Malaria Elimination in Costa Rica: Changes in Treatment and Mass Drug Administration
The objectives of this study were:
- To evaluate the changes observed in malaria transmission following the implementation in 2006 of a supervised seven-day chloroquine and primaquine treatment in Huétar Norte Region (HNR) of Costa Rica.
- To 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.
The remaining malaria transmission hotspots in Costa Rica 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. Our analysis showed 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 Mexico.