Climate change could shift disease burden from malaria to arboviruses in Africa

Low humidity enhances Zika virus infection and dissemination in Aedes aegypti mosquitoes

As climate change alters Earth's biomes, it is expected the transmission dynamics of mosquito-borne viruses will change. While the effects of temperature changes on mosquito-virus interactions and the spread of the pathogens have been elucidated over the last decade, the impact of relative humidity changes is still relatively unknown. To overcome this knowledge gap, we exposed Aedes aegypti females to various humidity conditions. We measured different components of vectorial capacity such as survival, blood-feeding rates, and changes in infection and dissemination of Zika virus. Survival decreased as the humidity level decreased, while infection rates increased as the humidity level decreased. Alternatively, blood feeding rates and disseminated infection rates peaked at the intermediate 50% relative humidity treatment but were the same in the 30% and 80% relative humidity treatments. These results provide empirical evidence that Ae. aegypti exposure to low humidity can enhance Zika virus infection in the mosquito, which has important implications in predicting how climate change will impact mosquito-borne viruses.IMPORTANCEViruses transmitted by mosquitoes to humans are a major public health burden and are expected to increase under climate change. While we know that temperature is an important driver of variation in arbovirus replication in the mosquito, very little is known about how other relevant climate variables such as humidity will influence the interaction between mosquitoes and the viruses they transmit. Given the variability in humidity across environments, and the predicted changes in humidity under climate change, it is imperative that we also study the impact that it has on mosquito infection and transmission of arboviruses.

Spatio-temporal occurrence and habitat characteristics of Aedes aegypti (Diptera: Culicidae) larvae in Southern Afar region, Ethiopia

BACKGROUND

Describing spatio-temporal occurrence and habitat characteristics of Aedes mosquito larvae is crucial for the control of Aedes borne viral diseases. This study assessed spatio-temporal abundance and habitat characteristics of Aedes larvae in the Southern Afar Region, Ethiopia.

METHODS

Immature mosquitoes were surveyed in Awash Sebat, Awash Arba, and Werer towns of the Southern Afar Region once per month from May 2022 to April 2023. Larvae and pupae surveys were carried out along the available water-holding containers. The collected larvae/pupae were reared to adults and identified by  species/genus morphologically. The physical and chemical properties of the habitats were also characterized.

RESULTS

A total of 9099 Aedes larvae/pupae were collected, of which 53.6% (4875) were from Awash Sebat, 29.5% (2687) from Awash Arba and 16.9% (1537) from Werer. Water-holding tyres harboured the highest number of Aedes larvae/pupae followed by water-storage drums. All the Aedes larvae/pupae reared to adults were morphologically identified as Aedes aegypti. The overall Container Index was 47.28%, House Index 18.19%, Breteau Index 59.94% and Pupal Index 171.94. Significant positive relations were observed in the occurrences of Ae. aegypti larvae/pupae with water-holding tyre (AOR = 15.89, CI = 3.55-71.09, p < 0.001), water storage drums (AOR = 19.84, CI = 4.64-84.89, p < 0.001), domestic habitat (AOR = 3.76, CI = 1.27-11.12, p = 0.017), and significant negative relations were observed with Ae. aegypti larvae/pupae occurrence and tap water source (AOR = 0.08, CI = 0.02-0.31, p = 0.001). Ae. aegypti larvae/pupae densities showed positive relations with dissolved oxygen (β = 0.523, p < 0.001) and total hardness (β = 0.475, p = 0.034) of water.

CONCLUSIONS

Diverse types of artificial water-holding containers were positive for Ae. aegypti larvae/pupae. Ae. aegypti larvae/pupae were abundant in used water-holding tyres, water storage drums, and cement tanks in Awash Sebat, Awash Arba, and Werer towns. This could  put the residents of the towns at high risk of infections with Ae. aegypti transmitted viral diseases such as chikungunya and dengue outbreaks. Thus, we recommend artificial water-holding container management as a strategy to control Ae. aegypti and hence the arboviral diseases transmission.

Effects of climate change and human activities on vector-borne diseases

Vector-borne diseases are transmitted by haematophagous arthropods (for example, mosquitoes, ticks and sandflies) to humans and wild and domestic animals, with the largest burden on global public health disproportionately affecting people in tropical and subtropical areas. Because vectors are ectothermic, climate and weather alterations (for example, temperature, rainfall and humidity) can affect their reproduction, survival, geographic distribution and, consequently, ability to transmit pathogens. However, the effects of climate change on vector-borne diseases can be multifaceted and complex, sometimes with ambiguous consequences. In this Review, we discuss the potential effects of climate change, weather and other anthropogenic factors, including land use, human mobility and behaviour, as possible contributors to the redistribution of vectors and spread of vector-borne diseases worldwide.

Increasing intensity of enterovirus outbreaks projected with climate change

Pathogens of the enterovirus genus, including poliovirus and coxsackieviruses, typically circulate in the summer months suggesting a possible positive association between warmer weather and transmission. Here we evaluate the environmental and demographic drivers of enterovirus transmission, as well as the implications of climate change for future enterovirus circulation. We leverage pre-vaccination era data on polio in the US as well as data on two enterovirus A serotypes in China and Japan that are known to cause hand, foot, and mouth disease. Using mechanistic modeling and statistical approaches, we find that enterovirus transmission appears positively correlated with temperature although demographic factors, particularly the timing of school semesters, remain important. We use temperature projections from Coupled Model Intercomparison Project Phase 6 (CMIP6) to simulate future outbreaks under late 21st-century climate change for Chinese provinces. We find that outbreak size increases with climate change on average, though results differ across climate models depending on the degree of wintertime warming. In the worst-case scenario, we project peak outbreaks in some locations could increase by up to 40%.

Delineating dengue risk zones in Jaipur: An interdisciplinary approach to inform public health strategies

Dengue fever (DF) is a pervasive public health concern in tropical climates, with densely populated regions, such as India, disproportionately affected. Addressing this issue requires a multifaceted understanding of the environmental and sociocultural factors that contribute to the risk of dengue infection. This study aimed to identify high-risk zones for DF in Jaipur, Rajasthan, India, by integrating physical, demographic, and epidemiological data in a comprehensive risk analysis framework. We investigated environmental variables, such as soil type and plant cover, to characterize the potential habitats of Aedes aegypti, the primary dengue vector. Concurrently, demographic metrics were evaluated to assess the population's susceptibility to dengue outbreaks. High-risk areas were systematically identified through a comparative analysis that integrated population density and incidence rates per ward. The results revealed a significant correlation between high population density and an increased risk of dengue, predominantly facilitated by vertical transmission. Spatially, these high-risk zones are concentrated in the northern and southern sectors of Jaipur, with the northern and southwestern wards exhibiting the most acute risk profiles. This study underscores the importance of targeted public health interventions and vaccination campaigns in vulnerable areas. It further lays the groundwork for future research to evaluate the effectiveness of such interventions, thereby contributing to the development of robust evidence-based strategies for dengue risk mitigation.

The Looming Threat of Dengue Fever: The Africa Context

In Africa, compared to 2019, dengue infections have surged ninefold by December 2023, with over 270 000 cases and 753 deaths reported across 18 African Union (AU) Member States. This commentary synthesises the context of dengue outbreaks in Africa and provides recommendations for sustainable control. In 2023, 18 African Union Member States reported outbreaks of dengue, among which seven had ongoing armed conflicts. These countries were amongst the top 15 African countries contributing to the most displaced persons on the continent and accounted for 98% of all dengue cases reported in the continent in 2023. Climate change remains an important driver, both through the displacement of people and global warming. The continent continues to face several challenges in detection, reporting and management, such as the lack of local laboratory capacity, misclassification of dengue cases and lack of medical countermeasures. Solutions targeting the strengthening of cross-border surveillance and early warning systems using a multisectoral one-health approach, local research and development for therapeutics and diagnostics and community engagement empowering communities to protect themselves and understand the gravity of the threat could help curb the spread of the disease in Africa.

A prospective cohort study of exposure to household pesticide with cardiovascular diseases mortality in older adults

OBJECTIVES

We examined the associations of self-reported exposures, and urinary metabolites related to household pesticide with cardiovascular disease (CVD) mortality in older adults based on the 2007 to 2014 waves of National Health and Nutrition Examination Survey (NHANES).

METHODS

Information on application and urinary metabolites related to household pesticide exposure were collected. We estimated the risks of household pesticide exposure, urinary metabolites with subsequent incident CVD death using Cox proportional hazards regression models. The indirect effects of urinary metabolites and effect modifications were examined.

RESULTS

The participants who reported exposure to household pesticide had a higher risk of incident CVD death (adjusted HR 1.40, 95% CI 1.08 to 1.81). Per 1-log10 increase in urinary N, N-diethyl-3-methylbenzamide (DEET) related to household insect repellents was associated with a higher risk of incident CVD death (adjusted HR 1.97, 95% CI 1.14 to 3.40). Urinary DEET explained 4.21% of the total association between household pesticide exposure and CVD death risk. The participants who persisted a low level of health diet exhibited pronounced CVD death risks with household pesticide exposures.

CONCLUSIONS

Exposure to household pesticide, especially household insect repellents, was consistently associated with an elevated CVD death risk in older adults. A heatlhy diet could partly attenuate the associations.

A scoping literature review of global dengue age-stratified seroprevalence data: estimating dengue force of infection in endemic countries

BACKGROUND

Dengue poses a significant burden worldwide, and a more comprehensive understanding of the heterogeneity in the intensity of dengue transmission within endemic countries is necessary to evaluate the potential impact of public health interventions.

METHODS

This scoping literature review aimed to update a previous study of dengue transmission intensity by collating global age-stratified dengue seroprevalence data published in the Medline, Embase and Web of Science databases from 2014 to 2023. These data were then utilised to calibrate catalytic models and estimate the force of infection (FOI), which is the yearly per-capita risk of infection for a typical susceptible individual.

FINDINGS

We found a total of 66 new publications containing 219 age-stratified seroprevalence datasets across 30 endemic countries. Together with the previously available average FOI estimates, there are now more than 250 dengue average FOI estimates obtained from seroprevalence studies from across the world.

INTERPRETATION

The results show large heterogeneities in average dengue FOI both across and within countries. These new estimates can be used to inform ongoing modelling efforts to improve our understanding of the drivers of the heterogeneity in dengue transmission globally, which in turn can help inform the optimal implementation of public health interventions.

FUNDING

UK Medical Research Council, Wellcome Trust, Community Jameel, Drugs for Neglected Disease initiative (DNDi) funded by the French Development Agency, Médecins Sans Frontières International; Swiss Agency for Development and Cooperation and UK aid.

Future malaria environmental suitability in Africa is sensitive to hydrology

Changes in climate shift the geographic locations that are suitable for malaria transmission because of the thermal constraints on vector Anopheles mosquitos and Plasmodium spp. malaria parasites and the lack of availability of surface water for vector breeding. Previous Africa-wide assessments have tended to solely represent surface water using precipitation, ignoring many important hydrological processes. Here, we applied a validated and weighted ensemble of global hydrological and climate models to estimate present and future areas of hydroclimatic suitability for malaria transmission. With explicit surface water representation, we predict a net decrease in areas suitable for malaria transmission from 2025 onward, greater sensitivity to future greenhouse gas emissions, and different, more complex, malaria transmission patterns. Areas of malaria transmission that are projected to change are smaller than those estimated by precipitation-based estimates but are associated with greater changes in transmission season lengths.

Association between ambient temperature and risk of notifiable infectious diseases in China from 2011 to 2019

Previous studies on temperature and infectious diseases primarily focused on individual disease types, yielding inconsistent conclusions. This study collected monthly data on notifiable infectious disease cases and meteorological variables across 7 provinces in China from 2011 to 2019. A distributed lag nonlinear model was used to evaluate the association between ambient temperature and infectious diseases within each province, and random meta-analysis was applied to evaluate the pooled effect. Extreme hot temperature (the 97.5th percentile) was positively associated with the risk of respiratory infectious diseases with the relative risk (RR) of 1.45 (95%CI: 1.01-2.08). Conversely, extreme cold temperature (the 2.5th percentile) was negatively associated with intestinal infectious diseases and zoonotic diseases and vector-borne diseases, reporting RRs of 0.43 (95%CI: 0.30-0.60) and 0.46 (95%CI: 0.38-0.57), respectively. This study described the nonlinear association between ambient temperature and infectious diseases with different transmission routes, informing comprehensive prevention and control strategies for temperature-related infectious diseases.

Neuroinvasion of emerging and re-emerging arboviruses: A scoping review

Background

Arboviruses are RNA viruses and some have the potential to cause neuroinvasive disease and are a growing threat to global health.

Objectives

Our objective is to identify and map all aspects of arbovirus neuroinvasive disease, clarify key concepts, and identify gaps within our knowledge with appropriate future directions related to the improvement of global health.

Methods

Sources of Evidence: A scoping review of the literature was conducted using PubMed, Scopus, ScienceDirect, and Hinari. Eligibility Criteria: Original data including epidemiology, risk factors, neurological manifestations, neuro-diagnostics, management, and preventive measures related to neuroinvasive arbovirus infections was obtained. Sources of evidence not reporting on original data, non-English, and not in peer-reviewed journals were removed. Charting Methods: An initial pilot sample of 30 abstracts were reviewed by all authors and a Cohen's kappa of κ = 0.81 (near-perfect agreement) was obtained. Records were manually reviewed by two authors using the Rayyan QCRI software.

Results

A total of 171 records were included. A wide array of neurological manifestations can occur most frequently, including parkinsonism, encephalitis/encephalopathy, meningitis, flaccid myelitis, and Guillain-Barré syndrome. Magnetic resonance imaging of the brain often reveals subcortical lesions, sometimes with diffusion restriction consistent with acute ischemia. Vertical transmission of arbovirus is most often secondary to the Zika virus. Neurological manifestations of congenital Zika syndrome, include microcephaly, failure to thrive, intellectual disability, and seizures. Cerebrospinal fluid analysis often shows lymphocytic pleocytosis, elevated albumin, and protein consistent with blood-brain barrier dysfunction.

Conclusions

Arbovirus infection with neurological manifestations leads to increased morbidity and mortality. Risk factors for disease include living and traveling in an arbovirus endemic zone, age, pregnancy, and immunosuppressed status. The management of neuroinvasive arbovirus disease is largely supportive and focuses on specific neurological complications. There is a need for therapeutics and currently, management is based on disease prevention and limiting zoonosis.

Advancing arbovirus diagnosis in Brazil: strengthening diagnostic strategies and public health data collection

BACKGROUND

The last five decades have seen a surge in viral outbreaks, particularly in tropical and subtropical regions like Brazil, where endemic arboviruses such as Dengue (DENV), Zika (ZIKV), and Chikungunya (CHIKV) pose significant threats. However, current diagnostic strategies exhibit limitations, leading to gaps in infection screening, arbovirus differential diagnoses, DENV serotyping, and life-long infection tracking. This deficiency impedes critical information availability regarding an individual's current infection and past infection history, disease risk assessment, vaccination needs, and policy formulation. Additionally, the availability of point-of-care diagnostics and knowledge regarding immune profiles at the time of infection are crucial considerations.

OBJECTIVES

This review underscores the urgent need to strengthen diagnostic methods for arboviruses in Brazil and emphasizes the importance of data collection to inform public health policies for improved diagnostics, surveillance, and policy formulation.

METHODS

We evaluated the diagnostic landscape for arboviral infections in Brazil, focusing on tailored, validated methods. We assessed diagnostic methods available for sensitivity and specificity metrics in the context of Brazil.

RESULTS

Our review identifies high-sensitivity, high-specificity diagnostic methods for arboviruses and co-infections. Grifols transcription-mediated amplification assays are recommended for DENV, CHIKV, and ZIKV screening, while IgG/IgM ELISA assays outperform Rapid Diagnostic Tests (RDTs). The Triplex real-time RT-PCR assay is recommended for molecular screening due to its sensitivity and specificity.

CONCLUSION

Enhanced diagnostic methods, on-going screening, and tracking are urgently needed in Brazil to capture the complex landscape of arboviral infections in the country. Recommendations include nationwide arbovirus differential diagnosis for DENV, ZIKV, and CHIKV, along with increased DENV serotyping, and lifelong infection tracking to combat enduring viral threats and reduce severe presentations.

Estimating the effects of temperature on transmission of the human malaria parasite, Plasmodium falciparum

Despite concern that climate change could increase the human risk to malaria in certain areas, the temperature dependency of malaria transmission is poorly characterized. Here, we use a mechanistic model fitted to experimental data to describe how Plasmodium falciparum infection of the African malaria vector, Anopheles gambiae, is modulated by temperature, including its influences on parasite establishment, conversion efficiency through parasite developmental stages, parasite development rate, and overall vector competence. We use these data, together with estimates of the survival of infected blood-fed mosquitoes, to explore the theoretical influence of temperature on transmission in four locations in Kenya, considering recent conditions and future climate change. Results provide insights into factors limiting transmission in cooler environments and indicate that increases in malaria transmission due to climate warming in areas like the Kenyan Highlands, might be less than previously predicted.

The effect of explicit convection on simulated malaria transmission across Africa

Malaria transmission across sub-Saharan Africa is sensitive to rainfall and temperature. Whilst different malaria modelling techniques and climate simulations have been used to predict malaria transmission risk, most of these studies use coarse-resolution climate models. In these models convection, atmospheric vertical motion driven by instability gradients and responsible for heavy rainfall, is parameterised. Over the past decade enhanced computational capabilities have enabled the simulation of high-resolution continental-scale climates with an explicit representation of convection. In this study we use two malaria models, the Liverpool Malaria Model (LMM) and Vector-Borne Disease Community Model of the International Centre for Theoretical Physics (VECTRI), to investigate the effect of explicitly representing convection on simulated malaria transmission. The concluded impact of explicitly representing convection on simulated malaria transmission depends on the chosen malaria model and local climatic conditions. For instance, in the East African highlands, cooler temperatures when explicitly representing convection decreases LMM-predicted malaria transmission risk by approximately 55%, but has a negligible effect in VECTRI simulations. Even though explicitly representing convection improves rainfall characteristics, concluding that explicit convection improves simulated malaria transmission depends on the chosen metric and malaria model. For example, whilst we conclude improvements of 45% and 23% in root mean squared differences of the annual-mean reproduction number and entomological inoculation rate for VECTRI and the LMM respectively, bias-correcting mean climate conditions minimises these improvements. The projected impact of anthropogenic climate change on malaria incidence is also sensitive to the chosen malaria model and representation of convection. The LMM is relatively insensitive to future changes in precipitation intensity, whilst VECTRI predicts increased risk across the Sahel due to enhanced rainfall. We postulate that VECTRI's enhanced sensitivity to precipitation changes compared to the LMM is due to the inclusion of surface hydrology. Future research should continue assessing the effect of high-resolution climate modelling in impact-based forecasting.

Climate Change, Emerging Vector-Borne Illnesses, and Anesthetic Considerations

As a result of the widespread prevalence of anesthetic usage, anesthesia-related complications are well studied, ranging from benign postoperative nausea and vomiting to potentially fatal complications, such as paralysis, malignant hyperthermia, and death. However, one intersection that still needs further analysis is the relationship between vector-borne illnesses (VBIs) and anesthetic complications. With the advent of climate change and global warming, what were previously endemic vectors have spread far beyond their typical regions, resulting in the spread of VBI. As the incidence of VBIs rapidly increases in the United States, operations for diagnostic testing, and thus the identification and treatments of these VBIs, have significantly diminished. A literature review was conducted to analyze case reports of patients with VBIs and anesthetic concerns with sources from PubMed and Google Scholar databases, and a wide range of complications were found.

The Perpetual Vector Mosquito Threat and Its Eco-Friendly Nemeses

Mosquitoes are the most notorious arthropod vectors of viral and parasitic diseases for which approximately half the world's population, ~4,000,000,000, is at risk. Integrated pest management programs (IPMPs) have achieved some success in mitigating the regional transmission and persistence of these diseases. However, as many vector-borne diseases remain pervasive, it is obvious that IPMP successes have not been absolute in eradicating the threat imposed by mosquitoes. Moreover, the expanding mosquito geographic ranges caused by factors related to climate change and globalization (travel, trade, and migration), and the evolution of resistance to synthetic pesticides, present ongoing challenges to reducing or eliminating the local and global burden of these diseases, especially in economically and medically disadvantaged societies. Abatement strategies include the control of vector populations with synthetic pesticides and eco-friendly technologies. These "green" technologies include SIT, IIT, RIDL, CRISPR/Cas9 gene drive, and biological control that specifically targets the aquatic larval stages of mosquitoes. Regarding the latter, the most effective continues to be the widespread use of Lysinibacillus sphaericus (Ls) and Bacillus thuringiensis subsp. israelensis (Bti). Here, we present a review of the health issues elicited by vector mosquitoes, control strategies, and lastly, focus on the biology of Ls and Bti, with an emphasis on the latter, to which no resistance has been observed in the field.

"Long COVID" and Its Impact on The Environment: Emerging Concerns and Perspectives

The COVID-19 pandemic has caused unprecedented global health and economic crises. The emergence of long COVID-19 has raised concerns about the interplay between SARS-CoV-2 infections, climate change, and the environment. In this context, a concise analysis of the potential long-term effects of the COVID-19 epidemic along with the awareness aboutenvironmental issues are realized. While COVID-19 effects in the short-term have reduced environmental air pollutants and pressures, CO2 emissions are projected to increase as the economy recovers and growth rates return to pre-COVID-19 levels. This review discusses the systematic effects of both the short-term and long-term effects of the pandemic on the clean energy revolution and environmental issues. This article also discusses opportunities to achieve long-term environmental benefits and emphasizes the importance of future policies in promoting global environmental sustainability. Future directions for growth and recovery are presented to cope with long COVID-19 epidemic along with the critical findings focussing on various aspects: waste management, air quality improvement.

A historical perspective on arboviruses of public health interest in Southern Africa

Arboviruses are an existing and expanding threat globally, with the potential for causing devastating health and socioeconomic impacts. Mitigating this threat necessitates a One Health approach that integrates vector surveillance, rapid disease detection, and innovative prevention and control measures. In Southern Africa, limited data on the epidemiology of arboviruses, their vectors, and their hosts prevent an effective response. We reviewed the current knowledge on arboviruses in Southern Africa and identified opportunities for further research. A literature search was conducted to identify studies published on arboviruses in 10 tropical and temperate countries of the Southern African Development Community (SADC) from 1900 onward. We identified 280 studies, half (51.1%) originating from South Africa, that described 31 arboviral species, their vectors, and their clinical effects on hosts reported in the region. Arboviral research flourished in the SADC in the mid-20th century but then declined, before reemerging in the last two decades. Recent research consists largely of case reports describing outbreaks. Historical vector surveillance and serosurveys from the mid-20th century suggest that arboviruses are plentiful across Southern Africa, but large gaps remain in the current understanding of arboviral distribution, transmission dynamics, and public health impact.

Autoinhibition of suicidal capsid protease from O'nyong'nyong virus

Alphaviruses pose a significant threat to public health. Capsid protein encoded in the alphaviral genomes constitutes an interesting therapy target, as it also serves as a protease (CP). Remarkably, it undergoes autoproteolysis, leading to the generation of the C-terminal tryptophan that localizes to the active pocket, deactivating the enzyme. Lack of activity hampers the viral replication cycle, as the virus is not capable of producing the infectious progeny. We investigated the structure and function of the CP encoded in the genome of O'nyong'nyong virus (ONNV), which has instigated outbreaks in Africa. Our research provides a high-resolution crystal structure of the ONNV CP in its active state and evaluates the enzyme's activity. Furthermore, we demonstrated a dose-dependent reduction in ONNV CP proteolytic activity when exposed to indole, suggesting that tryptophan analogs may be a promising basis for developing small molecule inhibitors. It's noteworthy that the capsid protease plays an essential role in virus assembly, binding viral glycoproteins through its glycoprotein-binding hydrophobic pocket. We showed that non-aromatic cyclic compounds like dioxane disrupt this vital interaction. Our findings provide deeper insights into ONNV's biology, and we believe they will prove instrumental in guiding the development of antiviral strategies against arthritogenic alphaviruses.

Influence of temperature combined with photodynamic inactivation on the development of Aedes aegypti

To reduce the speed of selection of populations resistant to chemical insecticides, photodynamic inactivation (PDI) against Aedes aegypti is a hot-topic and promising alternative technique to vector control. Temperature is an important factor in the survival of Ae. aegypti larvae and mosquitoes as it influences physiology, behavior, and ecology. This work aimed to evaluate parameters of the biological cycle of Ae. aegypti such as: hatching rate, larval development, adult mosquito longevity, sex ratio, weight, and lethal concentration of larval mortality (LC) through the combination of PDI with different temperatures. The number of larvae found after 48 h suggests that temperature affects hatching rate. Additionally, results showed a delay in development of surviving larvae after PDI when compared to control groups, and there was a reduction in the longevity of mosquitoes that undertook photodynamic action. PDI also led to a predominance of male insects, and observed weight indicates that the inactivation method may have also interfered in mosquito size. The results point to a satisfactory performance of PDI at all tested temperatures. Experimental conditions that were not lethal to all larvae implied that PDI impacts the mosquitoes' biological cycle. Though metabolism and development are improved at higher temperatures, so is PDI action, thus maintaining the net benefit. Therefore, it is assumed that the proposed photolarvicide can be useful in reducing arbovirus transmission, and results invite for future research in different abiotic conditions.

Low humidity enhances Zika virus infection and dissemination in Aedes aegypti mosquitoes

As climate change alters Earth's biomes, it is expected the transmission dynamics of mosquito-borne viruses will change. While the effects of temperature changes on mosquito-virus interactions and spread of the pathogens have been elucidated over the last decade, the effects of relative humidity changes are still relatively unknown. To overcome this knowledge gap, we exposed Ae. aegypti females to various low humidity conditions and measured different components of vectorial capacity such as survival, blood-feeding rates, and changes in infection and dissemination of Zika virus. Survival decreased as the humidity level decreased, while infection rates increased as the humidity level decreased. Alternatively, blood feeding rates and dissemination rates peaked at the intermediate humidity level, but returned to the levels of the control at the lowest humidity treatment. These results provide empirical evidence that Ae. aegypti exposure to low humidity can enhance Zika virus infection in the mosquito, which has important implications in predicting how climate change will impact mosquito-borne viruses.

Emerging and re-emerging pediatric viral diseases: a continuing global challenge

The twenty-first century has been marked by a surge in viral epidemics and pandemics, highlighting the global health challenge posed by emerging and re-emerging pediatric viral diseases. This review article explores the complex dynamics contributing to this challenge, including climate change, globalization, socio-economic interconnectedness, geopolitical tensions, vaccine hesitancy, misinformation, and disparities in access to healthcare resources. Understanding the interactions between the environment, socioeconomics, and health is crucial for effectively addressing current and future outbreaks. This scoping review focuses on emerging and re-emerging viral infectious diseases, with an emphasis on pediatric vulnerability. It highlights the urgent need for prevention, preparedness, and response efforts, particularly in resource-limited communities disproportionately affected by climate change and spillover events. Adopting a One Health/Planetary Health approach, which integrates human, animal, and ecosystem health, can enhance equity and resilience in global communities. IMPACT: We provide a scoping review of emerging and re-emerging viral threats to global pediatric populations This review provides an update on current pediatric viral threats in the context of the COVID-19 pandemic This review aims to sensitize clinicians, epidemiologists, public health practitioners, and policy stakeholders/decision-makers to the role these viral diseases have in persistent pediatric morbidity and mortality.

Understanding the connections between climate change, air pollution, and human health in Africa: Insights from a literature review

Climate change and air pollution are two interconnected global challenges that have profound impacts on human health. In Africa, a continent known for its rich biodiversity and diverse ecosystems, the adverse effects of climate change and air pollution are particularly concerning. This review study examines the implications of air pollution and climate change for human health and well-being in Africa. It explores the intersection of these two factors and their impact on various health outcomes, including cardiovascular disease, respiratory disorders, mental health, and vulnerable populations such as children and the elderly. The study highlights the disproportionate effects of air pollution on vulnerable groups and emphasizes the need for targeted interventions and policies to protect their health. Furthermore, it discusses the role of climate change in exacerbating air pollution and the potential long-term consequences for public health in Africa. The review also addresses the importance of considering temperature and precipitation changes as modifiers of the health effects of air pollution. By synthesizing existing research, this study aims to shed light on complex relationships and highlight the key findings, knowledge gaps, and potential solutions for mitigating the impacts of climate change and air pollution on human health in the region. The insights gained from this review can inform evidence-based policies and interventions to mitigate the adverse effects on human health and promote sustainable development in Africa.

Global malaria predictors at a localized scale

Malaria is a life-threatening disease caused by Plasmodium parasites transmitted by Anopheles mosquitoes. In 2021, more than 247 million cases of malaria were reported worldwide, with an estimated 619,000 deaths. While malaria incidence has decreased globally in recent decades, some public health gains have plateaued, and many endemic hotspots still face high transmission rates. Understanding local drivers of malaria transmission is crucial but challenging due to the complex interactions between climate, entomological and human variables, and land use. This study focuses on highly climatically suitable and endemic areas in Côte d'Ivoire to assess the explanatory power of coarse climatic predictors of malaria transmission at a fine scale. Using data from 40 villages participating in a randomized controlled trial of a household malaria intervention, the study examines the effects of climate variation over time on malaria transmission. Through panel regressions and statistical modeling, the study investigates which variable (temperature, precipitation, or entomological inoculation rate) and its form (linear or unimodal) best explains seasonal malaria transmission and the factors predicting spatial variation in transmission. The results highlight the importance of temperature and rainfall, with quadratic temperature and all precipitation models performing well, but the causal influence of each driver remains unclear due to their strong correlation. Further, an independent, mechanistic temperature-dependent R 0 model based on laboratory data aligns well with observed malaria incidence rates, emphasizing the significance and predictability of temperature suitability across scales. By contrast, entomological variables, such as entomological inoculation rate, were not strong predictors of human incidence in this context. Finally, the study explores the predictors of spatial variation in malaria, considering land use, intervention, and entomological variables. The findings contribute to a better understanding of malaria transmission dynamics at local scales, aiding in the development of effective control strategies in endemic regions.

Arthropod-Borne Viruses in Mauritania: A Literature Review

During the past four decades, recurrent outbreaks of various arthropod-borne viruses have been reported in Mauritania. This review aims to consolidate the current knowledge on the epidemiology of the major arboviruses circulating in Mauritania. Online databases including PubMed and Web of Science were used to retrieve relevant published studies. The results showed that numerous arboviral outbreaks of variable magnitude occurred in almost all 13 regions of Mauritania, with Rift Valley fever (RVF), Crimean-Congo hemorrhagic fever (CCHF), and dengue (DEN) being the most common infections. Other arboviruses causing yellow fever (YF), chikungunya (CHIK), o'nyong-nyong (ONN), Semliki Forest (SF), West Nile fever (WNF), Bagaza (BAG), Wesselsbron (WSL), and Ngari (NRI) diseases have also been found circulating in humans and/or livestock in Mauritania. The average case fatality rates of CCHF and RVF were 28.7% and 21.1%, respectively. RVF outbreaks have often occurred after unusually heavy rainfalls, while CCHF epidemics have mostly been reported during the dry season. The central and southeastern regions of the country have carried the highest burden of RVF and CCHF. Sheep, cattle, and camels are the main animal reservoirs for the RVF and CCHF viruses. Culex antennatus and Cx. poicilipes mosquitoes and Hyalomma dromedarii, H. rufipes, and Rhipicephalus everesti ticks are the main vectors of these viruses. DEN outbreaks occurred mainly in the urban settings, including in Nouakchott, the capital city, and Aedes aegypti is likely the main mosquito vector. Therefore, there is a need to implement an integrated management strategy for the prevention and control of arboviral diseases based on sensitizing the high-risk occupational groups, such as slaughterhouse workers, shepherds, and butchers for zoonotic diseases, reinforcing vector surveillance and control, introducing rapid point-of-care diagnosis of arboviruses in high-risk areas, and improving the capacities to respond rapidly when the first signs of disease outbreak are identified.

Identifying Knowledge Gaps through the Systematic Review of Temperature-Driven Variability in the Competence of Aedes aegypti and Ae. albopictus for Chikungunya Virus

Temperature is a well-known effector of several transmission factors of mosquito-borne viruses, including within mosquito dynamics. These dynamics are often characterized by vector competence and the extrinsic incubation period (EIP). Vector competence is the intrinsic ability of a mosquito population to become infected with and transmit a virus, while EIP is the time it takes for the virus to reach the salivary glands and be expectorated following an infectious bloodmeal. Temperatures outside the optimal range act on life traits, decreasing transmission potential, while increasing temperature within the optimal range correlates to increasing vector competence and a decreased EIP. These relatively well-studied effects of other Aedes borne viruses (dengue and Zika) are used to make predictions about transmission efficiency, including the challenges presented by urban heat islands and climate change. However, the knowledge of temperature and chikungunya (CHIKV) dynamics within its two primary vectors-Ae. aegypti and Ae. albopictus-remains less characterized, even though CHIKV remains a virus of public-health importance. Here, we review the literature and summarize the state of the literature on CHIKV and temperature dependence of vector competence and EIP and use these data to demonstrate how the remaining knowledge gap might confound the ability to adequately predict and, thus, prepare for future outbreaks.

Co-infection with Leucocytozoon and Other Haemosporidian Parasites Increases with Latitude and Altitude in New World Bird Communities

Establishing how environmental gradients and host ecology drive spatial variation in infection rates and diversity of pathogenic organisms is one of the central goals in disease ecology. Here, we identified the predictors of concomitant infection and lineage richness of blood parasites in New Word bird communities. Our multi-level Bayesian models revealed that higher latitudes and elevations played a determinant role in increasing the probability of a bird being co-infected with Leucocytozoon and other haemosporidian parasites. The heterogeneity in both single and co-infection rates was similarly driven by host attributes and temperature, with higher probabilities of infection in heavier migratory host species and at cooler localities. Latitude, elevation, host body mass, migratory behavior, and climate were also predictors of Leucocytozoon lineage richness across the New World avian communities, with decreasing parasite richness at higher elevations, rainy and warmer localities, and in heavier and resident host species. Increased parasite richness was found farther from the equator, confirming a reverse Latitudinal Diversity Gradient pattern for this parasite group. The increased rates of Leucocytozoon co-infection and lineage richness with increased latitude are in opposition with the pervasive assumption that pathogen infection rates and diversity are higher in tropical host communities.

A simulation-based method to inform serosurvey design for estimating the force of infection using existing blood samples

The extent to which dengue virus has been circulating globally and especially in Africa is largely unknown. Testing available blood samples from previous cross-sectional serological surveys offers a convenient strategy to investigate past dengue infections, as such serosurveys provide the ideal data to reconstruct the age-dependent immunity profile of the population and to estimate the average per-capita annual risk of infection: the force of infection (FOI), which is a fundamental measure of transmission intensity. In this study, we present a novel methodological approach to inform the size and age distribution of blood samples to test when samples are acquired from previous surveys. The method was used to inform SERODEN, a dengue seroprevalence survey which is currently being conducted in Ghana among other countries utilizing samples previously collected for a SARS-CoV-2 serosurvey. The method described in this paper can be employed to determine sample sizes and testing strategies for different diseases and transmission settings.

Health professionals' knowledge on dengue and health facility preparedness for case detection: A cross-sectional study in Dar es Salaam, Tanzania

Dengue presents a growing public health concern in the Dar es Salaam region of Tanzania, marked by the recurring incidence of outbreaks. Unfortunately, there is little information available on the region's preparedness in terms of health care workers' knowledge on dengue as well as the availability of reagents and equipment essential for diagnosing and monitoring of dengue infections. To elucidate this, 78 health facilities were visited in Temeke district and structured questionnaires were distributed to 324 health care workers. The aim was to evaluate health care workers' knowledge on dengue and to assess the availability of reagents and equipment essential for diagnosing and monitoring of dengue infections. Content validity of the questionnaire was achieved through extensive literature review and it exhibited high reliability (Cronbach Alpha coefficient = 0.813). Cumulative scores for responses on knowledge questions by health care workers were computed. Characteristics such as level of education, place of work and gender were tested for association with these scores using chi-square tests and logistics regression. Almost all health care workers (99.7%) were aware of dengue disease. However, less than half (46.9%) had knowledge scores of or over 40%. Clinicians had approximately four times higher knowledge scores than other cadres (AOR, 3.637; p-value≤ 0.0001), and those who worked in private facilities had twice the knowledge score than those working in government institutions (AOR, 2.071; p-value = 0.007). Only 8.6%, 35.6% and 14.7% of respondents reported the availability of dengue rapid tests, medical guidelines and refresher training respectively, showing a lack of health facilities readiness for the detection of dengue infections. Based on findings from this study, we recommend government authorities to build capacity of health care workers, to improve their understanding of dengue. We also urge the government and stakeholders to work together to ensure availability of diagnostic tests and other tools needed for diagnosis and surveillance of dengue.

Dehydration induced AePer50 regulates midgut infection in Ae. aegypti

In the face of climate change, mosquitoes will experience evolving climates including longer periods of drought. An important physiological response to dry environments is the protection against water loss or dehydration, here defined as desiccation tolerance. Various environmental factors including temperature are known to alter interactions between the mosquito, Aedes aegypti , and the arboviruses it transmits, but little is known about how low humidity impacts arboviral infection. Here, we report that a gene upregulated in response to desiccation is important for controlling midgut infection. We have identified two genetically diverse lines of Ae. aegypti with marked differences in desiccation tolerance. To understand if the genetic basis underlying desiccation tolerance is the same between the contrasting lines, we compared gene expression profiles between desiccant treated and non-desiccant treated individuals in both the desiccation tolerant and susceptible lines by RNAseq. Gene expression analysis demonstrates that different genes are differentially expressed in response to desiccation stress between desiccation tolerant and susceptible lines. The most highly expressed transcript under desiccation stress in the desiccation susceptible line encodes a peritrophin protein, Ae Per50. Peritrophins play a crucial role in peritrophic matrix formation after a bloodmeal. Gene silencing of Ae Per50 by RNAi demonstrates that expression of Ae Per50 is required for survival of the desiccation susceptible line under desiccation stress, but not for the desiccation tolerant line. Moreover, the knockdown of Ae Per50 results in higher infection rates and viral replication rates of ZIKV and higher infection rates of CHIKV. Finally, following a bloodmeal, the desiccation susceptible line develops a thicker peritrophic matrix than the desiccation tolerant line. Together these results provide a functional link between the protection against desiccation and midgut infection which has important implications in predicting how climate change will impact mosquito-borne viruses.

Mitigating the effects of climate change on human health with vaccines and vaccinations

Climate change represents an unprecedented threat to humanity and will be the ultimate challenge of the 21st century. As a public health consequence, the World Health Organization estimates an additional 250,000 deaths annually by 2030, with resource-poor countries being predominantly affected. Although climate change's direct and indirect consequences on human health are manifold and far from fully explored, a growing body of evidence demonstrates its potential to exacerbate the frequency and spread of transmissible infectious diseases. Effective, high-impact mitigation measures are critical in combating this global crisis. While vaccines and vaccination are among the most cost-effective public health interventions, they have yet to be established as a major strategy in climate change-related health effect mitigation. In this narrative review, we synthesize the available evidence on the effect of climate change on vaccine-preventable diseases. This review examines the direct effect of climate change on water-related diseases such as cholera and other enteropathogens, helminthic infections and leptospirosis. It also explores the effects of rising temperatures on vector-borne diseases like dengue, chikungunya, and malaria, as well as the impact of temperature and humidity on airborne diseases like influenza and respiratory syncytial virus infection. Recent advances in global vaccine development facilitate the use of vaccines and vaccination as a mitigation strategy in the agenda against climate change consequences. A focused evaluation of vaccine research and development, funding, and distribution related to climate change is required.

Seroprevalence of Dengue and Chikungunya Virus Infections in Children Living in Sub-Saharan Africa: Systematic Review and Meta-Analysis

Dengue and chikungunya viruses are frequent causes of malarial-like febrile illness in children. The rapid increase in virus transmission by mosquitoes is a global health concern. This is the first systematic review and meta-analysis of the childhood prevalence of dengue and chikungunya in Sub-Saharan Africa (SSA). A comprehensive search of the MEDLINE (Ovid), Embase (Ovid), and Cochrane Library (Wiley) databases was conducted on 28 June 2019, and updated on 12 February 2022. The search strategy was designed to retrieve all articles pertaining to arboviruses in SSA children using both controlled vocabulary and keywords. The pooled (weighted) proportion of dengue and chikungunya was estimated using a random effect model. The overall pooled prevalence of dengue and chikungunya in SSA children was estimated to be 16% and 7%, respectively. Prevalence was slightly lower during the period 2010-2020 compared to 2000-2009. The study design varied depending on the healthcare facility reporting the disease outbreak. Importantly, laboratory methods used to detect arbovirus infections differed. The present review documents the prevalence of dengue and chikungunya in pediatric patients throughout SSA. The results provide unprecedented insight into the transmission of dengue and chikungunya viruses among these children and highlight the need for enhanced surveillance and controlled methodology.

The influence of the larval microbiome on susceptibility to Zika virus is mosquito genotype-dependent

The microbiome of the mosquito Aedes aegypti is largely determined by the environment and influences mosquito susceptibility for arthropod-borne viruses (arboviruses). Larval interactions with different bacteria can have carry-over effects on adult Ae. aegypti replication of arboviruses, but little is known about the role that mosquito host genetics play in determining how larval-bacterial interactions shape Ae aegypti susceptibility to arboviruses. To address this question, we isolated single bacterial isolates and complex microbiomes from Ae. aegypti larvae from various field sites in Senegal. Either single bacterial isolates or complex microbiomes were added to two different genetic backgrounds of Ae. aegypti in a gnotobiotic larval system. Using 16S amplicon sequencing we showed that the bacterial community structure differs between the two genotypes of Ae. aegypti when given identical microbiomes, and the abundance of single bacterial taxa differed between Ae. aegypti genotypes. Using single bacterial isolates or the entire preserved complex microbiome, we tested the ability of specific larval microbiomes to drive differences in infection rates for Zika virus in different genetic backgrounds of Ae. aegypti. We observed that the proportion of Zika virus-infected adults was dependent on the interaction between the larval microbiome and Ae. aegypti host genetics. By using the larval microbiome as a component of the environment, these results demonstrate that interactions between the Ae. aegypti genotype and its environment can influence Zika virus infection. As Ae. aegypti expands and adapts to new environments under climate change, an understanding of how different genotypes interact with the same environment will be crucial for implementing arbovirus transmission control strategies.

Diverse novel Wolbachia bacteria strains and genera-specific co-infections with Asaia bacteria in Culicine mosquitoes from ecologically diverse regions of Cameroon

Background: The endosymbiotic bacterium Wolbachia infects numerous species of insects and Wolbachia transinfection of Aedes mosquito species is now being used for biocontrol programs as Wolbachia strains can both inhibit arboviruses and invade wild mosquito populations. The discovery of novel, resident Wolbachia strains in mosquito species warrants further investigation as potential candidate strains for biocontrol strategies. Methods: We obtained mosquito specimens from diverse Culicine mosquitoes from Cameroon including ecologically diverse locations in the Central and West Regions. Wolbachia prevalence rates were assessed in addition to the environmentally acquired bacterial species Asaia in major Culicine genera. PCR-based methods were also used with phylogenetic analysis to confirm identities of host mosquito species and Wolbachia strains were classified using multi-locus sequence typing (MLST). Results: We report high Wolbachia prevalence rates for Culicine species, including in a large cohort of Aedes africanus collected from west Cameroon in which 100% of mono-specific pools were infected. Furthermore, co-infections with Asaia bacteria were observed across multiple genera, demonstrating that these two bacteria can co-exist in wild mosquito populations.  Wolbachia strain MLST and phylogenetic analysis provided evidence for diverse Wolbachia strains in 13 different mosquito species across seven different genera.  Full or partial MLST profiles were generated from resident Wolbachia strains in six Culex species ( quinquefasciatus, watti, cinerus, nigripalpus, perexiguus and rima), two Aedes species (africanus and denderensis) and in Mansonia uniformis, Catageiomyia argenteopunctata, Lutzia tigripes, Eretmapodites chrysogaster and Uranotaenia bilineata. Conclusions: Our study provides further evidence that Wolbachia is widespread within wild mosquito populations of diverse Culicine species and provides further candidate strains that could be investigated as future options for Wolbachia-based biocontrol to inhibit arbovirus transmission.

Projecting the future incidence and burden of dengue in Southeast Asia

The recent global expansion of dengue has been facilitated by changes in urbanisation, mobility, and climate. In this work, we project future changes in dengue incidence and case burden to 2099 under the latest climate change scenarios. We fit a statistical model to province-level monthly dengue case counts from eight countries across Southeast Asia, one of the worst affected regions. We project that dengue incidence will peak this century before declining to lower levels with large variations between and within countries. Our findings reveal that northern Thailand and Cambodia will show the biggest decreases and equatorial areas will show the biggest increases. The impact of climate change will be counterbalanced by income growth, with population growth having the biggest influence on increasing burden. These findings can be used for formulating mitigation and adaptation interventions to reduce the immediate growing impact of dengue virus in the region.

Epidemiology and Transmission Dynamics of Viral Encephalitides in West Africa

Encephalitis is an inflammation of the brain, often caused by an autoimmune reaction, or in most cases because of a direct viral, bacterial, or parasitic infection. Viral encephalitides (VE) presents a significant public health concern globally, especially in West Africa. There are more than five hundred known arthropod-borne viruses (arboviruses), with over a hundred of them identified to cause encephalitic diseases in humans and animals, giving rise to a tremendous burden of the diseases and socioeconomic strains in tropical and subtropical regions worldwide. Despite their importance, few effective preventive and control measures in the form of vaccines and therapies are available, and when they are, their use is limited. These limitations are largely hinged on the paucity of information about the molecular epidemiology and transmission patterns of VE in West Africa. Here, we reviewed the transmission dynamics, molecular epidemiology, and the ecological drivers of VE in West Africa. Collectively, timely and accurate interventions are essential for encephalitic viral disease control. Moreover, the integrated health system approach, combining surveillance, vaccination, vector control, and community engagement, could be effective in preventing viral encephalitis globally.

ARCA: the interactive database for arbovirus reported cases in the Americas

BACKGROUND

Accurate case report data are essential to understand arbovirus dynamics, including spread and evolution of arboviruses such as Zika, dengue and chikungunya viruses. Giving the multi-country nature of arbovirus epidemics in the Americas, these data are not often accessible or are reported at different time scales (weekly, monthly) from different sources.

RESULTS

We developed a publicly available and user-friendly database for arboviral case data in the Americas: ARCA. ARCA is a relational database that is hosted on the ARCA website. Users can interact with the database through the website by submitting queries through the website, which generates displays results and allows users to download these results in different, convenient file formats. Users can choose to view arboviral case data through a table which containscontaining the number of cases for a particular week, a plot, or through a map.

CONCLUSION

Our ARCA database is a useful tool for arboviral epidemiology research allowing for complex queries, data visualization, integration, and formatting.

wMel replacement of dengue-competent mosquitoes is robust to near-term change

Rising temperatures are impacting the range and prevalence of mosquito-borne diseases. A promising biocontrol technology replaces wild mosquitoes with those carrying the virus-blocking Wolbachia bacterium. Because the most widely used strain, wMel, is adversely affected by heat stress, we examined how global warming may influence wMel-based replacement. We simulated interventions in two locations with successful field trials using Coupled Model Intercomparison Project Phase 5 climate projections and historical temperature records, integrating empirical data on wMel's thermal sensitivity into a model of Aedes aegypti population dynamics to evaluate introgression and persistence over one year. We show that in Cairns, Australia, climatic futures necessitate operational adaptations for heatwaves exceeding two weeks. In Nha Trang, Vietnam, projected heatwaves of three weeks and longer eliminate wMel under the most stringent assumptions of that symbiont's thermal limits. We conclude that this technology is generally robust to near-term (2030s) climate change. Accelerated warming may challenge this in the 2050s and beyond.

Non-target effects of chemical malaria vector control on other biological and mechanical infectious disease vectors

Public health insecticides play a crucial role in malaria control and elimination programmes. Many other arthropods, including mechanical and biological vectors of infectious diseases, have similar indoor feeding or resting behaviours, or both, as malaria mosquitoes, and could be exposed to the same insecticides. In this Personal View, we show that little is known about the insecticide susceptibility status and the extent of exposure to malaria interventions of other arthropod species. We highlight that there is an urgent need to better understand the selection pressure for insecticide resistance in those vectors, to ensure current and future active ingredients remain effective in targeting a broad range of arthropod species, allowing us to prevent and control future outbreaks of infectious diseases other than malaria.

Climate Change and Aging Health in Developing Countries

The climate of the Earth has changed throughout history. Climate change negatively impacts human rights in a wide range of ways. The study aims to find out the impact of climate change on aging health in developing countries. The study found that public health will be devastated if climate change continues unabated. Countries that are least responsible for global warming are most susceptible to the effects of higher temperatures, such as death and disease. In low- and middle-income countries, disasters are more likely to happen to people aged 60 and over. Although climate change affects all of us, older people are especially at risk from it, as evidenced by a growing body of research. The study also offers countermeasures and suggestions to develop aging health in developing countries affected by climate change.

High throughput human genotyping for variants associated with malarial disease outcomes using custom targeted amplicon sequencing

Malaria has exhibited the strongest known selective pressure on the human genome in recent history and is the evolutionary driving force behind genetic conditions, such as sickle-cell disease, glucose-6-phosphatase deficiency, and some other erythrocyte defects. Genomic studies (e.g., The 1000 Genomes project) have provided an invaluable baseline for human genetics, but with an estimated two thousand ethno-linguistic groups thought to exist across the African continent, our understanding of the genetic differences between indigenous populations and their implications on disease is still limited. Low-cost sequencing-based approaches make it possible to target specific molecular markers and genes of interest, leading to potential insights into genetic diversity. Here we demonstrate the versatility of custom dual-indexing technology and Illumina next generation sequencing to generate a genetic profile of human polymorphisms associated with malaria pathology. For 100 individuals diagnosed with severe malaria in Northeast Tanzania, variants were successfully characterised on the haemoglobin subunit beta (HBB), glucose-6-phosphate dehydrogenase (G6PD), atypical chemokine receptor 1 (ACKR1) genes, and the intergenic Dantu genetic blood variant, then validated using pre-existing genotyping data. High sequencing coverage was observed across all amplicon targets in HBB, G6PD, ACKR1, and the Dantu blood group, with variants identified at frequencies previously observed within this region of Tanzania. Sequencing data exhibited high concordance rates to pre-existing genotyping data (> 99.5%). Our work demonstrates the potential utility of amplicon sequencing for applications in human genetics, including to personalise medicine and understand the genetic diversity of loci linked to important host phenotypes, such as malaria susceptibility.

Humidity - The overlooked variable in the thermal biology of mosquito-borne disease

Vector-borne diseases cause significant financial and human loss, with billions of dollars spent on control. Arthropod vectors experience a complex suite of environmental factors that affect fitness, population growth and species interactions across multiple spatial and temporal scales. Temperature and water availability are two of the most important abiotic variables influencing their distributions and abundances. While extensive research on temperature exists, the influence of humidity on vector and pathogen parameters affecting disease dynamics are less understood. Humidity is often underemphasized, and when considered, is often treated as independent of temperature even though desiccation likely contributes to declines in trait performance at warmer temperatures. This Perspectives explores how humidity shapes the thermal performance of mosquito-borne pathogen transmission. We summarize what is known about its effects and propose a conceptual model for how temperature and humidity interact to shape the range of temperatures across which mosquitoes persist and achieve high transmission potential. We discuss how failing to account for these interactions hinders efforts to forecast transmission dynamics and respond to epidemics of mosquito-borne infections. We outline future research areas that will ground the effects of humidity on the thermal biology of pathogen transmission in a theoretical and empirical framework to improve spatial and temporal prediction of vector-borne pathogen transmission.

La Crosse Virus Circulation in Virginia, Assessed via Serosurveillance in Wildlife Species

Mosquito-borne La Crosse virus (LACV; family: Peribunyaviridae) is the leading cause of pediatric arboviral encephalitis in the United States, with clinical cases generally centered in the Midwest and Appalachian regions. Incidence of LACV cases in Appalachian states has increased, such that the region currently represents the majority of reported LACV cases in the USA. The amount of reported LACV cases from Virginia, however, is minimal compared to neighboring states such as North Carolina, West Virginia, and Tennessee, and non-Appalachian regions of Virginia are understudied. Here we examine the hypothesis that LACV is circulating widely in Virginia, despite a low clinical case report rate, and that the virus is circulating in areas not associated with LACV disease. In this study, we screened local mammalian wildlife in northwestern counties of Virginia using passive surveillance via patients submitted to wildlife rehabilitation centers. Blood sera (527 samples; 9 species, 8 genera) collected between October 2019 and December 2022 were screened for neutralizing antibodies against LACV, indicating prior exposure to the virus. We found an overall LACV seroprevalence of 1.90% among all wild mammals examined and reveal evidence of LACV exposure in several wild species not generally associated with LACV, including eastern cottontails and red foxes, along with established reservoirs, eastern gray squirrels, although there was no serological evidence in chipmunks. These data indicate the circulation of LACV in Virginia outside of Appalachian counties, however, at a lower rate than reported for endemic areas within the state and in other states.

Investigating the etiology of acute febrile illness: a prospective clinic-based study in Uganda

BACKGROUND

Historically, malaria has been the predominant cause of acute febrile illness (AFI) in sub-Saharan Africa. However, during the last two decades, malaria incidence has declined due to concerted public health control efforts, including the widespread use of rapid diagnostic tests leading to increased recognition of non-malarial AFI etiologies. Our understanding of non-malarial AFI is limited due to lack of laboratory diagnostic capacity. We aimed to determine the etiology of AFI in three distinct regions of Uganda.

METHODS

A prospective clinic-based study that enrolled participants from April 2011 to January 2013 using standard diagnostic tests. Participant recruitment was from St. Paul's Health Centre (HC) IV, Ndejje HC IV, and Adumi HC IV in the western, central and northern regions, which differ by climate, environment, and population density. A Pearson's chi-square test was used to evaluate categorical variables, while a two-sample t-test and Krukalis-Wallis test were used for continuous variables.

RESULTS

Of the 1281 participants, 450 (35.1%), 382 (29.8%), and 449 (35.1%) were recruited from the western, central, and northern regions, respectively. The median age (range) was 18 (2-93) years; 717 (56%) of the participants were female. At least one AFI pathogen was identified in 1054 (82.3%) participants; one or more non-malarial AFI pathogens were identified in 894 (69.8%) participants. The non-malarial AFI pathogens identified were chikungunya virus, 716 (55.9%); Spotted Fever Group rickettsia (SFGR), 336 (26.2%) and Typhus Group rickettsia (TGR), 97 (7.6%); typhoid fever (TF), 74 (5.8%); West Nile virus, 7 (0.5%); dengue virus, 10 (0.8%) and leptospirosis, 2 (0.2%) cases. No cases of brucellosis were identified. Malaria was diagnosed either concurrently or alone in 404 (31.5%) and 160 (12.5%) participants, respectively. In 227 (17.7%) participants, no cause of infection was identified. There were statistically significant differences in the occurrence and distribution of TF, TGR and SFGR, with TF and TGR observed more frequently in the western region (p = 0.001; p < 0.001) while SFGR in the northern region (p < 0.001).

CONCLUSION

Malaria, arboviral infections, and rickettsioses are major causes of AFI in Uganda. Development of a Multiplexed Point-of-Care test would help identify the etiology of non-malarial AFI in regions with high AFI rates.

Perception of health risks in contexts of extreme climate change in semiarid Northeastern Brazil: an analysis of the role of socioeconomic variables

BACKGROUND

Global climate change poses a significant challenge in contemporary society, particularly affecting vulnerable populations like small farmers residing in arid and semiarid regions. This study aims to investigate the perception of health risks and adaptive responses in the semiarid region of Northeast Brazil (NEB). Four questions were formulated: (1) How do socioeconomic factors influence the perception of health risks during extreme climate events? (2) How do socioeconomic factors impact the adoption of adaptive responses to mitigate health risks during extreme weather events? (3) How does the perceived risk level affect the utilization of adaptive responses? (4) What is the influence of extreme climate events on the perceived risks and the adoption of adaptive responses?

METHOD

The research was conducted in the rural community of Carão, situated in the Agreste region of the State of Pernambuco, NEB. Semi-structured interviews were conducted with 49 volunteers aged 18 and above. The interviews aimed to gather socioeconomic information, including sex, age, income, access to healthcare services, family size, and education level. Additionally, the interviews explored the perceived risks and responses employed during different extreme climate events such as droughts or heavy rainfall. The perceived risks and adaptive responses data were quantified to address the research questions. Generalized linear models were employed to analyze the data for the first three questions, while the nonparametric Mann-Whitney test was used for the fourth question.

RESULTS

The study found no significant differences in the level of perceived risk and adaptive responses between the two climate extremes. However, the quantity of adaptive responses was found to be directly influenced by the perceived risks, regardless of the type of extreme climate event.

CONCLUSION

The study concludes that risk perception is influenced by various complex factors, including socioeconomic variables, and plays a critical role in the adoption of adaptive responses during extreme climate events. The findings suggest that specific socioeconomic variables have a more pronounced influence on how individuals perceive and adapt to risks. Furthermore, the results indicate a cause-and-effect relationship between perceived risks and the generation of adaptive responses. These findings contribute to a better understanding of the factors shaping risk perception and provide valuable insights for future studies in regions prone to extreme climate events.

The current landscape of software tools for the climate-sensitive infectious disease modelling community

Climate-sensitive infectious disease modelling is crucial for public health planning and is underpinned by a complex network of software tools. We identified only 37 tools that incorporated both climate inputs and epidemiological information to produce an output of disease risk in one package, were transparently described and validated, were named (for future searching and versioning), and were accessible (ie, the code was published during the past 10 years or was available on a repository, web platform, or other user interface). We noted disproportionate representation of developers based at North American and European institutions. Most tools (n=30 [81%]) focused on vector-borne diseases, and more than half (n=16 [53%]) of these tools focused on malaria. Few tools (n=4 [11%]) focused on food-borne, respiratory, or water-borne diseases. The under-representation of tools for estimating outbreaks of directly transmitted diseases represents a major knowledge gap. Just over half (n=20 [54%]) of the tools assessed were described as operationalised, with many freely available online.

Climate variability, socio-economic conditions and vulnerability to malaria infections in Mozambique 2016-2018: a spatial temporal analysis

Background

Temperature, precipitation, relative humidity (RH), and Normalized Different Vegetation Index (NDVI), influence malaria transmission dynamics. However, an understanding of interactions between socioeconomic indicators, environmental factors and malaria incidence can help design interventions to alleviate the high burden of malaria infections on vulnerable populations. Our study thus aimed to investigate the socioeconomic and climatological factors influencing spatial and temporal variability of malaria infections in Mozambique.

Methods

We used monthly malaria cases from 2016 to 2018 at the district level. We developed an hierarchical spatial-temporal model in a Bayesian framework. Monthly malaria cases were assumed to follow a negative binomial distribution. We used integrated nested Laplace approximation (INLA) in R for Bayesian inference and distributed lag nonlinear modeling (DLNM) framework to explore exposure-response relationships between climate variables and risk of malaria infection in Mozambique, while adjusting for socioeconomic factors.

Results

A total of 19,948,295 malaria cases were reported between 2016 and 2018 in Mozambique. Malaria risk increased with higher monthly mean temperatures between 20 and 29°C, at mean temperature of 25°C, the risk of malaria was 3.45 times higher (RR 3.45 [95%CI: 2.37-5.03]). Malaria risk was greatest for NDVI above 0.22. The risk of malaria was 1.34 times higher (1.34 [1.01-1.79]) at monthly RH of 55%. Malaria risk reduced by 26.1%, for total monthly precipitation of 480 mm (0.739 [95%CI: 0.61-0.90]) at lag 2 months, while for lower total monthly precipitation of 10 mm, the risk of malaria was 1.87 times higher (1.87 [1.30-2.69]). After adjusting for climate variables, having lower level of education significantly increased malaria risk (1.034 [1.014-1.054]) and having electricity (0.979 [0.967-0.992]) and sharing toilet facilities (0.957 [0.924-0.991]) significantly reduced malaria risk.

Conclusion

Our current study identified lag patterns and association between climate variables and malaria incidence in Mozambique. Extremes in climate variables were associated with an increased risk of malaria transmission, peaks in transmission were varied. Our findings provide insights for designing early warning, prevention, and control strategies to minimize seasonal malaria surges and associated infections in Mozambique a region where Malaria causes substantial burden from illness and deaths.

Modelling the impact of climate change on dengue outbreaks and future spatiotemporal shift in Pakistan

Climate change has a significant impact on the intensity and spread of dengue outbreaks. The objective of this study is to assess the number of dengue transmission suitable days (DTSD) in Pakistan for the baseline (1976-2005) and future (2006-2035, 2041-2070, and 2071-2099) periods under Representative Concentration Pathway (RCP4.5 and RCP8.5) scenarios. Moreover, potential spatiotemporal shift and future hotspots of DTSD due to climate change were also identified. The analysis is based on fourteen CMIP5 models that have been downscaled and bias-corrected with quantile delta mapping technique, which addresses data stationarity constraints while preserving future climate signal. The results show a higher DTSD during the monsoon season in the baseline in the study area except for Sindh (SN) and South Punjab (SP). In future periods, there is a temporal shift (extension) towards pre- and post-monsoon. During the baseline period, the top ten hotspot cities with a higher frequency of DTSD are Karachi, Hyderabad, Sialkot, Jhelum, Lahore, Islamabad, Balakot, Peshawar, Kohat, and Faisalabad. However, as a result of climate change, there is an elevation-dependent shift in DTSD to high-altitude cities, e.g. in the 2020s, Kotli, Muzaffarabad, and Drosh; in the 2050s, Garhi Dopatta, Quetta, and Zhob; and in the 2080s, Chitral and Bunji. Karachi, Islamabad, and Balakot will remain highly vulnerable to dengue outbreaks for all the future periods of the twenty-first century. Our findings also indicate that DTSD would spread across Pakistan, particularly in areas where we have never seen dengue infections previously. The good news is that the DTSD in current hotspot cities is projected to decrease in the future due to climate change. There is also a temporal shift in the region during the post- and pre-monsoon season, which provides suitable breeding conditions for dengue mosquitos due to freshwater; therefore, local authorities need to take adaption and mitigation actions.