Early warning climate indices for malaria and meningitis in tropical ecological zones

Effects of ambient heat exposure on risk of all-cause mortality in children younger than 5 years in Africa: a pooled time-series analysis

BACKGROUND

Reducing child mortality is a Sustainable Development Goal, and climate change constitutes numerous challenges for Africa. Previous research has shown an association between leading causes of child mortality and climate change. However, few studies have examined these effects in detail. We aimed to explore the effects of ambient heat on neonate, post-neonate, and child mortality rates.

METHODS

For this pooled time-series analysis, health data were obtained from the International Network for the Demographic Evaluation of Populations and Their Health (INDEPTH) Health and Demographic Surveillance System. We included data from 29 settlements from 13 countries across Africa, collected via monthly surveys from Jan 1, 1993, to Dec 31, 2016. Climate data were obtained from ERA5, collected from Jan 1, 1991, to Dec 31, 2019. We pooled these data for monthly mean daily maximum wet bulb globe temperature (WBGT) and downscaled to geolocations. Due to data heaping, we pooled our health data on a monthly temporal scale and a spatial scale into six different climate regions (ie, Sahel [ie, Burkina Faso and northern Ghana], Guinea [ie, southern Ghana, Côte d'Ivoire, and Nigeria], Senegal and The Gambia, eastern Africa [ie, Kenya, Malawi, Tanzania, Mozambique, and Uganda], South Africa, and Ethiopia). Our outcomes were neonate (ie, younger than 28 days), post-neonate (ie, aged 28 days to 1 year), and child (ie, older than 1 year and younger than 5 years) mortality. To assess the association between WBGT and monthly all-cause mortality, we used a time-series regression with a quasi-Poisson, polynomial-distributed lag model.

FINDINGS

Between Jan 1, 1993, and Dec 31, 2016, there were 44 909 deaths in children younger than 5 years across the 29 sites in the 13 African countries: 10 078 neonates, 14 141 post-neonates, and 20 690 children. We observed differences in the association of heat with neonate, post-neonate, and child mortality by study region. For example, for Ethiopia, the relative risk ratio of mortality at the 95th percentile compared with median heat exposure during the study period was 1·14 (95% CI 1·06-1·23) for neonates, 0·99 (0·90-1·07) for post-neonates, and 0·79 (0·73-0·87) for children. Across the whole year, there was a significant increase in the relative risk of increased mortality for children in eastern Africa (relative risk 1·27, 95% CI 1·19-1·36) and Senegal and The Gambia (1·11, 1·04-1·18).

INTERPRETATION

Our results show that the influence of extreme heat on mortality risk in children younger than 5 years varies by age group, region, and season. Future research should explore potentially informative ways to measure subtleties of heat stress and the factors contributing to vulnerability.

FUNDING

EU Horizons as part of the Heat Indicators for Global Health (HIGH) Horizons project.

Spatiotemporal patterns and association with climate for malaria elimination in Lao PDR: a hierarchical modelling analysis with two-step Bayesian model selection

BACKGROUND

The government of Lao PDR has increased efforts to control malaria transmission in order to reach its national elimination goal by 2030. Weather can influence malaria transmission dynamics and should be considered when assessing the impact of elimination interventions but this relationship has not been well characterized in Lao PDR. This study examined the space-time association between climate variables and Plasmodium falciparum and Plasmodium vivax malaria incidence from 2010 to 2022.

METHODS

Spatiotemporal Bayesian modelling was used to investigate the monthly relationship, and model selection criteria were used to evaluate the performance of the models and weather variable specifications. As the malaria control and elimination situation was spatially and temporally dynamic during the study period, the association was examined annually at the provincial level.

RESULTS

Malaria incidence decreased from 2010 to 2022 and was concentrated in the southern regions for both P. falciparum and P. vivax. Rainfall and maximum humidity were identified as most strongly associated with malaria during the study period. Rainfall was associated with P. falciparum incidence in the north and central regions during 2010-2011, and with P. vivax incidence in the north and central regions during 2012-2015. Maximum humidity was persistently associated with P. falciparum and P. vivax incidence in the south.

CONCLUSIONS

Malaria remains prevalent in Lao PDR, particularly in the south, and the relationship with weather varies between regions but was strongest for rainfall and maximum humidity for both species. During peak periods with suitable weather conditions, vector control activities and raising public health awareness on the proper usage of intervention measures, such as indoor residual spraying and personal protection, should be prioritized.

Climate change and disorders of the nervous system

Anthropogenic climate change is affecting people's health, including those with neurological and psychiatric diseases. Currently, making inferences about the effect of climate change on neurological and psychiatric diseases is challenging because of an overall sparsity of data, differing study methods, paucity of detail regarding disease subtypes, little consideration of the effect of individual and population genetics, and widely differing geographical locations with the potential for regional influences. However, evidence suggests that the incidence, prevalence, and severity of many nervous system conditions (eg, stroke, neurological infections, and some mental health disorders) can be affected by climate change. The data show broad and complex adverse effects, especially of temperature extremes to which people are unaccustomed and wide diurnal temperature fluctuations. Protective measures might be possible through local forecasting. Few studies project the future effects of climate change on brain health, hindering policy developments. Robust studies on the threats from changing climate for people who have, or are at risk of developing, disorders of the nervous system are urgently needed.

Understanding the spatial non-stationarity in the relationships between malaria incidence and environmental risk factors using Geographically Weighted Random Forest: A case study in Rwanda

As found in the health studies literature, the levels of climate association between epidemiological diseases have been found to vary across regions. Therefore, it seems reasonable to allow for the possibility that relationships might vary spatially within regions. We implemented the geographically weighted random forest (GWRF) machine learning method to analyze ecological disease patterns caused by spatially non-stationary processes using a malaria incidence dataset for Rwanda. We first compared the geographically weighted regression (WGR), the global random forest (GRF), and the geographically weighted random forest (GWRF) to examine the spatial non-stationarity in the non-linear relationships between malaria incidence and their risk factors. We used the Gaussian areal kriging model to disaggregate the malaria incidence at the local administrative cell level to understand the relationships at a fine scale since the model goodness of fit was not satisfactory to explain malaria incidence due to the limited number of sample values. Our results show that in terms of the coefficients of determination and prediction accuracy, the geographical random forest model performs better than the GWR and the global random forest model. The coefficients of determination of the geographically weighted regression (R2), the global RF (R2), and the GWRF (R2) were 4.74, 0.76, and 0.79, respectively. The GWRF algorithm achieves the best result and reveals that risk factors (rainfall, land surface temperature, elevation, and air temperature) have a strong non-linear relationship with the spatial distribution of malaria incidence rates, which could have implications for supporting local initiatives for malaria elimination in Rwanda.

Association between temperature variability and global meningitis incidence

BACKGROUND

Meningitis can cause devastating epidemics and is susceptible to climate change. It is unclear how temperature variability, an indicator of climate change, is associated with meningitis incidence.

METHODS

We used global meningitis incidence data along with meteorological and demographic data over 1990-2019 to identify the association between temperature variability and meningitis. We also employed future (2020-2100) climate data to predict meningitis incidence under different emission levels (SSPs: Shared Socioeconomic Pathways).

RESULTS

We found that the mean temperature variability increased by almost 3 folds in the past 30 years. The largest changes occurred in Australasia, Tropical Latin America, and Central Sub-Saharan Africa. With a logarithmic unit increase in temperature variability, the overall global meningitis risk increases by 4.8 %. Australasia, Central Sub-Saharan Africa, and High-income North America are the most at-risk regions. Higher statistical differences were identified in males, children, and the elderly population. Compared to high-emission (SSP585) scenario, we predicted a median reduction of 85.8 % in meningitis incidence globally under the low-emission (SSP126) climate change scenario by 2100.

CONCLUSION

Our study provides evidence for temperature variability being in association with meningitis incidence, which suggests that global actions are urgently needed to address climate change and to prevent meningitis occurrence.

Using machine learning to understand microgeographic determinants of the Zika vector, Aedes aegypti

There are limited data on why the 2016 Zika outbreak in Miami-Dade County, Florida was confined to certain neighborhoods. In this research, Aedes aegypti, the primary vector of Zika virus, are studied to examine neighborhood-level differences in their population dynamics and underlying processes. Weekly mosquito data were acquired from the Miami-Dade County Mosquito Control Division from 2016 to 2020 from 172 traps deployed around Miami-Dade County. Using random forest, a machine learning method, predictive models of spatiotemporal dynamics of Ae. aegypti in response to meteorological conditions and neighborhood-specific socio-demographic and physical characteristics, such as land-use and land-cover type and income level, were created. The study area was divided into two groups: areas affected by local transmission of Zika during the 2016 outbreak and unaffected areas. Ae. aegypti populations in areas affected by Zika were more strongly influenced by 14- and 21-day lagged weather conditions. In the unaffected areas, mosquito populations were more strongly influenced by land-use and day-of-collection weather conditions. There are neighborhood-scale differences in Ae. aegypti population dynamics. These differences in turn influence vector-borne disease diffusion in a region. These results have implications for vector control experts to lead neighborhood-specific vector control strategies and for epidemiologists to guide vector-borne disease risk preparations, especially for containing the spread of vector-borne disease in response to ongoing climate change.

Nigeria at 62: Quagmire of malaria and the urgent need for deliberate and concerted control strategy

Background

Sub-Saharan Africa (SSA) has disproportionately contributed the majority (95%) of all malaria cases and deaths for more than a decade (2010-2021) and Nigeria contributes the highest in global malaria cases and deaths in the last decade.

Main body

Despite several malaria control initiatives, why is Nigeria still the most endemic malaria country? Published reports have underlined possible reasons for the sustenance of malaria transmission. Malaria transmission pattern in the country is largely and remarkably heterogeneous, hence control measures must take this uniqueness into consideration when designing intervention strategies. Nigeria became 62 years post-independence on the 1st of October, 2022, therefore making positive impacts on all aspects of the country, especially in the health sector becomes imperative more than ever before. To achieve a pre-elimination malaria status, we propose the implementation of focused and calculated research strategies. Such strategies would be consciously geared towards understanding vectorial capacity, susceptibility to approved insecticides, identifying malaria hotspots, and deciphering the genetic structure and architecture of P. falciparum within and between groups and regions. This will provide insight into delineating the inter/intra-regional migration of parasite populations, amongst others.

Conclusion

With regard to malaria elimination, Nigeria still has a long way to go. There is a need for dedicated prioritization of research efforts that would provide a basic understanding of the Plasmodium parasite in circulation. Such information will support the implementation of policies that will drive down malaria transmission in Nigeria.

High-spatial resolution epidemic surveillance of bacterial meningitis in the African meningitis belt in Burkina Faso

Despite improved surveillance capacities and WHO recommendations for subdistrict analysis, routine epidemic surveillance of acute bacterial meningitis in the African meningitis belt remains largely limited to the district level. We evaluated the appropriateness and performance of analyses at higher spatial resolution. We used suspected meningitis surveillance data at health centre (HC) resolution from Burkina Faso from 14 health districts spanning years 2004-2014 and analysed them using spatio-temporal statistics and generative models. An operational analysis compared epidemic signals at district and HC-level using weekly incidence thresholds. Eighty-four percent (N = 98/116) of epidemic clusters spanned only one HC-week. Spatial propagation of epidemic clusters was mostly limited to 10-30 km. During the 2004-2009 (with serogroup A meningitis) and 2010-2014 (after serogroup A elimination) period, using weekly HC-level incidence thresholds of 100 and 50 per 100,000 respectively, we found a gain in epidemic detection and timeliness in 9 (41% of total) and 10 (67%), respectively, district years with at least one HC signal. Individual meningitis epidemics expanded little in space, suggesting that a health centre level analysis is most appropriate for epidemic surveillance. Epidemic surveillance could gain in precision and timeliness by higher spatial resolution. The optimal threshold should be defined depending on the current background incidence of bacterial meningitis.

Pre-conceptional and prenatal exposure to pesticides and pediatric neuroblastoma. A meta-analysis of nine studies

Neuroblastoma is primarily an embryonal tumor of infancy. Recently, some toxicological agents used as pesticides have been associated with an increased incidence of this tumor. We intended to determine the potential association between prenatal exposure to pesticides and the incidence of neuroblastoma in children. Studies targeting the link between neuroblastoma and pesticides were searched in PUBMED, SCOPUS, and Google Scholar from January 1, 1960, through December 2020. We performed a PRISMA-based systematic review and meta-analysis. In addition, we took into consideration the IARC evaluation on pesticides issued in recent monographs. Prenatal pesticide exposure is associated with an increased risk of neuroblastoma with an OR of 1.6 (1.1-2.3; p = 0.013), while the OR is 1.0 (0.8-1.3; p = 0.723) for pesticide exposure after birth. There is a significant association between prenatal pesticide exposure and neuroblastoma. We emphasize the IARC conclusions evaluating the carcinogenicity of diazinon, glyphosate, malathion, parathion, and tetrachlorvinphos.

Exposure to pesticides and pediatric Wilms’ tumor. A meta-analysis on pre-conception and pregnancy parental exposure with an IARC/WHO commentary

Background

There are hereditary types of nephroblastoma or Wilms’ tumor associated with exposure of the germ cells of either parent to harmful environmental factors. Some studies have examined the exposure of compounds used pesticides and herbicides as a risk factor for Wilms’ tumor.

Methods

A systematic review and meta-analysis were carried out on case-control studies to establish the potential link between exposure to these organic molecules and Wilms’ tumor occurrence in children rigorously. We examined the monographs on some organo-phosphate insecticides and herbicides issued by the International Association for the Research on Cancer (IARC) under the auspices of the World Health Organization (WHO). PUBMED, SCOPUS, and Google Scholar studies (1960–2021) were identified and systematically reviewed following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Subgroup analyses were conducted after stratification for occupational versus residential exposure and before birth (prenatal) vs. after birth (postnatal) exposure. In addition, we revised the monographs on chemical compounds issued recently by the IARC/WHO.

Results

Our findings seem to consolidate that parental pesticide exposure during the preconception or pregnancy period is correlated with an increased occurrence risk for Wilms’ tumor. We confirm the validity of the WHO essays on certain organophosphate herbicides and insecticides, which support these compounds, may be highly relevant in future cancer prevention policies.

Conclusion

Parental exposure to pesticides, particularly in household settings, is poorly emphasized in our society. There is a strong association between these organophosphate compounds and pediatric cancer. Public health agencies may need to take stronger action than in the past.

Parental Pesticide Exposure and Childhood Brain Cancer: A Systematic Review and Meta-Analysis Confirming the IARC/WHO Monographs on Some Organophosphate Insecticides and Herbicides

Background: Brain tumors are the second most common neoplasm in the pediatric age. Pesticides may play an etiologic role, but literature results are conflicting. This review provides a systematic overview, meta-analysis, and IARC/WHO consideration of data on parental exposure to pesticides and childhood brain tumors. Methods: We searched PubMed, SCOPUS, and Google Scholar for literature (1 January 1966–31 December 2020) that assessed childhood brain tumors and parental exposure to pesticides. We undertook a meta-analysis addressing prenatal exposure, exposure after birth, occupational exposure, and residential exposure. A total of 130 case-control investigations involving 43,598 individuals (18,198 cases and 25,400 controls) were included. Results: Prenatal exposure is associated with childhood brain tumors (odds ratio, OR = 1.32; 95% CI: 1.17–1.49; I² = 41.1%). The same occurs after birth exposure (OR = 1.22; 95% CI: 1.03–1.45, I² = 72.3%) and residential exposure to pesticides (OR = 1.31; 95% CI: 1.11–1.54, I² = 67.2%). Parental occupational exposure is only marginally associated with CBT (OR = 1.17, 95% CI: 0.99–1.38, I² = 67.0%). Conclusions: There is an association between CBT and parental pesticides exposure before childbirth, after birth, and residential exposure. It is in line with the IARC Monograph evaluating the carcinogenicity of diazinon, glyphosate, malathion, parathion, and tetrachlorvinphos.

Understanding the relationship between viral infections and trace elements from a metallomics perspective: implications for COVID-19

Recently, the World Health Organization (WHO) declared a pandemic situation due to a new viral infection (COVID-19) caused by a novel virus (Sars-CoV-2). COVID-19 is today the leading cause of death from viral infections in the world. It is known that many elements play important roles in viral infections, both in virus survival, and in the activation of the host's immune system, which depends on the presence of micronutrients to maintain the integrity of its functions. In this sense, the metallome can be an important object of study for understanding viral infections. Therefore, this work presents an overview of the role of trace elements in the immune system and the state of the art in metallomics, highlighting the challenges found in studies focusing on viral infections.