Comparative analysis of midgut bacterial communities in Chikungunya virus-infected and non-infected Aedes aegypti Thai laboratory strain mosquitoes.

Chikungunya virus (CHIKV) poses a significant global health threat, re-emerging as a mosquito-transmitted pathogen that caused high fever, rash, and severe arthralgia. In Thailand, a notable CHIKV outbreak in 2019-2020 affected approximately 20,000 cases across 60 provinces, underscoring the need for effective mosquito control protocols. Previous studies have highlighted the role of midgut bacteria in the interaction between mosquito vectors and pathogen infections, demonstrating their ability to protect the insect from invading pathogens. However, research on the midgut bacteria of Aedes (Ae.) aegypti, the primary vector for CHIKV in Thailand remains limited. This study aims to characterize the bacterial communities in laboratory strains of Ae. aegypti, both infected and non-infected with CHIKV. Female mosquitoes from a laboratory strain of Ae. aegypti were exposed to a CHIKV-infected blood meal through membrane feeding, while the control group received a non-infected blood meal. At 7 days post-infection (dpi), mosquito midguts were dissected for 16S rRNA gene sequencing to identify midgut bacteria, and CHIKV presence was confirmed by E1-nested RT-PCR using mosquito carcasses. The study aimed to compare the bacterial communities between CHIKV-infected and non-infected groups. The analysis included 12 midgut bacterial samples, divided into three groups: CHIKV-infected (exposed and infected), non-infected (exposed but not infected), and non-exposed (negative control). Alpha diversity indices and Bray-Curtis dissimilarity matrix revealed significant differences in bacterial profiles among the three groups. The infected group exhibited an increased abundance of bacteria genus Gluconobacter, while Asaia was prevalent in both non-infected and negative control groups. Chryseobacterium was prominent in the negative control group. These findings highlight potential alterations in the distribution and abundance of gut microbiomes in response to CHIKV infection status. This study provides valuable insights into the dynamic relationship between midgut bacteria and CHIKV, underscoring the potential for alterations in bacterial composition depending on infection status. Understanding the relationships between mosquitoes and their microbiota holds promise for developing new methods and tools to enhance existing strategies for disease prevention and control. This research advances our understanding of the circulating bacterial composition, opening possibilities for new approaches in combating mosquito-borne diseases.

[Dengue, chikungunya and the mosquito vector at the Southern limit of distribution during the 2023 epidemic, Argentina]. / Dengue, chikungunya y el mosquito vector en el límite sur de distribución durante la epidemia 2023, Argentina.

OBJECTIVES: To monitor the oviposition activity of the mosquito Aedes aegypti and of dengue and chikungunya cases in four localities of temperate Argentina, during the 2023 epidemic. METHODS: During the summer and autumn of 2023, the oviposition activity of the mosquito vector was monitored weekly using ovitraps, and the arrival of cases with dengue or chikungunya in Tandil, Olavarría, Bahía Blanca and Laprida were registered. RESULTS: Monthly variations of the percentage of positive traps were similar in the first three locations; in Laprida the mosquito was not detected. On the contrary, a significant difference was observed in the percentage of total traps that ever tested positive in each locality, being higher in Olavarría (83.3%) than in Bahía Blanca (68.6%) and Tandil (48.7%). Regarding diseases, 18 imported cases of dengue and 3 of chikungunya were registered. In addition, the first autochthonous case of dengue in the region was recorded, being the southernmost until known. CONCLUSION: It is essential to raise awareness and train the members of the health systems of the new regions exposed to Ae. aegypti for early detection of cases, and to the general population to enhance prevention actions.

OBJETIVOS: Monitorear la actividad de oviposición del mosquito Aedes aegypti y de casos de dengue y chikungunya en cuatro localidades de Argentina templada, durante la epidemia del 2023. Métodos: Durante el verano y otoño del 2023, se monitoreó semanalmente mediante ovitrampas la actividad de oviposición del mosquito vector, y se registró el arribo de casos con dengue o chikungunya a Tandil, Olavarría, Bahía Blanca y Laprida. RESULTADOS: La variación mensual del porcentaje de trampas positivas fue similar en las tres primeras localidades; en Laprida no se detectó el mosquito. Por el contrario, se observó una diferencia significativa del porcentaje de trampas que alguna vez resultó positiva en cada localidad, siendo mayor en Olavarría (83%), que en Bahía Blanca (67%) y Tandil (49%). Respecto a las enfermedades, se registraron 18 casos importados de dengue y 3 de chikungunya. Además, se registró el primer caso autóctono de dengue en la región, siendo el más austral hasta el momento. Conclusión: Es imprescindible sensibilizar y capacitar a los integrantes de los sistemas de salud de las nuevas regiones expuestas al Ae. aegypti para la detección temprana de casos, y a la población en general para potenciar las acciones de prevención.

The High Capacity of Brazilian Aedes aegypti Populations to Transmit a Locally Circulating Lineage of Chikungunya Virus.

The incidence of chikungunya has dramatically surged worldwide in recent decades, imposing an expanding burden on public health. In recent years, South America, particularly Brazil, has experienced outbreaks that have ravaged populations following the rapid dissemination of the chikungunya virus (CHIKV), which was first detected in 2014. The primary vector for CHIKV transmission is the urban mosquito species Aedes aegypti, which is highly prevalent throughout Brazil. However, the impact of the locally circulating CHIKV genotypes and specific combinations of local mosquito populations on vector competence remains unexplored. Here, we experimentally analyzed and compared the infectivity and transmissibility of the CHIKV-ECSA lineage recently isolated in Brazil among four Ae. aegypti populations collected from different regions of the country. When exposed to CHIKV-infected AG129 mice for blood feeding, all the mosquito populations displayed high infection rates and dissemination efficiency. Furthermore, we observed that all the populations were highly efficient in transmitting CHIKV to a vertebrate host (naïve AG129 mice) as early as eight days post-infection. These results demonstrate the high capacity of Brazilian Ae. aegypti populations to transmit the locally circulating CHIKV-ECSA lineage. This observation could help to explain the high prevalence of the CHIKV-ECSA lineage over the Asian lineage, which was also detected in Brazil in 2014. However, further studies comparing both lineages are necessary to gain a better understanding of the vector's importance in the epidemiology of CHIKV in the Americas.

A metapopulation approach to identify targets for Wolbachia-based dengue control.

Over the last decade, the release of Wolbachia-infected Aedes aegypti into the natural habitat of this mosquito species has become the most sustainable and long-lasting technique to prevent and control vector-borne diseases, such as dengue, zika, or chikungunya. However, the limited resources to generate such mosquitoes and their effective distribution in large areas dominated by the Aedes aegypti vector represent a challenge for policymakers. Here, we introduce a mathematical framework for the spread of dengue in which competition between wild and Wolbachia-infected mosquitoes, the cross-contagion patterns between humans and vectors, the heterogeneous distribution of the human population in different areas, and the mobility flows between them are combined. Our framework allows us to identify the most effective areas for the release of Wolbachia-infected mosquitoes to achieve a large decrease in the global dengue prevalence.

Dynamics of a Fractional-Order Chikungunya Model with Asymptomatic Infectious Class.

In this paper, a nonlinear fractional-order chikungunya disease model that incorporates asymptomatic infectious individuals is proposed and analyzed. The main interest of this work is to investigate the role of memory effects on the dynamics of chikungunya. Qualitative analysis of the model's equilibria showed that there exists a threshold quantity which governs persistence and extinction of the disease. Model parameters were estimated based on the 2015 weekly reported cases in Colombia. The Adams-Bashforth-Moulton method was used to numerically solve the proposed model. We investigated the role of asymptomatic infectious patients on short- and long-term dynamics of the diseases. We also determined threshold levels for the efficacy of preventative strategies that results in effective management of the disease. We believe that our model can provide invaluable insights for public health authorities to predict the effect of chikungunya transmission and analyze its underlying factors and to guide new control efforts.

Spatiotemporal distribution, abundance, and host interactions of two invasive vectors of arboviruses, Aedes albopictus and Aedes japonicus, in Pennsylvania, USA.

BACKGROUND: Aedes albopictus and Aedes japonicus, two invasive mosquito species in the United States, are implicated in the transmission of arboviruses. Studies have shown interactions of these two mosquito species with a variety of vertebrate hosts; however, regional differences exist and may influence their contribution to arbovirus transmission. METHODS: We investigated the distribution, abundance, host interactions, and West Nile virus infection prevalence of Ae. albopictus and Ae. japonicus by examining Pennsylvania mosquito and arbovirus surveillance data for the period between 2010 and 2018. Mosquitoes were primarily collected using gravid traps and BG-Sentinel traps, and sources of blood meals were determined by analyzing mitochondrial cytochrome b gene sequences amplified in PCR assays. RESULTS: A total of 10,878,727 female mosquitoes representing 51 species were collected in Pennsylvania over the 9-year study period, with Ae. albopictus and Ae. japonicus representing 4.06% and 3.02% of all collected mosquitoes, respectively. Aedes albopictus was distributed in 39 counties and Ae. japonicus in all 67 counties, and the abundance of these species increased between 2010 and 2018. Models suggested an increase in the spatial extent of Ae. albopictus during the study period, while that of Ae. japonicus remained unchanged. We found a differential association between the abundance of the two mosquito species and environmental conditions, percent development, and median household income. Of 110 Ae. albopictus and 97 Ae. japonicus blood meals successfully identified to species level, 98% and 100% were derived from mammalian hosts, respectively. Among 12 mammalian species, domestic cats, humans, and white-tailed deer served as the most frequent hosts for the two mosquito species. A limited number of Ae. albopictus acquired blood meals from avian hosts solely or in mixed blood meals. West Nile virus was detected in 31 pools (n = 3582 total number of pools) of Ae. albopictus and 12 pools (n = 977 total pools) of Ae. japonicus. CONCLUSIONS: Extensive distribution, high abundance, and frequent interactions with mammalian hosts suggest potential involvement of Ae. albopictus and Ae. japonicus in the transmission of human arboviruses including Cache Valley, Jamestown Canyon, La Crosse, dengue, chikungunya, and Zika should any of these viruses become prevalent in Pennsylvania. Limited interaction with avian hosts suggests that Ae. albopictus might occasionally be involved in transmission of arboviruses such as West Nile in the region.

Emerging Chikungunya Virus Variants at the E1-E1 Interglycoprotein Spike Interface Impact Virus Attachment and Inflammation.

Chikungunya virus (CHIKV) is a reemerging arthropod-borne alphavirus and a serious threat to human health. Therefore, efforts toward elucidating how this virus causes disease and the molecular mechanisms underlying steps of the viral replication cycle are crucial. Using an in vivo transmission system that allows intrahost evolution, we identified an emerging CHIKV variant carrying a mutation in the E1 glycoprotein (V156A) in the serum of mice and saliva of mosquitoes. E1 V156A has since emerged in humans during an outbreak in Brazil, cooccurring with a second mutation, E1 K211T, suggesting an important role for these residues in CHIKV biology. Given the emergence of these variants, we hypothesized that they function to promote CHIKV infectivity and subsequent disease. Here, we show that E1 V156A and E1 K211T modulate virus attachment and fusion and impact binding to heparin, a homolog of heparan sulfate, a key entry factor on host cells. These variants also exhibit differential neutralization by antiglycoprotein monoclonal antibodies, suggesting structural impacts on the particle that may be responsible for altered interactions at the host membrane. Finally, E1 V156A and E1 K211T exhibit increased titers in an adult arthritic mouse model and induce increased foot-swelling at the site of injection. Taken together, this work has revealed new roles for E1 where discrete regions of the glycoprotein are able to modulate cell attachment and swelling within the host. IMPORTANCE Alphaviruses represent a growing threat to human health worldwide. The reemerging alphavirus chikungunya virus (CHIKV) has rapidly spread to new geographic regions in the last several decades, causing overwhelming outbreaks of disease, yet there are no approved vaccines or therapeutics. The CHIKV glycoproteins are key determinants of CHIKV adaptation and virulence. In this study, we identify and characterize the emerging E1 glycoprotein variants, V156A and K211T, that have since emerged in nature. We demonstrate that E1 V156A and K211T function in virus attachment to cells, a role that until now has only been attributed to specific residues of the CHIKV E2 glycoprotein. We also demonstrate E1 V156A and K211T increase foot-swelling of the ipsilateral foot in mice infected with these variants. Observing that these variants and other pathogenic variants occur at the E1-E1 interspike interface, we highlight this structurally important region as critical for multiple steps during CHIKV infection. Together, these studies further define the function of E1 in CHIKV infection and can inform the development of therapeutic or preventative strategies.

Vector Competence of the Invasive Mosquito Species Aedes koreicus for Arboviruses and Interference with a Novel Insect Specific Virus.

The global spread of invasive mosquito species increases arbovirus infections. In addition to the invasive species Aedes albopictus and Aedes japonicus, Aedes koreicus has spread within Central Europe. Extensive information on its vector competence is missing. Ae. koreicus from Germany were investigated for their vector competence for chikungunya virus (CHIKV), Zika virus (ZIKV) and West Nile virus (WNV). Experiments were performed under different climate conditions (27 ± 5 °C; 24 ± 5 °C) for fourteen days. Ae. koreicus had the potential to transmit CHIKV and ZIKV but not WNV. Transmission was exclusively observed at the higher temperature, and transmission efficiency was rather low, at 4.6% (CHIKV) or 4.7% (ZIKV). Using a whole virome analysis, a novel mosquito-associated virus, designated Wiesbaden virus (WBDV), was identified in Ae. koreicus. Linking the WBDV infection status of single specimens to their transmission capability for the arboviruses revealed no influence on ZIKV transmission. In contrast, a coinfection of WBDV and CHIKV likely has a boost effect on CHIKV transmission. Due to its current distribution, the risk of arbovirus transmission by Ae. koreicus in Europe is rather low but might gain importance, especially in regions with higher temperatures. The impact of WBDV on arbovirus transmission should be analyzed in more detail.

Past and future epidemic potential of chikungunya virus in Australia.

BACKGROUND: Australia is theoretically at risk of epidemic chikungunya virus (CHIKV) activity as the principal vectors are present on the mainland Aedes aegypti) and some islands of the Torres Strait (Ae. aegypti and Ae. albopictus). Both vectors are highly invasive and adapted to urban environments with a capacity to expand their distributions into south-east Queensland and other states in Australia. We sought to estimate the epidemic potential of CHIKV, which is not currently endemic in Australia, by considering exclusively transmission by the established vector in Australia, Ae. aegypti, due to the historical relevance and anthropophilic nature of the vector. METHODOLOGY/PRINCIPAL FINDINGS: We estimated the historical (1995-2019) epidemic potential of CHIKV in eleven Australian locations, including the Torres Strait, using a basic reproduction number equation. We found that the main urban centres of Northern Australia could sustain an epidemic of CHIKV. We then estimated future trends in epidemic potential for the main centres for the years 2020 to 2029. We also conducted uncertainty and sensitivity analyses on the variables comprising the basic reproduction number and found high sensitivity to mosquito population size, human population size, impact of vector control and human infectious period. CONCLUSIONS/SIGNIFICANCE: By estimating the epidemic potential for CHIKV transmission on mainland Australia and the Torres Strait, we identified key areas of focus for controlling vector populations and reducing human exposure. As the epidemic potential of the virus is estimated to rise towards 2029, a greater focus on control and prevention measures should be implemented in at-risk locations.

Entomological characterization of Aedes mosquitoes and arbovirus detection in Ibagué, a Colombian city with co-circulation of Zika, dengue and chikungunya viruses.

BACKGROUND: Dengue, Zika and chikungunya are arboviruses of significant public health importance that are transmitted by Aedes aegypti and Aedes albopictus mosquitoes. In Colombia, where dengue is hyperendemic, and where chikungunya and Zika were introduced in the last decade, more than half of the population lives in areas at risk. The objective of this study was to characterize Aedes spp. vectors and study their natural infection with dengue, Zika and chikungunya in Ibagué, a Colombian city and capital of the department of Tolima, with case reports of simultaneous circulation of these three arboviruses. METHODS: Mosquito collections were carried out monthly between June 2018 and May 2019 in neighborhoods with different levels of socioeconomic status. We used the non-parametric Friedman, Mann-Whitney and Kruskal-Wallis tests to compare mosquito density distributions. We applied logistic regression analyses to identify associations between mosquito density and absence/presence of breeding sites, and the Spearman correlation coefficient to analyze the possible relationship between climatic variables and mosquito density. RESULTS: We collected Ae. aegypti in all sampled neighborhoods and found for the first time Ae. albopictus in the city of Ibagué. A greater abundance of mosquitoes was collected in neighborhoods displaying low compared to high socioeconomic status as well as in the intradomicile compared to the peridomestic space. Female mosquitoes predominated over males, and most of the test females had fed on human blood. In total, four Ae. aegypti pools (3%) were positive for dengue virus (serotype 1) and one pool for chikungunya virus (0.8%). Interestingly, infected females were only collected in neighborhoods of low socioeconomic status, and mostly in the intradomicile space. CONCLUSIONS: We confirmed the co-circulation of dengue (serotype 1) and chikungunya viruses in the Ae. aegypti population in Ibagué. However, Zika virus was not detected in any mosquito sample, 3 years after its introduction into the country. The positivity for dengue and chikungunya viruses, predominance of mosquitoes in the intradomicile space and the high proportion of females fed on humans highlight the high risk for arbovirus transmission in Ibagué, but may also provide an opportunity for establishing effective control strategies.

Determinants of Aedes mosquito density as an indicator of arbovirus transmission risk in three sites affected by co-circulation of globally spreading arboviruses in Colombia, Ecuador and Argentina.

BACKGROUND: The global impact of Zika virus in Latin America has drawn renewed attention to circulating mosquito-borne viruses in this region, such as dengue and chikungunya. Our objective was to assess socio-ecological factors associated with Aedes mosquito vector density as a measure of arbovirus transmission risk in three cities of potentially recent Zika virus introduction: Ibagué, Colombia; Manta, Ecuador; and Posadas, Argentina, in order to inform disease mitigation strategies. METHODS: We sampled Aedes mosquito populations in a total of 1086 households, using indoor and peridomestic mosquito collection methods, including light traps, resting traps, traps equipped with chemical attractant and aspirators. For each sampled household, we collected socio-economic data using structured questionnaires and data on microenvironmental conditions using iButton data loggers. RESULTS: A total of 3230 female Aedes mosquitoes were collected, of which 99.8% were Aedes aegypti and 0.2% were Aedes albopictus. Mean female Aedes mosquito density per household was 1.71 (standard deviation: 2.84). We used mixed-effects generalized linear Poisson regression analyses to identify predictors of Aedes density, using month, neighborhood and country as random-effects variables. Across study sites, the number of household occupants [incidence rate ratio (IRR): 1.08, 95% confidence interval (CI): 1.01-1.14], presence of entry points for mosquitoes into the household (IRR: 1.51, 95% CI: 1.30-1.76) and presence of decorative vegetation (IRR: 1.52, 95% CI: 1.22-1.88) were associated with higher Aedes density; while being in the highest wealth tertile of household wealth (IRR: 0.78, 95% CI: 0.66-0.92), knowledge of how arboviruses are transmitted (IRR: 0.94, 95% CI: 0.89-1.00) and regular emptying of water containers by occupants (IRR: 0.79, 95% CI: 0.67-0.92) were associated with lower Aedes density. CONCLUSIONS: Our study addresses the complexities of arbovirus vectors of global significance at the interface between human and mosquito populations. Our results point to several predictors of Aedes mosquito vector density in countries with co-circulation of multiple Aedes-borne viruses, and point to modifiable risk factors that may be useful for disease prevention and control.

Suppressing mosquito populations with precision guided sterile males.

The mosquito Aedes aegypti is the principal vector for arboviruses including dengue/yellow fever, chikungunya, and Zika virus, infecting hundreds of millions of people annually. Unfortunately, traditional control methodologies are insufficient, so innovative control methods are needed. To complement existing measures, here we develop a molecular genetic control system termed precision-guided sterile insect technique (pgSIT) in Aedes aegypti. PgSIT uses a simple CRISPR-based approach to generate flightless females and sterile males that are deployable at any life stage. Supported by mathematical models, we empirically demonstrate that released pgSIT males can compete, suppress, and even eliminate mosquito populations. This platform technology could be used in the field, and adapted to many vectors, for controlling wild populations to curtail disease in a safe, confinable, and reversible manner.

Spatial analysis of the incidence of Dengue, Zika and Chikungunya and socioeconomic determinants in the city of Rio de Janeiro, Brazil.

In 2015-2016, simultaneous circulation of dengue, Zika and chikungunya in the municipality of Rio de Janeiro (Brazil) was reported. We conducted an ecological study to analyse the spatial distribution of dengue, Zika and chikungunya cases and to investigate socioeconomic factors associated with individual and combined disease incidence in 2015-2016. We then constructed thematic maps and analysed the bivariate global Moran indices. Classical and spatial models were used. A distinct spatial distribution pattern for dengue, Zika and chikungunya was identified in the municipality of Rio de Janeiro. The bivariate global Moran indices (P < 0.05) revealed negative spatial correlations between rates of dengue, Zika, chikungunya and combined arboviruses incidence and social development index and mean income. The regression models (P < 0.05) identified a negative relationship between mean income and each of these rates and between sewage and Zika incidence rates, as well as a positive relationship between urban areas and chikungunya incidence rates. In our study, spatial analysis techniques helped to identify high-risk and social determinants at the local level for the three arboviruses. Our findings may aid in backing effective interventions for the prevention and control of epidemics of these diseases.

Mother-to-Child Transmission of Arboviruses during Breastfeeding: From Epidemiology to Cellular Mechanisms.

Most viruses use several entry sites and modes of transmission to infect their host (parenteral, sexual, respiratory, oro-fecal, transplacental, transcutaneous, etc.). Some of them are known to be essentially transmitted via arthropod bites (mosquitoes, ticks, phlebotomes, sandflies, etc.), and are thus named arthropod-borne viruses, or arboviruses. During the last decades, several arboviruses have emerged or re-emerged in different countries in the form of notable outbreaks, resulting in a growing interest from scientific and medical communities as well as an increase in epidemiological studies. These studies have highlighted the existence of other modes of transmission. Among them, mother-to-child transmission (MTCT) during breastfeeding was highlighted for the vaccine strain of yellow fever virus (YFV) and Zika virus (ZIKV), and suggested for other arboviruses such as Chikungunya virus (CHIKV), dengue virus (DENV), and West Nile virus (WNV). In this review, we summarize all epidemiological and clinical clues that suggest the existence of breastfeeding as a neglected route for MTCT of arboviruses and we decipher some of the mechanisms that chronologically occur during MTCT via breastfeeding by focusing on ZIKV transmission process.

Andrographolide - A prospective remedy for chikungunya fever and viral arthritis.

AIM: Andrographolide, the major bioactive compound of the plant Andrographis paniculata, exerts anti-inflammatory, cyto-, neuro- and hepato-protective effects. Traditional remedies for infectious diseases include A. paniculata for maladies like fever, pain, rashes which are associated with chikungunya and other arboviral diseases. Since andrographolide and A. paniculata have potent antiviral properties, the present review aims to provide a comprehensive report of symptoms and immunological molecules involved in chikungunya virus (CHIKV) infection and the therapeutic role of andrographolide in the mitigation of chikungunya and associated symptoms. MATERIALS AND METHODS: Studies on the therapeutic role of A. paniculata and andrographolide in chikungunya and other viral infections published between 1991 and 2021 were searched on various databases. RESULTS AND DISCUSSION: The havoc created by chikungunya is due to the associated debilitating symptoms including arthralgia and myalgia which sometimes remains for years. The authors reviewed and summarized the various symptoms and immunological molecules related to CHIKV replication and associated inflammation, oxidative and unfolded protein stress, apoptosis and arthritis. Additionally, the authors suggested andrographolide as a remedy for chikungunya and other arboviral infections by highlighting its role in the regulation of molecules involved in unfolded protein response pathway, immunomodulation, inflammation, virus multiplication, oxidative stress, apoptosis and arthritis. CONCLUSION: The present review demonstrated the major complications associated with chikungunya and the role of andrographolide in alleviating the chikungunya associated symptoms to encourage further investigations using this promising compound towards early development of an anti-CHIKV drug. Chemical Compound studied: andrographolide (PubChem CID: 5318517).

Molecular characterization of chikungunya virus isolates from two localized outbreaks during 2014-2019 in Kerala, India.

After the 2005-2009 chikungunya epidemic, intermittent outbreaks were reported in many parts of India. The outbreaks were caused by either locally circulating strains or imported viruses. Virus transmission routes can be traced by complete genome sequencing studies. We investigated two outbreaks in 2014 and 2019 in Kerala, India. Chikungunya virus (CHIKV) was isolated from the samples, and whole genomes were sequenced for a 2014 isolate and a 2019 isolate. Phylogenetic analysis revealed that the isolates formed a separate group with a 2019 isolate from Pune, Maharashtra, and belonged to the East/Central/South African (ECSA) genotype, Indian subcontinent sublineage of the Indian Ocean Lineage (IOL). A novel mutation at amino acid position 76 of the E2 gene was observed in the group. The phylogenetic results suggest that the outbreaks might have been caused by a virus that had been circulating in India since 2014. A detailed study is needed to investigate the evolution of CHIKV in India.

Effectiveness of Wolbachia-infected mosquito deployments in reducing the incidence of dengue and other Aedes-borne diseases in Niterói, Brazil: A quasi-experimental study.

BACKGROUND: The introduction of the bacterium Wolbachia (wMel strain) into Aedes aegypti mosquitoes reduces their capacity to transmit dengue and other arboviruses. Evidence of a reduction in dengue case incidence following field releases of wMel-infected Ae. aegypti has been reported previously from a cluster randomised controlled trial in Indonesia, and quasi-experimental studies in Indonesia and northern Australia. METHODOLOGY/PRINCIPAL FINDINGS: Following pilot releases in 2015-2016 and a period of intensive community engagement, deployments of adult wMel-infected Ae. aegypti mosquitoes were conducted in Niterói, Brazil during 2017-2019. Deployments were phased across four release zones, with a total area of 83 km2 and a residential population of approximately 373,000. A quasi-experimental design was used to evaluate the effectiveness of wMel deployments in reducing dengue, chikungunya and Zika incidence. An untreated control zone was pre-defined, which was comparable to the intervention area in historical dengue trends. The wMel intervention effect was estimated by controlled interrupted time series analysis of monthly dengue, chikungunya and Zika case notifications to the public health surveillance system before, during and after releases, from release zones and the control zone. Three years after commencement of releases, wMel introgression into local Ae. aegypti populations was heterogeneous throughout Niterói, reaching a high prevalence (>80%) in the earliest release zone, and more moderate levels (prevalence 40-70%) elsewhere. Despite this spatial heterogeneity in entomological outcomes, the wMel intervention was associated with a 69% reduction in dengue incidence (95% confidence interval 54%, 79%), a 56% reduction in chikungunya incidence (95%CI 16%, 77%) and a 37% reduction in Zika incidence (95%CI 1%, 60%), in the aggregate release area compared with the pre-defined control area. This significant intervention effect on dengue was replicated across all four release zones, and in three of four zones for chikungunya, though not in individual release zones for Zika. CONCLUSIONS/SIGNIFICANCE: We demonstrate that wMel Wolbachia can be successfully introgressed into Ae. aegypti populations in a large and complex urban setting, and that a significant public health benefit from reduced incidence of Aedes-borne disease accrues even where the prevalence of wMel in local mosquito populations is moderate and spatially heterogeneous. These findings are consistent with the results of randomised and non-randomised field trials in Indonesia and northern Australia, and are supportive of the Wolbachia biocontrol method as a multivalent intervention against dengue, chikungunya and Zika.

Emerging and Re-emerging Infections in Children: COVID/ MIS-C, Zika, Ebola, Measles, Varicella, Pertussis ... Immunizations.

The role of the emergency provider lies at the forefront of recognition and treatment of novel and re-emerging infectious diseases in children. Familiarity with disease presentations that might be considered rare, such as vaccine-preventable and non-endemic illnesses, is essential in identifying and controlling outbreaks. As we have seen thus far in the novel coronavirus pandemic, susceptibility, severity, transmission, and disease presentation can all have unique patterns in children. Emergency providers also have the potential to play a public health role by using lessons learned from the phenomena of vaccine hesitancy and refusal.

Spatial and temporal invasion dynamics of the 2014-2017 Zika and chikungunya epidemics in Colombia.

Zika virus (ZIKV) and chikungunya virus (CHIKV) were recently introduced into the Americas resulting in significant disease burdens. Understanding their spatial and temporal dynamics at the subnational level is key to informing surveillance and preparedness for future epidemics. We analyzed anonymized line list data on approximately 105,000 Zika virus disease and 412,000 chikungunya fever suspected and laboratory-confirmed cases during the 2014-2017 epidemics. We first determined the week of invasion in each city. Out of 1,122, 288 cities met criteria for epidemic invasion by ZIKV and 338 cities by CHIKV. We analyzed risk factors for invasion using linear and logistic regression models. We also estimated that the geographic origin of both epidemics was located in Barranquilla, north Colombia. We assessed the spatial and temporal invasion dynamics of both viruses to analyze transmission between cities using a suite of (i) gravity models, (ii) Stouffer's rank models, and (iii) radiation models with two types of distance metrics, geographic distance and travel time between cities. Invasion risk was best captured by a gravity model when accounting for geographic distance and intermediate levels of density dependence; Stouffer's rank model with geographic distance performed similarly well. Although a few long-distance invasion events occurred at the beginning of the epidemics, an estimated distance power of 1.7 (95% CrI: 1.5-2.0) from the gravity models suggests that spatial spread was primarily driven by short-distance transmission. Similarities between the epidemics were highlighted by jointly fitted models, which were preferred over individual models when the transmission intensity was allowed to vary across arboviruses. However, ZIKV spread considerably faster than CHIKV.