge, attitude and practice (KAP) are important in order to prevent Aedes-borne disease transmission, yet so far they have not been assessed. To this scope we used multivariate logistic regression to investigate KAP of citizen-to-Aedes ecology and transmitted diseases. Data were collated by a structured questionnaire (18 questions) in 2016. Participants were selected in the Lazio region from members of native populations and two resident communities (RC) originating from the Indian subcontinent where Aedes-transmitted diseases are endemic. Results showed that compared to Italians, RC respondents had a higher knowledge and concern of Aedes-transmitted diseases (Odds Ratio = 2.61 (95%CI: 1.03-6.05); OR = 3.13 (2.15-4.65)) as well as their life cycles (OR = 2.49 (1.75-3.56); OR = 9.04 (6.22-13.66)). In contrast, they perceived a lower nuisance due to the presence of Ae. albopictus (OR = 0.2 (0.13-0.32); OR = 0.55 (0.38-0.78). These findings suggest that citizens in the Lazio region are not prepared to face a potential outbreak of arboviruses and further efforts should be made to increase knowledge, awareness and best practices.


Subject(s)
Aedes , Chikungunya Fever , Adult , Animals , Chikungunya Fever/epidemiology , Disease Outbreaks , Female , Humans , Italy/epidemiology , Mosquito Vectors , Surveys and Questionnaires
18.
PLoS Negl Trop Dis ; 14(5): e0008304, 2020 05.
Article in English | MEDLINE | ID: mdl-32379756

ABSTRACT

BACKGROUND: To counter the increasing global risk of Yellow fever (YF), the World Health Organisation initiated the Eliminate Yellow fever Epidemics (EYE) strategy. Estimating YF burden, as well as vaccine impact, while accounting for the features of urban YF transmission such as indirect benefits of vaccination, is key to informing this strategy. METHODS AND FINDINGS: We developed two model variants to estimate YF burden in sub-Saharan Africa, assuming all infections stem from either the sylvatic or the urban cycle of the disease. Both relied on an ecological niche model fitted to the local presence of any YF reported event in 34 African countries. We calibrated under-reporting using independent estimates of transmission intensity provided by 12 serological surveys performed in 11 countries. We calculated local numbers of YF infections, deaths and disability-adjusted life years (DALYs) lost based on estimated transmission intensity while accounting for time-varying vaccination coverage. We estimated vaccine demand and impact of future preventive mass vaccination campaigns (PMVCs) according to various vaccination scenarios. Vaccination activities conducted in Africa between 2005 and 2017 were estimated to prevent from 3.3 (95% CI 1.2-7.7) to 6.1 (95% CI 2.4-13.2) millions of deaths over the lifetime of vaccinees, representing extreme scenarios of none or maximal herd effects, respectively. By prioritizing provinces based on the risk of urban YF transmission in future PMVCs, an average of 37.7 million annual doses for PMVCs over eight years would avert an estimated 9,900,000 (95% CI 7,000,000-13,400,000) infections and 480,000 (180,000-1,140,000) deaths over the lifetime of vaccinees, corresponding to 1.7 (0.7-4.1) deaths averted per 1,000 vaccine doses. CONCLUSIONS: By estimating YF burden and vaccine impact over a range of spatial and temporal scales, while accounting for the specificity of urban transmission, our model can be used to inform the current EYE strategy.


Subject(s)
Cost of Illness , Disease Transmission, Infectious/prevention & control , Epidemics/prevention & control , Yellow Fever Vaccine/administration & dosage , Yellow Fever/epidemiology , Yellow Fever/prevention & control , Adolescent , Adult , Africa/epidemiology , Aged , Aged, 80 and over , Child , Child, Preschool , Epidemiologic Methods , Female , Humans , Infant , Infant, Newborn , Male , Middle Aged , Models, Statistical , Yellow Fever Vaccine/immunology , Young Adult
20.
Acta Trop ; 209: 105468, 2020 Sep.
Article in English | MEDLINE | ID: mdl-32416077

ABSTRACT

Arboviruses transmitted by Aedes mosquitoes are a growing global concern; however, there remain large gaps in surveillance of both arboviruses and their vectors in West Africa. We reviewed over 50 years of data including outbreak reports, peer-reviewed literature, and prior data compilations describing Zika, dengue, and chikungunya, and their vectors in West Africa. Large outbreaks of dengue, Zika, and chikungunya have recently occurred in the region with over 27,000 cases of Aedes-borne disease documented since 2007. Recent arboviral outbreaks have become more concentrated in urban areas, and Aedes albopictus, recently documented in the region, has emerged as an important vector in several areas. Seroprevalence surveys suggest reported cases are a gross underestimate of the underlying arboviral disease burden. These findings indicate a shifting epidemiology of arboviral disease in West Africa and highlight a need for increased research and implementation of vector and disease control. Rapid urbanization and climate change may further alter disease patterns, underscoring the need for improved diagnostic capacity, and vector and disease surveillance to address this evolving health challenge.


Subject(s)
Aedes/virology , Arbovirus Infections/epidemiology , Mosquito Vectors/virology , Africa, Western/epidemiology , Animals , Arbovirus Infections/transmission , Disease Outbreaks , Humans , Seroepidemiologic Studies
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