Disease Control and Vector Biology Unit, Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.
PLoS One. 2010 Feb 1;5(2):e8988. doi: 10.1371/journal.pone.0008988.
There is evidence that the age-pattern of Plasmodium falciparum malaria varies with transmission intensity. A better understanding of how this varies with the severity of outcome and across a range of transmission settings could enable locally appropriate targeting of interventions to those most at risk. We have, therefore, undertaken a pooled analysis of existing data from multiple sites to enable a comprehensive overview of the age-patterns of malaria outcomes under different epidemiological conditions in sub-Saharan Africa.
METHODOLOGY/PRINCIPAL FINDINGS: A systematic review using PubMed and CAB Abstracts (1980-2005), contacts with experts and searching bibliographies identified epidemiological studies with data on the age distribution of children with P. falciparum clinical malaria, hospital admissions with malaria and malaria-diagnosed mortality. Studies were allocated to a 3x2 matrix of intensity and seasonality of malaria transmission. Maximum likelihood methods were used to fit five continuous probability distributions to the percentage of each outcome by age for each of the six transmission scenarios. The best-fitting distributions are presented graphically, together with the estimated median age for each outcome. Clinical malaria incidence was relatively evenly distributed across the first 10 years of life for all transmission scenarios. Hospital admissions with malaria were more concentrated in younger children, with this effect being even more pronounced for malaria-diagnosed deaths. For all outcomes, the burden of malaria shifted towards younger ages with increasing transmission intensity, although marked seasonality moderated this effect.
The most severe consequences of P. falciparum malaria were concentrated in the youngest age groups across all settings. Despite recently observed declines in malaria transmission in several countries, which will shift the burden of malaria cases towards older children, it is still appropriate to target strategies for preventing malaria mortality and severe morbidity at very young children who will continue to bear the brunt of malaria deaths in sub-Saharan Africa.
有证据表明，恶性疟原虫疟疾的发病年龄模式随传播强度而变化。更好地了解这种变化如何随结局严重程度以及在一系列传播环境中变化，可使干预措施在当地针对最危险人群。因此，我们对多个地点的现有数据进行了汇总分析，以便全面了解在撒哈拉以南非洲不同流行病学环境下疟疾结局的年龄模式。
方法/主要发现：通过 PubMed 和 CAB Abstracts（1980-2005）、与专家联系和检索文献目录，进行了系统评价，确定了具有恶性疟原虫临床疟疾儿童发病年龄分布、疟疾住院和疟疾确诊死亡数据的流行病学研究。将研究分配到疟疾传播强度和季节性的 3x2 矩阵中。采用最大似然法将 6 种传播情景中每个结局的各年龄组百分比拟合到 5 种连续概率分布中。以图形方式呈现最佳拟合分布，并给出每个结局的估计中位数年龄。在所有传播情景中，临床疟疾发病率在生命的前 10 年相对均匀分布。疟疾住院的发病年龄更集中在年龄较小的儿童中，而疟疾确诊死亡的发病年龄更为显著。对于所有结局，随着传播强度的增加，疟疾负担向年龄较小的方向转移，尽管明显的季节性使这种效应有所缓和。
在所有环境中，恶性疟原虫疟疾最严重的后果都集中在年龄最小的年龄组。尽管最近一些国家的疟疾传播有所下降，这将使疟疾病例负担转移到年龄较大的儿童，但仍应针对预防疟疾死亡和严重发病的策略，针对非常年幼的儿童，他们将继续承受撒哈拉以南非洲疟疾死亡的主要负担。
