Nyawanda Bryan O, Beloconi Anton, Khagayi Sammy, Bigogo Godfrey, Obor David, Otieno Nancy A, Lange Stefan, Franke Jonas, Sauerborn Rainer, Utzinger Jürg, Kariuki Simon, Munga Stephen, Vounatsou Penelope
Kenya Medical Research Institute - Centre for Global Health Research, Kisumu, Kenya.
Swiss Tropical and Public Health Institute, Allschwil, Switzerland.
Parasite Epidemiol Control. 2023 Mar 15;21:e00297. doi: 10.1016/j.parepi.2023.e00297. eCollection 2023 May.
Despite considerable progress made over the past 20 years in reducing the global burden of malaria, the disease remains a major public health problem and there is concern that climate change might expand suitable areas for transmission. This study investigated the relative effect of climate variability on malaria incidence after scale-up of interventions in western Kenya.
Bayesian negative binomial models were fitted to monthly malaria incidence data, extracted from records of patients with febrile illnesses visiting the Lwak Mission Hospital between 2008 and 2019. Data pertaining to bed net use and socio-economic status (SES) were obtained from household surveys. Climatic proxy variables obtained from remote sensing were included as covariates in the models. Bayesian variable selection was used to determine the elapsing time between climate suitability and malaria incidence.
Malaria incidence increased by 50% from 2008 to 2010, then declined by 73% until 2015. There was a resurgence of cases after 2016, despite high bed net use. Increase in daytime land surface temperature was associated with a decline in malaria incidence (incidence rate ratio [IRR] = 0.70, 95% Bayesian credible interval [BCI]: 0.59-0.82), while rainfall was associated with increased incidence (IRR = 1.27, 95% BCI: 1.10-1.44). Bed net use was associated with a decline in malaria incidence in children aged 6-59 months (IRR = 0.78, 95% BCI: 0.70-0.87) but not in older age groups, whereas SES was not associated with malaria incidence in this population.
Variability in climatic factors showed a stronger effect on malaria incidence than bed net use. Bed net use was, however, associated with a reduction in malaria incidence, especially among children aged 6-59 months after adjusting for climate effects. To sustain the downward trend in malaria incidence, this study recommends continued distribution and use of bed nets and consideration of climate-based malaria early warning systems when planning for future control interventions.
尽管在过去20年里，全球在减轻疟疾负担方面取得了显著进展，但该疾病仍然是一个重大的公共卫生问题，人们担心气候变化可能会扩大疟疾传播的适宜区域。本研究调查了肯尼亚西部扩大干预措施后，气候变异性对疟疾发病率的相对影响。
将贝叶斯负二项式模型应用于2008年至2019年期间，从前往卢瓦克传教医院就诊的发热疾病患者记录中提取的每月疟疾发病率数据。与蚊帐使用和社会经济地位（SES）相关的数据来自家庭调查。从遥感获得的气候代理变量作为协变量纳入模型。使用贝叶斯变量选择来确定气候适宜性与疟疾发病率之间的时间间隔。
2008年至2010年，疟疾发病率增加了50%，然后到2015年下降了73%。尽管蚊帐使用率很高，但2016年后病例再次出现。白天陆地表面温度升高与疟疾发病率下降相关（发病率比[IRR]=0.70，95%贝叶斯可信区间[BCI]：0.59-0.82），而降雨量与发病率增加相关（IRR=1.27，95% BCI：1.10-1.44）。蚊帐的使用与6至59个月儿童的疟疾发病率下降相关（IRR=0.78，95% BCI：0.70-0.87），但在年龄较大的人群中不相关，而SES与该人群的疟疾发病率无关。
气候因素的变异性对疟疾发病率的影响比蚊帐使用更强。然而，蚊帐的使用与疟疾发病率的降低相关，尤其是在调整气候影响后，6至59个月的儿童中。为了维持疟疾发病率的下降趋势，本研究建议继续分发和使用蚊帐，并在规划未来的控制干预措施时考虑基于气候的疟疾早期预警系统。
