Exposure to Zika and chikungunya viruses impacts aspects of the vectorial capacity of Aedes aegypti and Culex quinquefasciatus.

Zika (ZIKV) and chikungunya (CHIKV) are arboviruses that cause infections in humans and can cause clinical complications, representing a worldwide public health problem. Aedes aegypti is the primary vector of these pathogens and Culex quinquefasciatus may be a potential ZIKV vector. This study aimed to evaluate fecundity, fertility, survival, longevity, and blood feeding activity in Ae. aegypti after exposure to ZIKV and CHIKV and, in Cx. quinquefasciatus exposed to ZIKV. Three colonies were evaluated: AeCamp (Ae. aegypti-field), RecL (Ae. aegypti-laboratory) and CqSLab (Cx. quinquefasciatus-laboratory). Seven to 10 days-old females from these colonies were exposed to artificial blood feeding with CHIKV or ZIKV. CHIKV caused reduction in fecundity and fertility in AeCamp and reduction in survival and fertility in RecL. ZIKV impacted survival in RecL, fertility in AeCamp and, fecundity and fertility in CqSLab. Both viruses had no effect on blood feeding activity. These results show that CHIKV produces a higher biological cost in Ae. aegypti, compared to ZIKV, and ZIKV differently alters the biological performance in colonies of Ae. aegypti and Cx. quinquefasciatus. These results provide a better understanding over the processes of virus-vector interaction and can shed light on the complexity of arbovirus transmission.

Zika emergence, persistence, and transmission rate in Colombia: a nationwide application of a space-time Markov switching model.

Zika, a viral disease transmitted to humans by Aedes mosquitoes, emerged in the Americas in 2015, causing large-scale epidemics. Colombia alone reported over 72,000 Zika cases between 2015 and 2016. Using national surveillance data from 1121 municipalities over 70 weeks, we identified sociodemographic and environmental factors associated with Zika's emergence, re-emergence, persistence, and transmission intensity in Colombia. We fitted a zero-state Markov-switching model under the Bayesian framework, assuming Zika switched between periods of presence and absence according to spatially and temporally varying probabilities of emergence/re-emergence (from absence to presence) and persistence (from presence to presence). These probabilities were assumed to follow a series of mixed multiple logistic regressions. When Zika was present, assuming that the cases follow a negative binomial distribution, we estimated the transmission intensity rate. Our results indicate that Zika emerged/re-emerged sooner and that transmission was intensified in municipalities that were more densely populated, at lower altitudes and/or with less vegetation cover. Warmer temperatures and less weekly-accumulated rain were also associated with Zika emergence. Zika cases persisted for longer in more densely populated areas with more cases reported in the previous week. Overall, population density, elevation, and temperature were identified as the main contributors to the first Zika epidemic in Colombia. We also estimated the probability of Zika presence by municipality and week, and the results suggest that the disease circulated undetected by the surveillance system on many occasions. Our results offer insights into priority areas for public health interventions against emerging and re-emerging Aedes-borne diseases.

Aedes albopictus is a competent vector of five arboviruses affecting human health, greater Paris, France, 2023.

Aedes albopictus collected in 2023 in the greater Paris area (Île-de-France) were experimentally able to transmit five arboviruses: West Nile virus from 3 days post-infection (dpi), chikungunya virus and Usutu virus from 7 dpi, dengue virus and Zika virus from 21 dpi. Given the growing number of imported dengue cases reported in early 2024 in France, surveillance of Ae. albopictus should be reinforced during the Paris Olympic Games in July, when many international visitors including from endemic countries are expected.

A naturally isolated symbiotic bacterium suppresses flavivirus transmission by Aedes mosquitoes.

The commensal microbiota of the mosquito gut plays a complex role in determining the vector competence for arboviruses. In this study, we identified a bacterium from the gut of field Aedes albopictus mosquitoes named Rosenbergiella sp. YN46 (Rosenbergiella_YN46) that rendered mosquitoes refractory to infection with dengue and Zika viruses. Inoculation of 1.6 × 103 colony forming units (CFUs) of Rosenbergiella_YN46 into A. albopictus mosquitoes effectively prevents viral infection. Mechanistically, this bacterium secretes glucose dehydrogenase (RyGDH), which acidifies the gut lumen of fed mosquitoes, causing irreversible conformational changes in the flavivirus envelope protein that prevent viral entry into cells. In semifield conditions, Rosenbergiella_YN46 exhibits effective transstadial transmission in field mosquitoes, which blocks transmission of dengue virus by newly emerged adult mosquitoes. The prevalence of Rosenbergiella_YN46 is greater in mosquitoes from low-dengue areas (52.9 to ~91.7%) than in those from dengue-endemic regions (0 to ~6.7%). Rosenbergiella_YN46 may offer an effective and safe lead for flavivirus biocontrol.

Impact of FDA's HCT/P ZIKV Recommendations on Cord Blood Unit Eligibility and Utilization in a Large Public Cord Blood Bank.

BACKGROUND: Cord blood units (CBUs) that are ineligible for licensure due to incomplete compliance with FDA recommendations may be used for hematopoietic stem cell transplantation under urgent medical need and an Investigational Drug Application. The largest reason for CBU donor ineligibility is Zika virus (ZIKV) risk. The study's objective was to analyze the impact of current FDA recommendations for ZIKA risk on a large public cord blood bank and propose updated recommendations. METHODS: We performed a retrospective analysis of Carolinas Cord Blood Bank (CCBB), an FDA licensed public CBB, using data from January 1, 2016 to November 21, 2023 and compared FDA recommendations for transfusion transmitted infections (TTI) for blood products and relevant communicable disease agents or diseases for human cell, tissue, or cellular or tissue-based products (HCT/Ps). RESULTS: CCBB: 9057 (84.3% licensed) CBUs were banked. 984/1682 (58.5%) of unlicensed CBUs had ZIKV risk. 22.0% of CBUs with ZIKV risk were from Hispanic parents, compared to 16.1% of all units. 31 of IND CBUs (11 due to ZIKV risk without reported ZIKV transmission) were safely infused. FDA Guidance: HCT/P ZIKV, HIV, and vCJD recommendations have not been updated since 2018 in contrast to FDA removal of ZIKV as a relevant TTI in 2021 and updating HIV and vCJD guidance related to TTI in 2023 and 2022, respectively. DISCUSSION: The FDA should consider new data to revise the HCT/P donor eligibility recommendations, which will increase the number of eligible HCT/P donors, and potentially improve access to therapies for a more diverse patient population.

Optimising the surveillance of Aedes aegypti in Brazil by selecting smaller representative areas within an endemic city.

OBJECTIVES: Arboviruses, such as dengue (DENV), zika (ZIKV), and chikungunya (CHIKV), constitute a growing urban public health threat. Focusing on Aedes aegypti mosquitoes, their primary vectors, is crucial for mitigation. While traditional immature-stage mosquito surveillance has limitations, capturing adult mosquitoes through traps yields more accurate data on disease transmission. However, deploying traps presents logistical and financial challenges, demonstrating effective temporal predictions but lacking spatial accuracy. Our goal is to identify smaller representative areas within cities to enhance the early warning system for DENV outbreaks. METHODS: We created Sentinel Geographic Units (SGUs), smaller areas of 1 km2 within each stratum, larger areas, with the aim of aligning the Trap Positivity Index (TPI) and Adult Density Index (ADI) with their respective strata. We conducted a two-step evaluation of SGUs. First, we examined the equivalence of TPI and ADI between SGUs and strata from January 2017 to July 2022. Second, we assessed the ability of SGU's TPI and ADI to predict DENV outbreaks in comparison to Foz do Iguaçu's Early-Warning System, which forecasts outbreaks up to 4 weeks ahead. Spatial and temporal analyses were carried out, including data interpolation and model selection based on Akaike information criteria (AIC). RESULTS: Entomological indicators produced in small SGUs can effectively replace larger sentinel areas to access dengue outbreaks. Based on historical data, the best predictive capability is achieved 2 weeks after infestation verification. Implementing the SGU strategy with more frequent sampling can provide more precise space-time estimates and enhance dengue control. CONCLUSIONS: The implementation of SGUs offers an efficient way to monitor mosquito populations, reducing the need for extensive resources. This approach has the potential to improve dengue transmission management and enhance the public health response in endemic cities.

Noninvasive detection of Zika virus in mosquito excreta sampled from wild mosquito populations in French Guiana.

Arboviruses can be difficult to detect in the field due to relatively low prevalence in mosquito populations. The discovery that infected mosquitoes can release viruses in both their saliva and excreta gave rise to low-cost methods for the detection of arboviruses during entomological surveillance. We implemented both saliva and excreta-based entomological surveillance during the emergence of Zika virus (ZIKV) in French Guiana in 2016 by trapping mosquitoes around households of symptomatic cases with confirmed ZIKV infection. ZIKV was detected in mosquito excreta and not in mosquito saliva in 1 trap collection out of 85 (1.2%). One female Ae. aegypti L. (Diptera: Culicidae) was found with a ZIKV systemic infection in the corresponding trap. The lag time between symptom onset in a ZIKV-infected individual living near the trap site and ZIKV detection in this mosquito was 1 wk. These results highlight the potential of detection in excreta from trapped mosquitoes as a sensitive and cost-effective method to non invasively detect arbovirus circulation.

A mosquito salivary protein-driven influx of myeloid cells facilitates flavivirus transmission.

Mosquitoes transmit many disease-relevant flaviviruses. Efficient viral transmission to mammalian hosts requires mosquito salivary factors. However, the specific salivary components facilitating viral transmission and their mechanisms of action remain largely unknown. Here, we show that a female mosquito salivary gland-specific protein, here named A. aegypti Neutrophil Recruitment Protein (AaNRP), facilitates the transmission of Zika and dengue viruses. AaNRP promotes a rapid influx of neutrophils, followed by virus-susceptible myeloid cells toward mosquito bite sites, which facilitates establishment of local infection and systemic dissemination. Mechanistically, AaNRP engages TLR1 and TLR4 of skin-resident macrophages and activates MyD88-dependent NF-κB signaling to induce the expression of neutrophil chemoattractants. Inhibition of MyD88-NF-κB signaling with the dietary phytochemical resveratrol reduces AaNRP-mediated enhancement of flavivirus transmission by mosquitoes. These findings exemplify how salivary components can aid viral transmission, and suggest a potential prophylactic target.

Gain without pain: adaptation and increased virulence of Zika virus in vertebrate host without fitness cost in mosquito vector.

IMPORTANCE: Previously, we modeled direct transmission chains of Zika virus (ZIKV) by serially passaging ZIKV in mice and mosquitoes and found that direct mouse transmission chains selected for viruses with increased virulence in mice and the acquisition of non-synonymous amino acid substitutions. Here, we show that these same mouse-passaged viruses also maintain fitness and transmission capacity in mosquitoes. We used infectious clone-derived viruses to demonstrate that the substitution in nonstructural protein 4A contributes to increased virulence in mice.

Dengue and zika viruses turn people into mosquito bait.

To spread, pathogens drive mice, people to make odorant.

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.

Zika en silencio epidemiológico / Zika in epidemiological silence

La enfermedad por virus del Zika ha sufrido una importante disminución en la notificación de casos. A nivel mundial se observa un descenso aproximado del 58%, comparado con el mismo periodo en 2020. En México ocurre una situación similar, pues en la semana epidemiológica 48 solamente se han confirmado 34 casos. Dicha situación coincide con la pandemia por SARS-CoV-2, la cual se vive desde el 2019; sin embargo, es de suma importancia reestablecer las acciones de vigilancia epidemiológica enfocadas en el Zika para así continuar con las medidas de prevención y control dirigidas a minimizar el impacto de la enfermedad.

Zika virus disease has suffered a significant decrease in case reporting. Worldwide, an approximate decrease of 58% is observed, compared to the same period in 2020. Mexico is experiencing a similar situation, given that at epidemiological week 48 only 34 cases have been confirmed. This situation coincides with the SARS-CoV-2 pandemic, which has been experienced since 2019; however, it is of the utmost importance to reestablish epidemiological surveillance actions aimed at Zika to continue with prevention and control measures focused on minimizing the impact of the illness.

Zika Virus Infection of Sertoli Cells Alters Protein Expression Involved in Activated Immune and Antiviral Response Pathways, Carbohydrate Metabolism and Cardiovascular Disease.

Zika virus (ZIKV), a re-emerging virus, causes congenital brain abnormalities and Guillain-Barré syndrome. It is mainly transmitted by Aedes mosquitoes, but infections are also linked to sexual transmissions. Infectious ZIKV has been isolated, and viral RNA has been detected in semen over a year after the onset of initial symptoms, but the mode of long-term persistence is not yet understood. ZIKV can proliferate in human Sertoli cells (HSerC) for several weeks in vitro, suggesting that it might be a reservoir for persistent ZIKV infection. This study determined proteomic changes in HSerC during ZIKV infections by TMT-mass spectrometry analysis. Levels of 4416 unique Sertoli cell proteins were significantly altered at 3, 5, and 7 days after ZIKV infection. The significantly altered proteins include enzymes, transcription regulators, transporters, kinases, peptidases, transmembrane receptors, cytokines, ion channels, and growth factors. Many of these proteins are involved in pathways associated with antiviral response, antigen presentation, and immune cell activation. Several immune response pathway proteins were significantly activated during infection, e.g., interferon signaling, T cell receptor signaling, IL-8 signaling, and Th1 signaling. The altered protein levels were linked to predicted activation of immune response in HSerC, which was predicted to suppress ZIKV infection. ZIKV infection also affected the levels of critical regulators of gluconeogenesis and glycolysis pathways such as phosphoglycerate mutase, phosphoglycerate kinase, and enolase. Interestingly, many significantly altered proteins were associated with cardiac hypertrophy, which may induce heart failure in infected patients. In summary, our research contributes to a better understanding of ZIKV replication dynamics and infection in Sertoli cells.

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.

Evidence against Zika virus infection of pets and peri-domestic animals in Latin America and Africa.

Decades after its discovery in East Africa, Zika virus (ZIKV) emerged in Brazil in 2013 and infected millions of people during intense urban transmission. Whether vertebrates other than humans are involved in ZIKV transmission cycles remained unclear. Here, we investigate the role of different animals as ZIKV reservoirs by testing 1723 sera of pets, peri-domestic animals and African non-human primates (NHP) sampled during 2013-2018 in Brazil and 2006-2016 in Côte d'Ivoire. Exhaustive neutralization testing substantiated co-circulation of multiple flaviviruses and failed to confirm ZIKV infection in pets or peri-domestic animals in Côte d'Ivoire (n=259) and Brazil (n=1416). In contrast, ZIKV seroprevalence was 22.2% (2/9, 95% CI, 2.8-60.1) in West African chimpanzees (Pan troglodytes verus) and 11.1% (1/9, 95% CI, 0.3-48.3) in king colobus (Colobus polycomos). Our results indicate that while NHP may represent ZIKV reservoirs in Africa, pets or peri-domestic animals likely do not play a role in ZIKV transmission cycles.

Using Sina-Weibo microblogs to inform the development and dissemination of health awareness material about Zika virus transmission, China, 2016-17.

BACKGROUND: On 1 February 2016, the World Health Organization declared Zika transmission a public health emergency of international concern. Monitoring and responding to community awareness, concern, and possible knowledge gaps are critical during public health emergencies. Here, we describe the review and analysis of micro-blogs posted on Sina-Weibo, China's largest social media platform, to develop and disseminate a Zika virus education campaign. METHODS: We used CYYUN Voice Express' Weibo Spider tool and the search terms of "Zhaika" OR "Zika" OR "Zikv" to capture microblogs about Zika virus retrospectively from February 1 to December 31, 2016 and prospectively from June 1 to November 15, 2017. We described microblogs meeting our inclusion criteria by month and Zika virus outbreaks in Asia and by source (e.g., government agency, individual, or other). We identified common misleading or inaccurate content authored by individual micro-bloggers (i.e., not supported by available scientific evidence) through a qualitative review. We used this information to develop and disseminate health awareness material about the Zika virus through China CDC's 12320 Health Hotline Weibo account. An online survey was conducted to obtain feedback on the material. RESULTS: We captured 15,888 microblogs meeting our inclusion criteria. Zika-related microblogs peaked in September 2016, corresponding to news reports about the Zika outbreak in Singapore (August to November 2016). Most microblogs (12,994 [82%]) were authored by individual users, followed by media agencies (842 [5%]), businesses (829 [5%]), international organizations (370 [2%]), and Chinese government agencies (235 [1%]). Relevant microblogs primarily focused on clinical symptoms and health risks, modes of transmission, and actions taken by individuals to prevent infection and seek health care. Incorrect and/or mis-leading information from individual users concentrated on modes of transmission and possible treatments. The microblog "#Zika is that far and this close" health campaign was posted on Sina-Weibo and Baidu (Internet search engine in China) on September 18, 2016. Younger respondents (p-value = 0.01), and those with at least a college education (p-value = 0.03), were more likely than other respondents to consider the online campaign reliable and trustworthy. CONCLUSION: Routine review of Sina-Weibo and other social media platforms could enhance the ability of public health staff to effectively respond to community concerns and awareness during public health emergencies. Advancements of social media monitoring tools and staff training could help to promote health awareness during emergencies by directly addressing public perceptions and concerns. Various approaches may be needed to reach different at-risk populations, particularly older and less educated populations who may prefer more traditional modes of communication.

Pathophysiological and molecular considerations of viral and bacterial infections during maternal-fetal and -neonatal interactions of SARS-CoV-2, Zika, and Mycoplasma infectious diseases.

During pregnancy, a series of physiological changes are determined at the molecular, cellular and macroscopic level that make the mother and fetus more susceptible to certain viral and bacterial infections, especially the infections in this and the companion review. Particular situations increase susceptibility to infection in neonates. The enhanced susceptibility to certain infections increases the risk of developing particular diseases that can progress to become morbidly severe. For example, during the current pandemic caused by the SARS-CoV-2 virus, epidemiological studies have established that pregnant women with COVID-19 disease are more likely to be hospitalized. However, the risk for intensive care unit admission and mechanical ventilation is not increased compared with nonpregnant women. Although much remains unknown with this particular infection, the elevated risk of progression during pregnancy towards more severe manifestations of COVID-19 disease is not associated with an increased risk of death. In addition, the epidemiological data available in neonates suggest that their risk of acquiring COVID-19 is low compared with infants (<12 months of age). However, they might be at higher risk for progression to severe COVID-19 disease compared with older children. The data on clinical presentation and disease severity among neonates are limited and based on case reports and small case series. It is well documented the importance of the Zika virus infection as the main cause of several congenital anomalies and birth defects such as microcephaly, and also adverse pregnancy outcomes. Mycoplasma infections also increase adverse pregnancy outcomes. This review will focus on the molecular, pathophysiological and biophysical characteristics of the mother/placental-fetal/neonatal interactions and the possible mechanisms of these pathogens (SARS-CoV-2, ZIKV, and Mycoplasmas) for promoting disease at this level.

First Report of Adult Aedes aegypti (Diptera: Culicidae) Resistance to Pyrethroids in Argentina.

Severe human arboviral diseases can be transmitted by the mosquito Aedes aegypti (Linnaeus), including dengue, chikungunya, Zika, and yellow fever. Adult control using spatial sprays with adulticides is recommended only when dengue outbreaks occur. In Argentina, mainly pyrethroids, like cis-permethrin, have been used as an adulticide, especially since 2008. The evolution and spread of resistance to insecticides is a major concern for vector control. This study reports for the first time pyrethroid resistance in Ae. aegypti adults from Argentina, in the city of Salvador Mazza (Salta). WHO discriminating doses of 0.75% were used for permethrin, 0.05% for deltamethrin, and 5% for malathion. Also the discriminating dose for cis-permethrin (0.6%) was calculated and evaluated for the first time. We found a resistance ratio 50 (RR50) of 10.3 (9.7-10.4) for cis-permethrin, which is considered as high resistance. Our results also indicated resistance to deltamethrin (22.6% mortality) and permethrin (53.6% mortality), and a total susceptibility to malathion (100% mortality). Results from this study highlight the importance of the correct use of insecticides within an Integrated Vector Management (IVM) approach and of early detection of resistance to enable Ae. aegypti control in Argentina. More studies are needed to determine the spread of mosquito resistance to pyrethroids.