Factors Associated with the Rapid and Durable Decline in Malaria Incidence in El Salvador, 1980-2017.

Robert A Burton,Kammerle Schneider,Caterina Guinovart,Richard W Steketee,Jaime Enrique Alemán Escobar,Matthew Boslego,Mirna Elizabeth Gavidia,Mauricio Sauerbrey,Carlos C (Kent) Campbell,Rachel Turkel,Laurence Slutsker,Angela Hartley,José Eduardo Romero Chévez,Geoffrey Kirkwood

doi:10.4269/ajtmh.17-0629

Abstract

.A decade after the Global Malaria Eradication Program, El Salvador had the highest burden of malaria in Mesoamerica, with approximately 20% due to Plasmodium falciparum. A resurgence of malaria in the 1970s led El Salvador to alter its national malaria control strategy. By 1995, El Salvador recorded its last autochthonous P. falciparum case with fewer than 20 Plasmodium vivax cases annually since 2011. By contrast, its immediate neighbors continue to have the highest incidences of malaria in the region. We reviewed and evaluated the policies and interventions implemented by the Salvadoran National Malaria Program that likely contributed to this progress toward malaria elimination. Decentralization of the malaria program, early regional stratification by risk, and data-driven stratum-specific actions resulted in the timely and targeted allocation of resources for vector control, surveillance, case detection, and treatment. Weekly reporting by health workers and volunteer collaborators—distributed throughout the country by strata and informed via the national surveillance system—enabled local malaria teams to provide rapid, adaptive, and focalized program actions. Sustained investments in surveillance and response have led to a dramatic reduction in local transmission, with most current malaria cases in El Salvador due to importation from neighboring countries. Additional support for systematic elimination efforts in neighboring countries would benefit the region and may be needed for El Salvador to achieve and maintain malaria elimination. El Salvador’s experience provides a relevant case study that can guide the application of similar strategies in other countries committed to malaria elimination.

Highlights

The malaria program in El Salvador is currently in the elimination stage, with only four cases of Plasmodium vivax reported in 2017 among its population of 6.1 million
We reviewed and evaluated the policies and interventions implemented by the Salvadoran National Malaria Program that likely contributed to this progress toward malaria elimination
The period of rapid decline in El Salvador’s malaria incidence began with a deliberate program transition following an evaluation of the national malaria control strategy in partnership with the Pan American Health Organization (PAHO) and the United States Centers for Disease Control’s (CDC) local research station in 1978.11,12 The objective of this evaluation was to course correct the program after a dramatic increase in cases in the late 1970s, a decade after the global malaria eradication campaign ended.[11,12]

Summary

Introduction

The malaria program in El Salvador is currently in the elimination stage, with only four cases of Plasmodium vivax reported in 2017 among its population of 6.1 million (three imported, one relapse from 2016) The last case of locally transmitted Plasmodium falciparum in El Salvador was recorded in 1995 and the last death from Plasmodium infection occurred in 1984.1 In 1980, the country contributed 37% of all reported cases in the region, whereas today it contributes less than 0.1%.2. Key differences include the extent of urbanization and the overall improved quality of the health system in El Salvador.[3] For most of its recent history, patterns of malaria transmission in the country were analogous to those in the region: periods of decline in incidence followed by periods of resurgence (Figure 1).[2] Beginning in the early 1980s, the number of cases detected each year began to decline, with a 90% reduction in cases occurring between 1980 (95,835 reported cases) and 1990 (9,269 reported cases).[2] El Salvador continued to reduce locally acquired cases each year as remaining transmission foci were cleared, with less than 50 cases annually since 2006; by contrast, its immediate neighbors continue to have the highest incidences of malaria in the region (Table 2, Figure 2).[2]

Methods

Results

Conclusion