The first introduced malaria case reported from Sri Lanka after elimination: implications for preventing the re-introduction of malaria in recently eliminated countries

Abstract

Background There has been no local transmission of malaria in Sri Lanka for 6 years following elimination of the disease in 2012. Malaria vectors are prevalent in parts of the country, and imported malaria cases continue to be reported. The country is therefore at risk of malaria being re-established. The first case of introduced vivax malaria in the country is reported here, and the surveillance and response system that contained the further spread of this infection is described. Methods Diagnosis of malaria was based on microscopy and rapid diagnostic tests. Entomological surveillance for anophelines used standard techniques for larval and adult surveys. Genotyping of parasite isolates was done using a multi-locus direct sequencing approach, combined with cloning and restriction fragment length polymorphism analyses. Treatment of vivax malaria infections was according to the national malaria treatment guidelines. Results An imported vivax malaria case was detected in a foreign migrant followed by a Plasmodium vivax infection in a Sri Lankan national who visited the residence of the former. The link between the two cases was established by tracing the occurrence of events and by demonstrating genetic identity between the parasite isolates. Effective surveillance was conducted, and a prompt response was mounted by the Anti Malaria Campaign. No further transmission occurred as a result. Conclusions Evidence points to the case of malaria in the Sri Lankan national being an introduced malaria case transmitted locally from an infection in the foreign migrant labourer, which was the index case. Case detection, treatment and investigation, followed by prompt action prevented further transmission of these infections. Entomological surveillance and vector control at the site of transmission were critically important to prevent further transmission. The case is a reminder that the risk of re-establishment of the disease in the country is high, and that the surveillance and response system needs to be sustained in this form at least until the Southeast Asian region is free of malaria. Several countries that are on track to eliminate malaria in the coming years are in a similar situation of receptivity and vulnerability. Regional elimination of malaria must therefore be considered a priority if the gains of global malaria elimination are to be sustained. Electronic supplementary material The online version of this article (10.1186/s12936-019-2843-6) contains supplementary material, which is available to authorized users.

Anopheline bionomics, insecticide resistance and transnational dispersion in the context of controlling a possible recurrence of malaria transmission in Jaffna city in northern Sri Lanka

“…2 Department of Geography, Faculty of Arts, University of Jaffna, Jaffna, Sri Lanka. 3 ID-FISH Technology, Milpitas, CA, USA.…”

“…However, the approximately 100 travelers with malaria who arrive every year from endemic countries, and the prevalence of potent anopheline vectors throughout the island, pose the risk of reinitiating local malaria transmission [2]. Indeed, an instance of local malaria transmission from a malaria-infected Indian national to a Sri Lankan resident was documented in late 2018 [3].…”

Using health facility-based serological surveillance to predict receptive areas at risk of malaria outbreaks in elimination areas

“…Resurgence of malaria is often associated with imported infections and/or P. vivax relapsing infections in areas that remain highly receptive to malaria [13][14][15][16]. Studies have demonstrated the usefulness of spatially referenced entomological data to characterise the heterogeneity of malaria receptivity in areas approaching elimination to prevent outbreaks in the future [17][18][19].…”

Mass radical treatment of a group of foreign workers to mitigate the risk of re-establishment of malaria in Sri Lanka

“…Following the elimination of malaria in 2012 and being free from indigenous transmission for six consecutive years, Sri Lanka reported the first case of introduced malaria in December 2018 [3], the source of the infection (index case) being one of a group of foreign workers from India who developed a Plasmodium vivax infection a few days after arriving in Sri Lanka. The location of transmission to the introduced case was a factory construction site in the District of Monaragala, a highly receptive remote area in southwestern Sri Lanka which was previously endemic for malaria; here a group of 32 workers of Indian origin including the index case were employed and resident.…”

“…The location of transmission to the introduced case was a factory construction site in the District of Monaragala, a highly receptive remote area in southwestern Sri Lanka which was previously endemic for malaria; here a group of 32 workers of Indian origin including the index case were employed and resident. The area was found to have a high prevalence of Anopheles culicifacies, the primary vector of malaria in the country [3].…”