Aedes aegypti, the dengue fever mosquito in Mexico City. Early invasion and its potential risks.

INTRODUCTION: Mexico City has no endemic presence of Aedes aegypti, and it is therefore free of vector-borne diseases, such as dengue fever, Zika and chikungunya. However, evidence has shown the presence of Aedes aegypti eggs in the city since 2015. OBJECTIVE: To report the constant and increasing presence of Aedes aegypti eggs in Mexico City from 2015 to 2018. METHODS: Surveillance was carried out using ovitraps. Eggs were counted and hatched in order to determine the species. RESULTS: From 2015 to 2018, 378 organisms were identified as Ae. aegypti. In total, 76 Aedes aegypti-positive ovitraps were collected at 50 different places in 11 boroughs of the city. Northeastern Mexico City was the area with the highest number of positive traps. CONCLUSIONS: The results may be indicating a period of early colonization and the probable existence of cryptic colonies of the mosquito; Mexico City could be at risk of experiencing vector-borne epidemics.

INTRODUCCIÓN: La Ciudad de México no tiene presencia endémica de Aedes aegypti, por lo que está libre de enfermedades transmitidas por vector como dengue, Zika y chikunguña. Sin embargo, existe evidencia de la presencia de huevecillos en la urbe desde 2015. OBJETIVO: Reportar la presencia constante y en aumento de huevecillos de Aedes aegypti en la Ciudad de México de 2015 a 2018. MÉTODO: Se realizó vigilancia a través de ovitrampas; se contabilizaron y eclosionaron huevecillos para determinar la especie. RESULTADOS: De 2015 a 2018 fueron identificados 378 organismos como Aedes aegypti. En total fueron colectadas 76 ovitrampas positivas a Aedes aegypti en 50 sitios distintos de 11 alcaldías. El noreste de la Ciudad de México fue el área con mayor positividad. CONCLUSIONES: Los resultados pueden estar indicando un periodo de colonización incipiente y la probable la existencia de colonias crípticas del mosquito, por lo que la Ciudad de México podría estar en riesgo de presentar epidemias de enfermedades transmitidas por vector.

Urban and semi-urban mosquitoes of Mexico City: A risk for endemic mosquito-borne disease transmission.

Since past century, vector-borne diseases have been a major public health concern in several states of Mexico. However, Mexico City continues to be free of endemic mosquito-borne viral diseases. The city is the most important politic and economic state of Mexico and one of the most important city of Latin America. Its subtropical highland climate and high elevation (2240 masl) had historically made the occurrence of Aedes species unlikely. However, the presence of other potential disease vectors (Culex spp, Culiseta spp), and the current intermittent introductions of Aedes aegypti, have revealed that control programs must adopt routine vector surveillance in the city. In this study, we provide an updated species list from a five-years of vector surveillance performed in Mexico City. A total of 18,553 mosquito larvae were collected. Twenty-two species from genus Culex, Aedes, Culiseta, Anopheles, Lutzia and Uranotaenia were observed. Nine new mosquito records for the city were found. Ae. albopictus was recorded for the first time in Mexico City. Interestingly, a new record, Ae. epactius was the most frequent species reported. Cx. pipiens quinquefasciatus exhibited the highest number of individuals collected. We detected six areas which harbor the highest mosquito species records in the city. Cemeteries included 68.9% of our collection sites. Temporarily ponds showed the highest species diversity. We detected an increasing presence of Ae. aegypti, which was detected for three consecutive years (2015-2017), predominantly in the warmer microclimates of the city. We found a possible correlation between increasing temperature and Ae. aegypti and Ae. albopictus expanding range. This study provides a starting point for developing strategies related to environmental management for mosquito control. The promotion of mosquito control practices through community participation, mass media and education programmes in schools should be introduced in the city.

El mosquito del dengue en la Ciudad de México. Invasión incipiente de Aedes aegypti y sus potenciales riesgos / Aedes aegypti, the dengue fever mosquito in Mexico City. Early invasion and its potential risks

Resumen Introducción: La Ciudad de México no tiene presencia endémica de Aedes aegypti, por lo que está libre de enfermedades transmitidas por vector como dengue, Zika y chikunguña. Sin embargo, existe evidencia de la presencia de huevecillos en la urbe desde 2015. Objetivo: Reportar la presencia constante y en aumento de huevecillos de Aedes aegypti en la Ciudad de México de 2015 a 2018. Método: Se realizó vigilancia a través de ovitrampas; se contabilizaron y eclosionaron huevecillos para determinar la especie. Resultados: De 2015 a 2018 fueron identificados 378 organismos como Aedes aegypti. En total fueron colectadas 76 ovitrampas positivas a Aedes aegypti en 50 sitios distintos de 11 alcaldías. El noreste de la Ciudad de México fue el área con mayor positividad. Conclusiones: Los resultados pueden estar indicando un periodo de colonización incipiente y la probable la existencia de colonias crípticas del mosquito, por lo que la Ciudad de México podría estar en riesgo de presentar epidemias de enfermedades transmitidas por vector.

Abstract Introduction: Mexico City has no endemic presence of Aedes aegypti, and it is therefore free of vector-borne diseases, such as dengue fever, Zika and chikungunya. However, evidence has shown the presence of Aedes aegypti eggs in the city since 2015. Objective: To report the constant and increasing presence of Aedes aegypti eggs in Mexico City from 2015 to 2018. Methods: Surveillance was carried out using ovitraps. Eggs were counted and hatched in order to determine the species. Results: From 2015 to 2018, 378 organisms were identified as Ae. aegypti. In total, 76 Aedes aegypti-positive ovitraps were collected at 50 different places in 11 boroughs of the city. Northeastern Mexico City was the area with the highest number of positive traps. Conclusions: The results may be indicating a period of early colonization and the probable existence of cryptic colonies of the mosquito, and Mexico City could be therefore at risk of experiencing vector-borne epidemics.