INTRODUCCIÓN
El dengue es una enfermedad febril que afecta a la región de las Américas. En Honduras, en los últimos cinco años se han declarado dos emergencias sanitarias por esta enfermedad, relacionadas con condiciones socioeconómicas y climáticas que facilitan la transmisión del virus. Por ello, se necesitan estrategias innovadoras e integrales para prevenirlo. El World Mosquito Program desarrolló un método basado en la introducción de la bacteria Wolbachia en poblaciones de mosquitos Ae. aegypti. Wolbachia actúa reduciendo la capacidad de Ae. aegypti para transmitir arbovirus a través de la restricción de la infección y replicación viral en los tejidos del mosquito. Médicos Sin Fronteras realizó la implementación del método, con especial énfasis en la aceptación y participación comunitaria, como parte integral del control vectorial y prevención de dengue en la comunidad de El Manchén, Tegucigalpa, Honduras.
OBJETIVOS
Los objetivos del estudio fueron evaluar la introgresión de Wolbachia en poblaciones locales de mosquitos Ae. aegypti en la zona de intervención, el impacto asociado en la incidencia de dengue, y la aceptación y participación comunitaria en la implementación del método Wolbachia.
METODOLOGÍA
Adoptando un enfoque de pacientes y población como socios (PPP), Médicos sin Fronteras colaboró con 51 voluntarios comunitarios para implementar el método Wolbachia en El Manchén, Tegucigalpa. En conjunto, los motoristas de MSF y los voluntarios comunitarios liberaron 8.3 millones de mosquitos desde agosto 2023 a febrero 2024 (26 semanas). La introgresión fue evaluada capturando zancudos de 49 puntos aleatorios en la comunidad, los cuales después fueron examinados para detectar las proteínas de superficie de Wolbachia, con la técnica de reacción en cadena de la polimerasa por el Laboratorio de Investigaciones en Microbiología de la Universidad Nacional Autónoma de Honduras. Las evaluaciones se realizaron quincenalmente durante el periodo de liberación, y trimestralmente después de terminar con las liberaciones. Para entender la perspectiva de la comunidad, se realizó una encuesta preliberaciones y post-liberaciones que evaluó aspectos socioeconómicos, conocimientos y aceptación sobre el método. Además, se realizaron 13 grupos de discusión focales con 161 miembros de la población. Los resultados de los procedimientos de recolección cualitativos fueron analizados en NVIVO siguiendo ejes temáticos relacionados con los factores que median la aceptabilidad y la experiencia de los habitantes con la implementación de la estrategia.
RESULTADOS
Se observó una tendencia creciente en la prevalencia de mosquitos Ae. aegypti portadores de Wolbachia. Los resultados preliminares durante las liberaciones muestran porcentajes progresivos de infección de Wolbachia: 16.3%, 30.52%, 62.45%, 72.53%, hasta febrero 2024 con 82.79%. Posterior a las liberaciones, se documentó una reducción inicial y esperada (65.18% en abril 2024 y 57.55% en junio 2024), seguido por un crecimiento en septiembre 2024 a 85.27%. Las encuestas de aceptabilidad, entrevistas, y grupos focales demostraron una alta aceptabilidad de Wolbachia. Ambos antes y después de la intervención, >90% de encuestados estuvieron de acuerdo con las liberaciones implementadas por MSF y la secretaria de Salud. Un aumento en las picaduras fue el comentario negativo más común. En los grupos focales las principales preocupaciones fueron el aumento de mosquitos o de casos de dengue por las liberaciones de mosquitos, además de la inocuidad de Wolbachia. Sin embargo, los habitantes de El Manchén señalaron una perspectiva positiva de la estrategia para el control vectorial. Desafíos de implementación incluyeron el escepticismo de la comunidad, la inseguridad, y factores ambientales que afectaron los huevos. Beneficios indirectos del trabajo conjunto con la comunidad incluyen 25 iniciativas nuevas de la comunidad para el control de vectores, a partir de la adopción del enfoque PPP y apoyo por MSF.
CONCLUSIONES Y RECOMENDACIONES
Los resultados sugieren que la implementación de la Wolbachia contra el dengue sea factible y aceptable en Tegucigalpa, Honduras, con el apoyo de la comunidad para la implementación de la estrategia. El establecimiento aparente de Wolbachia sugiere que pueda tener un impacto positivo en la incidencia de dengue. Se continuará monitoreando el establecimiento y las tasas de incidencia de arbovirus a través de un análisis de series temporales interrumpidas con datos históricos y prevalencias actuales de dengue. Se sugiere mantener mecanismos de prevención de arbovirus integrales.
Experiences of Wolbachia implementation in the control of arbovirus vectors in Tegucigalpa, Honduras
There is limited evidence regarding the accuracy of dengue rapid diagnostic kits despite their extensive use in India. We evaluated the performance of four immunochromatographic Rapid Diagnostic Test (RDTs) kits: Multisure dengue Ab/Ag rapid test (MP biomedicals; MP), Dengucheck combo (Zephyr Biomedicals; ZB), SD bioline dengue duo (Alere; SD) and Dengue day 1 test (J Mitra; JM).
METHODS
This is a laboratory-based diagnostic evaluation study. Rapid tests results were compared to reference non-structural (NS1) antigen or immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) results of 241 dengue-positive samples and 247 dengue-negative samples. Sensitivity and specificity of NS1 and IgM components of each RDT were calculated separately and in combination (either NS1 or IgM positive) against reference standard ELISA.
RESULTS
A total of 238, 226, 208, and 146 reference NS1 ELISA samples were tested with MP, ZB, SD, and JM tests, respectively. In comparison to the NS1 ELISA reference tests, the NS1 component of MP, ZB, SD, and JM RDTs demonstrated a sensitivity of 71.8%, 85.1%, 77.2% and 80.9% respectively and specificity of 90.1%, 92.8%, 96.1 %, and 93.6%, respectively. In comparison to the IgM ELISA reference test, the IgM component of RDTs showed a sensitivity of 40.0%, 50.3%, 47.3% and 20.0% respectively and specificity of 92.4%, 88.6%, 96.5%, and 92.2% respectively. Combining NS1 antigen and IgM antibody results led to sensitivities of 87.5%, 82.9%, 93.8% and 91.7% respectively, and specificities of 75.3%, 73.9%, 76.5%, and 80.0% respectively.
INTERPRETATION & CONCLUSIONS
Though specificities were acceptable, the sensitivities of each test were markedly lower than manufacturers' claims. These results also support the added value of combined antigen-and antibody-based RDTs for the diagnosis of acute dengue.
Methods: We report basic epidemiological characteristics in a series of 701 patients at the National Paediatric Hospital in Cambodia, recruited during a prospective clinical study (2011-2012). To more fully explore this cohort, we examined climatic factors using multivariate negative binomial models and spatial clustering of cases using spatial scan statistics to place the clinical study within a larger epidemiological framework.
Results: We identify statistically significant spatial clusters at the urban village scale, and find that the key climatic predictors of increasing cases are weekly minimum temperature, median relative humidity, but find a negative association with rainfall maximum, all at lag times of 1-6 weeks, with significant effects extending to 10 weeks.
Conclusions: Our results identify clustering of infections at the neighbourhood scale, suggesting points for targeted interventions, and we find that the complex interactions of vectors and climatic conditions in this setting may be best captured by rising minimum temperature, and median (as opposed to mean) relative humidity, with complex and limited effects from rainfall. These results suggest that real-time cluster detection during epidemics should be considered in Cambodia, and that improvements in weather data reporting could benefit national control programs by allow greater prioritization of limited health resources to both vulnerable populations and time periods of greatest risk. Finally, these results add to the increasing body of knowledge suggesting complex interactions between climate and dengue cases that require further targeted research.
Dengue is an endemic disease in India. Epidemics occur every year with incidence rising every year. Since 2010, Chandigarh has seen Dengue epidemics every year but the toll of reported confirmed cases has been very low. A study was undertaken to assess knowledge, awareness and practices among those who had already been diagnosed with dengue and followed up multiple times by Multipurpose Health Workers (MPHWs) at their homes. This study was conducted when both authors were post-graduate scholars at the Department of Public Health at Manipal Academy of Higher Education.
OBJECTIVE
To ascertain knowledge, awareness and practices regarding dengue among incident dengue cases of 2016 in Chandigarh.
METHODS
Retrospective Cohort study was conducted among the incident cases of dengue reported in 2016. The line list of cases was obtained from health department. Each household was visited once and face to face interviews were conducted with those willing to participate from January 2017 to March 2017. Using a modified WHO (World Health Organisation) questionnaire, 149 interviews were completed and analysed using descriptive analytical tools.
RESULTS
Data from the 149 interviews (57 males and 92 females) was used for primary analysis. Only 58.4% respondents were aware about dengue before diagnosis and 63.1% knew of its vector while only 10.1% were aware of the national programme and services available to them. Use of mosquito net was negligible (3.4%), even in rural areas. Screens on doors and windows were more common in urban area of Chandigarh.
CONCLUSION
Since the study was conducted among incident cases, even after multiple visits conducted by MPHWs to the houses of these respondents, the knowledge regarding dengue was lower than expected.
The spatial distribution and burden of dengue in sub-Saharan Africa remains highly uncertain, despite high levels of ecological suitability. The goal of this study was to describe the epidemiology of dengue among a cohort of febrile children presenting to outpatient facilities located in areas of western Uganda with differing levels of urbanicity and malaria transmission intensity.
METHODS
Eligible children were first screened for malaria using rapid diagnostic tests. Children with a negative malaria result were tested for dengue using a combination NS1/IgM/IgG rapid test (SD Bioline Dengue Duo). Confirmatory testing by RT-PCR was performed in a subset of participants. Antigen-capture ELISA was performed to estimate seroprevalence.
RESULTS
Only 6 of 1416 (0.42%) children had a positive dengue rapid test, while none of the RT-PCR results were positive. ELISA testing demonstrated reactive IgG antibodies in 28 (2.2%) participants with the highest prevalence seen at the urban site in Mbarara (19 of 392, 4.9%, p < 0.001).
CONCLUSIONS
Overall, these findings suggest that dengue, while present, is an uncommon cause of non-malarial, pediatric febrile illness in western Uganda. Further investigation into the eocological factors that sustain low-level transmission in urban settings are urgently needed to reduce the risk of epidemics.