Andrew A. Lover

Vegetation plays a critical role in shaping fine-scale tick density by structuring local microclimates, habitat resources, and host interactions that largely determine tick survival and activity, with implications for tick-borne disease transmission. Tick burden in the United States continues to increase, with annual reported tick-borne disease cases more than doubling from 2004 through 2019. These trends call for a broader scope of tick-mitigation strategies that go beyond traditional prevention measures that focus on personal protection; and there is an opportunity to inform habitat-level interventions. Here, we quantify fine-scale vegetation structure across 48 subplots at tick surveillance sites in Western Massachusetts to assess local habitat features associated with Ixodes scapularis density and potential for human-tick contact risk. In assessing understory and overstory vegetation attributes, this study identified life stage-specific differences in predicted tick density, with higher adult densities in areas with deeper leaf litter and presence of invasive plant species and nymphs associated with high presence of ferns. Both adult and nymphal Ix. scapularis were predicted at higher densities in relatively low basal area forests (18.9 to 26.9 m²/hectare). This study design provides a simple, low-cost framework for organizations looking to incorporate tick-informed forest measurement ecology into their public health tick surveillance protocols with minimal training.

Objective: To understand the attitudes and prevalence of peridomestic vector control across New England, and to identify factors associated with self-reported residential vector control uptake. Methods: An online-based survey captured 4855 responses from households across New England in 2023 and 2024. Multivariable Poisson regression was used to quantify factors, including attitudes towards ticks and mosquitoes, motivations for vector control and property characteristics, that are associated with total household residential vector control practices. Results: The majority of respondents reported using at least one household-level vector control intervention in 2023 (88%) and 2024 (93%). Overall, higher levels of concern for ticks, mosquitoes and mosquito-borne disease showed a gradient response and were associated with statistically significant increasing rates of peridomestic vector control; however, concern for tick-borne disease was not associated with vector control usage (p values >0.05). After adjustment for socio-economics, yard size, property type and levels of concern, Maine and Vermont both had lower incidence rates of total vector control interventions compared with the rest of New England ((adjusted incidence rate ratio (aIRR)=0.89; 95% CI 0.84 to 0.93; p value=<0.001), (aIRR=0.89, 95% CI 0.82 to 0.96; p value=0.002), respectively). Finally, protecting the health of family members had a strong association with peridomestic vector control uptake. Conclusions: This study reveals factors associated with increased uptake of peridomestic vector control, including levels of concern, state of residence and primary motivation for vector control use. Results support previous evidence and fill in gaps in geographical spread and the vector control interventions assessed. Future theory-based programming can help close gaps and increase uptake of peridomestic vector control.

Mechanical agitation (stirring) is a cornerstone of organic synthesis, but has received little scientific attention due to its “obvious” role in facilitating reactions. A very recent study by Huang and coworkers compared the isolated yields in approximately 600 paired stirred and unstirred reactions, across a range of standard synthetic reactions, and reported “almost no” differences. However, their study does not provide any quantitative metrics to estimate these differences. To more fully understand the magnitude of potential differences and to identify any reactions where yields do differ, a full multivariable statistical analysis was performed. Across all reaction types, in multivariable mixed models adjusted for reaction conditions including reaction scale, time, and reaction type, stirred reactions are associated with a 2.0 % (95% CI: 1.1 to 2.9%; p < 0.001) increase in isolated yield relative to unstirred reactions. Four reaction types also show statistically significant differences in individual mixed models. Cross-couplings (including Heck, Sonogoshira, and Suzuki reactions) showed a 2.1 % (95% CI: 1.4 to 2.9%; p < 0.001) increase in yield with stirring; electrochemical reactions (allylic C–H oxidation, silyl-Minisci) show a 3.0% (95% CI: 0.7 to 5.3%; p = 0.0091) greater yield; polar reactions (including the Fisher indole synthesis; Friedel-Crafts alkylations/acylations; Mannich reactions; Willamson ether synthesis; the Wittig reaction) show a 2.8 % increase (0.9 to 4.7%; p = 0.004) in yield in stirred versus unstirred reactions; and rearrangements (Claisen and Schmidt reactions), which overall show an 8.4% (95% CI: 6.5 to 10.4%; p < 0.001) increase in yield with stirring relative to unstirred paired reactions. Finally, to assess any interactions between overall yield and the impact of stirring, all reactions were classified using k-means cluster partitioning into three classes by paired yield; individual models for these classes show a clear gradient, where the lowest-yielding reaction group shows the largest overall increase in isolated yield (4.5%; 95% CI: 2.6 to 6.4%; p < 0.0001) with stirring. Stirring of moderate yield reactions is associated with a 1.6% (95% CI: 0.4 to 2.9%; p = 0.0082) increase in yield, while the highest yielding reactions show smaller effect sizes in stirred versus unstirred reactions (0.8% increase; 95% CI: 0.4 to 1.3%; p< 0.0001). These results suggest that while the overall changes in yields with stirring in these data for many reactions are modest, there is extensive variation of impact, and stirring is associated with real and practically important increases in isolated yields across a wide range of substrates and reaction manifolds. Future studies should incorporate design of experiment frameworks, to elucidate which reaction parameters drive these observed heterogeneous effects.

Objective: To understand the attitudes and prevalence of peridomestic vector control across New England, and to identify factors associated with self-reported residential vector control uptake. Methods: An online-based survey captured 4,957 responses from households across New England in 2023 and 2024. Multivariable Poisson regression was used to quantify factors, including attitudes towards ticks and mosquitoes, motivations for vector control, and property characteristics, that are associated with total household residential vector control practices. Results: The majority of respondents reported using at least one household-level vector control intervention in 2023 (88%) and 2024 (93%). Overall, higher levels of concern for ticks, mosquitoes, and mosquito-borne disease showed a gradient-response and were associated with statistically significant increasing rates of peridomestic vector control; however, concern for tick-borne disease was not associated with vector control usage (p-values > 0.05). After adjustment for socio-economics, yard size, property type, and levels of concern, Maine and Vermont both had lower incidence rates of total vector control interventions compared to the rest of New England [(aIRR = 0.89; 95% CI = 0.84 to 0.93; p-value = Policy implications : Differentials exist in state-level uptake of residential vector control interventions; mosquito-borne disease but not tick-borne disease, and protecting health of family members are associated with increasing rates of peridomestic vector control. Health promotion programs should incorporate these aspects in materials to foster appropriate levels of concern for all vector-borne diseases.

Background: SARS-CoV-2 has been responsible for extensive morbidity and mortality in Massachusetts, especially from 2021 – 2022. The true burden of infection is unknown as official reporting data during 2021 and 2022 was not able to capture subclinical/asymptomatic infections nor the results from home-based lateral flow tests (LFTs). Aim: This study was designed to better characterize the exposure of Massachusetts residents to SARS-CoV-2, and to understand demographic and behavioral factors associated with SARS-CoV-2 exposure during the highest burden years of the pandemic. Methods: A series of five sequential state-wide serosurveys were conducted with oversampling for underrepresented demographic groups from June 2021 to September 2022. These mail-based, repeated cross-sectional surveys (RCSs) captured data at periods of rapid vaccine uptake when different viral variants were predominant. This study also included collection of at-home nasal swabs for PCR-based SARS-CoV-2 virological testing, and collection of dried blood spot cards for ELISA-based testing of SARS-CoV-2 IgG antibody markers including spike and capsid, reported as seroprevelences. Neutralizing antibodies to spike-RBD were also measured. Results: Of the randomly selected 249,000 Massachusetts households invited to participate in this survey, a total of 2,220 participants completed the demographic questionnaire and submitted valid specimens for analysis. Of these participants, ten were PCR-positive for SARS-CoV-2 at time of survey. Across all five repeated cross-sectional surveys (RCS), spike antibody positivity ranged from 83.1% to 96.4%. Additionally, levels of the spike neutralizing antibody increased with each RCS; point prevalence values ranged from 20.5% in RCS 1 and 2 to 73.5% in RCS 5. Using weighted data, the seroprevalence of capsid remained relatively constant throughout the RCSs except for RCS 3. Multivariable regression results found a positive association between vaccination status and markers of SARS-CoV-2 exposure; individuals who had been vaccinated were more likely to be seropositive for all markers. Factors including race, age, income, and occupation did not show any statistically significant associations with serostatus. Conclusions: This survey indicates that while there was an increase in antibodies to spike protein and to associated neutralizing antibodies over time, there were no differences in neutralizing antibodies by socio-demographic factors, suggesting no major health disparities existed at the time of surveys in either vaccine coverage or infection-related antibody titers across the state. Response rates were higher among some demographic groups (Caucasians, households with a high income, and women), thus, oversampling and weighting allowed estimates of the larger Massachusetts population. Our findings that there were no statistically significant differences in neutralizing antibodies across demographic groups suggesting all groups were similarly protected from SARS-CoV-2 infection. These results highlight the success of Massachusetts in protecting individuals across all demographics.

Introduction High-density congregate housing, including cruise ships, hotels, residence halls and correctional facilities are epidemiologically important, and key aspects of pathogen transmission have been elucidated in these environments. A range of methods have been developed to detect unusual clusters of infections in these settings; however use of explicitly 3-D (x,y,z) spatial data has received little attention. In this study, we use data collected during the COVID-19 pandemic to assess the fine-scale spatial epidemiology and the clustering of confirmed cases to better understand impacts of spatial resolution and aggregation on spatio-temporal cluster detection. Methods Data for this analysis combined the results from mandatory weekly viral testing during the 2020-2021 academic year with high-resolution spatial data from university students residing in high-rise residence halls at the University of Massachusetts, Amherst campus. These data were analyzed for statistically-significant clustering of SARS-CoV-2 cases in three-dimensional space as well as time, within and between the high-density buildings on campus. Two sets of analyses were conducted. The first used a Space-Time Permutation Model, which scans for areas with a greater than expected number of cases (SaTScan). To assess the impact of data aggregation, analysis was done at several levels of spatial resolution. Additionally, we performed sensitivity analyses using a purely temporal surveillance algorithm, CDC’s Early Aberration Reporting System-EARS. Results and conclusions Analysis with SaTScan at the room- and floor-level identified multiple statistically significant clusters within one residence hall. Analyses with these same cases aggregated at the floor-level were found to be as sensitive, but far less computationally intensive, than room-level analysis. Analysis at both of these spatial scales was more sensitive than analysis aggregated at the street address-level. Two events exceeding alert thresholds were detected in the purely temporal analysis; one of which was also detected in spatio-temporal analyses. These results expand our understanding of spatio-temporal scan metrics to include 3-D analysis, and optimizing choice of spatial scales. These results have broad applicability in epidemiology in assessing the ability of spatio-temporal methods for public health surveillance, with potential expansion to ecological studies incorporating vertical movement.

Lao People’s Democratic Republic (Lao PDR) has made significant progress in reducing malaria in recent years. In the Greater Mekong Subregion, forest-going is often a risk factor contributing to continuing malaria transmission. This study assessed forest-going and other potential risk factors for malaria cases in Champasak Province, Lao PDR. Routine passive surveillance data from August 2017 to December 2018 were extracted from health facilities in three districts for a case-control study; at the time of presentation, all fever cases were asked to report any recent forest travel. Multivariable logistic regression was used to assess the relationship between forest-going and malaria infection while controlling for other covariates. Of 2933 fever cases with data available on forest-sleeping and malaria diagnosis from 25 health facilities, 244 (8%) tested positive (cases), and 2689 (92%) tested negative (controls). Compared with spending 0–2 nights in the forest, spending 3–7 nights in the forest was associated with 9.7 times the odds of having a malaria infection (95% CI: 4.67–20.31, p < 0.001) when adjusting for gender, occupation, and season. Forest-going, especially longer trips, is associated with increased risk for confirmed symptomatic malaria in southern Lao PDR, and appropriate and targeted intervention efforts are needed to protect this high-risk population.

While there has been significant progress in controlling falciparum malaria in the Lao People’s Democratic Republic (PDR), sporadic cases persist in southern provinces where the extent and patterns of transmission remain largely unknown. To assess parasite transmission in this area, 53 Plasmodium falciparum (Pf) positive cases detected through active test and treat campaigns from December 2017 to November 2018 were sequenced, targeting 204 highly polymorphic amplicons. Two R packages, MOIRE and Dcifer , were applied to assess the multiplicity of infections (MOI), effective MOI (eMOI), within-host parasite relatedness, and between-host parasite relatedness ( ). Genomic data were integrated with survey data to characterize the temporal and spatial structures of identified clusters. The positive cases were mainly captured during the focal test and treat campaign conducted in 2018, and in the Pathoomphone area, which had the highest test positivity and forest activity. About 30% of the cases were polyclonal infections, with over half of theses (63%) showing within-host relatedness greater than 0.6, suggesting that cotransmission rather than superinfection was primarily responsible for maintaining polyclonality. A large majority of cases (81%) were infected by parasites genetically linked to one or more other cases. We identified five genetically distinct clusters in forest fringe villages within the Pathoomphone district, characterized by a high degree of genetic relatedness between parasites (mean = 0.8). Four smaller clusters of 2-3 cases linked Moonlapamok and Pathoomphone districts, with an average of 0.6, suggesting cross-district transmission. Most of the clustered cases occurred within 20 km and 2 months of each other, consistent with focal transmission. Transmission clusters identified in this study confirm the role of ongoing focal parasite transmission occurring within the forest or forest-fringe in the highly mobile population. Author summary: In low-transmission settings, integrating genomic data could help capture fine-scale dynamics in circulating parasites that may not be easily detected by traditional surveillance. Our work demonstrates that even with very few malaria cases, incorporating active surveillance and genomic analysis can help track residual transmission pockets and routes, including among highly mobile populations whose infection sources are historically difficult to trace. Transmission clusters identified in this study provided clear evidence of ongoing focal transmission of Plasmodium falciparum in southern Laos. The addition of high-resolution genomic data to active surveillance can aid in targeting and assessing interventions in similar areas approaching elimination.

Background: Malaria elimination using current tools has stalled in many areas. Ivermectin (IVM) is a broad-antiparasitic drug and mosquitocide and has been proposed as a tool for accelerating progress towards malaria elimination. Under laboratory conditions, IVM has been shown to reduce the survival of adult Anopheles populations that have fed on IVM-treated mammals. Treating cattle with IVM has been proposed as an important contribution to malaria vector management, however, the impacts of IVM in this One Health use case have been untested in field trials in Southeast Asia. Methods: Through a randomized village-based trial, this study quantified the effect of IVM-treated cattle on anopheline populations in treated vs. untreated villages in Central Vietnam. Local zebu cattle in six rural villages were included in this study. In three villages, cattle were treated with IVM at established veterinary dosages, and in three additional villages cattle were left as untreated controls. For the main study outcome, the mosquito populations in all villages were sampled using cattle-baited traps for six nights before, and six nights after a 2-day IVM-administration (intervention) period. Anopheline species were characterized using taxonomic keys. The impact of the intervention was analyzed using a difference-in-differences (DID) approach with generalized estimating equations (with negative binomial distribution and robust errors). This intervention was powered to detect a 50% reduction in total nightly Anopheles spp. vector catches from cattle-baited traps. Given the unusual diversity in anopheline populations, exploratory analyses examined taxon-level differences in the ecological population diversity. Results: Across the treated villages, 1,112 of 1,523 censused cows (73% overall; range 67% to 83%) were treated with IVM. In both control and treated villages, there was a 30% to 40% decrease in total anophelines captured in the post-intervention period as compared to the pre-intervention period. In the control villages, there were 1,873 captured pre-intervention and 1,079 captured during the post-intervention period. In the treated villages, there were 1,594 captured pre-intervention, and 1,101 captured during the post-intervention period. The difference in differences model analysis comparing total captures between arms was not statistically significant (p = 0.61). Secondary outcomes of vector population diversity found that in three villages (one control and two treatment) Brillouin’s index increased, and in three villages (two control and one treatment) Brillouin’s index decreased. When examining biodiversity by trapping-night, there were no clear trends in treated or untreated vector populations. Additionally, there were no clear trends when examining the components of biodiversity: richness and evenness. Conclusions: The ability of this study to quantify the impacts of IVM treatment was limited due to unexpectedly large spatiotemporal variability in trapping rates; an area-wide decrease in trapping counts across all six villages post-intervention; and potential spillover effects. However, this study provides important data to directly inform future studies in the GMS and beyond for IVM-based vector control.