Peter John Diggle

Impact assessment surveys (IAS) are central to monitoring and evaluating the effectiveness of mass drug administration (MDA) programs targeting soil-transm

Prevalence surveys are routinely used to monitor the effectiveness of mass drug administration (MDA) programmes for controlling Neglected Tropical Diseases (NTDs). We propose a decay-adjusted spatio-temporal (DAST) model that explicitly accounts for the time-varying impact of MDA on NTD prevalence, providing a flexible and interpretable framework for estimating intervention effects from sparse survey data. Using case studies on soil-transmitted helminths and lymphatic filariasis, we show that DAST offers a practical alternative to standard geostatistical models when the objective includes quantifying MDA impact and supporting short-term programmatic forecasting. We also discuss extensions and identifiability challenges, advocating for data-driven parsimony over complexity in settings where the available data are too sparse to support the estimation of highly parameterized models.

Background: Snake envenoming (SE) remains an important public health problem, disproportionately affecting impoverished rural communities in tropical and subtropical regions. Although previous attempts have been made to quantify the global burden of SE, accurate, up-to-date data remain scarce. Here we present a comprehensive re-evaluation of the global burden of snakebite, 17 years after our initial estimate. Methods and findings: A new literature review was conducted on snakebites, SE and mortality published in any language, up to March 31, 2025, to update the knowledge accumulated since our first global burden estimate. Based on country- and region-level aggregated data, and hospital and community-based survey data, we modelled SE and mortality burden in relation to geographic location. Explanatory variables were selected to reflect the underlying social and natural environmental conditions. Low and high estimates of the global snakebite burden were calculated using geostatistical models that produced individual-country estimates, accounting for possible underreporting of data when appropriate. We estimate that at least 2.1 million envenomings and 274,000 deaths occur globally each year due to snakebites, and our high estimates suggest up to 7 million envenomings and 513,000 deaths annually. Low-income countries exhibit the highest incidence and mortality rates, with sub-Saharan Africa accounting for 45% of global envenomings and deaths, nearly three times the incidence observed in South Asia. These estimates suggest that previous burden estimates could substantially underestimate the scale of the problem. The main limitations of this study are the scarcity and heterogeneity of empirical data in many countries and the reliance on modelling assumptions to estimate burden in settings with limited or no direct observations. Conclusions: Snake envenoming is a significant cause of morbidity and mortality globally, with sub-Saharan Africa, South Asia, and Southeast Asia being the most severely affected regions. Further improvement in the quality of epidemiological data is required for more accurate estimates of the global burden, particularly in sub-Saharan Africa.

There is an extensive literature around the problem of estimating a mean from spatially correlated data; for a review, see Vallejo and Osorio (2014). Most of this literature focuses on the fact tha...

Objectives: The rapid spread of SARS-CoV-2 infection caused high levels of hospitalisation and deaths in late 2020 and early 2021 during the second wave in England. COVID-19 disease during this period was associated with marked health inequalities across ethnic and sociodemographic subgroups. In this paper, we aim to investigate and quantify inequalities in the risk of SARS-CoV-2 infection across ethnic and sociodemographic subgroups during a key period before widespread vaccination, thereby identifying the populations that bore a disproportionate burden of risk. Methods: We analysed risk factors for test-positivity for SARS-CoV-2, based on self-administered throat and nose swabs in the community during rounds 5–10 of the REal-time Assessment of Community Transmission-1 (REACT-1) study between 18 September 2020 and 30 March 2021. Results: Compared with the White ethnicity, people of Asian and the Black ethnicity had a higher risk of infection during rounds 5–10, with odds of 1.45 (1.27, 1.66) and 1.34 (1.11, 1.63), respectively, adjusted for demographic factors including age, sex, region, key work status, ethnicity and deprivation. Among ethnic subgroups, the highest and the second-highest odds were found in Bangladeshi and Pakistani participants at 3.28 (2.24, 4.80) and 2.12 (1.70, 2.64), respectively, when compared with the White British participants. People in larger (compared with smaller) households had higher odds of infection. Healthcare workers with direct patient contact and care home workers showed higher odds of infection compared with other essential/key workers. Additionally, the odds of infection among participants in public-facing activities or settings were greater than among those not working in those activities or settings. Conclusion: Our findings highlight the differences in the risk of SARS-CoV-2 infection in a global north population during a period when the risk of infection was high, and there were substantial levels of social mixing. Planning for future waves of severe respiratory pathogens should include policies to reduce inequality in the risk of infection by ethnicity, household size and occupational activity in order to reduce inequality in disease.

Background: Snakebite is a priority neglected tropical disease, but incidence data are lacking; current estimates rely upon incomplete health facility reports or ad hoc surveys. Spatial analysis methods harness statistical associations between case incidence and spatially varying factors to improve estimates. This systematic review aimed to identify variables associated with snakebite risk in spatial and temporal analyses for inclusion in geospatial studies to improve risk estimation accuracy. Methods: We searched MEDLINE, Global Health, PubMed and Web of Science in January 2023 for studies published since 1980 assessing snakebite outcomes and spatially varying factors at the setting level. Study quality was assessed using an adapted Joanna Briggs Institute tool. The results are presented by narrative synthesis. Results: Thirty-five studies were eligible; the majority were from Central and South America (18), then Asia (11). Climate and environment were most frequently assessed, with temperature, humidity and tree cover predominantly positively associated with snakebite risk, drought negatively associated and altitude negative/mixed. Crop and livestock variables mostly showed positive associations; population density and urban residence overwhelmingly displayed negative associations. Conclusions: This review identifies key variables that should be considered in future snakebite risk research. Limitations include low research availability from the highest risk regions. There is an evident need for greater research into snakebite risk variation, particularly in sub-Saharan Africa.

Background: Snakebite envenoming is a medical emergency that requires rapid access to essential medicines and well-trained personnel. In resource-poor countries, mapping snakebite incidence can help policymakers to make evidence-based decisions for resource prioritisation. This study aimed to characterise the spatial variation in snakebite risk, and in particular to identify areas of relatively high and low risk, in Eastern Province, Rwanda. Methods: Snakebite surveillance of people bitten in 2020 was conducted in Eastern Province through household visits and case verification. Geostatistical modelling and predictive mapping were applied to data from 617 villages in six districts to develop sector-level and district-level risk maps. Results: There were 1217 individuals bitten by snakes across six districts. The estimated population-weighted snakebite incidence in Eastern Province was 440 (95% predictive interval 421 to 460) cases per 100 000 people, corresponding to 13 500 (95% predictive interval 12 950 to 14 150) snakebite events per year. Two sectors in the southwest, Gashanda and Jarama, showed >1500 snakebite events per 100 000 annually. The lowest incidence was observed in the north. Conclusions: Considerable differences exist in snakebite risk between sectors in Eastern Province, with the highest risk concentrated in the southwest. Policymakers should consider prioritising resources related to snakebite prevention, essential medicines and health worker training in this region.