An epidemiological risk assessment of imported malaria cases and potential local transmission in Qatar

Preventing local transmission of malaria from imported cases is crucial for achieving and maintaining malaria elimination. This study aimed to investigate the epidemiological characteristics of imported malaria cases and assess the distribution of malaria vectors in Qatar. Data from January 2016 to December 2022 on imported malaria, including demographic and epidemiological characteristics, travel-related information, and diagnostic results, were collected and analysed using descriptive statistics. Field surveys conducted in 2021-22 collected mosquitoes using various traps across Qatar. The collected samples underwent morphological and molecular characterization at Qatar University. A total of 2693 cases were reported, with a mean incidence of 13.5/100 000 population, decreasing from 18.8/100 000 in 2016 to 5.5/100 000 in 2020. Most cases were Plasmodium vivax (57.4%) followed by P. falciparum (40.4%). The median age was 32.9 +/- 12.5 years, primarily males (86.7%), expatriates (99.6%) and notified during the hot months (July to September). Cases were mainly imported from the Eastern Mediterranean Region followed by the African and South-East Asia Region with no deaths and indigenous cases. Anopheles stephensi was identified as a widely distributed species, but none carried the Plasmodium pathogen. Despite no reports of local transmission, the presence of An. stephensi and favourable environmental conditions pose a risk in Qatar. Strengthening surveillance for imported malaria and reviewing epidemic protocols are necessary. Conventional field studies are imperative to address knowledge gaps in Anopheles mosquito ecology and biting habits in Qatar, accurately assessing the risk of local malaria transmission to support Qatar's malaria-free status.