Health policy impacts on malaria transmission in Costa Rica.

Costa Rica is near malaria elimination. This achievement has followed shifts in malaria health policy. Here, we evaluate the impacts that different health policies have had on malaria transmission in Costa Rica from 1913 to 2018. We identified regime shifts and used regression models to measure the impact of different health policies on malaria transmission in Costa Rica using annual case records. We found that vector control and prophylactic treatments were associated with a 50% malaria case reduction in 1929-1931 compared with 1913-1928. DDT introduction in 1946 was associated with an increase in annual malaria case reduction from 7.6% (1942-1946) to 26.4% (1947-1952). The 2006 introduction of 7-day supervised chloroquine and primaquine treatments was the most effective health policy between 1957 and 2018, reducing annual malaria cases by 98% (2009-2018) when compared with 1957-1968. We also found that effective malaria reduction policies have been sensitive to natural catastrophes and extreme climatic events, both of which have increased malaria transmission in Costa Rica. Currently, outbreaks follow malaria importation into vulnerable areas of Costa Rica. This highlights the need to timely diagnose and treat malaria, while improving living standards, in the affected areas.

Anopheles albimanus (Diptera: Culicidae) Ensemble Distribution Modeling: Applications for Malaria Elimination.

In the absence of entomological information, tools for predicting Anopheles spp. presence can help evaluate the entomological risk of malaria transmission. Here, we illustrate how species distribution models (SDM) could quantify potential dominant vector species presence in malaria elimination settings. We fitted a 250 m resolution ensemble SDM for Anopheles albimanus Wiedemann. The ensemble SDM included predictions based on seven different algorithms, 110 occurrence records and 70 model projections. SDM covariates included nine environmental variables that were selected based on their importance from an original set of 28 layers that included remotely and spatially interpolated locally measured variables for the land surface of Costa Rica. Goodness of fit for the ensemble SDM was very high, with a minimum AUC of 0.79. We used the resulting ensemble SDM to evaluate differences in habitat suitability (HS) between commercial plantations and surrounding landscapes, finding a higher HS in pineapple and oil palm plantations, suggestive of An. albimanus presence, than in surrounding landscapes. The ensemble SDM suggested a low HS for An. albimanus at the presumed epicenter of malaria transmission during 2018-2019 in Costa Rica, yet this vector was likely present at the two main towns also affected by the epidemic. Our results illustrate how ensemble SDMs in malaria elimination settings can provide information that could help to improve vector surveillance and control.

Modeling the association between Aedes aegypti ovitrap egg counts, multi-scale remotely sensed environmental data and arboviral cases at Puntarenas, Costa Rica (2017-2018).

Problems with vector surveillance are a major barrier for the effective control of vector-borne disease transmission through Latin America. Here, we present results from a 80-week longitudinal study where Aedes aegypti (L.) (Diptera: Culicidae) ovitraps were monitored weekly at 92 locations in Puntarenas, a coastal city in Costa Rica with syndemic Zika, chikungunya and dengue transmission. We used separate models to investigate the association of either Ae. aegypti-borne arboviral cases or Ae. aegypti egg counts with remotely sensed environmental variables. We also evaluated whether Ae. aegypti-borne arboviral cases were associated with Ae. aegypti egg counts. Using cross-correlation and time series modeling, we found that arboviral cases were not significantly associated with Ae. aegypti egg counts. Through model selection we found that cases had a non-linear response to multi-scale (1-km and 30-m resolution) measurements of temperature standard deviation (SD) with a lag of up to 4 weeks, while simultaneously increasing with finely-grained NDVI (30-m resolution). Meanwhile, median ovitrap Ae. aegypti egg counts increased, and respectively decreased, with temperature SD (1-km resolution) and EVI (30-m resolution) with a lag of 6 weeks. A synchrony analysis showed that egg counts had a travelling wave pattern, with synchrony showing cyclic changes with distance, a pattern not observed in remotely sensed data with 30-m and 10-m resolution. Spatially, using generalized additive models, we found that eggs were more abundant at locations with higher temperatures and where EVI was leptokurtic during the study period. Our results suggest that, in Puntarenas, remotely sensed environmental variables are associated with both Ae. aegypti-borne arbovirus transmission and Ae. aegypti egg counts from ovitraps.

Malaria Elimination in Costa Rica: Changes in Treatment and Mass Drug Administration.

Costa Rica is a candidate to eliminate malaria by 2020. The remaining malaria transmission hotspots are located within the Huétar Norte Region (HNR), where 90% of the country's 147 malaria cases have occurred since 2016, following a 33-month period without transmission. Here, we examine changes in transmission with the implementation of a supervised seven-day chloroquine and primaquine treatment (7DCPT). We also evaluate the impact of a focal mass drug administration (MDA) in January 2019 at Boca Arenal, the town in HNR reporting the greatest local transmission. We found that the change to a seven-day treatment protocol, from the prior five-day program, was associated with a 98% reduction in malaria transmission. The MDA helped to reduce transmission, keeping the basic reproduction number, RT, significantly below 1, for at least four months. However, following new imported cases from Nicaragua, autochthonous transmission resumed. Our results highlight the importance of appropriate treatment delivery to reduce malaria transmission, and the challenge that highly mobile populations, if their malaria is not treated, pose to regional elimination efforts in Mesoamerica and México.

Desafíos en la implementación de la Estrategia de Gestión Integrada para la prevención y control del dengue, Costa Rica 2016 / Challenges posed by the implementation of the Integrated Management Strategy for dengue prevention and control, Costa Rica 2016

Introducción: En 2004 las autoridades de Costa Rica se comprometieron con la implementación de la Estrategia de Gestión Integrada que busca reducir la morbilidad, la mortalidad y la carga social y económica por los brotes y las epidemias del dengue. Sin embargo, tal como indican los datos de incidencia del dengue, a lo largo del tiempo no hay un descenso sostenido en los cantones. Objetivo: Identificar los niveles de cumplimiento de la Estrategia de Gestión Integrada orientada a la prevención y control del dengue en Costa Rica. Métodos: Se aplicó una lista de verificación sobre los indicadores de cumplimiento de la Estrategia de Gestión Integrada a siete áreas rectoras del Ministerio de Salud del Pacífico Central. Además, se realizaron entrevistas a funcionarios de las áreas locales. Resultados: El nivel de cumplimiento de la Estrategia de Gestión Integrada para la prevención y control del dengue en las áreas rectoras obtuvo un puntaje máximo del 78 por ciento. Los componentes con menor nivel de cumplimiento fueron manejo integrado de vectores y comunicación social. Conclusiones: A nivel local existen múltiples barreras para el cumplimiento de los indicadores propuestos en la Estrategia de Gestión Integrada. Por tanto, se requiere un mayor acompañamiento del nivel central y regional, con el fin de articular los diferentes componentes y alcanzar los objetivos y metas planteadas a nivel local(AU)

Introduction: In the year 2004 Costa Rican authorities pledged to implement an Integrated Management Strategy aimed at reducing the morbidity, mortality and social and economic burden caused by dengue outbreaks and epidemics. However, incidence data show that there has not been a sustained decrease of the disease in cantons. Objective: Identify the degree of compliance with the Integrated Management Strategy for dengue prevention and control in Costa Rica. Methods: A checklist about indicators for compliance with the Integrated Management Strategy was applied in seven leading areas of the Central Pacific Health Ministry. Additionally, interviews were conducted with local area officials. Results: Compliance with the Integrated Management Strategy for dengue prevention and control in the leading areas reached a maximum score of 78 percent. The components with the lowest compliance values were integrated vector management and social communication. Conclusions: A large number of barriers hamper compliance with Integrated Management Strategy indicators on the local level. Greater support by the central and regional levels is therefore required to articulate the various components and achieve local objectives and goals(AU)