Malaria at international borders presents particular challenges with regards to elimination. International borders share common malaria ecologies, yet neighboring countries are often at different stages of the control-to-elimination pathway. Herein, we present a case study on malaria, and its control, at the border between Saudi Arabia and Yemen. Malaria program activity reports, case data, and ancillary information have been assembled from national health information systems, archives, and other related sources. Information was analyzed as a semi-quantitative time series, between 2000 and 2017, to provide a plausibility framework to understand the possible contributions of factors related to control activities, conflict, economic development, migration, and climate. The malaria recession in the Yemeni border regions of Saudi Arabia is a likely consequence of multiple, coincidental factors, including scaled elimination activities, cross-border vector control, periods of low rainfall, and economic development. The temporal alignment of many of these factors suggests that economic development may have changed the receptivity to the extent that it mitigated against surges in vulnerability posed by imported malaria from its endemic neighbor Yemen. In many border areas of the world, malaria is likely to be sustained through a complex congruence of factors, including poverty, conflict, and migration.Electronic supplementary materialThe online version of this article (10.1186/s12916-018-1081-z) contains supplementary material, which is available to authorized users.

Introduction: Jazan Region, in the Southwestern Saudi Arabia is known as the mostly affected region with malaria. Malaria occurs at hypo-to hyperendimic level where P. falciparum is the commonest parasite and An. arabiensis is the principal vector. Different types of crop irrigation systems were often blamed for aggravating the health risks of local communities. Reservoirs, irrigation canals, and dams are closely associated with vector-borne parasitic diseases. Thus, seasonal transmission period of a disease such as malaria may be extended as a result of these irrigation systems. The present study is meant to investigate vector breeding and transmission sites associated with the irrigation system in Jazan area for malaria through vector sampling and direct observation. Methods:The study was conducted in three villages in irrigated and three villages in non-irrigated areas in Jazan Region. Entomological surveys were conducted over 12 months from January to December 2004. Larvae were sampled by standard dipping technique and adults were sampled by pyrethrum knockdown collection and CDC light traps. Anopheline mosquitoes were morphologically identifi ed and further verifi ed at the Natural History Museum, London, UK. Mosquito blood meals were tested by direct enzyme linked immune sorbent assay technique for source identifi cation. Results:Of the 3498 anophelines larvae collected, during this study, 53.2% were from the irrigated sites. The total collection of larvae revealed the prevalence of 7 Anopheles spp., of these An. d`thali and An. pretoriensis were the most abundant, and comprised about 50.77 % and 36.91%, of the total collection, respectively. Larvae of the known malaria vector, An. arabiensis comprised 9.43% (330), of which, 69.4% were harvested from habitats at the irrigated area. A total of 2938 adult anophelines were caught from both areas and 1539 (52.4%) were An. d`thali, An. multicolor and An. arabiensis from irrigated area. A total of 106 blood-meal specimens from An. d`thali and An. arabiensis females, were examined and 95.3% were of human origin. Discussion and Conclusion:Of the seven anopheline species encountered, An. sergentii, An. multicolor and An. fl uviatilis are fi rst record in Jazan Region. The study showed no signifi cant difference between irrigated and non-irrigated areas can provide mosquitoes with various breeding habitat types. The known malaria vector in the region, An. arabiensis were more abundant in irrigated areas as larvae (69.3%) and as adults (69.4%) and together with An. d`thali showed high tendency towards anthropophagic behaviour (95.33%).