Rice and Malaria in Africa: A Systematic Review and Meta-Analysis

Background: Rice fields in Africa are major breeding sites for malaria vectors. Surprisingly, when reviewed in the 1990s, in settings where transmission was more or less intense, there was no tendency for malaria indices to be higher in villages with irrigated rice. Since then, there has been a massive scale-up of intervention coverage in sub-Saharan Africa, and malaria infection prevalence has halved. It is therefore time to re-examine this rice-malaria relationship to find out whether nowadays, with lower malaria transmission, malaria risk is greater in rice areas. Methods: For this systematic review and meta-analysis, EMBASE, Global Health, PubMed, Scopus, and Web of Science were searched to identify observational studies published from 1 January 1900 to 18 September 2020. Studies were considered eligible if they were observational community-based studies comparing rice- and non-rice-growing rural areas in sub-Saharan Africa. A standardised data extraction form was used to collect epidemiological and entomological information from eligible studies. We did random-effects meta-analyses to obtain and compare pooled prevalences of malaria infection before and after 2003. Findings: Of 2913 studies screened, 53 studies with 113 160 participants from 14 African countries were eligible for inclusion. All included studies were observational, with very low quality evidence, as evaluated by the GRADE approach. In studies performed before 2003, malaria infection prevalence was not higher in rice communities (RR 0·82, 95% CI 0·63–1·06) but was 70% higher in those performed after 2003 (RR 1·73, 95% CI 1·01–2·96). Potential limitations of this study include its basis on observational studies as well as its omission for the effects of seasonality and type of rice being cultivated. Interpretation: Irrigated rice communities in Africa are exposed to greater malaria risk, as well as more mosquitoes. The two development aims (rice production and malaria elimination) cannot be reconciled by ignoring the problem. There is an urgent need to improve methods for growing rice without growing mosquitoes. Registration Information: The study is registered with PROSPERO, number CRD42020204936. Funding Information: CGIAR Agriculture for Nutrition and Health. Declaration of Interests: We declare no competing interests.