Arbovirus Surveillance near the Mexico-U.S. Border: Isolation and Sequence Analysis of Chikungunya Virus from Patients with Dengue-like Symptoms in Reynosa, Tamaulipas

Insight into Preventing Global Dengue Spread: Nanoengineered Niclosamide for Viral Infections

Millions of cases of dengue virus (DENV) infection yearly from Aedes mosquitoes stress the need for effective antivirals. No current drug effectively combats dengue efficiently. Transient immunity and severe risks highlight the need for broad-spectrum antivirals targeting all serotypes of DENV. Niclosamide, an antiparasitic, shows promising antiviral activity against the dengue virus, but enhancing its bioavailability is challenging. To overcome this issue and enable niclosamide to address the global dengue problem, nanoengineered niclosamides can be the solution. Not only does it address cost issues but also with its broad-spectrum antiviral effects nanoengineered niclosamide offers hope in addressing the current health crisis associated with DENV and will play a crucial role in combating other arboviruses as well.

Accurate Recapitulation of Chikungunya Virus Complete Coding Sequence Phylogeny Using Variable Genome Regions for Genomic Surveillance

Chikungunya virus (CHIKV) is transmitted by mosquito bites and causes chikungunya fever (CHIKF). CHIKV has a single-stranded RNA genome and belongs to a single serotype with three genotypes. The Asian lineage has recently emerged in the Western Hemisphere, likely due to travel-associated introduction. Genetic variation accumulates in the CHIKV genome as the virus replicates, creating new lineages. Whole genome sequencing is ideal for studying virus evolution and spread but is expensive and complex. This study investigated whether specific, highly variable regions of the CHIKV genome could recapitulate the phylogeny obtained with a complete coding sequence (CDS). Our results revealed that concatenated highly variable regions accurately reconstructed CHIKV phylogeny, exhibiting statistically indistinguishable branch lengths and tree confidence compared to CDS. In addition, these regions adequately inferred the evolutionary relationships among CHIKV isolates from the American outbreak with similar results to the CDS. This finding suggests that highly variable regions can effectively capture the evolutionary relationships among CHIKV isolates, offering a simpler approach for future studies. This approach could be particularly valuable for large-scale surveillance efforts.

Convergent trends and spatiotemporal patterns of Aedes-borne arboviruses in Mexico and Central America

BACKGROUND

Aedes-borne arboviruses cause both seasonal epidemics and emerging outbreaks with a significant impact on global health. These viruses share mosquito vector species, often infecting the same host population within overlapping geographic regions. Thus, comparative analyses of the virus evolutionary and epidemiological dynamics across spatial and temporal scales could reveal convergent trends.

METHODOLOGY/PRINCIPAL FINDINGS

Focusing on Mexico as a case study, we generated novel chikungunya and dengue (CHIKV, DENV-1 and DENV-2) virus genomes from an epidemiological surveillance-derived historical sample collection, and analysed them together with longitudinally-collected genome and epidemiological data from the Americas. Aedes-borne arboviruses endemically circulating within the country were found to be introduced multiple times from lineages predominantly sampled from the Caribbean and Central America. For CHIKV, at least thirteen introductions were inferred over a year, with six of these leading to persistent transmission chains. For both DENV-1 and DENV-2, at least seven introductions were inferred over a decade.

CONCLUSIONS/SIGNIFICANCE

Our results suggest that CHIKV, DENV-1 and DENV-2 in Mexico share evolutionary and epidemiological trajectories. The southwest region of the country was determined to be the most likely location for viral introductions from abroad, with a subsequent spread into the Pacific coast towards the north of Mexico. Virus diffusion patterns observed across the country are likely driven by multiple factors, including mobility linked to human migration from Central towards North America. Considering Mexico's geographic positioning displaying a high human mobility across borders, our results prompt the need to better understand the role of anthropogenic factors in the transmission dynamics of Aedes-borne arboviruses, particularly linked to land-based human migration.

COVID-19: A unique opportunity to improve laboratory capacity for neglected tropical diseases in sub-Saharan Africa

While many public health and university laboratories have become involved in COVID-19 testing during the pandemic, these laboratories now run the risk of being underutilized as COVID-19 testing wanes. This is particularly true of established COVID-19 laboratories in many low- and middle-income countries (LMICs). In this article, we make a case for repurposing many of these laboratories to support control programs for neglected tropical diseases (NTDs) in endemic countries as they contemplate how to strengthen laboratory capacity for all endemic and emerging epidemiological diseases.

Genetic Diversity and Spatiotemporal Dynamics of Chikungunya Infections in Mexico during the Outbreak of 2014-2016

Chikungunya virus (CHIKV) is an alphavirus transmitted by Aedes mosquitoes, which causes Chikungunya fever. Three CHIKV genotypes have been identified: West African, East-Central-South African and Asian. In 2014, CHIKV was detected for the first time in Mexico, accumulating 13,569 confirmed cases in the following three years. Studies on the molecular diversification of CHIKV in Mexico focused on limited geographic regions or investigated only one structural gene of the virus. To describe the dynamics of this outbreak, we analyzed 309 serum samples from CHIKV acute clinical cases from 15 Mexican states. Partial NSP3, E1, and E2 genes were sequenced, mutations were identified, and their genetic variability was estimated. The evolutionary relationship with CHIKV sequences sampled globally were analyzed. Our sequences grouped with the Asian genotype within the Caribbean lineage, suggesting that the Asian was the only circulating genotype during the outbreak. Three non-synonymous mutations (E2 S248F and NSP3 A437T and L451F) were present in our sequences, which were also identified in sequences of the Caribbean lineage and in one Philippine sequence. Based on the phylogeographic analysis, the viral spread was reconstructed, suggesting that after the introduction through the Mexican southern border (Chiapas), CHIKV dispersed to neighboring states before reaching the center and north of the country through the Pacific Ocean states and Quintana Roo. This is the first viral phylogeographic reconstruction in Mexico characterizing the CHIKV outbreak across the country.

Chikungunya in Guerrero, Mexico, 2019 and Evidence of Gross Underreporting in the Region

The local public health authorities reported nine cases of chikungunya in Mexico in 2019, none of which occurred in Guerrero, a coastal state in the southwest. To test the hypothesis that chikungunya is grossly underreported in Mexico, acute sera were collected from 639 febrile patients from low-income households in Guerrero in 2019 and serologically assayed for chikungunya virus (CHIKV). Analysis of the sera by plaque reduction neutralization test revealed that 181 (28.3%) patients were seropositive for CHIKV. To identify patients with acute CHIKV infections, a subset of sera samples were tested for CHIKV-specific IgM by ELISA. Sera samples from 21 of 189 (11.1%) patients were positive. These patients met the chikungunya case definition established by the WHO. In conclusion, we provide evidence that CHIKV remains an important public health problem in Mexico and that the true number of cases is severely underestimated.

Vertebrate-Aedes aegypti and Culex quinquefasciatus (Diptera)-arbovirus transmission networks: Non-human feeding revealed by meta-barcoding and next-generation sequencing

Background

Aedes aegypti mosquito-borne viruses including Zika (ZIKV), dengue (DENV), yellow fever (YFV), and chikungunya (CHIKV) have emerged and re-emerged globally, resulting in an elevated burden of human disease. Aedes aegypti is found worldwide in tropical, sub-tropical, and temperate areas. The characterization of mosquito blood meals is essential to understand the transmission dynamics of mosquito-vectored pathogens.

Methodology/principal findings

Here, we report Ae. aegypti and Culex quinquefasciatus host feeding patterns and arbovirus transmission in Northern Mexico using a metabarcoding-like approach with next-generation deep sequencing technology. A total of 145 Ae. aegypti yielded a blood meal analysis result with 107 (73.8%) for a single vertebrate species and 38 (26.2%) for two or more. Among the single host blood meals for Ae. aegypti, 28.0% were from humans, 54.2% from dogs, 16.8% from cats, and 1.0% from tortoises. Among those with more than one species present, 65.9% were from humans and dogs. For Cx. quinquefasciatus, 388 individuals yielded information with 326 (84%) being from a single host and 63 (16.2%) being from two or more hosts. Of the single species blood meals, 77.9% were from dogs, 6.1% from chickens, 3.1% from house sparrows, 2.4% from humans, while the remaining 10.5% derived from other 12 host species. Among those which had fed on more than one species, 11% were from dogs and humans, and 89% of other host species combinations. Forage ratio analysis revealed dog as the most over-utilized host by Ae. aegypti (= 4.3) and Cx. quinquefasciatus (= 5.6) and the human blood index at 39% and 4%, respectively. A total of 2,941 host-seeking female Ae. aegypti and 3,536 Cx. quinquefasciatus mosquitoes were collected in the surveyed area. Of these, 118 Ae. aegypti pools and 37 Cx. quinquefasciatus pools were screened for seven arboviruses (ZIKV, DENV 1–4, CHIKV, and West Nile virus (WNV)) using qRT-PCR and none were positive (point prevalence = 0%). The 95%-exact upper limit confidence interval was 0.07% and 0.17% for Ae. aegypti and Cx. quinquefasciatus, respectively

Conclusions/significance

The low human blood feeding rate in Ae. aegypti, high rate of feeding on mammals by Cx. quinquefasciatus, and the potential risk to transmission dynamics of arboviruses in highly urbanized areas of Northern Mexico is discussed.

Elucidating arbovirus-vector-host contact networks is critical to understand and control mosquito-borne virus transmission, including pathogens such as ZIKV, DENV 1–4, CHIKV, and WNV. Here, we report the results of metabarcoding of blood meals of two primary pathogen mosquito vectors, Aedes aegypti and Culex quinquefasciatus. We found limited human blood feeding by Ae. aegypti and high preference for feeding on mammals by Cx. quinquefasciatus. Interestingly, blood meal analysis revealed dogs as the most utilized host for both vector species suggesting the potential for zooprophylaxis for human-amplified urban arboviruses. Pools of these vector species were tested for seven arboviruses and all were negative. We calculated vectorial capacity to discuss the potential risk and transmission dynamics of pathogens transmitted by these two important vectors in an urban location in Northern Mexico.

Sugar Feeding Patterns for Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae) Mosquitoes in South Texas

Effective mosquito surveillance and management depend on a thorough understanding of the biology and feeding patterns unique to species and sex. Given that a propensity to sugar feed is necessary for some mosquito surveillance and newer control strategies, we sought to document the amount of total sugar in wild Aedes aegypti (L.) and Culex quinquefasciatus (Say) captured from five different locations in the Lower Rio Grande Valley (LRGV) of South Texas over 2 yr. We used Biogents Sentinel 2 (BGS2) traps in year 1 and aspirators, BGS2, and CDC resting traps in years 2 and 3 to collect adult mosquitoes. The hot anthrone test was used to quantify total sugar content in each mosquito. Additionally, the cold and hot anthrone tests were used to distinguish fructose content from total sugars for mosquitoes captured in 2019. Overall, Ae. aegypti females had significantly lower total sugar content than Ae. aegypti males as well as both sexes of Cx. quinquefasciatus. However, the percentage of Ae. aegypti positive for fructose consumption was four to eightfold higher than Ae. aegypti previously reported in other regions. The difference between locations was significant for males of both species, but not for females. Seasonality and trapping method also revealed significant differences in sugar content of captured mosquitoes. Our results reinforce that sugar feeding in female Ae. aegypti is less than Cx. quinquefasciatus, although not absent. This study provides necessary data to evaluate the potential effectiveness of sugar baits in surveillance and control of both Ae. aegypti and Cx. quinquefasciatus mosquitoes.

Simultaneous zika and dengue serotype-4 viral detection and isolation from a donor plasma unit

During zika and dengue viruse (ZIKV and DENV) outbreaks, the majority of the infected individuals remain clinically asymptomatic. Such asymptomatic individuals may occasionally acquire both arboviruses, donate blood, and contaminate haemoderivatives. The aim of this study was to characterize a ZIKV/DENV-4 coinfection in asymptomatic blood donor who donated blood during a large mixed ZIKV/DENV outbreak in the Säo Paulo State, Brazil. On the basis of post-donation information, one blood donor sample was found positive for ZIKV and DENV RNA. The DENV molecular serotyping was performed by molecular testing. The sample was also titrated on VERO E6 cells in order to define the presence of infectious arboviruses. The real-time PCR testing of the blood donor sample demonstrated very high viral load for both ZIKV and DENV. Further, molecular serotyping of DENV showed that the presence of DENV-4. The viral titration in cell culture indicated a titre of 2.75x10^[6] PFU/ml which was concordant with the presence of infectious viruses in the blood donation. This is an interesting report for the simultaneous presence of infectious ZIKV and DENV-4 in asymptomatic blood sample. Special attention must be paid during mixed arboviral outbreaks for the possibility of transfusion-transmission of multiple arboviral agents.

Genetic Variability of Chikungunya Virus in Southern Mexico

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes Chikungunya fever. CHIKV entered Mexico through the state of Chiapas in October 2014. To fully understand the Chikungunya fever outbreak that occurred in southern Chiapas during 2015, we evaluated 22 PCR-confirmed CHIKV-positive patients, identified CHIKV genetic variability, reconstructed viral dispersal, and assessed possible viral mutations. Viruses were isolated and E2, 6K, and E1 genes were sequenced. We applied phylogenetic and phylogeographic approaches, modeled mutations, and estimated selective pressure. Different CHIKV strains circulated in Chiapas during summer 2015. Three isolates grouped themselves in a well-supported clade. Estimates show that the outbreak started in Ciudad Hidalgo and posteriorly dispersed towards Tapachula and neighboring municipalities. We found six non-synonymous mutations in our isolates. Two mutations occurred in one isolate and the remaining mutations occurred in single isolates. Mutations E2 T116I and E2 K221R changed the protein surface in contact with the host cell receptors. We could not find positive selected sites in our CHIKV sequences from southern Chiapas. This is the first viral phylogeographic reconstruction in Mexico characterizing the CHIKV outbreak in southern Chiapas.

Surveillance for Flaviviruses Near the Mexico-U.S. Border: Co-circulation of Dengue Virus Serotypes 1, 2, and 3 and West Nile Virus in Tamaulipas, Northern Mexico, 2014-2016

A clinical, serological, and molecular investigation was performed to determine the presence of dengue virus (DENV) and other flaviviruses among residents of the city of Reynosa, Tamaulipas, on the Mexico-U.S. border in 2014-2016. The sample population consisted of 2,355 patients with suspected dengue, in addition to 346 asymptomatic individuals recruited during a household-based epidemiological investigation designed to identify flavivirus seroconversions. Sera were collected from patients with suspected dengue in the acute phase of illness and from asymptomatic individuals at enrollment and every 5-7 months for 19 months. Sera from suspected dengue patients were tested for DENV antigen by enzyme-linked immunosorbent assay (ELISA), and select antigen-positive sera were further tested using a serotype-specific, quantitative reverse transcription-polymerase chain reaction. Sera from the household cohort were tested for flavivirus-reactive antibodies by immunoglobulin (Ig) M and IgG ELISAs using DENV antigen. A total of 418 (17.7%) patients with suspected dengue had laboratory-confirmed DENV infections, including 82 patients who were positive for DENV RNA. The most frequently detected serotype was DENV-1 (61 patients), followed by DENV-2 (16 patients) and DENV-3 (five patients). A total of 217 (62.7%) asymptomatic individuals had flavivirus-reactive antibodies at enrollment, and nine flavivirus-naïve individuals seroconverted. Sera from a subset of dengue patients and household participants, including all those who seroconverted, were further tested by plaque reduction neutralization test, resulting in the detection of antibodies to DENV-1, DENV-2, and West Nile virus. In summary, we provide evidence for the co-circulation of multiple flaviviruses in Reynosa, Tamaulipas, on the Mexico-U.S. border.