Poverty and Arbovirus Outbreaks: When Chikungunya Virus Hits More Precarious Populations Than Dengue Virus in French Guiana

Pathogenicity and virulence of chikungunya virus

Chikungunya virus (CHIKV) is a mosquito-transmitted, RNA virus that causes an often-severe musculoskeletal illness characterized by fever, joint pain, and a range of debilitating symptoms. The virus has re-emerged as a global health threat in recent decades, spreading from its origin in Africa across Asia and the Americas, leading to widespread outbreaks impacting millions of people. Despite more than 50 years of research into the pathogenesis of CHIKV, there is still no curative treatment available. Current management of CHIKV infections primarily involves providing supportive care to alleviate symptoms and improve the patient's quality of life. Given the ongoing threat of CHIKV, there is an urgent need to better understand its pathogenesis. This understanding is crucial for deciphering the mechanisms underlying the disease and for developing effective strategies for both prevention and management. This review aims to provide a comprehensive overview of CHIKV and its pathogenesis, shedding light on the complex interactions of viral genetics, host factors, immune responses, and vector-related factors. By exploring these intricate connections, the review seeks to contribute to the knowledge base surrounding CHIKV, offering insights that may ultimately lead to more effective prevention and management strategies for this re-emerging global health threat.

The role of health mediation in investigation of Hantavirus cases among informal settlements inhabitants of Cayenne area, French Guiana, 2022-2023

Context

In 2022, four severe cases of Hantavirus pulmonary syndrome (HPS) were reported in patients from informal settlements around Cayenne, the main city in French Guiana. Regional Health Agency (RHA) was commissioned by the French Public Health Agency to estimate the seroprevalence of Hantavirus infections in the neighborhoods of confirmed cases of HPS. RHA then commissioned the French Red Cross (FRC) mobile public health team, providing support in environmental health issues to the population living in informal settlements by health mediators, to facilitate the investigation. The objective of this study was to describe the health mediators' activities set up to improve the efficiency of the investigation.

Methods

The health mediators' team was specifically trained by virologist and infectiologist specialized in HPS. They helped the investigating team and health workers at various steps of the investigation. These interventions are then described in the results section.

Results

The investigation took place between Nov. 2022 and March 2023 in three neighborhoods. During the pre-investigation activities, the mediators raised awareness about HPS of 343 people, among whom 319 (93%) planned to participate in the investigation. Altogether, 274 people finally participated in the investigation, including, i.e., 30.8% of the estimated population living in the three concerned settlements. The global proportion of patients with positive IgG anti-Hantavirus was 5.1%. The health mediators team supported the following steps: preliminary meetings and training modules, identification of resource persons, field visits and awareness and information campaigns (pre-investigation); on field data collection in informal settlements (per-investigation) and communication of individual results, public feedback meeting (post-investigation).

Discussion/Conclusion

The involvement of mediators was probably a factor in the success of the public health response to socially vulnerable people living in the investigated neighborhoods. The preliminary prevention activities helped to raise awareness of the health risk and to enroll participants. Health mediation and outreach activities seem relevant tools of epidemiological field investigations in diseases affecting inhabitants of informal settlements.

Emerging and re-emerging infectious diseases in pregnant women in an amazonian region: a large retrospective study from French Guiana

PURPOSE

Over the past decade, the Amazon basin has faced numerous infectious epidemics. Our comprehension of the actual extent of these infections during pregnancy remains limited. This study aimed to clarify the clinical and epidemiological features of emerging and re-emerging infectious diseases during pregnancy in western French Guiana and along the Maroni River over the previous nine years.

METHODS

This retrospective cohort study enrolled pregnant women living in west French Guiana territory and giving birth in the only local referral center after 22 weeks of gestation between 2013 and 2021. Data on symptomatic or asymptomatic biologically confirmed emerging or re-emerging diseases during pregnancy was collected.

RESULTS

Six epidemic waves were experienced during the study period, including 498 confirmed Zika virus infections (2016), 363 SARS-CoV-2 infections (2020-2021), 87 chikungunya virus infections (2014), 76 syphilis infections (2013-2021), and 60 dengue virus infections (2013-2021) at different gestational ages. Furthermore, 1.1% (n = 287) and 1.4% (n = 350) of pregnant women in west French Guiana were living with HIV and HTLV, respectively. During the study period, at least 5.5% (n = 1,371) faced an emerging or re-emerging infection during pregnancy.

CONCLUSION

These results highlight the diversity, abundance, and dynamism of emerging and re-emerging infectious agents faced by pregnant women in the Amazon basin. Considering the maternal and neonatal adverse outcomes associated with these infections, increased efforts are required to enhance diagnosis, reporting, and treatment of these conditions.

Contrasted life trajectories: reconstituting the main population exposomes in French Guiana

In French Guiana, life expectancy is between 2 and 3 years below that of France, reflecting differences in mortality rates that are largely sensitive to primary healthcare and thus preventable. However, because poverty affects half of the population in French Guiana, global measurements of life expectancy presumably conflate at least two distinct situations: persons who have similar life expectancies as in mainland France and persons living in precariousness who have far greater mortality rates than their wealthier counterparts. We thus aimed to synthesize what is known about statistical regularities regarding exposures and sketch typical French Guiana exposomes in relation to health outcomes. We conducted a narrative review on common exposures in French Guiana and made comparisons between French Guiana and mainland France, between rich and poor in French Guiana, and between urban and rural areas within French Guiana. The most striking fact this panorama shows is that being a fetus or a young child in French Guiana is fraught with multiple threats. In French Guiana, poverty and poor pregnancy follow-up; renouncing healthcare; wide variety of infectious diseases; very high prevalence of food insecurity; psychosocial stress; micronutrient deficiencies; obesity and metabolic problems; and frequent exposure to lead and mercury in rural areas constitute a stunningly challenging exposome for a new human being to develop into. A substantial part of the population's health is hence affected by poverty and its sources of nutrition.

Migration in French Guiana: Implications in health and infectious diseases

In French Guiana, more than a third of the population, and nearly half of the adults, are of foreign origin. This immigration is explained by the French standard of living, which is attractive to nationals of surrounding countries. Infectious diseases remain in the top 10 causes of premature death, often in the most precarious populations. In this context we aimed to synthesize the state of the knowledge regarding immigration and infectious diseases in French Guiana and the general implications that follow this diagnosis. For HIV, although the majority of patients are of foreign origin, estimates of the presumed date of infection based on CD4 erosion modelling and from molecular analyses suggest that the majority of transmissions in foreign-born individuals occur in French Guiana and that the Guiana shield has been a crossroad between Latin America and the Caribbean. Among key populations bridging these regions illegal gold miners are very mobile and have the greatest proportion B Caribbean HIV viruses. Gold miners have been a key vulnerable population for falciparum malaria and other tropical diseases such as leishmaniasis, leprosy, or leptospirosis. The complex history of migrations in French Guiana and on the Guiana Shield is also reflected in the fingerprinting of mycobacterium tuberculosis and the high incidence of tuberculosis in French Guiana, notably in immigrants, reflects the incidences in the countries of origin of patients. The high burden of infectious diseases in immigrants in French Guiana is first and foremost a reflection of the precarious living conditions within French Guiana and suggests that community-based proactive interventions are crucial to reduce transmission, morbidity, and mortality from infectious diseases.

Review on Main Arboviruses Circulating on French Guiana, An Ultra-Peripheric European Region in South America

French Guiana (FG), a French overseas territory in South America, is susceptible to tropical diseases, including arboviruses. The tropical climate supports the proliferation and establishment of vectors, making it difficult to control transmission. In the last ten years, FG has experienced large outbreaks of imported arboviruses such as Chikungunya and Zika, as well as endemic arboviruses such as dengue, Yellow fever, and Oropouche virus. Epidemiological surveillance is challenging due to the differing distributions and behaviors of vectors. This article aims to summarize the current knowledge of these arboviruses in FG and discuss the challenges of arbovirus emergence and reemergence. Effective control measures are hampered by the nonspecific clinical presentation of these diseases, as well as the Aedes aegypti mosquito's resistance to insecticides. Despite the high seroprevalence of certain viruses, the possibility of new epidemics cannot be ruled out. Therefore, active epidemiological surveillance is needed to identify potential outbreaks, and an adequate sentinel surveillance system and broad virological diagnostic panel are being developed in FG to improve disease management.

Density of Aedes aegypti (Diptera: Culicidae) in a low-income Brazilian urban community where dengue, Zika, and chikungunya viruses co-circulate

BACKGROUND

Low-income urban communities in the tropics often lack sanitary infrastructure and are overcrowded, favoring Aedes aegypti proliferation and arboviral transmission. However, as Ae. aegypti density is not spatially homogeneous, understanding the role of specific environmental characteristics in determining vector distribution is critical for planning control interventions. The objectives of this study were to identify the main habitat types for Ae. Aegypti, assess their spatial densities to identify major hotspots of arbovirus transmission over time and investigate underlying factors in a low-income urban community in Salvador, Brazil. We also tested the field-collected mosquitoes for arboviruses.

METHODS

A series of four entomological and socio-environmental surveys was conducted in a random sample of 149 households and their surroundings between September 2019 and April 2021. The surveys included searching for potential breeding sites (water-containing habitats) and for Ae. aegypti immatures in them, capturing adult mosquitoes and installing ovitraps. The spatial distribution of Ae. aegypti density indices were plotted using kernel density-ratio maps, and the spatial autocorrelation was assessed for each index. Visual differences on the spatial distribution of the Ae. aegypti hotspots were compared over time. The association of entomological findings with socio-ecological characteristics was examined. Pools of female Ae. aegypti were tested for dengue, Zika and chikungunya virus infection.

RESULTS

Overall, 316 potential breeding sites were found within the study households and 186 in the surrounding public spaces. Of these, 18 (5.7%) and 7 (3.7%) harbored a total of 595 and 283 Ae. aegypti immatures, respectively. The most productive breeding sites were water storage containers within the households and puddles and waste materials in public areas. Potential breeding sites without cover, surrounded by vegetation and containing organic matter were significantly associated with the presence of immatures, as were households that had water storage containers. None of the entomological indices, whether based on immatures, eggs or adults, detected a consistent pattern of vector clustering in the same areas over time. All the mosquito pools were negative for the tested arboviruses.

CONCLUSIONS

This low-income community displayed high diversity of Ae. aegypti habitats and a high degree of heterogeneity of vector abundance in both space and time, a scenario that likely reflects other low-income communities. Improving basic sanitation in low-income urban communities through the regular water supply, proper management of solid wastes and drainage may reduce water storage and the formation of puddles, minimizing opportunities for Ae. aegypti proliferation in such settings.

[Overview of infectious and non-infectious diseases in French Guiana in 2022]

Source of many myths, French Guiana represents an exceptional territory due to the richness of its biodiversity and the variety of its communities. The only European territory in Amazonia, surrounded by the Brazilian giant and the little-known Suriname, Ariane 6 rockets are launched from Kourou while 50% of the population lives below the poverty line. This paradoxical situation is a source of health problems specific to this territory, whether they be infectious diseases with unknown germs, intoxications or chronic pathologies.Some infectious diseases such as Q fever, toxoplasmosis, cryptococcosis or HIV infection are in common with temperate countries, but present specificities leading to sometimes different management and medical reasoning. In addition to these pathologies, many tropical diseases are present in an endemic and / or epidemic mode such as malaria, leishmaniasis, Chagas disease, histoplasmosis or dengue. Besides, Amazonian dermatology is extremely varied, ranging from rare but serious pathologies (Buruli ulcer, leprosy) to others which are frequent and benign such as agouti lice (mites of the family Trombiculidae) or papillonitis. Envenomations by wild fauna are not rare, and deserve an appropriate management of the incriminated taxon. Obstetrical, cardiovascular and metabolic cosmopolitan pathologies sometimes take on a particular dimension in French Guiana that must be taken into account in the management of patients. Finally, different types of intoxication are to be known by practitioners, especially due to heavy metals.European-level resources offer diagnostic and therapeutic possibilities that do not exist in the surrounding countries and regions, thus allowing the management of diseases that are not well known elsewhere.Thanks to these same European-level resources, research in Guyana occupies a key place within the Amazon region, despite a smaller population than in the surrounding countries. Thus, certain pathologies such as histoplasmosis of the immunocompromised patient, Amazonian toxoplasmosis or Q fever are hardly described in neighboring countries, probably due to under-diagnosis linked to more limited resources. French Guiana plays a leading role in the study of these diseases.The objective of this overview is to guide health care providers coming to or practicing in French Guiana in their daily practice, but also practitioners taking care of people returning from French Guiana.

Sociodemographic and environmental factors associated with dengue, Zika, and chikungunya among adolescents from two Brazilian capitals

Among the emerging and reemerging arboviral diseases, Zika, dengue and chikungunya deserve special attention due to their wide geographical distribution and clinical severity. The three arboviruses are transmitted by the same vector and can present similar clinical syndromes, bringing challenges to their identification and register. Demographic characteristics and individual and contextual social factors have been associated with the three arboviral diseases. However, little is known about such associations among adolescents, whose relationships with the social environment are different from those of adult populations, implying potentially different places, types, and degrees of exposure to the vector, particularly in the school context. This study aims to identify sociodemographic and environmental risk factors for the occurrence of Zika, dengue, and chikungunya in a cohort of adolescents from the Study of Cardiovascular Risks in Adolescents-ERICA-in the cities of Rio de Janeiro/RJ and Fortaleza/CE, from January 2015 to March 2019. Cases were defined as adolescents with laboratory or clinical-epidemiological diagnosis of Zika, dengue, or chikungunya, notified and registered in the Information System for Notifiable Diseases (SINAN). The cases were identified by linkage between the databases of the ERICA cohort and of SINAN. Multilevel Cox regression was employed to estimate hazard ratios (HR) as measures of association and respective 95% confidence intervals (95%CI). In comparison with adolescents living in lower socioeconomic conditions, the risk of becoming ill due to any of the three studied arboviral diseases was lower among those living in better socioeconomic conditions (HR = 0.43; 95%CI: 0.19-0.99; p = 0.047) and in the adolescents who attended school in the afternoon period (HR = 0.17; 95%CI: 0.06-0.47; p<0.001). When compared to areas whose Building Infestation Index (BII) for Aedes aegypti was considered satisfactory, a BII in the school region classified as "alert" and "risk" was associated with a higher risk of arboviral diseases (HR = 1.62, 95%CI: 0.98-2.70; p = 0.062; HR = 3.72, 95%CI: 1.27-10.9; p = 0.017, respectively). These findings indicate that living in less favored socioeconomic conditions, attending school in the morning, and having a high BII for Ae. aegypti in school's region can contribute to an increased risk of infection by Zika, dengue, or chikungunya in adolescents. The identification of residential or school areas based on those variables can contribute to the implementation of control measures in population groups and priority locations.

Spatio-temporal dynamics of three diseases caused by Aedes-borne arboviruses in Mexico

Background

The intensity of transmission of Aedes-borne viruses is heterogeneous, and multiple factors can contribute to variation at small spatial scales. Illuminating drivers of heterogeneity in prevalence over time and space would provide information for public health authorities. The objective of this study is to detect the spatiotemporal clusters and determine the risk factors of three major Aedes-borne diseases, Chikungunya virus (CHIKV), Dengue virus (DENV), and Zika virus (ZIKV) clusters in Mexico.

Methods

We present an integrated analysis of Aedes-borne diseases (ABDs), the local climate, and the socio-demographic profiles of 2469 municipalities in Mexico. We used SaTScan to detect spatial clusters and utilize the Pearson correlation coefficient, Randomized Dependence Coefficient, and SHapley Additive exPlanations to analyze the influence of socio-demographic and climatic factors on the prevalence of ABDs. We also compare six machine learning techniques, including XGBoost, decision tree, Support Vector Machine with Radial Basis Function kernel, K nearest neighbors, random forest, and neural network to predict risk factors of ABDs clusters.

Results

DENV is the most prevalent of the three diseases throughout Mexico, with nearly 60.6% of the municipalities reported having DENV cases. For some spatiotemporal clusters, the influence of socio-economic attributes is larger than the influence of climate attributes for predicting the prevalence of ABDs. XGBoost performs the best in terms of precision-measure for ABDs prevalence.

Conclusions

Both socio-demographic and climatic factors influence ABDs transmission in different regions of Mexico. Future studies should build predictive models supporting early warning systems to anticipate the time and location of ABDs outbreaks and determine the stand-alone influence of individual risk factors and establish causal mechanisms.

High endemicity of Q fever in French Guiana: A cross sectional study (2007–2017)

Q fever (QF) is a zoonosis caused by Coxiella burnetii (Cb). French Guiana (FG) had a high incidence but no data have been published since 2006. The objective of this study was to update the incidence and epidemiological data on QF in FG. A retrospective study of all FG Q fever serodiagnosis between 2007 and 2017 was carried out. Among the 695 patients included, the M/F sex-ratio was 2.0 and the median age of 45.3 years (IQR 33.7–56.3). The annual QF incidence rate was 27.4 cases (95%CI: 7.1–47.7) per 100,000 inhabitants ranging from 5.2 in 2007 to 40.4 in 2010. Risk factors associated with Q fever compared to general population were male gender, being born in mainland France, an age between 30 to 59 years-old and a residence in Cayenne and surroundings. The incidence of QF in FG remains high and stable and the highest in the world.

We present here a study showing the exceptional nature of the incidence of Q fever in French Guiana. Indeed, this zoonosis due to the bacterium Coxiella burnetii, is a real public health problem in French Guiana, a French ultra-marine territory located in the North East of South America. The study found an endemic state with a stable incidence between 2010 and 2017 around 25–30 cases per 100,000 inhabitants per year. More than 90% of cases are concentrated in the territory’s capital, Cayenne, and its surroundings. The risk factors for Q fever are being male, being between 30 and 59 years old, which are risk factors found elsewhere, but also living in Cayenne and its surroundings and being born in mainland France or Europe.

Socioeconomic risk markers of arthropod-borne virus (arbovirus) infections: a systematic literature review and meta-analysis

Introduction

Arthropod-borne viruses (arboviruses) are of notable public health importance worldwide, owing to their potential to cause explosive outbreaks and induce debilitating and potentially life-threatening disease manifestations. This systematic review and meta-analysis aims to assess the relationship between markers of socioeconomic position (SEP) and infection due to arboviruses with mosquito vectors.

Methods

We conducted a systematic search on PubMed, Embase, and LILACS databases to identify studies published between 1980 and 2020 that measured the association of SEP markers with arbovirus infection. We included observational studies without geographic location or age restrictions. We excluded studies from grey literature, reviews and ecological studies. Study findings were extracted and summarised, and pooled estimates were obtained using random-effects meta-analyses.

Results

We identified 36 observational studies using data pertaining to 106 524 study participants in 23 geographic locations that empirically examined the relationship between socioeconomic factors and infections caused by seven arboviruses (dengue, chikungunya, Japanese encephalitis, Rift Valley fever, Sindbis, West Nile and Zika viruses). While results were varied, descriptive synthesis pointed to a higher risk of arbovirus infection associated with markers of lower SEP, including lower education, income poverty, low healthcare coverage, poor housing materials, interrupted water supply, marital status (married, divorced or widowed), non-white ethnicities and migration status. Pooled crude estimates indicated an increased risk of arboviral infection associated with lower education (risk ratio, RR 1.5 95% CI 1.3 to 1.9); I²=83.1%), interruption of water supply (RR 1.2; 95% CI 1.1 to 1.3; I²=0.0%) and having been married (RR 1.5 95% CI 1.1 to 2.1; I²=85.2%).

Conclusion

Evidence from this systematic review suggests that lower SEP increases the risk of acquiring arboviral infection; however, there was large heterogeneity across studies. Further studies are required to delineate the relationship between specific individual, household and community-level SEP indicators and arbovirus infection risks to help inform targeted public health interventions.

PROSPERO registration number

CRD42019158572.

Silent circulation of Chikungunya virus among pregnant women and newborns in the Western Brazilian Amazon before the first outbreak of chikungunya fever

The prevalence of immunity to Chikungunya virus (CHIKV) in pregnant women and newborns in the Western Brazilian Amazon was assessed at a time when previous studies did not report chikungunya fever in the area. In 435 asymptomatic pregnant women and 642 healthy unrelated newborns, the presence of IgM and IgG antibodies to CHIKV were determined by a commercial ELISA. All participants were negative to IgM anti-CHIKV. Anti-CHIKV IgG was identified in 41 (9.4%) pregnant women and 66 (10.3%) newborns. The presence of anti-CHIKV IgG was positively associated with the lowest socioeconomic status in pregnant women (OR 2.54, 95% CI 1.15-5.62, p=0.021) and in the newborns’ mothers (OR 5.10, 95% CI 2.15-12.09, p< 0.001). Anti-CHIKV IgG was also associated with maternal age in both, the pregnant women (OR 1.06, 95% CI 1.00-1.11, p=0.037) and the newborns’mothers (OR 1.08, 95% CI 1.03-1.12, p=0.001). Pregnancy outcomes in which the mother or the newborn was anti-CHIKV IgG positive proceeded normally. Negative CHIKV serology was associated with being positive for DENV antibodies and having had malaria during pregnancy. These findings showed that there was already a silent circulation of CHIKV in this Amazon region before the first outbreak of chikungunya fever. Furthermore, seropositivity for CHIKV was surprisingly frequent (10%) in both, pregnant women and newborns, affecting mainly low-income women.

Field validation of the performance of paper-based tests for the detection of the Zika and chikungunya viruses in serum samples

In low-resource settings, resilience to infectious disease outbreaks can be hindered by limited access to diagnostic tests. Here we report the results of double-blinded studies of the performance of paper-based diagnostic tests for the Zika and chikungunya viruses in a field setting in Latin America. The tests involved a cell-free expression system relying on isothermal amplification and toehold-switch reactions, a purpose-built portable reader and onboard software for computer vision-enabled image analysis. In patients suspected of infection, the accuracies and sensitivities of the tests for the Zika and chikungunya viruses were, respectively, 98.5% (95% confidence interval, 96.2–99.6%, 268 serum samples) and 98.5% (95% confidence interval, 91.7–100%, 65 serum samples) and approximately 2 aM and 5 fM (both concentrations are within clinically relevant ranges). The analytical specificities and sensitivities of the tests for cultured samples of the viruses were equivalent to those of the real-time quantitative PCR. Cell-free synthetic biology tools and companion hardware can provide de-centralized, high-capacity and low-cost diagnostics for use in low-resource settings.

Neighbourhood-level income and Zika virus infection during pregnancy in Recife, Pernambuco, Brazil: an ecological perspective, 2015-2017

Zika virus (ZIKV) infections during pregnancy can lead to adverse neurodevelopmental and clinical outcomes in congenitally infected offspring. As the city of Recife in Pernambuco State, Brazil—the epicentre of the Brazilian microcephaly epidemic—has considerable disparities in living conditions, this study used an ecological approach to investigate the association between income at the neighbourhood level and the risk of ZIKV infections in pregnant individuals between December 2015 and April 2017. The spatial distribution of pregnant individuals with ZIKV infection was plotted on a map of Recife stratified into four categories based on mean monthly income of household heads. Additionally, a Poisson regression model with robust variance was fitted to compare proportions of ZIKV infections among pregnant individuals in relation to the mean monthly income of household heads, based on the 2010 census data, across 94 neighbourhoods in Recife. The results provide evidence that the risk of ZIKV infection to pregnant individuals was higher among those residing in lower-income neighbourhoods: relative to neighbourhoods that had a mean monthly income of ≥5 times minimum wage, neighbourhoods with <1 and 1 to <2 times minimum wage had more than four times the risk (incidence rate ratio, 95% CI 4.08, 1.88 to 8.85 and 4.30, 2.00 to 9.20, respectively). This study provides evidence of a strong association between neighbourhood-level income and ZIKV infection risks in the pregnant population of Recife. In settings prone to arboviral outbreaks, locally targeted interventions to improve living conditions, sanitation, and mosquito control should be a key focus of governmental interventions to reduce risks associated with ZIKV infections during pregnancy.

Arboviral diseases and poverty in Alabama, 2007-2017

Mosquito-borne viruses cause diseases of great public health concern. Arboviral disease case distributions have complex relationships with socioeconomic and environmental factors. We combined information about socio-economic (population, and poverty rate) and environmental (precipitation, and land use) characteristics with reported human cases of arboviral disease in the counties of Alabama, USA, from 2007–2017. We used county level data on West Nile virus (WNV), dengue virus (DENV), chikungunya virus (CHIKV), Zika virus (ZIKV), California serogroup virus, Eastern equine encephalitis virus, and Saint Louis encephalitis virus to provide a detailed description of their spatio-temporal pattern. We found a significant spatial convergence between incidence of WNV and poverty rate clustered in the southern part of Alabama. DENV, CHIKV and ZIKV cases showed a different spatial pattern, being mostly located in the northern part, in areas of high socioeconomic status. The results of our study establish that poverty-driven inequities in arboviral risk exist in the southern USA, and should be taken into account when planning prevention and intervention strategies.

Mosquito-borne arboviruses like West Nile virus (WNV), dengue virus (DENV), chikungunya virus (CHIKV), Zika virus (ZIKV), California serogroup virus (CSV), Eastern equine encephalitis virus (EEE), and Saint Louis encephalitis virus (SLE) are on the rise globally. Socioeconomic and environmental conditions have played a role in directing in this expansion by creating conditions ideal for mosquito vectors and transmission. In this study, we used 10 years (2007–2017) of county level human arboviral case data from the US state of Alabama to better understand the roles socioeconomics (poverty rate) and environmental (land use, precipitation, land cover) conditions may play in driving patterns of arboviral disease in the southern US. We found a significant association between poverty rate and incidence of WNV, an arbovirus primarily transmitted by Culex spp. mosquitoes, which are known for thriving in contaminated water sources and sewage overflow. Conversely, cases of DENV, CHIKV, and ZIKV, arboviruses primarily transmitted by Aedes spp. mosquitoes, were reported in areas of high socioeconomic status. These findings suggest differential distribution of arboviruses relevant to human health in Alabama, and that poverty in the southern US is a significant factor that should be considered when planning WNV prevention and intervention strategies.

Contribution of Research in the West Indies and Northeast Amazonia to Knowledge of the 2014-2015 Chikungunya Epidemic in the Americas

Purpose of Review

Although the chikungunya virus was discovered more than 60 years ago, it has only really been studied since the outbreak in La Reunion in 2005-2006. Ten years later, between 2014 and 2015, the chikungunya virus spread throughout the Americas, affecting millions of people. The objective of this review is to describe the contributions of research on chikungunya virus infection gained from epidemic in the West Indies and the Guiana Shield.

Recent Findings

Prevalence data were similar to those found in the Indian Ocean or Asia during epidemics. Clinically, there is now a better understanding of the typical, atypical, and severe forms. Several studies have insisted on the presence of neurological forms of chikungunya infection, such as encephalitis or Guillain-Barré syndrome. Cases of septic shock due to chikungunya virus as well as thrombotic thrombocytopenic purpura were described for the first time. Given the magnitude of the epidemic and the large number of people affected, this has led to a better description and new classifications of chikungunya virus infections in specific populations such as pregnant women, the elderly, and children. Several studies also described the behavior of populations faced with an emerging disease.

Summary

Current epidemiological data from tropical regions highlights the risk of spreading emerging diseases at higher latitudes, especially concerning arboviruses, since the vector Aedes albopictus is already established in many parts of northern countries. A better understanding of the disease and its epidemic dynamics will foster better management, the crucial importance of which was demonstrated during the COVID-19 epidemic.

Spatio-temporal modelling of the first Chikungunya epidemic in an intra-urban setting: The role of socioeconomic status, environment and temperature

Three key elements are the drivers of Aedes-borne disease: mosquito infestation, virus circulating, and susceptible human population. However, information on these aspects is not easily available in low- and middle-income countries. We analysed data on factors that influence one or more of those elements to study the first chikungunya epidemic in Rio de Janeiro city in 2016. Using spatio-temporal models, under the Bayesian framework, we estimated the association of those factors with chikungunya reported cases by neighbourhood and week. To estimate the minimum temperature effect in a non-linear fashion, we used a transfer function considering an instantaneous effect and propagation of a proportion of such effect to future times. The sociodevelopment index and the proportion of green areas (areas with agriculture, swamps and shoals, tree and shrub cover, and woody-grass cover) were included in the model with time-varying coefficients, allowing us to explore how their associations with the number of cases change throughout the epidemic. There were 13627 chikungunya cases in the study period. The sociodevelopment index presented the strongest association, inversely related to the risk of cases. Such association was more pronounced in the first weeks, indicating that socioeconomically vulnerable neighbourhoods were affected first and hardest by the epidemic. The proportion of green areas effect was null for most weeks. The temperature was directly associated with the risk of chikungunya for most neighbourhoods, with different decaying patterns. The temperature effect persisted longer where the epidemic was concentrated. In such locations, interventions should be designed to be continuous and to work in the long term. We observed that the role of the covariates changes over time. Therefore, time-varying coefficients should be widely incorporated when modelling Aedes-borne diseases. Our model contributed to the understanding of the spatio-temporal dynamics of an urban Aedes-borne disease introduction in a tropical metropolitan city.

Are Vulnerable Communities Thoroughly Informed on Mosquito Bio-Ecology and Burden?

Mosquitoes account for a significant burden of morbidity and mortality globally. Despite evidence of (1) imminent anthropogenic climate and environmental changes, (2) vector-pathogen spatio-temporal dynamics and (3) emerging and re-emerging mosquito borne infections, public knowledge on mosquito bio-ecology remain scant. In particular, knowledge, attitude and practices (KAPs) on mosquitoes are often neglected despite otherwise expensive remedial efforts against consequent infections and other indirect effects associated with disease burden. To gather baseline KAPs that identify gaps for optimising vector-borne disease control, we surveyed communities across endemic and non-endemic malaria sub-districts (Botswana). The study revealed limited knowledge of mosquitoes and their infections uniformly across endemic and non-endemic areas. In addition, a significant proportion of respondents were concerned about mosquito burdens, although their level of personal, indoor and environmental protection practices varied significantly across sub-districts. Given the limited knowledge displayed by the communities, this study facilitates bridging KAP gaps to minimise disease burdens by strengthening public education. Furthermore, it provides a baseline for future studies in mosquito bio-ecology and desirable control practices across differential spheres of the rural-urban lifestyle, with implications for enhanced livelihoods as a consequence of improved public health.

In-silico and biophysical investigation of biomolecular interaction between naringin and nsP2 of the chikungunya virus

Chikungunya virus; the pathogen for chikungunya febrile and arthritic disease, having 11.8 kb positive-sense RNA genome encodes polyproteins for structural and non-structural regions. The polyprotein (P1234) corresponding to the non-structural part from 5' end gets auto-cleaved by the action of nsP2 protease, which leads to the generation of individual functional enzymatic proteins like nsP4, nsP1, nsP2 and nsP3. Thus, nsP2 protein initiates viral replication. Targeting nsP2 to block virus replication has always been the foremost strategy to develop antivirals. Plant-based molecules are one of the top choices to develop as inhibitor due to their less toxicity and wide availability. Using a combination of receptor-based docking and MD simulations, we identified a flavanone glycoside- naringin, which binds to nsP2 protease at nM affinity. The biomolecular interaction between naringin and nsP2 was established through SPR. As discerned through FTIR and intrinsic fluorescence studies, upon binding with naringin, a global structural change in nsP2 occurs. This structural modulation in nsP2 due to binding of naringin is likely to interfere with the normal functioning of this enzyme during the viral life cycle. In conclusion, this report highlights the potential of naringin as an anti-viral agent against Chikungunya.

Computer-Aided Design, Synthesis, and Antiviral Evaluation of Novel Acrylamides as Potential Inhibitors of E3-E2-E1 Glycoproteins Complex from Chikungunya Virus

Chikungunya virus (CHIKV) causes an infectious disease characterized by inflammation and pain of the musculoskeletal tissues accompanied by swelling in the joints and cartilage damage. Currently, there are no licensed vaccines or chemotherapeutic agents to prevent or treat CHIKV infections. In this context, our research aimed to explore the potential in vitro anti-CHIKV activity of acrylamide derivatives. In silico methods were applied to 132 Michael's acceptors toward the six most important biological targets from CHIKV. Subsequently, the ten most promising acrylamides were selected and synthesized. From the cytotoxicity MTT assay, we verified that LQM330, 334, and 336 demonstrate high cell viability at 40 µM. Moreover, these derivatives exhibited anti-CHIKV activities, highlighting the compound LQM334 which exhibited an inhibition value of 81%. Thus, docking simulations were performed to suggest a potential CHIKV-target for LQM334. It was observed that the LQM334 has a high affinity towards the E3-E2-E1 glycoproteins complex. Moreover, LQM334 reduced the percentage of CHIKV-positive cells from 74.07 to 0.88%, 48h post-treatment on intracellular flow cytometry staining. In conclusion, all virtual simulations corroborated with experimental results, and LQM334 could be used as a promising anti-CHIKV scaffold for designing new drugs in the future.

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.

Space-time dynamics of a triple epidemic: dengue, chikungunya and Zika clusters in the city of Rio de Janeiro

Dengue, an arboviral disease transmitted by Aedes mosquitoes, has been endemic in Brazil for decades. However, vector-control strategies have not led to a significant reduction in the disease burden and have not been sufficient to prevent chikungunya and Zika entry and establishment in the country. In Rio de Janeiro city, the first Zika and chikungunya epidemics were detected between 2015 and 2016, coinciding with a dengue epidemic. Understanding the behaviour of these diseases in a triple epidemic scenario is a necessary step for devising better interventions for prevention and outbreak response. We applied scan statistics analysis to detect spatio-temporal clustering for each disease separately and for all three simultaneously. In general, clusters were not detected in the same locations and time periods, possibly owing to competition between viruses for host resources, depletion of susceptible population, different introduction times and change in behaviour of the human population (e.g. intensified vector-control activities in response to increasing cases of a particular arbovirus). Simultaneous clusters of the three diseases usually included neighbourhoods with high population density and low socioeconomic status, particularly in the North region of the city. The use of space–time cluster detection can guide intensive interventions to high-risk locations in a timely manner, to improve clinical diagnosis and management, and pinpoint vector-control measures.

Islands as Hotspots for Emerging Mosquito-Borne Viruses: A One-Health Perspective

During the past ten years, an increasing number of arbovirus outbreaks have affected tropical islands worldwide. We examined the available literature in peer-reviewed journals, from the second half of the 20th century until 2018, with the aim of gathering an overall picture of the emergence of arboviruses in these islands. In addition, we included information on environmental and social drivers specific to island setting that can facilitate the emergence of outbreaks. Within the context of the One Health approach, our review highlights how the emergence of arboviruses in tropical islands is linked to the complex interplay between their unique ecological settings and to the recent changes in local and global sociodemographic patterns. We also advocate for greater coordination between stakeholders in developing novel prevention and mitigation approaches for an intractable problem.

Atypical and severe manifestations of chikungunya virus infection in French Guiana: A hospital-based study

BACKGROUND

French Guiana (FG) was the first country in South America to declare chikungunya virus infection (CHIKV). The outbreak affected about 16,000 persons between February 2014 and October 2015, with several atypical cases, but only two fatal cases. We aimed to describe the clinical presentation of patients hospitalized for CHIKV infection, to estimate and identify risk factors of unusual and severe forms in adult patients.

MATERIALS AND METHODS

A monocentric retrospective study was conducted in Cayenne hospital, the main city and the main hospital in FG, from March 1st 2014 to August 31st 2015. All patients admitted for at least one night with a biological diagnosis of CHIKV infection during the 2014/2015 outbreak were included, except pregnant women and children under 15 years.

RESULTS

During the study period, 285 patients with a diagnosis of CHIKV infection were hospitalized in Cayenne hospital, among whom 96 nonpregnant adults were studied. Five were classified as severe forms (5.2%) and 23 as unusual forms (23.9%). The most frequent atypical and/or severe form was neurological (n = 20), followed by cardio-respiratory failure (acute respiratory failure n = 4, acute heart failure n = 2), digestive and hepatic disorders (acute hepatitis n = 3, acute pancreatitis n = 2), renal disorders (acute renal failure n = 5) and muscular impairment (rhabdomyolysis n = 3).

CONCLUSION

During the outbreak, hospitalizations were frequent, particularly for common forms, driven by algic clinical presentations and concerns due to the novelty of this infection. Despite atypical neurological and liver forms of CHIKV infection, case-fatality was low in French Guiana. No specific risk factor of atypical and/or severe forms was found in our study.

Prevalence and risk factors of post chikungunya rheumatic musculoskeletal disorders: a prospective follow-up study in French Guiana

The estimated seroprevalence in the general population after chikungunya virus (CHIKV) epidemics ranged from 38 to 63%. Despite a low case fatality, subacute and chronic rheumatic forms of CHIKV infection generate significant morbidity and have a socioeconomic impact. The objective of the study was to estimate the prevalence of chronic post-CHIKV rheumatic or musculoskeletal pain (pCHIK-RMSP) at 3 and 6 months after the initial symptoms. An observational study was conducted at Cayenne General Hospital in French Guiana between April 1 and June 30, 2014. All patients seen for CHIKV infection confirmed by RT-PCR were prospectively included. Pregnant women and children under 15 were excluded from the study. All patients were called by phone at 3 and 6 months to enquire about the presence of pCHIK-RMSP. Out of a total of 254 eligible patients, 168 were selected. The mean age was 45.3 years (SD ± 1.4 yo) and the sex ratio (M/F) was 0.75. No death was reported. At 3 months, 40.2% (95% CI 31.1-49.3) of patients (n = 45/112) had pCHIK-RMSP and 31.3% (95% CI 22.2-40.4) of patients (n = 31/99) at 6 months. The median time of end to pain was 2 weeks after the date of onset of signs. The present study provides succinct but informative data about pCHIK-RMSP, which represents the real burden of the disease. There are few studies on that subject in the Amazonian region, but our study shows a lower impact than in the Indian Ocean islands where the population is older.

Individual and contextual risk factors for chikungunya virus infection: the SEROCHIK cross-sectional population-based study

The purpose of the study was to weigh the community burden of chikungunya determinants on Reunion island. Risk factors were investigated within a subset of 2101 adult persons from a population-based cross-sectional serosurvey, using Poisson regression models for dichotomous outcomes. Design-based risk ratios and population attributable fractions (PAF) were generated distinguishing individual and contextual (i.e. that affect individuals collectively) determinants. The disease burden attributable to contextual determinants was twice that of individual determinants (overall PAF value 89.5% vs. 44.1%). In a model regrouping both categories of determinants, the independent risk factors were by decreasing PAF values: an interaction term between the reporting of a chikungunya history in the neighbourhood and individual house (PAF 45.9%), a maximal temperature of the month preceding the infection higher than 28.5 °C (PAF 25.7%), a socio-economically disadvantaged neighbourhood (PAF 19.0%), altitude of dwelling (PAF 13.1%), cumulated rainfalls of the month preceding the infection higher than 65 mm (PAF 12.6%), occupational inactivity (PAF 11.6%), poor knowledge on chikungunya transmission (PAF 7.3%) and obesity/overweight (PAF 5.2%). Taken together, these covariates and their underlying causative factors uncovered 80.8% of chikungunya at population level. Our findings lend support to a major role of contextual risk factors in chikungunya virus outbreaks.