Abstract
BackgroundSuccessful control programs have impeded local malaria transmission in almost all Gulf Cooperation Council (GCC) countries: Qatar, Bahrain, Kuwait, Oman, the United Arab Emirates (UAE) and Saudi Arabia. Nevertheless, a prodigious influx of imported malaria via migrant workers sustains the threat of local transmission. Here we examine the origin of imported malaria in Qatar, assess genetic diversity and the prevalence of drug resistance genes in imported Plasmodium falciparum, and finally, address the potential for the reintroduction of local transmission.MethodsThis study examined imported malaria cases reported in Qatar, between 2013 and 2016. We focused on P. falciparum infections and estimated both total parasite and gametocyte density, using qPCR and qRT-PCR, respectively. We also examined ten neutral microsatellites and four genes associated with drug resistance, Pfmrp1, Pfcrt, Pfmdr1, and Pfkelch13, to assess the genetic diversity of imported P. falciparum strains, and the potential for propagating drug resistance genotypes respectively.ResultsThe majority of imported malaria cases were P. vivax, while P. falciparum and mixed species infections (P. falciparum / P. vivax) were less frequent. The primary origin of P. vivax infection was the Indian subcontinent, while P. falciparum was mostly presented by African expatriates. Imported P. falciparum strains were highly diverse, carrying multiple genotypes, and infections also presented with early- and late-stage gametocytes. We observed a high prevalence of mutations implicated in drug resistance among these strains, including novel SNPs in Pfkelch13.ConclusionsThe influx of genetically diverse P. falciparum, with multiple drug resistance markers and a high capacity for gametocyte production, represents a threat for the reestablishment of drug-resistant malaria into GCC countries. This scenario highlights the impact of mass international migration on the reintroduction of malaria to areas with absent or limited local transmission.
Highlights
Successful control programs have impeded local malaria transmission in almost all Gulf Cooperation Council (GCC) countries: Qatar, Bahrain, Kuwait, Oman, the United Arab Emirates (UAE) and Saudi Arabia
The present study examines the source of imported malaria to the transmission-free country of Qatar, and assesses the genetic diversity, prevalence of drug resistance mutations, and ability of P. falciparum to produce gametocytes and be transmitted to mosquito vectors
Parasitaemia and gametocytaemia among imported malaria cases Ninety of the 118 P. falciparum infections were examined for (1) total parasite density, (2) total gametocyte density, (3) diversity within 10 microsatellites, and (4) four genes linked to drug resistance
Summary
Successful control programs have impeded local malaria transmission in almost all Gulf Cooperation Council (GCC) countries: Qatar, Bahrain, Kuwait, Oman, the United Arab Emirates (UAE) and Saudi Arabia. In Saudi Arabia, limited foci of indigenous malaria still exist [1, 2], and in Oman sporadic outbreaks still occur periodically [3] These successes have encouraged health ministries in GCC countries to shift policy toward a malaria-free Arabian Peninsula [4] and to focus on preventing reintroduction via sustainable vector control policy, improved surveillance, and prompt case management [5]. Over the past two decades there has been an increase in the flow of migrant workers to Qatar in particular This migratory trend has been associated with a positive trend in reported cases of imported malaria [7, 9, 10]. In addition to an increase in imported malaria, the receptivity and risk of malaria reintroduction is evident by the continued presence of the mosquito vectors Anopheles stephensi and An. multicolor [11]
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