Although the study is of a high
Although the study is of a high quality given the constraints of the case-control design, we question whether it alone provides sufficient evidence for this policy recommendation. Observational studies of ITNs are notoriously fraught with challenges. Even in settings in which randomised trials show ITN provide good protection, it is not unusual for case-control analyses to find a lack of protection or even ITN use being associated with increased risk of malaria. This counterintuitive finding can happen because people who live in houses more exposed to mosquitoes are more likely to use ITNs, or, when cases are recruited in health facilities, because individuals who have good health-seeking behaviour are more likely to use nets than those who tend to not attend health facilities. What is commendable about the Haiti study is the lengths to which Steinhardt and colleagues went to control for such factors. These efforts included campaigns to encourage anyone with fever to come to free health facilities and a propensity scoring analysis, for which individuals were matched on a range of demographic, health behavioural, and socioeconomic indicators, enabling comparison of people who were similar with respect to many risk factors but not their recent ITN use. Nonetheless, even well conducted observational studies can fail to capture the true effect of interventions. For example, in sub-Saharan Africa where the impact of ITNs has been well established by cluster randomised trials, a multi-country, individually-matched analysis of cross-sectional data found that only two of seven country datasets showed a significant association between ITN use and reduced parasite prevalence, and two showed no lorcaserin buy online at all.
Another complication in areas approaching local elimination such as Haiti is high spatiotemporal variation in transmission. Steinhardt and colleagues made every effort to match malaria exposure in cases and controls by comparing individuals experiencing fever close in time and living in the same commune. Nevertheless, a commune still equates to a relatively large geographical area relative to the focality of malaria transmission. Cases could have also acquired infection outside the local area. The lack of recent entomological data from the study sites on biting times and exophagy of the primary vector, , hampers interpretation of the results. These data gaps are currently being addressed. Historical data suggest that although outdoor biting is more common, a non-negligible proportion of bites occurs indoors. Existence of indoor biting is suggested by the finding in Steinhardt\'s study that good-quality roofing material on houses (but not other socioeconomic indicators) was protective against malaria. Furthermore, some randomised studies of ITNs in areas where is the primary vector have shown significant effect, although this effect is not consistent across studies. Steinhardt reported surprisingly low ITN use given the recent mass distribution of ITN and issues around this low use might need further investigation. Such coverage is probably too low to substantially suppress the vector population, which can be an important component of the impact of ITNs on malaria transmission.
Steinhardt\'s study emphasises the difficulty of measuring the effect of ITN in low-transmission settings. Nevertheless, the quantification of ITN effect in different settings is essential to inform malaria elimination. Observational studies like this need to be considered together with good-quality local entomological monitoring and evidence from other relevant studies of ITNs. Indeed, ITNs have been shown to be effective in parts of Southeast Asia with exophagic vectors. The Haiti context highlights the absence of a one-size-fits-all solution for malaria control and the difficulties of providing the evidence-base for locally appropriate strategies against diverse vectors.
One major contribution of the study by Christopher Grollman and colleagues in to the strand of literature on the resource tracking of reproductive, maternal, newborn, and child health lies in the construction of a comprehensive estimate of the official development assistance plus grants from the Bill & Melinda Gates Foundation (termed ODA+) for reproductive, maternal, newborn, and child health classified by donor countries, recipient countries, and area of spending (malaria, HIV/AIDS, immunisation, child health activities, etc). This nicely brings a close to the tracking exercise across the lifetime of the Countdown to 2015 project. This study also presents new data for reproductive, maternal, newborn, and child health (for 2013), reproductive and sexual health expenditures, including estimates for 2003–08, and presents trend data for reproductive, maternal, newborn, and child health, child health alone, maternal and newborn health, and reproductive and sexual health for the period 2003–13. This adds to the extant literature on tracking the ODA to various health sectors and purpose codes.