One assay to test them all: Multiplex assays for expansion of respiratory virus surveillance

Molecular multiplex assays (MPAs) for simultaneous detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza and respiratory syncytial virus (RSV) in a single RT-PCR reaction reduce time and increase efficiency to identify multiple pathogens with overlapping clinical presentation but different treatments or public health implications. Clinical performance of XpertXpress® SARS-CoV-2/Flu/RSV (Cepheid, GX), TaqPath™ COVID-19, FluA/B, RSV Combo kit (Thermo Fisher Scientific, TP), and PowerChek™ SARS-CoV-2/Influenza A&B/RSV Multiplex RT-PCR kit II (KogeneBiotech, PC) was compared to individual Standards of Care (SoC). Thirteen isolates of SARS-CoV-2, human seasonal influenza, and avian influenza served to assess limit of detection (LoD). Then, positive and negative residual nasopharyngeal specimens, collected under public health surveillance and pandemic response served for evaluation. Subsequently, comparison of effectiveness was assessed. The three MPAs confidently detect all lineages of SARS-CoV-2 and influenza viruses. MPA-LoDs vary from 1 to 2 Log10 differences from SoC depending on assay and strain. Clinical evaluation resulted in overall agreement between 97 and 100%, demonstrating a high accuracy to detect all targets. Existing differences in costs, testing burden and implementation constraints influence the choice in primary or community settings. TP, PC and GX, reliably detect SARS-CoV-2, influenza and RSV simultaneously, with reduced time-to-results and simplified workflows. MPAs have the potential to enhance diagnostics, surveillance system, and epidemic response to drive policy on prevention and control of viral respiratory infections.

Mosquito diversity (Diptera: Culicidae) and medical importance in four Cambodian forests

BACKGROUND

A total of 290 mosquito species are recorded in Cambodia among which 43 are known vectors of pathogens. As Cambodia is heavily affected by deforestation, a potential change in the dynamic of vector-borne diseases (VDBs) could occur through alteration of the diversity and density of sylvatic vector mosquitoes and induce an increase in their interactions with humans. Understanding mosquito diversity is therefore critical, providing valuable data for risk assessments concerning the (re)emergence of local VBDs. Consequently, this study mainly aimed to understand the spatial and temporal distribution of sylvatic mosquito populations of Cambodia by determining which factors impact on their relative abundance and presence.

METHODS

A study was conducted in 12 sites from four forests in Cambodia. All mosquitoes, collected during the dry and rainy seasons, were morphologically identified. The diversity and relative density of mosquito species in each site were calculated along with the influence of meteorological and geographical factors using a quasi-Poisson generalized linear model.

RESULTS

A total of 9392 mosquitoes were collected belonging to 13 genera and 85 species. The most represented genera were Culex, accounting for 46% of collected mosquitoes, and Aedes (42%). Besides being the most abundant species, Culex pseudovishnui and Aedes albopictus, which are known vectors of numerous arboviruses, were present in all sites during both dry and rainy seasons. The presence of mosquito species reported to be zoo-anthropophilic feeders was also observed in both forested and urban areas. Finally, this study demonstrated that altitude, temperature and precipitation impacted the abundance of mosquitoes but also influenced species community composition.

CONCLUSION

The results indicate an important diversity of mosquitoes in the four forests and an influence of meteorological and geographical factors on their community. Additionally, this work highlights in parallel the abundance of species considered to be of medical importance and therefore underlines the high risk of pathogen emergence/re-emergence in the region.

Influx of Backyard Farming with Limited Biosecurity Due to the COVID-19 Pandemic Carries an Increased Risk of Zoonotic Spillover in Cambodia

Backyard farming with limited biosecurity creates a massive potential for zoonotic spillover. Cambodia, a developing nation in Southeast Asia, is a hub for emerging and endemic infectious diseases. Due to pandemic-induced job losses in the tourism sector, rumors suggest that many former Cambodian tour guides have turned to backyard farming as a source of income and food security. A cross-sectional study including 331 tour guides and 69 poultry farmers in Cambodia before and during the novel coronavirus disease 2019 (COVID-19) pandemic was conducted. Participants were administered a survey to assess food security, income, and general farming practices. Survey data were collected to evaluate the risk perceptions for avian influenza virus (AIV), antimicrobial resistance (AMR), and general biosecurity management implemented on these poultry farms. Overall, food security decreased for 80.1% of the tour guides during the COVID-19 pandemic. Approximately 21% of the tour guides interviewed used backyard poultry farming to supplement losses of income and food insecurity during the COVID-19 pandemic, with a significantly higher risk than for traditional poultry farmers. Agricultural intensification in Cambodia due to the COVID-19 pandemic has caused an influx of makeshift farms with limited biosecurity. Inadequate biosecurity measures in animal farms can facilitate spillover and contribute to future pandemics. Improved biosecurity and robust viral surveillance systems are critical for reducing the risk of spillover from backyard farms. IMPORTANCE While this study highlights COVID-19-associated changes in poultry production at a small scale in Cambodia, poultry production is expected to expand due to an increase in the global demand for poultry protein during the pandemic, changes in urbanization, and the reduction of the global pork supply caused by African swine fever (ASF). The global demand and surge in poultry products, combined with inadequate biosecurity methods, can lead to an increased risk of domestic animal and human spillovers of zoonotic pathogens such as avian influenza. Countries in regions of endemicity are often plagued by complex emergency situations (i.e., food insecurity and economic fallouts) that hinder efforts to effectively address the emergence (or reemergence) of zoonotic diseases. Thus, novel surveillance strategies for endemic and emerging infectious diseases require robust surveillance systems and biosecurity training programs to prevent future global pandemics.

Dynamics of SARS-CoV-2 lineages in French Guiana in 2020-2021: 4 epidemic waves with cross-influences from Europe and South America

Since the first cases of SARS-CoV-2 infection in Wuhan in December 2019, this RNA virus gave rise to different viral lineages with different virological, epidemiological and immunological properties. Here we describe the dynamics of circulation of SARS-CoV-2 lineages in an Amazonian South American French overseas territory, French Guiana (FG). The data analyzed are based on the general epidemic course, and genomic surveillance data come from whole genome sequencing (WGS) as well as typing PCRs. From March 2020 to October 2021, four COVID-19 epidemic waves were observed in FG with an evolution of viral lineages influenced by virus introductions from continental France and above all by land-based introductions from neighbouring countries. The third epidemic wave from March to June 2021 was driven by a predominant Gamma introduced from Brazil and a less frequent Alpha introduced from France. This coexistence was completely substituted by Delta that initiated the fourth epidemic wave.

Transmission dynamics of Q fever in French Guiana: A population-based cross-sectional study

Background

Q fever is a zoonosis caused by Coxiella burnetii which is among the major agents of community-acquired pneumonia in French Guiana. Despite its relatively high incidence, its epidemiology in French Guiana remains unclear, and all previous studies have considered transmission from livestock unlikely, suggesting that a wild reservoir is responsible for transmission.

Methods

A country-wide seroprevalence survey of 2697 participants from French Guiana was conducted. Serum samples were tested for phase II IgG antibodies by ELISA and indirect immunofluorescence assays (IFAs). Factors associated with Q fever were investigated, and a serocatalytic model was used to reconstruct the annual force of infection.

Findings

The overall weighted seroprevalence was estimated at 9.6% (95% confidence interval (CI): 8.2%-11.0%). The model revealed constant, low-level circulation across French Guiana, particularly affecting middle-aged males (odds ratio (OR): 3.0, 95% credible interval (CrI): 1.7-5.8) and individuals living close to sheep farms (OR: 4, 95% CrI: 1.5-12). The overall annual number of cases was estimated at 579 (95% CrI: 492-670). In the region around Cayenne, the main urban municipality, the high seroprevalence was explained by an outbreak that may have occurred between 1996 and 2003 and that infected 10% (95% CrI: 6.9%-14%) of the population and males and females alike.

Interpretation

This study reveals for the first time Q fever dynamics of transmission and the role of domestic livestock in transmission in French Guiana and highlights the urgent need to reinforce Q fever surveillance in livestocks of the entire Guianese territory.

Funding

This study was supported by the "European Regional Development Fund" under EPI-ARBO grant agreement (GY0008695), the "Regional Health Agency of French Guiana" and the "National Center of Spatial Studies". The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Seroprevalence of anti-SARS-CoV-2 IgG at the first epidemic peak in French Guiana, July 2020

BACKGROUND

While Latin America has been heavily affected by the pandemic, only a few seroprevalence studies have been conducted there during the first epidemic wave in the first half of 2020.

METHODOLOGY/PRINCIPAL FINDINGS

A cross-sectional survey was performed between 15 July 2020 and 23 July 2020 among individuals who visited 4 medical laboratories or 5 health centers for routine screening or clinical management, with the exception of symptomatic suggestive cases of covid-19. Samples were screened for the presence of anti-SARS-CoV-2 IgG directed against domain S1 of the SARS-CoV-2 spike protein using the anti-SARS-CoV-2 enzyme-linked immunosorbent assay (ELISA) from Euroimmun.

CONCLUSIONS/SIGNIFICANCE

The overall seroprevalence was 15.4% [9.3%-24.4%] among 480 participants, ranging from 4.0% to 25.5% across the different municipalities. The seroprevalence did not differ according to gender (p = 0.19) or age (p = 0.51). Among SARS-CoV-2 positive individuals, we found that 24.6% [11.5%-45.2%] reported symptoms consistent with COVID-19. Our findings revealed high levels of infection across the territory but a low number of resulting deaths, which can be explained by French Guiana's young population structure.

Ecology, evolution, and epidemiology of zoonotic and vector-borne infectious diseases in French Guiana: Transdisciplinarity does matter to tackle new emerging threats

French Guiana is a European ultraperipheric region located on the northern Atlantic coast of South America. It constitutes an important forested region for biological conservation in the Neotropics. Although very sparsely populated, with its inhabitants mainly concentrated on the Atlantic coastal strip and along the two main rivers, it is marked by the presence and development of old and new epidemic disease outbreaks, both research and health priorities. In this review paper, we synthetize 15 years of multidisciplinary and integrative research at the interface between wildlife, ecosystem modification, human activities and sociodemographic development, and human health. This study reveals a complex epidemiological landscape marked by important transitional changes, facilitated by increased interconnections between wildlife, land-use change and human occupation and activity, human and trade transportation, demography with substantial immigration, and identified vector and parasite pharmacological resistance. Among other French Guianese characteristics, we demonstrate herein the existence of more complex multi-host disease life cycles than previously described for several disease systems in Central and South America, which clearly indicates that today the greater promiscuity between wildlife and humans due to demographic and economic pressures may offer novel settings for microbes and their hosts to circulate and spread. French Guiana is a microcosm that crystallizes all the current global environmental, demographic and socioeconomic change conditions, which may favor the development of ancient and future infectious diseases.

Evaluating the impact of curfews and other measures on SARS-CoV-2 transmission in French Guiana

While general lockdowns have proven effective to control SARS-CoV-2 epidemics, they come with enormous costs for society. It is therefore essential to identify control strategies with lower social and economic impact. Here, we report and evaluate the control strategy implemented during a large SARS-CoV-2 epidemic in June-July 2020 in French Guiana that relied on curfews, targeted lockdowns, and other measures. We find that the combination of these interventions coincided with a reduction in the basic reproduction number of SARS-CoV-2 from 1.7 to 1.1, which was sufficient to avoid hospital saturation. We estimate that thanks to the young demographics, the risk of hospitalisation following infection was 0.3 times that of metropolitan France and that about 20% of the population was infected by July. Our model projections are consistent with a recent seroprevalence study. The study showcases how mathematical modelling can be used to support healthcare planning in a context of high uncertainty.

Informing children citizens efficiently to better engage them in the fight against COVID-19 pandemic

Since the beginning of the year, the world’s attention has rightly been focused on the spread of the Coronavirus Disease 2019 (COVID-19) pandemic and the implementation of drastic mitigation strategies to limit disease transmission. However, public health information campaigns tailored to children are very rare. Now more than ever, at a time when some governments are taking populations out of lockdown and youth are returning to schools, children around the world need to fully grasp the modes of transmission of the disease, the health risks, the scientific notions of the immune system, the value of barrier measures, and the progress of scientific research. In the context of the COVID-19 pandemic, comics can be very useful for communicating quickly and effectively abstract and important information to children who might be under the influence of a large amount of sometimes contradictory information. Conveying precise, reliable, and accessible information to children is key in a world overwhelmingly impacted by the outbreak. This should be the role and the responsibility of world health official leaders and governments in compliance with the United Nations Convention on the Rights of the Child. In partnership with mainstream medias, consortia of scientists, communication experts, and education specialists, it is urgent that world leaders engage children in this worldwide public health fight.

Impact of Zika Virus Emergence in French Guiana: A Large General Population Seroprevalence Survey

BACKGROUND

Since the identification of Zika virus (ZIKV) in Brazil in May 2015, the virus has spread throughout the Americas. However, ZIKV burden in the general population in affected countries remains unknown.

METHODS

We conducted a general population survey in the different communities of French Guiana through individual interviews and serologic survey during June-October 2017. All serum samples were tested for anti-ZIKV immunoglobulin G antibodies using a recombinant antigen-based SGERPAxMap microsphere immunoassay, and some of them were further evaluated through anti-ZIKV microneutralization tests.

RESULTS

The overall seroprevalence was estimated at 23.3% (95% confidence interval [CI], 20.9%-25.9%) among 2697 participants, varying from 0% to 45.6% according to municipalities. ZIKV circulated in a large majority of French Guiana but not in the most isolated forest areas. The proportion of reported symptomatic Zika infection was estimated at 25.5% (95% CI, 20.3%-31.4%) in individuals who tested positive for ZIKV.

CONCLUSIONS

This study described a large-scale representative ZIKV seroprevalence study in South America from the recent 2015-2016 Zika epidemic. Our findings reveal that the majority of the population remains susceptible to ZIKV, which could potentially allow future reintroductions of the virus.

ZIKA Virus infection in pregnant women in French Guiana: More precarious-more at risk

Background

A recent study in French Guiana suggested that populations living in precarious neighborhoods were more at risk for Chikungunya CHIKV than those living in more privileged areas. The objective of the present study was to test the hypothesis that Zika virus (ZIKV) infection was more frequent in precarious pregnant women than in non-precarious pregnant women, as reflected by their health insurance status.

Methods

A multicentric cross-sectional study was conducted in Cayenne hospital including ZIKV pregnant women with serological or molecular proof of ZIKV during their pregnancy between January and December 2016. Health insurance information was recorded at delivery, which allowed separating women in: undocumented foreigners, precarious but with residence permit, and non-precarious.

Results

A total of 6654 women were included. Among them 1509 (22,7%) had confirmed ZIKV infection. Most women were precarious (2275/3439) but the proportion of precarious women was significantly greater in ZIKV-confirmed 728/906 (80.4%) than the ZIKV-negatives 1747/2533 (69.0%), p<0.0001. There were 1142 women classified as non-precarious, 1671 were precarious legal residents, and 1435 were precarious and undocumented. Precariousness and undocumented status were associated with a higher prevalence of ZIKV during pregnancy (adjusted prevalence ratio = 1.59 (95%CI = 1.29–1.97), p<0.0001), (adjusted prevalence ratio = 1.5 (95%CI = 1.2–1.8), p<0.0001), respectively.

Conclusions

These results illustrate that in French Guiana ZIKV transmission disproportionately affected the socially vulnerable pregnant women, presumably because of poorer housing conditions, and lack of vector control measures in poor neighborhoods.

A recent study in French Guiana suggested that populations living in precarious neighborhoods were more at risk for chikungunya CHIKV than those living in more privileged areas. The objective of the present study was to test the hypothesis that Zika virus (ZIKV) infection was more frequent in precarious pregnant women than in non-precarious pregnant women as reflected by their health insurance status. A multicenter cross-sectional study was conducted including ZIKV pregnant women with serological or molecular proof of ZIKV during their pregnancy between January and December 2016. Health insurance information was recorded at delivery, which allowed separating women into: undocumented foreigners, precarious but with residence permit, and non-precarious. Overall 6654 women were included. Among them, 1509 (22,7%) had confirmed ZIKV infection. The majority of women were precarious, but the proportion of precarious women was significantly greater in ZIKV-confirmed 728/906 (80.4%) than the ZIKV-negatives 1747/2533 (69.0%). Precariousness and undocumented status were associated with a higher prevalence of ZIKV acquisition during pregnancy. The present results illustrate that in French Guiana, as elsewhere, ZIKV transmission disproportionately affected the socially vulnerable pregnant women, presumably because of poorer housing conditions, and lack of vector control measures in poor neighborhoods.

Vaccination coverage in the context of the emerging Yellow Fever threat in French Guiana

Background

French Guiana, a French overseas department located in South America between Brazil and Surinam, is the only European territory geographically located in the Amazonian forest complex and is considered endemic for yellow fever (YF).

In the context of the emergent threat of YF in Latin America, we conducted a large household cross-sectional survey from June to October 2017 to estimate vaccination coverage in the population and to determine associations with sociodemographic and geographical characteristics.

Methodology/Principal findings

In total, 1,415 households and 2,697 individuals were included from the 22 municipalities of French Guiana. YF vaccination coverage was estimated at 95.0% (95% CI: 93.4–96.2) in the entire territory but was spatially heterogeneous, with the lowest levels estimated in the western part of the territory along the Surinamese cross-border region, particularly in children under 16 years who were not enrolled in school, immigrant adults and disadvantaged populations with low socioeconomic indexes.

Conclusions/Significance

Despite the good vaccination coverage against YF in the general population of French Guiana resulting from the compulsory nature of YF vaccination for residents and travelers, there is an urgent need to improve vaccination coverage in vulnerable populations living in the northwestern part of the territory to limit the risk of transmission in the context of the emerging YF threat in South America.

Despite the relative rarity of YF and the significant number of infectious and tropical diseases in French Guiana, clinicians should adopt a high index of suspicion for YF, particularly in vulnerable and at-risk populations.

Yellow fever (YF) is the most severe arbovirus to circulate in the Americas. French Guiana, a French overseas department located in South America between Brazil and Surinam, is the only European territory geographically located in the Amazonian forest complex and is considered endemic for YF. We conducted a large general population survey from June to October 2017 to estimate vaccination coverage in the population and to identify target vulnerable populations for catch-up vaccination strategies. In total, 1,415 households and 2,697 individuals were included from the 22 municipalities of French Guiana. YF vaccination coverage was estimated at 95.0% (95% CI: 93.4–96.2) in the entire territory but was spatially heterogeneous, with the lowest levels estimated in the western part of the territory along the Surinamese cross-border region, particularly in children under 16 years who were not enrolled in school, immigrant adults and disadvantaged groups of populations with low socioeconomic indexes. Our findings showed that vaccination campaigns should be prioritized and adapted to improve vaccination coverage among vulnerable populations living in the northwestern part of the territory to limit the risk of transmission in the context of the emerging YF threat in South America. Despite the relative rarity of YF and the significant number of infectious and tropical diseases in French Guiana, clinicians should adopt a high index of suspicion for YF, particularly in vulnerable and at-risk populations.

Understanding health behaviour changes in response to outbreaks: Findings from a longitudinal study of a large epidemic of mosquito-borne disease

RATIONALE

Although greater attention has been recently given to the ecological determinants of health behaviours, we still do not know much about the behavioural changes induced by the spread of infectiousdiseases.

OBJECTIVE

In this study, we took advantage of a large epidemic of chikungunya, an emerging mosquito-borne disease, in French Guiana to examine the dynamic interaction between risk-related perceptions and behaviours that occurs in response to a disease outbreak. In particular, we tested empirically the assumption that both risk perceptions and health behaviours were elastic with respect to prevalence of chikungunya.

METHODS

A representative sample of French Guianan (N=434) was interviewed in January 2015 just after the peak of the epidemic, and again 2 months later. Participants were asked about their perceptions of the threat, as well as their engagement in a range of protective behaviours promoted by the regional health authorities to control the spread of the disease.

RESULTS

The surveys showed that (1) the frequency of some health behaviours - those related to visible control methods - significantly increased with the subjective and objective prevalence of the disease, (2) perceived risk of infection for oneself tended to decrease considerably over time, and (3) the risk reappraisal hypothesis failed to account for this paradoxical trend in the people's response to the risk of contracting the disease.

CONCLUSION

These findings suggest that people may fail to adjust their risk perceptions, and to a lesser extent their health protective behaviours, to the course of an epidemic. Notably, the prevalence elasticity of preventive action found in previous studies of behavioural response to infectious diseases differed substantially according to the type of intervention (personal versus environmental methods). This paradoxical trend may be attributed to risk habituation effects, which seem to vary significantly according to the social visibility of thepreventive actions.

Current challenges and implications for dengue, chikungunya and Zika seroprevalence studies worldwide: A scoping review

BACKGROUND

Arboviral infections are a public health concern and an escalating problem worldwide. Estimating the burden of these diseases represents a major challenge that is complicated by the large number of unapparent infections, especially those of dengue fever. Serological surveys are thus required to identify the distribution of these diseases and measure their impact. Therefore, we undertook a scoping review of the literature to describe and summarize epidemiological practices, findings and insights related to seroprevalence studies of dengue, chikungunya and Zika virus, which have rapidly expanded across the globe in recent years.

METHODOLOGY/PRINCIPAL FINDINGS

Relevant studies were retrieved through a literature search of MEDLINE, WHOLIS, Lilacs, SciELO and Scopus (2000 to 2018). In total, 1389 publications were identified. Studies addressing the seroprevalence of dengue, chikungunya and/or Zika written in English or French and meeting the inclusion and exclusion criteria were included. In total, 147 studies were included, from which 185 data points were retrieved, as some studies used several different samples. Most of the studies were exclusively conducted on dengue (66.5%), but 16% were exclusively conducted on chikungunya, and 7 were exclusively conducted on Zika; the remainder were conducted on multiple arboviruses. A wide range of designs were applied, but most studies were conducted in the general population (39%) and in households (41%). Although several assays were used, enzyme-linked immunosorbent assays (ELISAs) were the predominant test used (77%). The temporal distribution of chikungunya studies followed the virus during its rapid expansion since 2004. The results revealed heterogeneity of arboviruses seroprevalence between continents and within a given country for dengue, chikungunya and Zika viruses, ranging from 0 to 100%, 76% and 73% respectively.

CONCLUSIONS/SIGNIFICANCE

Serological surveys provide the most direct measurement for defining the immunity landscape for infectious diseases, but the methodology remains difficult to implement. Overall, dengue, chikungunya and Zika serosurveys followed the expansion of these arboviruses, but there remain gaps in their geographic distribution. This review addresses the challenges for researchers regarding study design biases. Moreover, the development of reliable, rapid and affordable diagnosis tools represents a significant issue concerning the ability of seroprevalence surveys to differentiate infections when multiple viruses co-circulate.

Zika virus outbreak in Suriname, a report based on laboratory surveillance data

INTRODUCTION

Since the identification of ZIKV in Brazil in May 2015, the virus has spread extensively throughout the Americas. Cases of ZIKV infection have been reported in Suriname since October 2, 2015.

METHODS

A laboratory-based surveillance system was quickly implemented according to previous experience with the emergence of chikungunya. General practitioners and public health centers located in different districts of Suriname were asked to send blood samples from suspicious cases to Academic Hospital for molecular diagnosis of Zika virus infection. We investigated Zika-related laboratory data collected during surveillance and response activities to provide the first outbreak report in Suriname in terms of time, location and person.

RESULTS

A total of 791 molecularly confirmed cases were reported during a 48-week interval from October 2015 to August 2016. The majority of ZIKV-positive cases involved women between 20 and 39 years of age, reflecting concern about Zika infection during pregnancy. The outbreak peaked in mid-January and gradually spread from the district of Paramaribo to western coastal areas.

DISCUSSION

This report provides a simple and comprehensive description of the outbreak in Suriname and demonstrates the utility of laboratory data to highlight the spatiotemporal dynamics of the outbreak in that country.

The proportion of asymptomatic infections and spectrum of disease among pregnant women infected by Zika virus: systematic monitoring in French Guiana, 2016

Zika virus (ZIKV) infection has been associated with complications during pregnancy. Although the presence of symptoms might be a risk factor for complication, the proportion of ZIKV-infected pregnant women with symptoms remains unknown. Following the emergence of ZIKV in French Guiana, all pregnancies in the territory were monitored by RT-PCR and/or detection of ZIKV antibodies. Follow-up data collected during pregnancy monitoring interviews were analysed from 1 February to 1 June 2016. We enrolled 3,050 pregnant women aged 14–48 years and 573 (19%) had laboratory-confirmed ZIKV infection. Rash, arthralgia, myalgia and conjunctival hyperaemia were more frequently observed in ZIKV-positive women; 23% of them (95% confidence interval (CI): 20–27) had at least one symptom compatible with ZIKV infection. Women 30 years and older were significantly more likely to have symptoms than younger women (28% vs 20%). The proportion of symptomatic infections varied from 17% in the remote interior to 35% in the urbanised population near the coast (adjusted risk ratio: 1.6; 95% CI: 1.4–1.9.). These estimates put findings on cohorts of symptomatic ZIKV-positive pregnant women into the wider context of an epidemic with mainly asymptomatic infections. The proportion of symptomatic ZIKV infections appears to vary substantially between populations.

Are Perceived Prevalences of Infection also Biased and How? Lessons from Large Epidemics of Mosquito-Borne Diseases in Tropical Regions

BACKGROUND

Although people are likely to underestimate the frequencies of risks to health from common diseases and overestimate those from rare diseases, we still do not know much about reasons for this systematic bias, which is also referred to as "primary bias" in the literature. In this study, we take advantage of a series of large epidemics of mosquito-borne diseases to examine the accuracy of judgments of risk frequencies. In this aim, we assessed the perceived v. observed prevalence of infection by Zika, chikungunya or dengue fever during these outbreaks, as well as their variations among different subpopulations and epidemiological settings.

METHODS

We used data drawn from 4 telephone surveys, conducted between 2006 and 2016, among representative samples of the adult population in tropical regions (Reunion, Martinique, and French Guiana). The participants were asked to estimate the prevalence of these infections by using a natural frequency scale.

RESULTS

The surveys showed that 1) most people greatly overestimated the prevalence of infection by arbovirus, 2) these risk overestimations fell considerably as the actual prevalence of these diseases increased, 3) the better-educated and male participants consistently yielded less inaccurate risk estimates across epidemics, and 4) these biases in the perception of prevalence of these infectious diseases are relatively well predicted by the probability weighting function developed in the field of behavioral decision making.

CONCLUSIONS

These findings suggest that the primary bias, which has been found in laboratory experiments to characterize a variety of probabilistic judgments, equally affects perception of prevalence of acute infectious diseases in epidemic settings. They also indicate that numeracy may play a considerable role in people's ability to transform epidemiological observations from their social environment to more accurate risk estimates.

Emerging trends of Zika apprehension in an epidemic setting

Background

French Guiana is a territory that has a decades-long history of dengue outbreaks and more recently, in 2014, a chikungunya outbreak. Zika virus (ZIKV) emerged in late 2015 and subsequently led to an important outbreak.

Methodology/Principal findings

A cross-sectional phone survey was conducted among the general population during the outbreak in June 2016 with a total of 1,129 individuals interviewed to assess perceptions, knowledge and behaviors regarding zika infection. The population seemed aware of zika, and perceived the infection as a more serious health threat than other common mosquito-borne diseases. Furthermore, both the perceptions and behaviors related to zika and its prevention were found to vary considerably among different social groups, geographic areas and gender; less educated female participants were found to perceive the disease as more worrisome and were less likely to adopt protective behaviors. Moreover, female population has been particularly responsive to awareness campaigns and rapidly understood the extent of risks associated with ZIKV infection.

Conclusions/Significance

These results revealed that ZIKV appeared at the time of the survey as a new health threat that concerns the public more than chikungunya and dengue fever with differences observed among subgroups of population. These results have implications for the development of multifaceted infection control programs, including strategies for prevention and awareness, helping the population to develop an accurate perception of the threat they are facing and encouraging behavior changes.

Although dengue fever has been a focus of many awareness campaigns in Latin America, very little information is available about beliefs, attitudes and behaviors regarding vector-borne diseases among the population of French Guiana. Following the end of the first chikungunya outbreak and at the initial onset of the first zika outbreak, a quantitative survey was conducted among 1129 individuals aiming to study the emotional, cognitive and behavioral response to the risk of zika infection and assess variations among different groups of population. People from French Guiana were found to perceive zika substantially differently from other Aedes mosquito-borne diseases. Overall, ZIKV appeared at the time of the survey as a new health threat that makes the population more scared than chikungunya and dengue fever. Furthermore, both the beliefs and behaviors related to zika and its prevention were found to vary considerably among different social groups, gender and geographic areas. Education had an impact on perceptions and behaviors among women. Female population has been particularly responsive to awareness campaigns and rapidly understood the extent of risks associated with ZIKV infection. Overall, findings emphasize the importance of developing appropriate and relevant strategies helping population to engage in protective behaviors adapted to the health threat they are facing. Given the importance of the public response and precautionary actions to control the spread of an emergent threat, additional research on risk perceptions and other behavioral determinants is warranted.

The Role of Risk Proximity in the Beliefs and Behaviors Related to Mosquito-Borne Diseases: The Case of Chikungunya in French Guiana

Human behaviors are increasingly recognized to play a key role in the spread of infectious diseases. Although a set of social and cognitive determinants has been consistently found to affect the adoption of health protective behaviors aiming to control and prevent a variety of infections, little is currently known about the ecological drivers of these behaviors in epidemic settings. In this article, we took advantage of the outbreak of chikungunya, a reemerging mosquito-borne disease, that occurred in French Guiana in 2014–15 to test empirically the assumption proposed by Zielinski-Gutierrez and Hayden that the proximity of the disease and perceptions of the natural environment may considerably shape public response to an emerging health threat. To achieve this, a cross-sectional survey was conducted among high school students of the region (N = 1462) at an early stage of the epidemic. Surprisingly, spatial analysis of the collected data leads to counterintuitive results as the participants who lived in the most affected area expressed less concern about the disease and practiced preventive behaviors less frequently than did other participants. These paradoxical results may be attributed to the possible activation of risk denial processes which have previously been observed in the risk perception literature, and described by several social and psychological defensiveness theories.

Knowledge, Attitude and Practices of Vector-Borne Disease Prevention during the Emergence of a New Arbovirus: Implications for the Control of Chikungunya Virus in French Guiana

Background

During the last decade, French Guiana has been affected by major dengue fever outbreaks. Although this arbovirus has been a focus of many awareness campaigns, very little information is available about beliefs, attitudes and behaviors regarding vector-borne diseases among the population of French Guiana. During the first outbreak of the chikungunya virus, a quantitative survey was conducted among high school students to study experiences, practices and perceptions related to mosquito-borne diseases and to identify socio-demographic, cognitive and environmental factors that could be associated with the engagement in protective behaviors.

Methodology/Principal Findings

A cross-sectional survey was administered in May 2014, with a total of 1462 students interviewed. Classrooms were randomly selected using a two-stage selection procedure with cluster samples. A multiple correspondence analysis (MCA) associated with a hierarchical cluster analysis and with an ordinal logistic regression was performed. Chikungunya was less understood and perceived as a more dreadful disease than dengue fever. The analysis identified three groups of individual protection levels against mosquito-borne diseases: “low” (30%), “moderate” (42%) and “high” (28%)”. Protective health behaviors were found to be performed more frequently among students who were female, had a parent with a higher educational status, lived in an individual house, and had a better understanding of the disease.

Conclusions/Significance

This study allowed us to estimate the level of protective practices against vector-borne diseases among students after the emergence of a new arbovirus. These results revealed that the adoption of protective behaviors is a multi-factorial process that depends on both sociocultural and cognitive factors. These findings may help public health authorities to strengthen communication and outreach strategies, thereby increasing the adoption of protective health behaviors, particularly in high-risk populations.

Although dengue fever has been a focus of many awareness campaigns in Latin America, very little information is available about beliefs, attitudes and behaviors regarding vector-borne diseases among the population of French Guiana. At the initial onset of the first chikungunya outbreak, a quantitative survey was conducted among 1462 high school students aiming to study experiences, practices and perceptions related to mosquito-borne diseases and to identify factors that could be associated with protective behaviors. Chikungunya was less understood and perceived as a more dreadful disease than dengue fever. Students were clustered in three different groups according to their level of protection: “low” (30%), “moderate” (42%) and “high” (28%). Protective health behaviors were found to be performed more frequently among students who were female, lived with a parent who had a higher educational status, lived in an individual house, and had a better understanding of the disease. The results revealed that the adoption of protective behaviors is a multi-factorial process that depends on both socio-economic and cognitive factors. These findings may help the public health authorities to strengthen their communication and outreach strategy, thereby increasing the adoption of protective health behaviors, particularly in endemic countries and high-risk populations.

Predicting Dengue Fever Outbreaks in French Guiana Using Climate Indicators

BACKGROUND

Dengue fever epidemic dynamics are driven by complex interactions between hosts, vectors and viruses. Associations between climate and dengue have been studied around the world, but the results have shown that the impact of the climate can vary widely from one study site to another. In French Guiana, climate-based models are not available to assist in developing an early warning system. This study aims to evaluate the potential of using oceanic and atmospheric conditions to help predict dengue fever outbreaks in French Guiana.

METHODOLOGY/PRINCIPAL FINDINGS

Lagged correlations and composite analyses were performed to identify the climatic conditions that characterized a typical epidemic year and to define the best indices for predicting dengue fever outbreaks during the period 1991-2013. A logistic regression was then performed to build a forecast model. We demonstrate that a model based on summer Equatorial Pacific Ocean sea surface temperatures and Azores High sea-level pressure had predictive value and was able to predict 80% of the outbreaks while incorrectly predicting only 15% of the non-epidemic years. Predictions for 2014-2015 were consistent with the observed non-epidemic conditions, and an outbreak in early 2016 was predicted.

CONCLUSIONS/SIGNIFICANCE

These findings indicate that outbreak resurgence can be modeled using a simple combination of climate indicators. This might be useful for anticipating public health actions to mitigate the effects of major outbreaks, particularly in areas where resources are limited and medical infrastructures are generally insufficient.

Knowledge, attitudes, behaviors, and practices differences regarding HIV in populations living along the Maroni river: particularities of operational interest for Amerindian and Maroon populations

The Maroni basin, an isolated region delineating the border between Suriname and French Guiana has been affected by the human immunodeficiency virus (HIV) epidemic 10 years after coastal French Guiana. However, the rise in HIV prevalence was sharp, exceeding 1% within 10 years. The aim of the present study is to compare, using the first quantitative data from the general population in remote villages, the knowledge, attitudes, and behaviors regarding HIV between Maroon and Amerindian populations, the two most frequent populations living along the Maroni. Data were collected in 2012 using a structured questionnaire among a random sample of 896 individuals residing in the remote villages on the Maroni river. Proportions were compared between the Maroni and the coastal general population, and between Maroon and Amerindian populations. The present study shows significant differences between territories and between communities living on the Maroni river: the multiple sexual partnerships, more common among population living on the Maroni river, were more frequently reported in Maroons than in Amerindians. Condom use was more frequently reported among men on the Maroni river than on the coast, but these findings were reversed for women. Moreover, among people living on the Maroni river, condom use was more frequently reported among Maroons than among Amerindians. Regarding genital factors that may affect transmission, penile implant seemed to have no ethnic boundaries, steam baths seemed specific to Maroon women. The present results should help to improve community-based specific interventions.

Recent epidemiological trends of dengue in the French territories of the Americas (2000-2012): a systematic literature review

Dengue is a public health concern across the globe, and an escalating problem in the Americas. As part of a wider programme (covering Latin America and South East Asia) to characterize the epidemiology of dengue in dengue endemic areas, we undertook a systematic literature review to assess epidemiological trends (incidence, timing and duration of outbreaks/epidemics, age and sex distribution, serotype distribution, seroprevalence and disease severity) for dengue across the French Territories of the Americas (FTA), in French Guiana, Guadeloupe, Martinique, Saint Martin and Saint Barthélemy between 2000 and 2012 (CRD42012002341: http://www.crd.york.ac.uk/prospero/display_record.asp?ID=CRD42012002341). Of 413 relevant data sources identified, 45 were eligible for inclusion. A large proportion of the available data were from national surveillance reports, and 12 publications were from peer-reviewed journals. During the review period, 3-5 epidemics were identified in each of the island territories and French Guiana, and epidemics were often associated with a shift in the predominant circulating dengue virus serotype. Substantial gaps in epidemiological knowledge were identified. In particular, information regarding dengue virus genotype distribution, seroprevalence and age distribution of dengue were lacking. Additionally, much of the available data were from epidemic years; data from inter-epidemic periods were sparse. Nevertheless, the available epidemiological data showed that dengue is endemic across the FTA and suggest an evolution towards hyperendemicity, highlighting the need to continue the efforts with the existing surveillance programmes to assist in planning an effective vaccination programme once a dengue vaccine is deployed.

PROTOCOL REGISTRATION

PROSPERO CRD42012002341.

Mining local climate data to assess spatiotemporal dengue fever epidemic patterns in French Guiana

OBJECTIVE

To identify local meteorological drivers of dengue fever in French Guiana, we applied an original data mining method to the available epidemiological and climatic data. Through this work, we also assessed the contribution of the data mining method to the understanding of factors associated with the dissemination of infectious diseases and their spatiotemporal spread.

METHODS

We applied contextual sequential pattern extraction techniques to epidemiological and meteorological data to identify the most significant climatic factors for dengue fever, and we investigated the relevance of the extracted patterns for the early warning of dengue outbreaks in French Guiana.

RESULTS

The maximum temperature, minimum relative humidity, global brilliance, and cumulative rainfall were identified as determinants of dengue outbreaks, and the precise intervals of their values and variations were quantified according to the epidemiologic context. The strongest significant correlations were observed between dengue incidence and meteorological drivers after a 4-6-week lag.

DISCUSSION

We demonstrated the use of contextual sequential patterns to better understand the determinants of the spatiotemporal spread of dengue fever in French Guiana. Future work should integrate additional variables and explore the notion of neighborhood for extracting sequential patterns.

CONCLUSIONS

Dengue fever remains a major public health issue in French Guiana. The development of new methods to identify such specific characteristics becomes crucial in order to better understand and control spatiotemporal transmission.

Prevalence and predictive factors of stigmatizing attitudes towards people living with HIV in the remote villages on the Maroni River in French Guiana

The Maroni basin, an isolated region which lies between Suriname and French Guiana, has been affected by the HIV epidemic 10 years after coastal French Guiana. However, the rise in HIV prevalence was sharp with a prevalence exceeding 1% within 10 years. Stigma and discrimination towards people living with HIV (PLWHIV) or "suspected to have HIV" is rampant as reported by health professionals or non-governmental organisations. The objective of this article is to present the first quantitative data from the general population of this region on stigma towards people living with HIV. Data were collected in 2012 by a structured questionnaire among a random sample of 896 individuals residing in remote villages on the Maroni River. Proportion comparisons between the Maroni sample and the sample from the general population on the coastline in 2011 were conducted. Simple and multivariate logistic regression models were used to predict stigmatising attitudes. For all situations involving PLWHIV, the proportion of negative attitudes was significantly higher on the Maroni than in coastal French Guiana (p < 0.001). Findings indicate that the different levels of knowledge, erroneous beliefs and poor situation (not having electricity in one's home; not having French health insurance) were associated with stigmatising attitudes. The present data could help both sides coordinate interventions both at the individual level by improving knowledge and at the community level to change norms in order to reduce stigma and discrimination aiming for increased impact.

Dengue epidemics and adverse obstetrical outcomes in French Guiana: a semi-ecological study

OBJECTIVE

To determine whether dengue epidemics are associated with an increase in adverse obstetrical outcomes.

METHODS

Semi-ecological study combining individual data on obstetrical events from the perinatal registry and aggregated exposure data from the epidemiologic surveillance of dengue in Cayenne, French Guiana between 2004 and 2007.

RESULTS

After adjustment for individual risk factors, analysis showed that an epidemic level of dengue transmission during the first trimester was associated with an increased risk of post-partum haemorrhage and preterm birth. The associated risks seemed to depend on the epidemic level.

CONCLUSIONS

Despite its limitations, this study suggests that dengue in the first trimester may be related to preterm birth and to post-partum bleeding, thus leading to specific hypotheses that should be tested in prospective studies.

Risk of rabies transmission and adverse effects of postexposure prophylaxis in health care workers exposed to a fatal case of human rabies

On May 27, 2008, a patient died from rabies at the Cayenne Hospital in French Guiana. Postexposure prophylaxis vaccination was implemented for all health care workers exposed to this patient. Examining the management of such a rare risk reveals important factors in the education of personnel who may have contact with a patient with rabies, to permit appropriate risk assessment and reduce unnecessary postexposure prophylaxis, taking into account the risks and costs of adverse events.

Investigation of a sudden malaria outbreak in the isolated Amazonian village of Saul, French Guiana, January-April 2009

Malaria is endemic in French Guiana. Plasmodium falciparum and Plasmodium vivax are the predominant species responsible and Anopheles darlingi is described as the major vector. In mid-August 2008, an increase in malaria incidence was observed in Saül. A retrospective cohort survey was performed. In vitro susceptibility profiles to antimalarials were determined on P. falciparum isolates. Collections of mosquitoes were organized. The malaria attack rate reached 70.6/100. The risk of malaria increased for people between 40 and 49 years of age, living in a house not subjected to a recent indoor residual insecticide spraying or staying overnight in the surrounding forest. All isolates were susceptible. Anopheles darlingi females and larvae were collected in the village suggesting a local transmission. Our results strongly support a role of illegal mining activities in the emergence of new foci of malaria. Therefore, public health authorities should define policies to fight malaria at a transborder level.

First human rabies case in French Guiana, 2008: epidemiological investigation and control

BACKGROUND

Until 2008, human rabies had never been reported in French Guiana. On 28 May 2008, the French National Reference Center for Rabies (Institut Pasteur, Paris) confirmed the rabies diagnosis, based on hemi-nested polymerase chain reaction on skin biopsy and saliva specimens from a Guianan, who had never travelled overseas and died in Cayenne after presenting clinically typical meningoencephalitis.

METHODOLOGY/PRINCIPAL FINDINGS

Molecular typing of the virus identified a Lyssavirus (Rabies virus species), closely related to those circulating in hematophagous bats (mainly Desmodus rotundus) in Latin America. A multidisciplinary Crisis Unit was activated. Its objectives were to implement an epidemiological investigation and a veterinary survey, to provide control measures and establish a communications program. The origin of the contamination was not formally established, but was probably linked to a bat bite based on the virus type isolated. After confirming exposure of 90 persons, they were vaccinated against rabies: 42 from the case's entourage and 48 healthcare workers. To handle that emergence and the local population's increased demand to be vaccinated, a specific communications program was established using several media: television, newspaper, radio.

CONCLUSION/SIGNIFICANCE

This episode, occurring in the context of a Department far from continental France, strongly affected the local population, healthcare workers and authorities, and the management team faced intense pressure. This observation confirms that the risk of contracting rabies in French Guiana is real, with consequences for population educational program, control measures, medical diagnosis and post-exposure prophylaxis.

The epidemiologic surveillance of dengue-fever in French Guiana: when achievements trigger higher goals

The epidemiology of dengue fever in French Guiana is marked by a combination of permanent transmission of the virus in the whole country and the occurrence of regular epidemics. Since 2006, a multi data source surveillance system was implemented to monitor dengue fever patterns, to improve early detection of outbreaks and to allow a better provision of information to health authorities, in order to guide and evaluate prevention activities and control measures. This report illustrates the validity and the performances of the system. We describe the experience gained by such a surveillance system and outline remaining challenges. Future works will consist in the use of other data sources such as environmental factors in order to improve knowledge on virus transmission mechanisms and determine how to use them for outbreaks prediction.

[Epidemic of influenza A(H1N1) 2009 in the French overseas territories of the Americas: epidemiological surveillance set up and main results, April 2009-January 2010]

Guadeloupe, French Guiana, Martinique, St. Martin and St. Barthelemy were the French territories most exposed to the new influenza A(H1N1)v, and adequate epidemiological surveillance tools were promptly developed in order to detect its emergence. The first stage, "containment phase", consisted in detection and management of individual cases. Then, when an autochthonous A(H1N1)v circulation was confirmed, its evolution has been monitored within the whole population, mainly through data collected from sentinel doctors' networks and virological surveillance. This allowed to detect very early the occurrence of epidemics, and to follow their evolution until they were over. Like all the other Caribbean countries, the five French overseas territories were hit by an outbreak of influenza A(H1N1)v. Although they had globally similar characteristics, each epidemic had its specificity in terms of scale and severity. They started between August and September 2009 in four of the five territories, while the last one, St. Barthelemy, was not affected until the end of the year. Attack rate estimates varied from 28 to 70 per 1000 inhabitants according to the territory, and hospitalisation rate varied from 4.3 to 10.3 per 1000 cases. Severity rate didn't reach 1 per 1000 cases in any of the territories. Compared to metropolitan France, the surveillance system presented several strengths, including the pre-existence of both an active sentinel network and an expert committee on emerging diseases in each territory. On the other hand, specific difficulties appeared, notably linked with logistical aspects of virological surveillance and the co-circulation of dengue virus in Guadeloupe and St. Barthelemy. Despite these difficulties, the different tools allowed early detection of the epidemics and follow-up of their evolution. All of them lead to very concordant results, suggesting that they are completely appropriate to monitor a potential new epidemic wave.

Validation of a syndromic surveillance system using a general practitioner house calls network, Bordeaux, France

A new syndromic surveillance system has been developed in Bordeaux City, South West France, using a general practitioners' house calls network. Routinely collected, sociodemographic data, patients' complaints and medical diagnoses made at the end of the visit were monitored using syndrome groups such as influenza syndromes, bronchiolitis, gastrointestinal, respiratory syndromes and others, based on International Classification of Primary Care (ICPC)-2 codes. A process control chart was implemented in order to distinguish signals of interest from "background noise". In 2005 and 2006, a total of 303,936 visits were recorded. Seasonal epidemics of influenza-like illness, bronchiolitis or gastrointestinal were identified. The automated and real time nature of the system also allowed the early detection of unusual events such as an acute increase in the number of heat syndromes during the heat-wave that occurred in France in July 2006. This new system complements existing surveillance programs by assessing a large part of episodes of illness that do not require hospital admissions or the identification of an etiologic agent. Attributes and advantages of the system, such as timeliness and diagnostic specificity, demonstrated its utility and validity in term of syndromic surveillance purposes, and its extension at the national level is in process.

Validation of a syndromic surveillance system using a general practitioner house calls network, Bordeaux, France

Binary file ES_Abstracts_Final_ECDC.txt matches

Impact of subsistence production on the management options to reduce the food exposure of the Martinican population to Chlordecone

Chlordecone is an organochlorine insecticide used until 1993 in the banana plantations of the French Antilles. Recent surveys revealed its wide presence in the environment. This current paper focuses on the impact of different management options on the Martinican population's food exposure, taking into account that an appreciable part of the food consumed in Martinique corresponds to subsistence production. Food exposure is assessed through deterministic models. Consumption data derive from the ESCAL Survey on 1814 subjects aged 3 and over. Residues data come from the Monitoring Programs 2002-2004. Different scenarios are studied depending on whether the subjects live on a soil-contaminated place or not and on their supply habits. The impact of various maximum limits is then analysed. The probability of exceeding the chronic health-based guidance value (CHGV) of 0.5 microg/kg bw/day is, respectively, 20.9% (CI(95th) [6.2; 34.4]) and 15.6% (CI(95th) [9.6; 20.8]) for children and adults living in a soil-contaminated area and null for the remaining population. MLs below 300 microg/kg fw would reduce significantly the exposure but the probability of exceeding the CHGV remains statistically different from zero when only commercialised products are taken into account. This study shows the supply habits may have significant impacts on food exposure to contaminants. It reveals that setting MLs, which can only be controlled on commercialised products, is not enough in such situations. Other management options like consumption recommendations for self-produced foodstuffs are necessary to protect the Martinican consumer.