The first confirmed outbreak of chikungunya reported in Timor-Leste, 2024.

Abstract: Timor-Leste is a mountainous, half-island nation with a population of 1.3 million, which shares a land border with Indonesia and is 550 km from Darwin, Australia. Since independence in 2002, Timor-Leste has achieved significant development; however, high levels of poverty remain. Chikungunya virus (CHIKV) is endemic in over 100 countries in Africa, Asia, Europe and in the Americas. It is transmitted by the bite of infected Aedes aegypti or Ae. albopictus mosquitoes, which are present in Timor-Leste and which contribute to annual rainy-season dengue virus (DENV) outbreaks. Symptomatic people typically suffer from acute onset of fever, usually accompanied by severe arthritis or arthralgia. Joint pain can be debilitating for several days, and may sometimes last for weeks, months or years. Unlike DENV infection which has significant mortality, most people recover completely. Between 2002 and 2023, there were 26 cases of CHIKV notified in Australia who acquired their infection in Timor-Leste; however, laboratory testing capability for CHIKV in Timor-Leste only became available in 2021 using polymerase chain reaction (PCR). The first locally diagnosed case was notified in November 2023. In January 2024, an outbreak of CHIKV was recognised in Timor-Leste for the first time, with 195 outbreak cases reported during 1-31 January 2024; all were PCR positive. There were no cases hospitalised, and no deaths. The median age of cases was 17 years (range 1-76 years); 51% were males. Cases were reported across the country; most (88/195) were from Dili, although the highest incidence was seen in the neighbouring municipality of Ermera (monthly incidence rate of 58.8 cases per 100,000 population). This first reported outbreak of CHIKV in Timor-Leste highlights the need for improved mosquito-borne illness control and response strategies, including minimising breeding sites and promoting early presentation for treatment and differential diagnosis from DENV, and consideration of the deployment of Wolbachia-infected mosquitoes, particularly as they have shown to reduce the transmission of CHIKV, DENV and Zika virus, all of which pose threats in Timor-Leste.

Design, development, and validation of multi-epitope proteins for serological diagnosis of Zika virus infections and discrimination from dengue virus seropositivity.

Zika virus (ZIKV), an arbovirus from the Flaviviridae family, is the causative agent of Zika fever, a mild and frequent oligosymptomatic disease in humans. Nonetheless, on rare occasions, ZIKV infection can be associated with Guillain-Barré Syndrome (GBS), and severe congenital complications, such as microcephaly. The oligosymptomatic disease, however, presents symptoms that are quite similar to those observed in infections caused by other frequent co-circulating arboviruses, including dengue virus (DENV). Moreover, the antigenic similarity between ZIKV and DENV, and even with other members of the Flaviviridae family, complicates serological testing due to the high cross-reactivity of antibodies. Here, we designed, produced in a prokaryotic expression system, and purified three multiepitope proteins (ZIKV-1, ZIKV-2, and ZIKV-3) for differential diagnosis of Zika. The proteins were evaluated as antigens in ELISA tests for the detection of anti-ZIKV IgG using ZIKV- and DENV-positive human sera. The recombinant proteins were able to bind and detect anti-ZIKV antibodies without cross-reactivity with DENV-positive sera and showed no reactivity with Chikungunya virus (CHIKV)- positive sera. ZIKV-1, ZIKV-2, and ZIKV-3 proteins presented 81.6%, 95%, and 66% sensitivity and 97%, 96%, and 84% specificity, respectively. Our results demonstrate the potential of the designed and expressed antigens in the development of specific diagnostic tests for the detection of IgG antibodies against ZIKV, especially in regions with the circulation of multiple arboviruses.

Occurrence of arbovirus infections in two riverine populations in the municipality of Humaitá, Amazonas, Brazil.

BACKGROUND: The riverine communities of the Amazon comprise different social groups that inhabit the rural areas on the banks of rivers and lakes. Residents usually travel by river to rural and urban areas and are then exposed to urbanized diseases such as those caused by arbovirus infection. In Brazil, emerging diseases such as dengue, Zika, chikungunya, and those caused by infection with Oropouche and Mayaro viruses necessitate epidemiological surveillance. This study was aimed at determining the frequency of positivity for immunoglobulin (Ig)G and IgM antibodies against Zika, chikungunya, and dengue viruses and performing molecular analyses to detect viral RNA for the Zika, chikungunya, dengue virus, Oropouche, and Mayaro viruses, in the same serum samples obtained from riverside populations. METHODS: This cross-sectional study was conducted in a riverside population in the Humaitá municipality of the Brazilian Amazon. More than 80% of the local population participated in this study. Entomological samples were collected to identify local mosquito vectors. RESULTS: Analysis of 205 human serological samples revealed IgG antibodies against the dengue virus in 85 individuals. No molecular positivity was observed in human samples. Entomological analyses revealed 3,187 Diptera species, with Mansonia being the most frequent genus. Aedes aegypti and Aedes albopictus were not detected in the two collections. CONCLUSIONS: IgG antibodies against the dengue virus were highly prevalent, suggesting previous exposure. The absence of the arbovirus vectors Aedes aegypti and Aedes albopictus in the samples supports the hypothesis that the infections recorded likely occurred outside the riverside communities investigated.

N6-methyladenosine modification is not a general trait of viral RNA genomes.

Despite the nuclear localization of the m6A machinery, the genomes of multiple exclusively-cytoplasmic RNA viruses, such as chikungunya (CHIKV) and dengue (DENV), are reported to be extensively m6A-modified. However, these findings are mostly based on m6A-Seq, an antibody-dependent technique with a high rate of false positives. Here, we address the presence of m6A in CHIKV and DENV RNAs. For this, we combine m6A-Seq and the antibody-independent SELECT and nanopore direct RNA sequencing techniques with functional, molecular, and mutagenesis studies. Following this comprehensive analysis, we find no evidence of m6A modification in CHIKV or DENV transcripts. Furthermore, depletion of key components of the host m6A machinery does not affect CHIKV or DENV infection. Moreover, CHIKV or DENV infection has no effect on the m6A machinery's localization. Our results challenge the prevailing notion that m6A modification is a general feature of cytoplasmic RNA viruses and underscore the importance of validating RNA modifications with orthogonal approaches.

Clinical description of dengue and chikungunya virus infections amongst acute febrile patients in a malaria endemic area of Mfou, the Centre region of Cameroon.

This study aims to determine the frequency and clinical manifestations of dengue and chikungunya viral infections in the district hospital of Mfou, Centre region of Cameroon where malaria is endemic. Blood samples were collected from suspected cases and tested for Plasmodium parasites and for the molecular detection of viral RNAs (dengue, zika and chikungunya viruses) using TRIOPLEX qPCR. A total of 108 patients were clinically suspected among which 25 % were male and 50 % were less than 15.5 years old. Of these 14.8 % (16/108) and 2.8 % (3/108) had acute dengue and chikungunya fevers respectively. Co-infection with malaria was reported in 56.3 % (9/16) of Dengue cases and 33.3 % (1/3) of chikungunya cases. Clinical profiling further revealed that nausea and vomiting show a significant difference in dengue infected individuals to those of non-infected individuals (P = 0.027). The presence of dengue fever and chikungunya fever and the absence of specific clinical manifestations highlight the need to strengthen surveillance of acute febrile infections for a better estimation of the burden of arboviruses.

Detecting the impacts of humidity, rainfall, temperature, and season on chikungunya, dengue and Zika viruses in Aedes albopictus mosquitoes from selected sites in Cebu city, Philippines.

BACKGROUND: Aedes albopictus is the secondary vector for dengue virus (DENV) in the Philippines, and also harbors chikungunya (CHIKV) and Zika (ZIKV) viruses. This study aimed to determine the minimum infection rates (MIRs) of CHIKV, DENV serotypes, and ZIKV in Ae. albopictus collected from selected two-site categories by altitude (highland [H] and lowland [L] sites) in Cebu city, Philippines during the wet (WS) and dry seasons (DS) of 2021-2022, and to explore the relationships between these arboviral MIRs and the local weather. METHODS: The viral RNA extracts in pooled and reared adult Ae. albopictus collected during the DS and WS from two-site categories were subjected to RT-PCR to amplify and detect gene loci specific for CHIKV, DENV-1 to DENV-4, and ZIKV and analyzed with the weather data. RESULTS: The range of CHIKV MIRs was higher in the WS (13.61-107.38 infected individuals per 1,000 mosquitoes) than in the DS (13.22-44.12), but was similar between the two-site categories. Rainfall (RF) influenced the CHIKV MIR. The MIR ranges of both DENV-2 (WS: H = 0, L = 0; DS: H = 0-5.92; L = 0-2.6) and DENV-4 (WS: H = 0, L = 0-2.90; DS: H = 2.96-6.13, L = 0-15.63) differed by season but not between the two-site categories. Relative humidity (RH), RF, and temperature did not influence DENVs' MIRs. The MIR range of ZIKV was similar in both seasons (WS: 11.36-40.27; DS: 0-46.15) and two-site categories (H = 0-90.91, L = 0-55.56). RH and temperature influenced ZIKV MIR. CONCLUSIONS: RF influenced CHIKV MIR in Ae. albopictus, whereas RH and temperature influenced that of ZIKV. Season influenced the MIRs of CHIKV and DENVs but not in ZIKV. Ae. albopictus were co-infected with CHIKV, DENVs, and ZIKV in both highland and lowland sites in Cebu city. Recommendations include all-year-round implementation of the Philippine Department of Health's  4S enhanced strategy and installation of water pipelines in rural highlands for vector and disease control. Our findings are relevant to protect public health in the tropics in this climate change.

Challenges and epidemiological implications of the first outbreak of dengue and chikungunya in Sudan.

Background: Dengue and chikungunya are mosquito-borne infections that are spreading rapidly worldwide. The highest burden lies in tropical and subtropical countries. In 2022 Sudan encountered the most widespread infection of both diseases. Aim: To describe the magnitude of the first outbreak of dengue and chikungunya infections in Tandalti Town, White Nile State, southern part of Sudan. Methods: Following the report of a high number of undifferentiated febrile illnesses in 32 health clinics in Tandalti Town, an area with high densities of Aedes aegypti, we collected blood samples from symptomatic suspected cases. The samples were tested for major arboviral infections using arboviral-specific enzyme-linked immunosorbent assays (IgM capture ELISA), and serologically positive samples were confirmed using commercially available Real Time RT-PCR Kits. Results: Out of 773 suspected cases, 63 (8.15%) were confirmed. Eleven (17.46%) of the confirmed cases were DENV, 49 (77.77%) were CHIKV, and 3 (4.76%) were DENV and CHIKV co-infections. The outbreak started at the beginning of October and ended by mid December 2022. Both dengue and chikungunya infection was higher (41(65.08%)) among young females than males (22 (34.92%)). Conclusions: White Nile State may experience larger outbreaks of dengue and chikungunya in the future, there is, therefore, an urgent need for proper vector control interventions in the state and nearby states.

Estimating the potential risk of transmission of arboviruses in the Americas and Europe: a modelling study.

BACKGROUND: Estimates of the spatiotemporal distribution of different mosquito vector species and the associated risk of transmission of arboviruses are key to design adequate policies for preventing local outbreaks and reducing the number of human infections in endemic areas. In this study, we quantified the abundance of Aedes albopictus and Aedes aegypti and the local transmission potential for three arboviral infections at an unprecedented spatiotemporal resolution in areas where no entomological surveillance is available. METHODS: We developed a computational model to quantify the daily abundance of Aedes mosquitoes, leveraging temperature and precipitation records. The model was calibrated on mosquito surveillance data collected in 115 locations in Europe and the Americas between 2007 and 2018. Model estimates were used to quantify the reproduction number of dengue virus, Zika virus, and chikungunya in Europe and the Americas, at a high spatial resolution. FINDINGS: In areas colonised by both Aedes species, A aegypti was estimated to be the main vector for the transmission of dengue virus, Zika virus, and chikungunya, being associated with a higher estimate of R0 when compared with A albopictus. Our estimates highlighted that these arboviruses were endemic in tropical and subtropical countries, with the highest risks of transmission found in central America, Venezuela, Colombia, and central-east Brazil. A non-negligible potential risk of transmission was also estimated for Florida, Texas, and Arizona (USA). The broader ecological niche of A albopictus could contribute to the emergence of chikungunya outbreaks and clusters of dengue autochthonous cases in temperate areas of the Americas, as well as in mediterranean Europe (in particular, in Italy, southern France, and Spain). INTERPRETATION: Our results provide a comprehensive overview of the transmission potential of arboviral diseases in Europe and the Americas, highlighting areas where surveillance and mosquito control capacities should be prioritised. FUNDING: EU and Ministero dell'Università e della Ricerca, Italy (Piano Nazionale di Ripresa e Resilienza Extended Partnership initiative on Emerging Infectious Diseases); EU (Horizon 2020); Ministero dell'Università e della Ricerca, Italy (Progetti di ricerca di Rilevante Interesse Nazionale programme); Brazilian National Council of Science, Technology and Innovation; Ministry of Health, Brazil; and Foundation of Research for Minas Gerais, Brazil.

Does a patient with acquired arbovirus infection have a hearing impairment? A scoping review of hearing changes in an adult with Dengue, Chikungunya, and Zika.

OBJECTIVES: To identify and understand the evidence regarding hearing changes related to acquired Dengue, Chikungunya, and Zika virus infection in adult individuals. METHODS: A scoping review was performed according to the recommendations of The Joanna Briggs Institute and guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews in the Embase, PubMed/Medline, ScienceDirect, Scopus, and Web of Science databases without restriction on language and year of publication. Case studies, observational studies, and clinical trials reporting hearing loss in adult subjects (>18-60 years of age) of both sexes with DENV, CHIKV, or ZIKV diagnosed by positive molecular/serological examination by RT-PCR or IgM/IgG by ELISA method were included. RESULTS: Thirteen studies met the inclusion criteria and were selected for review. The occurrence of auditory symptoms caused by arboviroses and the presence of permanent or transient sensorineural hearing loss was variable in adults. CONCLUSIONS: Dengue, Chikungunya, and Zika infections in adults are associated with a variety of auditory symptoms. The frequency of permanent or transient sensorineural hearing loss is low but not negligible.

Molecular detection of dengue and chikungunya viruses in surveillance of wild-caught Aedes mosquitoes in Punjab, North India.

BACKGROUND: Dengue (DENV), Zika (ZIKV) and chikungunya (CHIKV) viruses are transmitted mainly by Aedes mosquitoes and are responsible for a significant global healthcare burden. The current study aimed to detect arboviruses in the Aedes mosquitoes in close proximity of patients during the transmission season. METHODS: Both immature and adult mosquitoes were collected from in and around the patients' houses. Mosquito pools were homogenized and extracted RNA was subjected to reverse transcription polymerase chain reaction for arboviral detection. Transovarian transmission (TOT) was assessed by screening F0 adults. Mosquito positivity was correlated with the aetiological agents identified in patients. RESULTS: Of 46 pools, 19 consisted of wild Aedes, with arboviral positivity in 53% (10/19) of pools. Among wild A. aegypti pools, positivity of DENV mono-infection, CHIKV mono-infection and DENV+CHIKV co-infection was noted in four, two and three pools, respectively. One wild pool of Aedes albopictus was positive for DENV-1. Similarly, A. aegypti F0 (adult Aedes developed from immatures) pools showed 59.2% (16/27) positivity for arboviruses. F0 Aedes showed positivity in three, six and seven pools for DENV-2, CHIKV and DENV+CHIKV, respectively, suggestive of TOT. DENV serotypes and CHIKV from 24 patients' serum samples were matched with strains isolated from Aedes and correlation was observed in four instances. CONCLUSIONS: The study detected DENV and CHIKV from wild-caught Aedes and found evidence of DENV and CHIKV TOT in F0 adults.

IgM-specific linear epitopes on the E2 protein for serodiagnosis of Chikungunya.

Chikungunya virus (CHIKV) and Dengue virus (DENV) are vector-borne diseases transmitted by Aedes aegypti and Aedes albopictus that pose a significant threat to global public health. Cases of acute Chikungunya fever often present similar clinical symptoms to other vector-borne diseases, such as Dengue fever. In regions where multiple vector-borne diseases coexist, CHIKV is often overlooked or misdiagnosed as Dengue virus, West Nile virus, Zika virus or other viral infections, which delays its prevention and control. However, IgM antibodies directed against the E2 protein of CHIKV have not yet been generalized to clinical settings due to the low sensitivity and high cost in commercial kits. Indirect ELISA with peptides provides an effective supplementary tool for detecting CHIKV IgM antibodies. Our study aims at examining the potential of linear epitopes on the E2 glycoprotein that specifically bind to IgM antibodies as serodiagnostic tool for CHIKV. The sensitivity of the established peptide indirect ELISA method for detecting clinical samples is significantly better than that of commercial kits, realizing a beneficial supplement to the existing IgM antibody assay. It also established the groundwork for comprehending the biological mechanisms of the CHIKV E2 protein and the advancement of innovative epitope peptide vaccines.

Rapid On-Site Detection of Arboviruses by a Direct RT-qPCR Assay.

Arthropod-borne diseases currently constitute a source of major health concerns worldwide. They account for about 50% of global infectious diseases and cause nearly 700,000 deaths every year. Their rapid increase and spread constitute a huge challenge for public health, highlighting the need for early detection during epidemics, to curtail the virus spread, and to enhance outbreak management. Here, we compared a standard quantitative polymerase chain reaction (RT-qPCR) and a direct RT-qPCR assay for the detection of Zika (ZIKV), Chikungunya (CHIKV), and Rift Valley Fever (RVFV) viruses from experimentally infected-mosquitoes. The direct RT-qPCR could be completed within 1.5 h and required 1 µL of viral supernatant from homogenized mosquito body pools. Results showed that the direct RT-qPCR can detect 85.71%, 89%, and 100% of CHIKV, RVFV, and ZIKV samples by direct amplifications compared to the standard method. The use of 1:10 diluted supernatant is suggested for CHIKV and RVFV direct RT-qPCR. Despite a slight drop in sensitivity for direct PCR, our technique is more affordable, less time-consuming, and provides a better option for qualitative field diagnosis during outbreak management. It represents an alternative when extraction and purification steps are not possible because of insufficient sample volume or biosecurity issues.

High Seroprevalence of IgG Antibodies to Multiple Arboviruses in People Living with HIV (PLWHIV) in Madagascar.

To estimate the prevalence of IgG antibodies against six arboviruses in people living with HIV-1 (PLWHIV) in Madagascar, we tested samples collected between January 2018 and June 2021. We used a Luminex-based serological assay to detect IgG antibodies against antigens from Dengue virus serotypes 1-4 (DENV1-4), Zika virus (ZIKV), West Nile virus (WNV), Usutu virus (USUV), Chikungunya virus (CHIKV), and O'nyong nyong virus (ONNV). Of the 1036 samples tested, IgG antibody prevalence was highest for ONNV (28.4%), CHIKV (26.7%), WNV-NS1 (27.1%), DENV1 (12.4%), USUV (9.9%), and DENV3 (8.9%). ZIKV (4.9%), DENV2 (4.6%), WNV-D3 (5.1%), and DENV4 (1.4%) were lower. These rates varied by province of origin, with the highest rates observed in Toamasina, on the eastern coast (50.5% and 56.8%, for CHIKV and ONNV, respectively). The seroprevalence increased with age for DENV1 and 3 (p = 0.006 and 0.038, respectively) and WNV DIII (p = 0.041). The prevalence of IgG antibodies against any given arborvirus varied over the year and significantly correlated with rainfalls in the different areas (r = 0.61, p = 0.036). Finally, we found a significant correlation between the seroprevalence of antibodies against CHIKV and ONNV and the HIV-1 RNA plasma viral load. Thus, PLWHIV in Madagascar are highly exposed to various arboviruses. Further studies are needed to explain some of our findings.

Arbovirus surveillance in pregnant women in north-central Nigeria, 2019-2022.

BACKGROUND: The adverse impact of Zika (ZIKV), dengue (DENV), and chikungunya (CHIKV) virus infection in pregnancy has been recognized in Latin America and Asia but is not well studied in Africa. Although originally discovered in sub-Saharan Africa the non-specific clinical presentation of arbovirus infection may have hampered our detection of adverse clinical outcomes and outbreak. OBJECTIVE: This prospective study of arbovirus infection in pregnant women in north-central Nigeria sought to characterize the prevalence of acute arbovirus infection and determine the impact on pregnancy and infant outcomes. METHODS: In Nigeria, we screened 1006 pregnant women for ZIKV, DENV and CHIKV IgM/IgG by rapid test (2019-2022). Women with acute infection were recruited for prospective study and infants were examined for any abnormalities from delivery through six months. A subset of rapid test-reactive samples were confirmed using virus-specific ELISAs and neutralization assays. RESULTS: The prevalence of acute infection (IgM+) was 3.8 %, 9.9 % and 11.8 % for ZIKV, DENV and CHIKV, respectively; co-infections represented 24.5 % of all infections. The prevalence in asymptomatic women was twice the level of symptomatic infection. We found a significant association between acute maternal ZIKV/DENV/CHIKV infection and any gross abnormal birth outcome (p = 0.014). CONCLUSIONS: Over three rainy seasons, regular acute infection with ZIKV, DENV, and CHIKV was observed with significantly higher rates in pregnant women without symptoms. The potential association arbovirus infection with abnormal birth outcome warrants further prospective study to ascertain the clinical significance of these endemic arboviruses in Africa.

Detection of coinfection with Primate Erythroparvovirus 1 and arboviruses (DENV, CHIKV and ZIKV) in individuals with acute febrile illness in the state of Rio Grande do Norte in 2016.

BACKGROUND: Arthropod-borne viruses, known as arboviruses, pose substantial risks to global public health. Dengue (DENV), Chikungunya (CHIKV) and Zika (ZIKV) viruses stand out as significant concerns in Brazil and worldwide. Their overlapping clinical manifestations make accurate diagnosis a challenge, underscoring the need for reliable laboratory support. This study employs a comprehensive molecular diagnostic approach to track viral infections in individuals with acute febrile illness, a period marked by widespread outbreaks of DENV, CHIKV and ZIKV. METHODS: Between January and August 2016, we received a total of 713 serum samples obtained from individuals with acute febrile illness, previously tested for DENV, CHIKV or ZIKV, with initial negative results, from LACEN-NATAL. Of the total 713 samples, 667 were from females (354 of them pregnant) and 46 from males. Molecular diagnosis was conducted using the Multiplex RT-qPCR technique for simultaneous detection of DENV, CHIKV and ZIKV. Additionally, we performed differential diagnosis by RT-qPCR for other viruses of the Flavivirus, Alphavirus Enterovirus genera and qPCR for Primate Erythroparvovirus 1 (B19V) species, in accordance with Ministry of Health guidelines. RESULTS: Among the 713 cases, 78.2% tested positive for viral infections, including 48% with CHIKV viremia, 0.6% with DENV and 0.1% with ZIKV. Arboviral coinfections totaled 2.4%, including DENV-CHIKV (1.7%) and CHIKV-ZIKV (0.7%). Moreover, 8% exhibited B19V viremia. Simultaneous infections were identified in 17.5%, encompassing B19V-CHIKV (17.1%), B19V-DENV (0.1%), and B19V-ZIKV (0.3%) Triple infections were observed in 1.3% of cases with B19V-DENV-CHIKV (1%) and B19V-CHIKV-ZIKV (0.3%). CONCLUSION: Molecular testing demonstrated high efficacy in diagnosing prevalent arboviruses and detecting multiple coinfections. This approach helps to elucidate etiologies for symptomatic cases, especially during arbovirus outbreaks, and aids comprehensive surveillance. Our findings underscore the importance of monitoring co-circulating pathogens, such as B19V, with implications for clinical management, particularly in pregnant individuals. This study enhances our understanding of arbovirus epidemiology and reinforces the critical role of molecular diagnosis in disease surveillance and control.

Synthesis of novel rhodamine type Anthrone Spiro-lactam (ASL) analogues and evaluation of antiviral activity against dengue and chikungunya viruses.

A series of Rhodamine type Anthrone-Spirolactam (ASL) derivatives Benzylimin-Anthrone-Spirolactam (ASL-1 to ASL-10) and Benzamide-Anthrone-Spirolactam (ASL-11 and ASL-12) were synthesized via a simple condensation reaction between Anthrone Spiro-lactamine (2) and various aromatic aldehyde and acyl chlorides respectively. Since rhodamine-based compounds were reported to have antiviral activity, the ASL derivatives were examined for in vitro antiviral activity against dengue and chikungunya viruses. Among all the analogues, ASL-3, ASL-6, ASL-7, ASL-8, ASL-9 and ASL-10 were the most potent against dengue virus (DENV) and exerted around one log reduction in virus titre under post-treatment conditions. At the same time ASL-3 was effective under co-treatment conditions. Two analogues ASL-6 and ASL-12 exerted anti-chikungunya virus (CHIKV) activity under post-treatment conditions. In silico docking studies revealed that the ASL derivatives interacted with the proteins of DENV and CHIKV. Together, the results suggest the anti-DENV and CHIKV activity of ASL derivatives which may be exploited further for therapeutic purposes.

Distribution of Aedes mosquito species along the rural-urban gradient in Lambaréné and its surrounding.

BACKGROUND: Aedes albopictus and Aedes aegypti are known for their potential as vectors of dengue (DENV) and chikungunya (CHIKV) viruses. However, entomological surveys are mostly carried out during epidemics. In Gabon where outbreaks of both viruses have occurred, there is no vector control program targeting these arboviruses. Therefore, we assessed the presence of Aedes species along a rural-urban gradient in Lambaréné (Gabon) and its surroundings and determined ecological factors associated to their presence. METHODS: An entomological survey was conducted in Lambaréné and its surrounding rural areas. Mosquitoes were collected with aspirators around human dwellings, and ecological and environmental data were collected from each study area. Morphological identification keys were used to identify Aedes species. RNA was extracted from pools of female mosquitoes and amplified by RT-qPCR to detect the presence of DENV and CHIKV. RESULTS: Overall, the most common vector collected was Aedes albopictus (97%, 4236/4367 specimens), followed by Aedes aegypti (3%, 131/4367). Albopictus vectors was more abundant in the rural area (Wilcoxon signed-rank test, Z = 627, P = 0.043) than in the urban area. In the urban area, a higher number of mosquitoes (45%) were recorded in the economic zone (zone 3) than in the historical and administrative zones (zone 1 and 2). In the rural area, the proportions of species numbers were significantly higher along the south rural transect (92%) compared to the north rural transect (Wilcoxon signed-rank test, Z = 43, P ˂ 0.016). We also noted a high abundance of vectors in environments characterized by monocultures of Hevea brasiliensis (Hevea) and Manihot esculenta (cassava) (Kruskal-Wallis H-test, H = 25.7, df = 2, P < 0.001). Finally, no mosquito pools were positive for either DENV or CHIKV. CONCLUSION: Aedes albopictus was the dominant vector across the study sites due to its high invasiveness capacity. This presence re-affirms the potential for local transmission of both DENV and CHIKV, as indicated previously by serological surveys conducted in our study area, even though no transmission was detected during the current study. These findings underscore the need for regular arbovirus surveillance in the study region, with the aim of supporting vector control efforts in the event of outbreaks.

A Bayesian spatiotemporal approach to modelling arboviral diseases in Mexico.

BACKGROUND: The objective of this study was to evaluate the spatial and temporal patterns of disease prevalence clusters of dengue (DENV), chikungunya (CHIKV) and Zika (ZIKV) virus and how socio-economic and climatic variables simultaneously influence the risk and rate of occurrence of infection in Mexico. METHODS: To determine the spatiotemporal clustering and the effect of climatic and socio-economic covariates on the rate of occurrence of disease and risk in Mexico, we applied correlation methods, seasonal and trend decomposition using locally estimated scatterplot smoothing, hotspot analysis and conditional autoregressive Bayesian models. RESULTS: We found cases of the disease are decreasing and a significant association between DENV, CHIKV and ZIKV cases and climatic and socio-economic variables. An increment of cases was identified in the northeastern, central west and southeastern regions of Mexico. Climatic and socio-economic covariates were significantly associated with the rate of occurrence and risk of the three arboviral disease cases. CONCLUSION: The association of climatic and socio-economic factors is predominant in the northeastern, central west and southeastern regions of Mexico. DENV, CHIKV and ZIKV cases showed an increased risk in several states in these regions and need urgent attention to allocate public health resources to the most vulnerable regions in Mexico.

Arboviral Risk Associated with Solid Organ and Hematopoietic Stem Cell Grafts: The Prophylactic Answers Proposed by the French High Council of Public Health in a National Context.

Diseases caused by arboviruses are on the increase worldwide. In addition to arthropod bites, most arboviruses can be transmitted via accessory routes. Products of human origin (labile blood products, solid organs, hematopoietic stem cells, tissues) present a risk of contamination for the recipient if the donation is made when the donor is viremic. Mainland France and its overseas territories are exposed to a complex array of imported and endemic arboviruses, which differ according to their respective location. This narrative review describes the risks of acquiring certain arboviral diseases from human products, mainly solid organs and hematopoietic stem cells, in the French context. The main risks considered in this study are infections by West Nile virus, dengue virus, and tick-borne encephalitis virus. The ancillary risks represented by Usutu virus infection, chikungunya, and Zika are also addressed more briefly. For each disease, the guidelines issued by the French High Council of Public Health, which is responsible for mitigating the risks associated with products of human origin and for supporting public health policy decisions, are briefly outlined. This review highlights the need for a "One Health" approach and to standardize recommendations at the international level in areas with the same viral epidemiology.

The Innate Immune Response in DENV- and CHIKV-Infected Placentas and the Consequences for the Fetuses: A Minireview.

Dengue virus (DENV) and chikungunya (CHIKV) are arthropod-borne viruses belonging to the Flaviviridae and Togaviridae families, respectively. Infection by both viruses can lead to a mild indistinct fever or even lead to more severe forms of the diseases, which are characterized by a generalized inflammatory state and multiorgan involvement. Infected mothers are considered a high-risk group due to their immunosuppressed state and the possibility of vertical transmission. Thereby, infection by arboviruses during pregnancy portrays a major public health concern, especially in countries where epidemics of both diseases are regular and public health policies are left aside. Placental involvement during both infections has been already described and the presence of either DENV or CHIKV has been observed in constituent cells of the placenta. In spite of that, there is little knowledge regarding the intrinsic earlier immunological mechanisms that are developed by placental cells in response to infection by both arboviruses. Here, we approach some of the current information available in the literature about the exacerbated presence of cells involved in the innate immune defense of the placenta during DENV and CHIKV infections.