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Little is known about the epidemiology of leptospirosis in the Dominican Republic, the second most populous country in the Caribbean. We report on findings from a multi-stage household survey across two regions in the country that reveals a previously under-estimated burden of human Leptospira infection. Our findings, based on the reference-standard microscopic agglutination test, indicate a complex picture of serogroup diversity, spatial heterogeneity in infection and risk, and a marked discrepancy between reported cases and serologically estimated infections. Given an overall seroprevalence of 11.3% (95% CI: 10.8-13.0%) and a lower estimated force of infection (0.30% per year [0.27%-0.35%]) the number of infections may exceed national reported case data by 145-fold or more. Icterohaemorrhagiae, associated with severe Weil's disease, was the most commonly identified serogroup with a serogroup-specific prevalence of 4.4%. Consistent with other settings, risk factors including age, male sex, and rat exposure were associated with higher seroprevalence. Our study highlights the need for targeted public health interventions informed by serogroup-specific dynamics, detailed spatial analyses, knowledge of local animal reservoirs, and strengthened laboratory surveillance to effectively control this pathogen., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: EJN is the PI on a US CDC funded U01 award that funded the study, and CLL, AK, DD, MdSA, ACR, HM, SG, MCE, WD, NI, GA, BH, KD, and MB have received salaries, consultancy fees, or travel paid through this award. EZG and BL are employees of the US CDC. BH, CT, LC, FP, and RSR are employees of the Ministry of Ministry of Health and Social Assistance, Dominican Republic, that was subcontracted with funds from the US CDC award. AK is supported by the Wellcome Trust, UK. CLL is supported by the Australian National Health and Medical Research Council. We declare no other competing interests., (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)

The 2014 chikungunya outbreak in the Dominican Republic resulted in intense local transmission, with high postoutbreak seroprevalence. The resulting population immunity will likely minimize risk for another large outbreak through 2035, but changes in population behavior or environmental conditions or emergence of different virus strains could lead to increased transmission.

Background: Individual immune responses to SARS-CoV-2 are well-studied, while the combined effect of these responses on population-level immune dynamics remains poorly understood. Given the key role of population immunity on pathogen transmission, delineation of the factors that drive population immune evolution has critical public health implications., Methods: We enrolled individuals 5 years and older selected using a multistage cluster survey approach in the Northwest and Southeast of the Dominican Republic. Paired blood samples were collected mid-pandemic (Aug 2021) and late pandemic (Nov 2022). We measured serum pan-immunoglobulin antibodies against the SARS-CoV-2 spike protein. Generalized Additive Models (GAMs) and random forest models were used to analyze the relationship between changes in antibody levels and various predictor variables. Principal component analysis and partial dependence plots further explored the relationships between predictors and antibody changes., Findings: We found a transformation in the distribution of antibody levels from an irregular to a normalized single peak Gaussian distribution that was driven by titre-dependent boosting. This led to the convergence of antibody levels around a common immune setpoint, irrespective of baseline titres and vaccination profile., Interpretation: Our results suggest that titre-dependent kinetics driven by widespread transmission direct the evolution of population immunity in a consistent manner. These findings have implications for targeted vaccination strategies and improved modeling of future transmission, providing a preliminary blueprint for understanding population immune dynamics that could guide public health and vaccine policy for SARS-CoV-2 and potentially other pathogens., Funding: The study was primarily funded by the Centers for Disease Control and Prevention grant U01GH002238 (EN). Salary support was provided by Wellcome Trust grant 206250/Z/17/Z (AK) and the Australian National Health and Medical Research Council Investigator grant APP1158469 (CLL)., Competing Interests: Declaration of interests EJN is the PI on a US Centers for Disease Control and Prevention (CDC) funded U01 award that funded the study. AK and CLL are co-investigators on the same award. DD, MdSA, SG, MCE, WD, GA, MB, and KWR have received salary support, consultancy fees, or travel paid through this award. BL is an employee of the US CDC. CTP, LC, IMS and RSR are employees of the Ministry of Ministry of Health and Social Assistance, Dominican Republic, that was subcontracted with funds from the US CDC award. AK is supported by the Wellcome Trust, UK. CLL is supported by the Australian National Health and Medical Research Council. CDC staff supported the design and manuscript editing. We declare no other competing interests., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: COVID-19 dynamics are driven by a complex interplay of factors including population behaviour, new variants, vaccination and immunity from prior infections. We quantify drivers of SARS-CoV-2 transmission in the Dominican Republic, an upper-middle income country of 10.8 million people. We then assess the impact of the vaccination campaign implemented in February 2021, primarily using CoronaVac, in saving lives and averting hospitalisations., Methods: We fit an age-structured, multi-variant transmission dynamic model to reported deaths, hospital bed occupancy, and seroprevalence data until December 2021, and simulate epidemic trajectories under different counterfactual scenarios., Findings: We estimate that vaccination averted 7210 hospital admissions (95% credible interval, CrI: 6830-7600), 2180 intensive care unit admissions (95% CrI: 2080-2280) and 766 deaths (95% CrI: 694-859) in the first 6 months of the campaign. If no vaccination had occurred, we estimate that an additional decrease of 10-20% in population mobility would have been required to maintain equivalent death and hospitalisation outcomes. We also found that early vaccination with CoronaVac was preferable to delayed vaccination using a product with higher efficacy., Interpretation: SARS-CoV-2 transmission dynamics in the Dominican Republic were driven by a substantial accumulation of immunity during the first two years of the pandemic but, despite this, vaccination was essential in enabling a return to pre-pandemic mobility levels without considerable additional morbidity and mortality., Funding: Medical Research Council, Wellcome Trust, Royal Society, US CDC and Australian National Health and Medical Research Council., Competing Interests: EF was supported by the Medical Research Council (MR/N013638/1); AJK was supported by Wellcome Trust (206250/Z/17/Z) and the US CDC (U01GH002238); RL was supported by a Royal Society Dorothy Hodgin Fellowship; EJN was supported by the US CDC (U01GH002238), CLL was supported by an Australian National Health and Medical Research Council Investigator Grant (APP1158469) and the US CDC (U01GH002238). AJK, EF, CLL have received salaries, consultancy fees, or travel paid through the US CDC award (U01GH002238). CTP and RS-R are employees of the Ministry of Health and Social Assistance, Dominican Republic, that was subcontracted with funds from the US CDC award., (© 2024 Published by Elsevier Ltd.)

Background: Proper hand hygiene (HH), which includes sanitizing with alcohol-based hand rub (ABHR) (or handwashing with soap and water if ABHR is unavailable), is key for preventing healthcare-associated infections (HCAI), including COVID-19. Understanding drivers of HH is key to improving adherence., Aim: This study aims to explore drivers and barriers to HH practice at two hospitals in the Dominican Republic in the context of the COVID-19 pandemic to inform development of HH behaviour change interventions., Methods: We conducted in-depth interviews with 20 hospital staff during September 2021. We used the COM-B (capability, opportunity, motivation, behaviour) model to explore HH experiences and preferences. Interviews were recorded, transcribed, coded, and analysed using a thematic approach., Results: A total of 11 parent codes and 27 sub-codes were identified, and 1145 coded segments were analysed. Use of handwashing with soap and water and/or sanitizing with ABHR was reported by all participants; handwashing was generally preferred. Participants expressed knowledge of proper HH methods (capability), but inconsistent supplies and lack of time presented HH challenges (opportunity). Interviewees described practicing HH to protect themselves and their families from COVID-19 and other infections (reflective motivation) or out of habit (automatic motivation)., Discussion: By understanding and addressing underlying factors affecting HH, hospitals can decrease the risk of HCAIs. Our findings suggest that interventions implemented to improve HH in these hospitals should target motivation and opportunity. These findings informed a multimodal intervention to increase ABHR access and implement message-tested communications campaigns; end-point assessments will provide insights into the intervention's impact.

Incidence of COVID-19 has been associated with sociodemographic factors. We investigated variations in SARS-CoV-2 seroprevalence at sub-national levels in the Dominican Republic and assessed potential factors influencing variation in regional-level seroprevalence. Data were collected in a three-stage cross-sectional national serosurvey from June to October 2021. Seroprevalence of antibodies against the SARS-CoV-2 spike protein (anti-S) was estimated and adjusted for selection probability, age, and sex. Multilevel logistic regression was used to estimate the effect of covariates on seropositivity for anti-S and correlates of 80% protection (PT 80 ) against symptomatic infection for the ancestral and Delta strains. A total of 6683 participants from 134 clusters in all 10 regions were enrolled. Anti-S, PT80 for the ancestral and Delta strains odds ratio varied across regions, Enriquillo presented significant higher odds for all outcomes compared with Yuma. Compared to being unvaccinated, receiving ≥2 doses of COVID-19 vaccine was associated with a significantly higher odds of anti-S positivity (OR 85.94, [10.95-674.33]) and PT 80 for the ancestral (OR 4.78, [2.15-10.62]) and Delta strains (OR 3.08, [1.57-9.65]) nationally and also for each region. Our results can help inform regional-level public health response, such as strategies to increase vaccination coverage in areas with low population immunity against currently circulating strains.

To assess changes in SARS-CoV-2 spike binding antibody prevalence in the Dominican Republic and implications for immunologic protection against variants of concern, we prospectively enrolled 2,300 patients with undifferentiated febrile illnesses in a study during March 2021-August 2022. We tested serum samples for spike antibodies and tested nasopharyngeal samples for acute SARS-CoV-2 infection using a reverse transcription PCR nucleic acid amplification test. Geometric mean spike antibody titers increased from 6.6 (95% CI 5.1-8.7) binding antibody units (BAU)/mL during March-June 2021 to 1,332 (95% CI 1,055-1,682) BAU/mL during May-August 2022. Multivariable binomial odds ratios for acute infection were 0.55 (95% CI 0.40-0.74), 0.38 (95% CI 0.27-0.55), and 0.27 (95% CI 0.18-0.40) for the second, third, and fourth versus the first anti-spike quartile; findings were similar by viral strain. Combining serologic and virologic screening might enable monitoring of discrete population immunologic markers and their implications for emergent variant transmission.

Background: Population-level SARS-CoV-2 immunological protection is poorly understood but can guide vaccination and non-pharmaceutical intervention priorities. Our objective was to characterise cumulative infections and immunological protection in the Dominican Republic., Methods: Household members ≥5 years were enrolled in a three-stage national household cluster serosurvey in the Dominican Republic. We measured pan-immunoglobulin antibodies against the SARS-CoV-2 spike (anti-S) and nucleocapsid glycoproteins, and pseudovirus neutralising activity against the ancestral and B.1.617.2 (Delta) strains. Seroprevalence and cumulative prior infections were weighted and adjusted for assay performance and seroreversion. Binary classification machine learning methods and pseudovirus neutralising correlates of protection were used to estimate 50% and 80% protection against symptomatic infection., Findings: Between 30 Jun and 12 Oct 2021 we enrolled 6683 individuals from 3832 households. We estimate that 85.0% (CI 82.1-88.0) of the ≥5 years population had been immunologically exposed and 77.5% (CI 71.3-83) had been previously infected. Protective immunity sufficient to provide at least 50% protection against symptomatic SARS-CoV-2 infection was estimated in 78.1% (CI 74.3-82) and 66.3% (CI 62.8-70) of the population for the ancestral and Delta strains respectively. Younger (5-14 years, OR 0.47 [CI 0.36-0.61]) and older (≥75-years, 0.40 [CI 0.28-0.56]) age, working outdoors (0.53 [0.39-0.73]), smoking (0.66 [0.52-0.84]), urban setting (1.30 [1.14-1.49]), and three vs no vaccine doses (18.41 [10.69-35.04]) were associated with 50% protection against the ancestral strain., Interpretation: Cumulative infections substantially exceeded prior estimates and overall immunological exposure was high. After controlling for confounders, markedly lower immunological protection was observed to the ancestral and Delta strains across certain subgroups, findings that can guide public health interventions and may be generalisable to other settings and viral strains., Funding: This study was funded by the US CDC., Competing Interests: E.J.N. is the PI on a US CDC funded U01 award that funded the study, and C.L.L., A.K., D.D., M.d.S.A., A.C.R., H.M., S.G., M.C.E., W.D., N.I., G.A., B.H., K.D., M.B., E.F., and L.I. have received salaries, consultancy fees, or travel paid through this award. E.Z.G., B.L., and A.E.-B. are employees of the US CDC. B.H., C.T., L.C., F.P., and R.S.-R. are employees of the Ministry of Ministry of Health and Social Assistance, Dominican Republic, that was subcontracted with funds from the US CDC award. A.K. and E.F. are supported by the Welcome Trust, UK. D.B. had a patent for COVID-19 vaccine licensed to Janssen. We declare no other competing interests., (© 2022 The Author(s).)

Background: Research has been conducted on interventions to control dengue transmission and respond to outbreaks. A summary of the available evidence will help inform disease control policy decisions and research directions, both for dengue and, more broadly, for all Aedes-borne arboviral diseases., Method: A research-to-policy forum was convened by TDR, the Special Programme for Research and Training in Tropical Diseases, with researchers and representatives from ministries of health, in order to review research findings and discuss their implications for policy and research., Results: The participants reviewed findings of research supported by TDR and others. Surveillance and early outbreak warning. Systematic reviews and country studies identify the critical characteristics that an alert system should have to document trends reliably and trigger timely responses (i.e., early enough to prevent the epidemic spread of the virus) to dengue outbreaks. A range of variables that, according to the literature, either indicate risk of forthcoming dengue transmission or predict dengue outbreaks were tested and some of them could be successfully applied in an Early Warning and Response System (EWARS). Entomological surveillance and vector management. A summary of the published literature shows that controlling Aedes vectors requires complex interventions and points to the need for more rigorous, standardised study designs, with disease reduction as the primary outcome to be measured. House screening and targeted vector interventions are promising vector management approaches. Sampling vector populations, both for surveillance purposes and evaluation of control activities, is usually conducted in an unsystematic way, limiting the potentials of entomological surveillance for outbreak prediction. Combining outbreak alert and improved approaches of vector management will help to overcome the present uncertainties about major risk groups or areas where outbreak response should be initiated and where resources for vector management should be allocated during the interepidemic period., Conclusions: The Forum concluded that the evidence collected can inform policy decisions, but also that important research gaps have yet to be filled.

The chikungunya epidemic in the Dominican Republic began in February 2014. During the first six months 429 421 cases were recorded, representing 65% of all those notified to the Pan American Health Organization by 33 countries and territories of the Region of the Americas. This epidemic has spread quickly in the Dominican Republic, requiring a focused intersectoral response, led by the Ministry of Public Health and involving major efforts by the National Epidemiological System and the health services network. Given that the virus will affect thousands of people, this article seeks to describe the actions that have already been carried out, and to share the results and lessons learned during these first months with health ministries and professionals in the countries of the Region, in order to assist them to prepare an appropriate response to confront the epidemic effectively and efficiently.

The Dominican Republic (DR) has experienced tremendous increase in the number of cases of dengue virus (DENV) reported in the past few years. There are four serotypes of DENV (1-4), and each can cause classic dengue fever (DF), dengue hemorrhagic fever (DHF), or dengue shock syndrome (DSS). DENV-1-4 are currently circulating in the DR; however, the Department of Epidemiology of the Dominican Republic (DIEGPI) has been able to isolate only DENV-2 and DENV-4. In the DR, the development of DENV infection occurred primarily in the second semester of the year. Since the DR instituted a vigilant approach to dengue infections, there have been three major outbreaks detected: one in 1998, one in 2000, and one in 2002. DF is the clinical presentation most currently seen at clinics, accounting for about 75% of cases, while patients with DHF account for about 19% of cases seen. Currently, there are seven provinces in which the total number of dengue cases per 100,000 inhabitants is higher than 32. With a vigilant approach, the DR should continue to see success in controlling the DENV outbreak., (2005 Wiley-Liss, Inc.)

The objective of this study was to identify the impact of cultural and ecological change on intestinal helminth infections in traditional indigenous communities in the Peruvian rainforest and to identify the ways of transmission of helminth eggs. A remote indigenous settlement was compared with a more developed mestizo town. Stool specimens as well as soil, dust, air and water were examined for Ascaris and Trichuris eggs. A significantly lower infection intensity of Ascaris and Trichuris could be demonstrated for the traditional Indian community. Here the hygienic conditions were found to be better than in the town. The mestizo teacher and his family, who had come from the town to the Indian settlement, showed poorer hygienic standards and higher levels of Ascaris and Trichuris egg excretion than the Indian dwellers. The distribution of Ascaris and Trichuris eggs in the soil, house dust and in the air suggests that the contaminated dust from defaecation sites was distributed through the whole community by feet, animals (chickens) and wind. It was observed that many traditional habits that contributed to the good hygiene of the native population were being abandoned in the process of cultural change.