Esu et al. [42] focussed on effectiveness of peridomestic insecticide spraying. They included 15 studies some of which were included in earlier reviews. The authors found that many studies were of poor quality and few took account of possible confounders. This is in accordance with GRADE which suggested very low quality evidence. No meta-analysis was reported, presumably because of the poor comparability of studies. In a narrative analysis the authors concluded that the evidence for any value of peridomestic space spraying was weak as only some studies showed an effect, which was not sustained, with mosquito populations returning to the same level or higher within few weeks.