El Salvador's malaria elimination success story
Authors: Vijay Shankar Balakrishnan
Journal: The Lancet Microbe (2021)

On Feb 25, 2021, WHO declared El Salvador malaria-free. It is the first nation in central America to achieve this result, with malaria still prevalent in other countries in the region, such as Guatemala, Honduras, Costa Rica, Belize, Nicaragua, and Mexico. The path to malaria elimination in El Salvador, which began in the 1940s, was not smooth and was complicated by periods of civil unrest. Early malaria-control efforts involved draining of swamps—ideal ecosystems for the survival of both mosquito vectors and Plasmodium parasites—to prevent mosquito breeding, and indoor spraying of insecticides (eg, DDT) to control residual mosquito infestation. “I'm not sure how effective the DDT spraying program was at that time, since the country didn't have robust data to evaluate it; but surely wherever it was efficiently done, it has shown good results” said Carlos Kent Campbell, a retired PATH malariologist. These interventions enabled some control of the vector in El Salvador, but parasite-control measures only began in the 1950s, with the creation of the National Anti-Malaria Campain (CNAP). Around this time, WHO launched its Global Malaria Eradication Program (GMEP) and, with technical guidance from WHO, the country started using mosquito larvicides and ramped up active case detection and mass chloroquine administration. In the mid-1950s, CNAP established voluntary collaborator networks, which engaged community health workers in disease surveillance and which were further strengthened by the involvement and training of highly respected individuals in local communities. “Soon, the voluntary collaborators became traditional symbols of the country and they began to proudly share their responsibilities by teaching the surveillance process to a respected successor in their families”, Eduardo Romero, head of CNAP, told The Lancet Microbe (translation from Spanish). “Now, the voluntary collaborator network has generations of knowledge and experience in data collection and identifying endemic regions within the country.” Until the mid-1960s, El Salvador recorded remarkable declines in malaria cases. However, a resurgence started in the late 1960s and continued for decades afterwards, probably due to the emergence of mosquito resistance to DDT and parasite resistance to chloroquine. Numbers of cases rose from 10 000 in 1960, to 45 000 in 1970, to 95 000 in 1980, with many deaths and cases of severe febrile disease. This resurgence in malaria prompted a revision of CNAP and the introduction of risk stratification of cases in different geographical endemic regions of the country. The risk-stratification process represented an important step in the decentralisation and management of case control, and despite a civil war starting in 1979, and unrest persisting until 1992, the malaria-control programme continued. “The malaria programme workers wore a light blue uniform and the warring factions recognised it, so they would let them go everywhere in the country and distribute drugs and supplies that the health workers needed everywhere, collect the blood smears to send them to the laboratories”, Romero said. “Although there were occasional interruptions, overall, the programme ran smoothly.” During the war period, Salvadorans decentralised the malaria diagnostic laboratory network and expanded drug administration programmes, on the basis of risk stratification data. These efforts led to the last death due to malaria being recorded in 1984. Towards the end of the civil war, the country saw a gradual decline in malaria cases, with a further pronounced decrease in 1992–2011. “We didn’t even have computers until 2013 so all the work we did was to employ intensive human power and extensive surveillance and control programmes to bring down the cases, all using only domestic funds in this period”, said Romero. In 2020, El Salvador had 276 vector-control personnel and 247 diagnostic laboratories, as well as nurses and doctors involved in case detection, epidemiologists, management teams and personnel, and more than 3000 community health workers. “The victory of El Salvador belongs only to the Salvadorans—not WHO, PAHO, The Global Fund, or the Bill & Melinda Gates Foundation—but only their people, particularly the voluntary collaborator network”, said Kent Campbell, echoed by Mauricio Saurbrey, who worked in El Salvador during the civil war as a USAID expert. “Decentralisation of surveillance, granular risk stratification, strict drug regimens, committed national priorities through financial and human resources were the reasons for El Salvador's success and that's a lesson for other countries that suffer from malaria”, said Caterina Guinovart (Barcelona Institute for Global Health, Barcelona, Spain). Now, El Salvador must ensure control of the importation of cases from neighbouring endemic countries. Sir Brian Greenwood, chairman of WHO's expert group evaluating countries’ applications to be declared malaria-free, agreed that the multifocal approach of El Salvador is highly commendable and could serve as a model for other countries, particularly the neighbouring Guatemala and Honduras. “I’m sure they’ve been watching what's been happening in El Salvador and I suspect that they will be going for a certification study soon amid other countries such as Azerbaijan, Kazakhstan, Cape Verde, and Belize”, he said.