Long-lasting household damage from Cyclone Idai increases malaria risk in rural western Mozambique.

Cyclone Idai in 2019 was one of the worst tropical cyclones recorded in the Southern Hemisphere. The storm caused catastrophic damage and led to a humanitarian crisis in Mozambique. The affected population suffered a cholera epidemic on top of housing and infrastructure damage and loss of life. The housing and infrastructure damage sustained during Cyclone Idai still has not been addressed in all affected communities. This is of grave concern because storm damage results in poor housing conditions which are known to increase the risk of malaria. Mozambique has the 4th highest malaria prevalence in sub-Saharan Africa and is struggling to control malaria in most of the country. We conducted a community-based cross-sectional survey in Sussundenga Village, Manica Province, Mozambique in December 2019-February 2020. We found that most participants (64%) lived in households that sustained damage during Cyclone Idai. The overall malaria prevalence was 31% measured by rapid diagnostic test (RDT). When controlling for confounding variables, the odds of malaria infection was nearly threefold higher in participants who lived in households damaged by Cyclone Idai nearly a year after the storm. This highlights the need for long-term disaster response to improve the efficiency and success of malaria control efforts.

A case-control survey study of environmental risk factors for primary hypoadrenocorticism in dogs.

BACKGROUND: Primary hypoadrenocorticism in dogs is thought to be multifactorial with roles for both genetic and environmental factors. The contributions of environmental factors remain unexplored. OBJECTIVE: Identify environmental and lifestyle exposures associated with primary hypoadrenocorticism in 2 dog breeds with high risk of developing the disease. ANIMALS: Animals were not used in this study. Owners of Standard Poodles (STPDs) and Portuguese water dogs (POWDs) participated in a survey. METHODS: Retrospective case-control study. Dog owners were invited to participate in an online survey through convenience sampling. Questions regarded the demographics, health histories, and indoor/outdoor environments in which their dogs live and play. Responses for dogs with primary hypoadrenocorticism were compared to those without the disease using univariate and multivariate logistic regression models. RESULTS: Five thousand forty-seven responses (358 cases, 4689 controls) met initial inclusion criteria. Significant associations with modest effect size were found for community type, ingestion of canned food, and use of lawn fertilizer in some analysis models. Reproductive (spay/neuter) status exhibited the strongest association with high effect size across all models with adjusted odds ratio (OR) 2.5 (95% confidence interval [CI], 1.4-4.5; P = .003) for spayed females and 6.0 (95% CI, 2.6-13.9; P < .001) for neutered males. CONCLUSIONS AND CLINICAL IMPORTANCE: The large effect size for reproductive status reflects its high potential clinical relevance, whereas modest effect sizes for other environmental variables suggest lower potential clinical relevance. These findings are associations and do not necessarily imply causation. Before any actionable recommendations are warranted, additional evidence regarding biological mechanisms is needed.

COVID-19 vaccine decision-making among Black women: A qualitative study.

OBJECTIVE: To understand COVID-19 vaccine decision-making among Black women in the United States. METHODS: We conducted qualitative interviews with 60 Black women (both African American and first- and second-generation immigrants originating from Africa and the Caribbean) living in the Minneapolis/St. Paul Metropolitan Area. RESULTS: Participants who were highly motivated to get vaccinated described their trust in science and a desire to protect themselves and those around them; while those who delayed vaccination reported doubts about vaccine safety. Many reported being influenced by targeted misinformation including the pervasive vaccine myths related to reproductive health. Historical trauma from unethical biomedical research and experiences of racism were also motivating factors. There were several concerns raised that were specific to ethnic groups. CONCLUSIONS: Current public health strategies that are intended to promote COVID vaccination are failing Black communities. Participants highlighted the need for clear and culturally appropriate communication about COVID-19 and the vaccines that is aligned with their communities' values and addresses misinformation. The critical insights we have gained by listening to these communities should be used to develop novel vaccination policy approaches.

Quantifying social contact patterns in Minnesota during stay-at-home social distancing order.

SARS-CoV-2 is primarily transmitted through person-to-person contacts. It is important to collect information on age-specific contact patterns because SARS-CoV-2 susceptibility, transmission, and morbidity vary by age. To reduce the risk of infection, social distancing measures have been implemented. Social contact data, which identify who has contact with whom especially by age and place are needed to identify high-risk groups and serve to inform the design of non-pharmaceutical interventions. We estimated and used negative binomial regression to compare the number of daily contacts during the first round (April-May 2020) of the Minnesota Social Contact Study, based on respondent's age, gender, race/ethnicity, region, and other demographic characteristics. We used information on the age and location of contacts to generate age-structured contact matrices. Finally, we compared the age-structured contact matrices during the stay-at-home order to pre-pandemic matrices. During the state-wide stay-home order, the mean daily number of contacts was 5.7. We found significant variation in contacts by age, gender, race, and region. Adults between 40 and 50 years had the highest number of contacts. The way race/ethnicity was coded influenced patterns between groups. Respondents living in Black households (which includes many White respondents living in inter-racial households with black family members) had 2.7 more contacts than respondents in White households; we did not find this same pattern when we focused on individual's reported race/ethnicity. Asian or Pacific Islander respondents or in API households had approximately the same number of contacts as respondents in White households. Respondents in Hispanic households had approximately two fewer contacts compared to White households, likewise Hispanic respondents had three fewer contacts than White respondents. Most contacts were with other individuals in the same age group. Compared to the pre-pandemic period, the biggest declines occurred in contacts between children, and contacts between those over 60 with those below 60.

Association of anthelmintic treatment with malaria prevalence in Rural Sussundenga, Mozambique.

Background: Mozambique has the 4 th highest malaria incidence and mortality globally. Despite the existing malaria control strategies, malaria prevalence remains stagnant. These challenges have increased calls for innovative strategies in areas with the highest disease burden. Community mass treatment with anthelmintic agents have been used as an effective tool for the control of major helminth infections and has emerged as a potential tool for vector control in the fight against malaria. Methods: This was an analysis of data from a cross-sectional community-based survey designed to study malaria risk, prevention, and health seeking behaviors in Sussundenga, Mozambique. Using logistic regression models, we quantified the association between ever receiving anthelmintic treatment and P. falciparum infection. We also fit models to determine the association between recent anthelmintic treatment and malaria infection. Results: Two-hundred, seventy-seven (277) participants from 83 households were included in this analysis. The prevalence of P. falciparum infection measured by rapid diagnostic test (RDT) was 30%. 77% of participants reported having ever received anthelmintics. The prevalence of malaria was slightly higher among participants who reported ever taking anthelmintics. There was no statistically significant association between prior receipt of anthelmintic and P. falciparum malaria infection after adjusting for age, ITN use and head of household full-time employment (OR = 1.37, 95% CI, 0.70-2.70, p = 0.36). However, recent intake of anthelmintics was associated with lower odds of testing positive for in the adjusted models (OR = 0.35, 95% CI, 0.07-1.80, p = 0.21), but this was not statistically significant. Conclusions: Our findings show that the benefit of anthelmintics treatment as a control tool for P. falciparum malaria infection is likely tied to when it is administered rather than if it was ever administered. These findings offer evidence for making decisions in planning mass community deworming in sub-Saharan Africa.

Household structure is independently associated with malaria risk in rural Sussundenga, Mozambique.

Introduction: Mozambique has the fourth highest malaria cases and malaria mortality globally. Locally, malaria incidence increases from low in the southern region to high in the central and northern regions. Manica Province in central Mozambique has the fourth highest prevalence of malaria out of the 11 provinces, and the highest in the central region of the country. In this area where coverage of interventions has been limited, household level risk factors can be important for understanding the natural history of infection, as well as the implementation of current and future interventions. There has been indication that the relationship between household structure and malaria risk is actually a mediating one between the true relationship between household income and education and Plasmodium falciparum infection. The objective of this study was to determine and quantify these complex relationships. Methods: We conducted a community-based cross-sectional study in Sussundenga village. Sussundenga is a rural village, located in Sussundenga District, Manica Province, Mozambique. We enrolled 303 participants from 83 randomly selected households. We collected information on demographics, household construction, and administered a P. falciparum rapid diagnostic test (RDT). We constructed several generalized estimating equations logistic regression models to determine the independent effects of housing construction on malaria risk. We also constructed models separate from generalized estimating equations logistic mediation models to determine the proportion of effects mediated by household construction material in the relationship between head of household occupation and education and malaria risk. Results: The overall malaria prevalence among the study population by RDT was 30.8%. In the multivariable model adjusting for all individual and household factors as potential confounders, rudimentary roof structure was the only household structural variable that was statistically significantly associated with increased malaria risk [OR 2.41 (1.03-5.63)]. We found no evidence that household structure mediated the relationship between head of household education or employment and malaria risk in our study population. Discussion: Household structure was a significant risk factor for malaria infection in our study population. These findings are consistent with malaria being a disease of poverty and an area that could be targeted for future interventions that could have long-term impacts.

Characterizing human movement patterns using GPS data loggers in an area of persistent malaria in Zimbabwe along the Mozambique border.

BACKGROUND: Human mobility is a driver for the reemergence or resurgence of malaria and has been identified as a source of cross-border transmission. However, movement patterns are difficult to measure in rural areas where malaria risk is high. In countries with malaria elimination goals, it is essential to determine the role of mobility on malaria transmission to implement appropriate interventions. METHODS: A study was conducted in Mutasa District, Zimbabwe, to investigate human movement patterns in an area of persistent transmission along the Mozambique border. Over 1 year, a convenience sample of 20 participants/month was recruited from active malaria surveillance cohorts to carry an IgotU® GT-600 global positioning system (GPS) data logger during all daily activities. Consenting participants were tested for malaria at data logger distribution using rapid antigen diagnostic tests and completed a survey questionnaire. GPS data were analyzed using a trajectory analysis tool, and participant movement patterns were characterized throughout the study area and across the border into Mozambique using movement intensity maps, activity space plots, and statistical analyses. RESULTS: From June 2016-May 2017, 184 participants provided movement tracks encompassing > 350,000 data points and nearly 8000 person-days. Malaria prevalence at logger distribution was 3.7%. Participants traveled a median of 2.8 km/day and spent a median of 4.6 h/day away from home. Movement was widespread within and outside the study area, with participants traveling up to 500 km from their homes. Indices of mobility were higher in the dry season than the rainy season (median km traveled/day = 3.5 vs. 2.2, P = 0.03), among male compared to female participants (median km traveled/day = 3.8 vs. 2.0, P = 0.0008), and among adults compared to adolescents (median total km traveled = 104.6 vs. 59.5, P = 0.05). Half of participants traveled outside the study area, and 30% traveled into Mozambique, including 15 who stayed in Mozambique overnight. CONCLUSIONS: Study participants in Mutasa District, Zimbabwe, were highly mobile throughout the year. Many participants traveled long distances from home, including overnight trips into Mozambique, with clear implications for malaria control. Interventions targeted at mobile populations and cross-border transmission may be effective in preventing malaria introductions in this region.

What Heterogeneities in Individual-level Mobility Are Lost During Aggregation? Leveraging GPS Logger Data to Understand Fine-scale and Aggregated Patterns of Mobility.

Human movement drives spatial transmission patterns of infectious diseases. Population-level mobility patterns are often quantified using aggregated data sets, such as census migration surveys or mobile phone data. These data are often unable to quantify individual-level travel patterns and lack the information needed to discern how mobility varies by demographic groups. Individual-level datasets can capture additional, more precise, aspects of mobility that may impact disease risk or transmission patterns and determine how mobility differs across cohorts; however, these data are rare, particularly in locations such as sub-Saharan Africa. Using detailed GPS logger data collected from three sites in southern Africa, we explore metrics of mobility such as percent time spent outside home, number of locations visited, distance of locations, and time spent at locations to determine whether they vary by demographic, geographic, or temporal factors. We further create a composite mobility score to identify how well aggregated summary measures would capture the full extent of mobility patterns. Although sites had significant differences in all mobility metrics, no site had the highest mobility for every metric, a distinction that was not captured by the composite mobility score. Further, the effects of sex, age, and season on mobility were all dependent on site. No factor significantly influenced the number of trips to locations, a common way to aggregate datasets. When collecting and analyzing human mobility data, it is difficult to account for all the nuances; however, these analyses can help determine which metrics are most helpful and what underlying differences may be present.

Plasmodium falciparum community prevalence and health-seeking behaviours in rural Sussundenga District, Mozambique.

BACKGROUND: Impacts of nationally directed malaria control interventions hinge on understanding malaria transmission and prevention at the community level. The decision to seek care or health-seeking behaviours provide valuable insight on knowledge of malaria, access to care, and efficacy of malaria case management. Thus far, few studies have focused on central Mozambique. The aim was to describe community level Plasmodium falciparum prevalence and health-seeking behaviours among residents of Sussundenga, Mozambique, a rural village in Manica Province with high malaria incidence reported at the Sussundenga-Sede health centre (RHC). METHODS: A cross-sectional community-based survey was conducted from December 2019 to February 2020. A random household sampling method was used, based on enumerated households from satellite imagery. All consenting participants completed a survey about malaria risk, prevention, and health-seeking behaviours, and received a P. falciparum malaria rapid diagnostic test (RDT). RESULTS: The study enrolled 358 individuals from 96 households. The P. falciparum prevalence was 31.6% (95% CI [26.6-36.5%]). Ninety-three percent of participants reported using the Sussundenga-Sede RHC for healthcare. Sixty-six percent of participants (N = 233) experienced at least one malaria symptom in the past month, with self-reported fever most frequently reported (19.3%). Of these, 176 (76.5%) sought care in a health facility and 174 (79%) received an RDT with 130 (63%) having a positive test. Of those with a positive RDT, 127 (97%) received artemether-lumefantrine. Following treatment, 123 (97%) participants' symptoms resolved within a median of 3 days (IQR: 3-5) ranging from 2 to 14 days. In this high transmission setting, a high proportion of participants recognized malaria related symptoms then received a proper diagnostic test and treatment in a health facility. CONCLUSIONS: Future interventions that leverage this health-seeking behaviour and strengthen health systems for community interventions will improve malaria control and inform the efficacy of potential interventions at this particular international border.

Modelling sociodemographic factors that affect malaria prevalence in Sussundenga, Mozambique: a cross-sectional study.

Background: Malaria is still one of the leading causes of mortality and morbidity in Mozambique with little progress in malaria control over the past 20 years. Sussundenga is one of most affected areas. Malaria transmission has a strong association with environmental and sociodemographic factors. The knowledge of sociodemographic factors that affects malaria, may be used to improve the strategic planning for its control. Currently such studies have not been performed in Sussundenga. Thus, the objective of this study is to model the relationship between malaria and sociodemographic factors in Sussundenga, Mozambique. Methods: Houses in the study area were digitalized and enumerated using Google Earth Pro version 7.3. In this study 100 houses were randomly selected to conduct a community survey of Plasmodiumfalciparum parasite prevalence using rapid diagnostic test (RDT). During the survey, a questionnaire was conducted to assess the sociodemographic factors of the participants. Descriptive statistics were analyzed and backward stepwise logistic regression was performed establishing a relationship between positive cases and the factors. The analysis was carried out using SPSS version 20 package. Results: The overall P. falciparum prevalence was 31.6%. Half of the malaria positive cases occurred in age group 5 to 14 years. Previous malaria treatment, population density and age group were significant predictors for the model. The model explained 13.5% of the variance in malaria positive cases and sensitivity of the final model was 73.3%. Conclusion: In this area the highest burden of P. falciparum infection was among those aged 5-14 years old. Malaria infection was related to sociodemographic factors. Targeting malaria control at community level can combat the disease more effectively than waiting for cases at health centers. These finding can be used to guide more effective interventions in this region.

Does mothers' and caregivers' access to information on their child's vaccination card impact the timing of their child's measles vaccination in Uganda?

INTRODUCTION: On-time measles vaccination is essential for preventing measles infection among children as early in life as possible, especially in areas where measles outbreaks occur frequently. Characterizing the timing of routine measles vaccination (MCV1) among children and identifying risk factors for delayed measles vaccination is important for addressing barriers to recommended childhood vaccination and increasing on-time MCV1 coverage. We aim to assess the timing of children's MCV1 vaccination and to investigate the association between demographic and healthcare factors, mothers'/caregivers' ability to identify information on their child's vaccination card, and achieving on-time (vs. delayed) MCV1 vaccination. METHODS: We conducted a population-based, door-to-door survey in Kampala, Uganda, from June-August of 2019. We surveyed mothers/caregivers of children aged one to five years to determine how familiar they were with their child's vaccination card and to determine their child's MCV1 vaccination status and timing. We assessed the proportion of children vaccinated for MCV1 on-time and delayed, and we evaluated the association between mothers'/caregivers' ability to identify key pieces of information (child's birth date, sex, and MCV1 date) on their child's vaccination card and achieving on-time MCV1 vaccination. RESULTS: Of the 999 mothers/caregivers enrolled, the median age was 27 years (17-50), and median child age was 29 months (12-72). Information on vaccination status was available for 66.0% (n = 659) of children. Of those who had documentation of MCV1 vaccination (n = 475), less than half (46.5%; n = 221) achieved on-time MCV1 vaccination and 53.5% (n = 254) were delayed. We found that only 47.9% (n = 264) of the 551 mothers/caregivers who were asked to identify key pieces of information on their child's vaccination card were able to identify the information, but ability to identify the key pieces of information on the card was not independently associated with achieving on-time MCV1 vaccination. CONCLUSION: Mothers'/caregivers' ability to identify key pieces of information on their child's vaccination card was not associated with achieving on-time MCV1 vaccination. Further research can shed light on interventions that may prompt or remind mothers/caregivers of the time and age when their child is due for measles vaccine to increase the chance of the child receiving it at the recommended time.

Healthcare worker perspectives on COVID-19 vaccines: Implications for increasing vaccine acceptance among healthcare workers and patients.

OBJECTIVE: To understand COVID-19 vaccine perspectives among healthcare workers serving diverse communities. METHODS: A dual English/Spanish survey was distributed to healthcare workers in the United States from 3/12/2021-4/22/2021 by the Migrant Clinicians Network, Society of Refugee Healthcare Providers, a Federally Qualified Healthcare Center, and social media advertisement to general primary care workers. RESULTS: 517 responses were at least 50% complete and included in the analysis. Among these, 88% (457/517) indicated vaccine acceptance. Factors associated with acceptance included not reporting any vaccine concerns, identifying as male, ≥65 years of age, being a physician or advanced practice provider, and interacting directly with patients from refugee, immigrant, and migrant (RIM) communities. Participants identified educational information as most helpful for themselves when making a vaccine decision, but a healthcare provider's recommendation as most helpful for their patients. CONCLUSION: Healthcare workers, especially those serving RIM communities, are vaccine accepting. Tailoring vaccine-related information to healthcare workers may improve vaccine confidence for both themselves and patients who rely on them for information.

Understudied Anophelines Contribute to Malaria Transmission in a Low-Transmission Setting in the Choma District, Southern Province, Zambia.

Malaria transmission has declined substantially in Southern Province, Zambia, which is considered a low-transmission setting. The Zambian government introduced a reactive test-and-treat strategy to identify active zones of transmission and treat parasitemic residents. This study was conducted in the Choma District, Southern Province, Zambia, concurrently with an evaluation of this strategy to identify vectors responsible for sustaining transmission, and to identify entomological, spatial, and ecological risk factors associated with increased densities of mosquitoes. Anophelines were collected with CDC light traps indoors and near animal pens in index cases and neighboring households. Outdoor collections captured significantly more anophelines than indoor traps, and 10 different anopheline species were identified. Four species (Anopheles arabiensis, An. rufipes, An. squamosus, and An. coustani) were positive for Plasmodium falciparum circumsporozoite protein by ELISA, and 61% of these 26 anophelines were captured outdoors. Bloodmeal assays confirm plasticity in An. arabiensis foraging, feeding both on humans and animals, whereas An. rufipes, An. squamosus, and An. coustani were largely zoophilic and exophilic. Linear regression of count data for indoor traps revealed that households with at least one parasitemic resident by polymerase chain reaction testing was associated with higher female anopheline counts. This suggests that targeting households with parasitemic individuals for vector interventions may reduce indoor anopheline populations. However, many vectors species responsible for transmission may not be affected by indoor interventions because they are primarily exophilic and forage opportunistically. These data underscore the necessity for further evaluation of vector surveillance and control tools that are effective outdoors, in conjunction with current indoor-based interventions.

Spatiotemporal analysis of 11 years of Chlamydia trachomatis data from southern China.

BACKGROUND: Urogenital Chlamydia trachomatis is the most prevalent bacterial sexually transmitted infection (STI) globally. Reviews suggest high and persistently endemic STI epidemics in low and middle income countries. However population-based prevalence estimates in these settings are less common, underscoring the need for analyses of available data to characterize patterns of disease burden. We identified spatio-temporal clusters and key behavioral, social, or environmental factors contribution to transmission in order to inform the prioritization and targeting of evidence based interventions. METHODS: Using 11 years of data (2006-2016) from the chlamydia case report system of Guangdong, China, we identified county level spatio-temporal hot and cold spots using the Getis-Ord Gi* statistic and discrete Poisson models in SaTScan 9.6. We also estimated associations between observed distribution patterns and area-level demographic, social, and economic factors using quasi-Poisson regression models that controlled for annual counts of certified laboratories to account for fluctuations in location-specific detection capacity. FINDINGS: Cluster analysis indicates an expanding chlamydia epidemic in Guangdong, with cases clustered in regions of greatest economic activity. Greater male-to-female sex ratio (RR, 3.63; 95% CI, 1.41-9.45) and greater urbanicity (RR, 2.44; 95% CI, 1.98-2.99) were predictive of higher chlamydia case occurrence. INTERPRETATION: We found that chlamydia case occurrence in Guangdong province has been accelerating over the past 11 years and that its expansion is tied to indicators of social and economic development. These estimates not only identify high prevalence regions to target but also areas where data gaps potentially remain. The salience of sex ratios and urbanicity may best be understood through the lens of China's modern history of labor migration which has reshaped the gender dynamics and health access landscape of urban China. Future chlamydia control efforts will require a population-based approach focused on reengaging sexually active adults of diverse economic and migratory backgrounds. FUNDING: This was an unfunded study using routinely collected public health data.

Malaria Temporal Variation and Modelling Using Time-Series in Sussundenga District, Mozambique.

Malaria is one of the leading causes of morbidity and mortality in Mozambique, which has the fifth highest prevalence in the world. Sussundenga District in Manica Province has documented high P. falciparum incidence at the local rural health center (RHC). This study's objective was to analyze the P. falciparum temporal variation and model its pattern in Sussundenga District, Mozambique. Data from weekly epidemiological bulletins (BES) was collected from 2015 to 2019 and a time-series analysis was applied. For temporal modeling, a Box-Jenkins method was used with an autoregressive integrated moving average (ARIMA). Over the study period, 372,498 cases of P. falciparum were recorded in Sussundenga. There were weekly and yearly variations in incidence overall (p < 0.001). Children under five years had decreased malaria tendency, while patients over five years had an increased tendency. The ARIMA (2,2,1) (1,1,1) 52 model presented the least Root Mean Square being the most appropriate for forecasting. The goodness of fit was 68.15% for malaria patients less than five years old and 73.2% for malaria patients over five years old. The findings indicate that cases are decreasing among individuals less than five years and are increasing slightly in those older than five years. The P. falciparum case occurrence has a weekly temporal pattern peaking during the wet season. Based on the spatial and temporal distribution using ARIMA modelling, more efficient strategies that target this seasonality can be implemented to reduce the overall malaria burden in both Sussundenga District and regionally.

Mapping Risk of Malaria as a Function of Anthropic and Environmental Conditions in Sussundenga Village, Mozambique.

Mozambique is a country in Southern Africa with around 30 million inhabitants. Malaria is the leading cause of mortality in the country. According to the WHO, Mozambique has the third highest number of malaria cases in the world, representing approximately 5% of the world total cases. Sussundenga District has the highest incidence in the Manica province and environmental conditions are the major contributor to malaria transmission. There is a lack of malaria risk maps to inform transmission dynamics in Sussundenga village. This study develops a malaria risk map for Sussundenga Village in Mozambique and identifies high risk areas to inform on appropriate malaria control and eradication efforts. One hundred houses were randomly sampled and tested for malaria in Sussundenga Rural Municipality. To construct the map, a spatial conceptual model was used to estimate risk areas using ten environmental and anthropic factors. Data from Worldclim, 30 × 30 Landsat images were used, and layers were produced in a raster data set. Layers between class values were compared by assigning numerical values to the classes within each layer of the map with equal rank. Data set input was classified, using diverse weights depending on their appropriateness. The reclassified data outputs were combined after reclassification. The map indicated a high risk for malaria in the northeast and southeast, that is, the neighborhoods of Nhamazara, Nhamarenza, and Unidade. The central eastern areas, that is, 25 de Junho, 1 and 2, 7 de Abril, and Chicueu presented a moderate risk. In Sussundenga village there was 92% moderate and 8% high risk. High malaria risk areas are most often located in densely populated areas and areas close to water bodies. The relevant findings of this study can inform on effective malaria interventions.

Sustained Malaria Transmission despite Reactive Screen-and-Treat in a Low-Transmission Area of Southern Zambia.

Malaria elimination strategies are designed to more effectively identify and treat infected individuals to interrupt transmission. One strategy, reactive screen-and-treat, starts with passive detection of symptomatic cases at health facilities. Individuals residing within the index case and neighboring households are screened with a malaria rapid diagnostic test (RDT) and treated if positive. However, it is unclear to what extent this strategy is effective in reducing transmission. Reactive screen-and-treat was implemented in Choma district, Southern Province, Zambia, in 2013, in which residents of the index case and neighboring households within 140 m were screened with an RDT. From March 2016 to July 2018, the screening radius was extended to 250-m, and additional follow-up visits at 30 and 90 days were added to evaluate the strategy. Plasmodium falciparum parasite prevalence was measured using an RDT and by quantitative PCR (qPCR). A 24-single nucleotide polymorphism molecular bar-code assay was used to genotype parasites. Eighty-four index case households with 676 residents were enrolled between March 2016 and March 2018. Within each season, parasite prevalence declined significantly in index households at the 30-day visit and remained low at the 90-day visit. However, parasite prevalence was not reduced to zero. Infections identified by qPCR persisted between study visits and were not identified by RDT. Parasites identified within the same household were most genetically related; however, overall parasite relatedness was low and similar across time and space. Thus, despite implementation of a reactive screen-and-treat program, parasitemia was not eliminated, and persisted in targeted households for at least 3 months.

Improving the efficiency of reactive case detection for malaria elimination in southern Zambia: a cross-sectional study.

BACKGROUND: Reactive case detection (RCD) seeks to enhance malaria surveillance and control by identifying and treating parasitaemic individuals residing near index cases. In Zambia, this strategy starts with passive detection of symptomatic incident malaria cases at local health facilities or by community health workers, with subsequent home visits to screen-and-treat residents in the index case and neighbouring (secondary) households within a 140-m radius using rapid diagnostic tests (RDTs). However, a small circular radius may not be the most efficient strategy to identify parasitaemic individuals in low-endemic areas with hotspots of malaria transmission. To evaluate if RCD efficiency could be improved by increasing the probability of identifying parasitaemic residents, environmental risk factors and a larger screening radius (250 m) were assessed in a region of low malaria endemicity. METHODS: Between January 12, 2015 and July 26, 2017, 4170 individuals residing in 158 index and 531 secondary households were enrolled and completed a baseline questionnaire in the catchment area of Macha Hospital in Choma District, Southern Province, Zambia. Plasmodium falciparum prevalence was measured using PfHRP2 RDTs and quantitative PCR (qPCR). A Quickbird™ high-resolution satellite image of the catchment area was used to create environmental risk factors in ArcGIS, and generalized estimating equations were used to evaluate associations between risk factors and secondary households with parasitaemic individuals. RESULTS: The parasite prevalence in secondary (non-index case) households was 0.7% by RDT and 1.8% by qPCR. Overall, 8.5% (n = 45) of secondary households had at least one resident with parasitaemia by qPCR or RDT. The risk of a secondary household having a parasitaemic resident was significantly increased in proximity to higher order streams and marginally with increasing distance from index households. The adjusted OR for proximity to third- and fifth-order streams were 2.97 (95% CI 1.04-8.42) and 2.30 (95% CI 1.04-5.09), respectively, and that for distance to index households for each 50 m was 1.24 (95% CI 0.98-1.58). CONCLUSION: Applying proximity to streams as a screening tool, 16% (n = 3) more malaria-positive secondary households were identified compared to using a 140-m circular screening radius. This analysis highlights the potential use of environmental risk factors as a screening strategy to increase RCD efficiency.

The use of spatial and genetic tools to assess Plasmodium falciparum transmission in Lusaka, Zambia between 2011 and 2015.

BACKGROUND: Zambia has set itself the ambitious target of eliminating malaria by 2021. To continue tracking transmission to zero, new interventions, tools and approaches are required. METHODS: Urban reactive case detection (RCD) was performed in Lusaka city from 2011 to 2015 to better understand the location and drivers of malaria transmission. Briefly, index cases were followed to their home and all consenting individuals living in the index house and nine proximal houses were tested with a malaria rapid diagnostic test and treated if positive. A brief survey was performed and for certain responses, a dried blood spot sample collected for genetic analysis. Aggregate health facility data, individual RCD response data and genetic results were analysed spatially and against environmental correlates. RESULTS: Total number of malaria cases remained relatively constant, while the average age of incident cases and the proportion of incident cases reporting recent travel both increased. The estimated R0 in Lusaka was < 1 throughout the study period. RCD responses performed within 250 m of uninhabited/vacant land were associated with a higher probability of identifying additional infections. CONCLUSIONS: Evidence suggests that the majority of malaria infections are imported from outside Lusaka. However there remains some level of local transmission occurring on the periphery of urban settlements, namely in the wet season. Unfortunately, due to the higher-than-expected complexity of infections and the small number of samples tested, genetic analysis was unable to identify any meaningful trends in the data.

The Association Between Neighborhood Socioeconomic and Housing Characteristics with Hospitalization: Results of a National Study of Veterans.

BACKGROUND: Social determinants of health (SDOH) have an inextricable impact on health. If remained unaddressed, poor SDOH can contribute to increased health care utilization and costs. We aimed to determine if geographically derived neighborhood level SDOH had an impact on hospitalization rates of patients receiving care at the Veterans Health Administration's (VHA) primary care clinics. METHODS: In a 1-year observational cohort of veterans enrolled in VHA's primary care medical home program during 2015, we abstracted data on individual veterans (age, sex, race, Gagne comorbidity score) from the VHA Corporate Data Warehouse and linked those data to data on neighborhood socioeconomic status (NSES) and housing characteristics from the US Census Bureau on census tract level. We used generalized estimating equation modeling and spatial-based analysis to assess the potential impact of patient-level demographic and clinical factors, NSES, and local housing stock (ie, housing instability, home vacancy rate, percentage of houses with no plumbing, and percentage of houses with no heating) on hospitalization. We defined hospitalization as an overnight stay in a VHA hospital only and reported the risk of hospitalization for veterans enrolled in the VHA's primary care medical home clinics, both across the nation and within 1 specific case study region of the country: King County, WA. RESULTS: Nationally, 6.63% of our veteran population was hospitalized within the VHA system. After accounting for patient-level characteristics, veterans residing in census tracts with a higher NSES index had decreased odds of hospitalization. After controlling all other factors, veterans residing in census tracts with higher percentage of houses without heating had 9% (Odds Ratio, 1.09%; 95% CI, 1.04 to 1.14) increase in the likelihood of hospitalization in our regional Washington State analysis, though not our national level analyses. CONCLUSIONS: Our results present the impact of neighborhood characteristics such as NSES and lack of proper heating system on the likelihood of hospitalization. The application of placed-based data at the geographic level is a powerful tool for identification of patients at high risk of health care utilization.