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In Asia Pacific, several nations that were part of the World Health Organization's initiative to eliminate malaria by 2020 or the E2020 Initiative reported being off-track. The COVID-19 pandemic further strained health systems and has the potential to stall the efforts and reverse earlier progress made towards the fight against malaria. These nations have since recommitted to eliminating malaria by 2025, in a renewed E2025 Initiative. This viewpoint presents efforts of the national malaria programs in Bhutan and Timor-Leste as they prepare for this new commitment. It includes insights on the approaches adapted by both countries that have helped them keep the spotlight on malaria whilst preventing large COVID-19 outbreaks. This viewpoint proposes key strategies that near-elimination countries can consider to sustain malaria interventions and realize their elimination goal. Of note, it calls for national strategic plans to consider a whole-of-government approach to ensure progress - which includes sustaining political commitment, systematically collaborating across borders, empowering communities and strengthening health systems particularly through surveillance and data management - that will benefit all existing and future infectious threats and pave the way for integrated response mechanisms across diseases.

The present paper records, for the first time, the Anopheles fauna of Bhutan, determined from surveys conducted from 2007 to early 2018. Adult mosquitoes were collected mainly on cattle bait and occasionally in human landing catches. Collections of immature stages were performed in various aquatic habitats. Larvae were preserved or reared to adults. Identification was based on morphological characters using available keys. A total of 30 species were identified, including nine species of subgenus Anopheles and 21 species of subgenus Cellia. Distribution and collection data are provided with notes on the locations and habitats of the species. Anopheles pseudowillmori is suspected to be a vector of malarial parasites in the plains and hilly forested areas of the country because it is widely distributed and the most common species collected in human landing catches. Notes also include observed morphological variation observed in An. baileyi and An. lindesayi, which differ from the type forms. Corrections are made for previous reports of Anopheles in Bhutan. The need for further surveys and molecular identification of members of species complexes and morphological variants is emphasized.

Culex (Culiciomyia) spiculothorax was described from Thailand based on the presence of spiculation on the thorax of larvae. Adult females are characterized but are indistinguishable from those of related species, such as Cx. pallidothorax. Phylogenetic analysis of mitochondrial oxidase subunit I (COI) sequences revealed that specimens identified as Cx. spiculothorax from Thailand, Japan and Bhutan form a single clade with Cx. sasai from Japan (Kimura 2-parameter genetic distances 0-0.9%) that is clearly distinct from clades comprised of other species of subgenus Culiciomyia. Attempts to collect Cx. sasai from several locations in Japan were unsuccessful - only larvae with thoracic vesicular-like spicules identified as Cx. spiculothorax were collected. Careful examination of specimens collected near the type locality of Cx. sasai revealed the presence of spicules on the thorax. Based on these findings, Cx. spiculothorax is formally synonymized with Cx. sasai, which replaces the former as the species present in Thailand and is a new country record for Bhutan.

Background Bhutan has made substantial progress in reducing malaria incidence. The national guidelines recommend chloroquine (CQ) and primaquine (PQ) for radical cure of uncomplicated Plasmodium vivax, but the local efficacy has not been assessed. The impact of cases imported from India on the genetic make-up of the local vivax populations is currently unknown. Methods Patients over 4 years of age with uncomplicated P. vivax mono-infection were enrolled into a clinical efficacy study and molecular survey. Study participants received a standard dose of CQ (25 mg/kg over 3 days) followed by weekly review until day 28. On day 28 a 14-day regimen of PQ (0.25 mg/kg/day) was commenced under direct observation. After day 42, patients were followed up monthly for a year. The primary and secondary endpoints were risk of treatment failure at day 28 and at 1 year. Parasite genotyping was undertaken at nine tandem repeat markers, and standard population genetic metrics were applied to examine population diversity and structure in infections thought to be acquired inside or outside of Bhutan. Results A total of 24 patients were enrolled in the clinical study between April 2013 and October 2015. Eight patients (33.3 %) were lost to follow-up in the first 6 months and another eight patients lost between 6 and 12 months. No (0/24) treatment failures occurred by day 28 and no (0/8) parasitaemia was detected following PQ treatment. Some 95.8 % (23/24) of patients were aparasitaemic by day 2. There were no haemolytic or serious events. Genotyping was undertaken on parasites from 12 autochthonous cases and 16 suspected imported cases. Diversity was high (HE 0.87 and 0.90) in both populations. There was no notable differentiation between the autochthonous and imported populations. Conclusions CQ and PQ remains effective for radical cure of P. vivax in Bhutan. The genetic analyses indicate that imported infections are sustaining the local vivax population, with concomitant risk of introducing drug-resistant strains. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1320-8) contains supplementary material, which is available to authorized users.

Additional file 1. Chloroquine and primaquine dosing charts.

The Asia Pacific Malaria Elimination Network (APMEN) is a collaboration of 18 country partners committed to eliminating malaria from within their borders. Over the past 5 years, APMEN has helped to build the knowledge, tools and in-country technical expertise required to attain this goal. At its inaugural meeting in Brisbane in 2009, Plasmodium vivax infections were identified across the region as a common threat to this ambitious programme; the APMEN Vivax Working Group was established to tackle specifically this issue. The Working Group developed a four-stage strategy to identify knowledge gaps, build regional consensus on shared priorities, generate evidence and change practice to optimize malaria elimination activities. This case study describes the issues faced and the solutions found in developing this robust strategic partnership between national programmes and research partners within the Working Group. The success of the approach adopted by the group may facilitate similar applications in other regions seeking to deploy evidence-based policy and practice. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0958-y) contains supplementary material, which is available to authorized users.