Insecticide susceptibility status of Anopheles albimanus populations in historical malaria foci in Quintana Roo, Mexico.

BACKGROUND: Mexico has experienced a significant reduction in malaria cases over the past two decades. Certification of localities as malaria-free areas (MFAs) has been proposed as a steppingstone before elimination is achieved throughout the country. The Mexican state of Quintana Roo is a candidate for MFA certification. Monitoring the status of insecticide susceptibility of major vectors is crucial for MFA certification. This study describes the susceptibility status of Anopheles albimanus, main malaria vector, from historically important malaria foci in Quintana Roo, using both phenotypic and genotypic approaches. METHODS: Adult mosquito collections were carried out at three localities: Palmar (Municipality of Othon P. Blanco), Buenavista (Bacalar) and Puerto Morelos (Puerto Morelos). Outdoor human-landing catches were performed by pairs of trained staff from 18:00 to 22:00 during 3-night periods at each locality during the rainy season of 2022. Wild-caught female mosquitoes were exposed to diagnostic doses of deltamethrin, permethrin, malathion, pirimiphos-methyl or bendiocarb using CDC bottle bioassays. Mortality was registered at the diagnostic time and recovery was assessed 24 h after exposure. Molecular analyses targeting the Voltage-Gated Sodium Channel (vgsc) gene and acetylcholinesterase (ace-1) gene were used to screen for target site polymorphisms. An SNP analysis was carried out to identify mutations at position 995 in the vgsc gene and at position 280 in the ace-1 gene. RESULTS: A total of 2828 anophelines were collected. The main species identified were Anopheles albimanus (82%) and Anopheles vestitipennis (16%). Mortalities in the CDC bottle bioassay ranged from 99% to 100% for all the insecticides and mosquito species. Sequence analysis was performed on 35 An. albimanus across the three localities; of those, 25 were analysed for vgsc and 10 for ace-1 mutations. All individuals showed wild type alleles. CONCLUSION: The results demonstrated that An. albimanus populations from historical malaria foci in Quintana Roo are susceptible to the main insecticides used by the Ministry of Health.

Web Geographic Information System: A Support Tool for the Study, Evaluation, and Monitoring of Foci of Malaria Transmission in Mexico.

Malaria is currently an endemic disease in Mexico. The country joined the WHO's E-25 initiative for the elimination of Plasmodium vivax to achieve elimination and certification within the established period. Having a Web-based information system was, therefore, deemed necessary to assist in the detection, investigation, and elimination of transmission in the foci, as well as for the timely treatment of malaria-positive cases. The "Information System for the Elimination of Malaria in Mexico" was designed, developed, and implemented with a geographic vision, which includes a Web tool to georeference homes and aquatic systems, a dashboard and an indicator evaluation card for monitoring activities, notification of probable cases, and vector control among other indicators. The implementation of the system was gradual in the seven states that are currently in the malaria elimination phase; subsequently, the system was implemented in non-transmission states. In 2020, the system implementation stage began; first, the basic data of more than 96,000 homes throughout the country were georeferenced, and then the primary data capture tools of 17 formats, 32 reports, and 2 geographic viewers were enabled for information queries. A total of 56 active foci have been identified in 406 localities as well as 71 residual foci in 320 localities. Recently, the Foci Manager was developed, which is a specific tool for the study, evaluation, and monitoring of active foci through a GIS, a dashboard, and a systematized evaluation certificate. Georeferencing tools decreased the cost of spatial data collection.