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Abstract：
UNASSIGNED: The prevalence of HIV varies greatly between and within countries. We aimed to build a comprehensive mathematical modelling tool capable of exploring the reasons of this heterogeneity and test its applicability by simulating the Malawian HIV epidemic.
UNASSIGNED: We developed a flexible individual-based mathematical model for HIV transmission that comprises a spatial representation and individual-level determinants. We tested this model by calibrating it to the HIV epidemic in Malawi and exploring whether the heterogeneity in HIV prevalence could be reproduced. We ran the model for 1975-2030 with five alternative realizations of the geographical structure and mobility: (I) no geographical structure; 28 administrative districts including (II) only permanent inter-district relocations, (III) inter-district permanent relocations and casual sexual relationships, or (IV) permanent relocations between districts and to/from abroad and inter-district casual sex; and (V) a grid of 10 × 10km2 cells, with permanent relocations and between-cell casual relationships. We assumed HIV was present in 1975 in the districts with >10 % prevalence in 2010. We calibrated the models to national and district-level prevalence estimates.
UNASSIGNED: Reaching the national prevalence required all adults to have at least 22 casual sex acts/year until 1990. Models II, III and V reproduced the geographical heterogeneity in prevalence in 2010 to some extent if between-district relationships were excluded (Model II; 4.9 %-21.1 %). Long-distance casual partnership mixing mitigated the differences in prevalence substantially (range across districts 4.1%-18.9 % in 2010 in Model III; 4.0%-17.6 % in Model V); with international migration the differences disappeared (Model IV; range across districts 6.9%-13.3 % in 2010). National prevalence decreased to 5 % by 2030.
UNASSIGNED: Earlier introduction of HIV into the Southern part of Malawi may cause some level of heterogeneity in HIV prevalence. Other factors such as sociobehavioural characteristics are likely to have a major impact and need investigation.
UNASSIGNED: We developed a flexible individual-based mathematical model for HIV transmission that comprises a spatial representation and individual-level determinants. We tested this model by calibrating it to the HIV epidemic in Malawi and exploring whether the heterogeneity in HIV prevalence could be reproduced. We ran the model for 1975-2030 with five alternative realizations of the geographical structure and mobility: (I) no geographical structure; 28 administrative districts including (II) only permanent inter-district relocations, (III) inter-district permanent relocations and casual sexual relationships, or (IV) permanent relocations between districts and to/from abroad and inter-district casual sex; and (V) a grid of 10 × 10km2 cells, with permanent relocations and between-cell casual relationships. We assumed HIV was present in 1975 in the districts with >10 % prevalence in 2010. We calibrated the models to national and district-level prevalence estimates.
UNASSIGNED: Reaching the national prevalence required all adults to have at least 22 casual sex acts/year until 1990. Models II, III and V reproduced the geographical heterogeneity in prevalence in 2010 to some extent if between-district relationships were excluded (Model II; 4.9 %-21.1 %). Long-distance casual partnership mixing mitigated the differences in prevalence substantially (range across districts 4.1%-18.9 % in 2010 in Model III; 4.0%-17.6 % in Model V); with international migration the differences disappeared (Model IV; range across districts 6.9%-13.3 % in 2010). National prevalence decreased to 5 % by 2030.
UNASSIGNED: Earlier introduction of HIV into the Southern part of Malawi may cause some level of heterogeneity in HIV prevalence. Other factors such as sociobehavioural characteristics are likely to have a major impact and need investigation.
摘要：
■各国之间和各国内部的艾滋病毒流行率差异很大。我们旨在建立一个全面的数学建模工具，能够探索这种异质性的原因，并通过模拟马拉维艾滋病毒流行来测试其适用性。
■我们开发了一种灵活的基于个体的HIV传播数学模型，该模型包括空间表示和个体水平的决定因素。我们通过将其校准到马拉维的HIV流行来测试该模型，并探索是否可以复制HIV流行率的异质性。我们运行了1975-2030年的模型，对地理结构和流动性进行了五种替代实现：（I）没有地理结构；28个行政区，包括（II）仅永久性的区际搬迁，(三)区际永久搬迁和随意的性关系，或（IV）地区之间以及往返国外和地区间随意性行为的永久迁移；（V）10×10km2单元的网格，永久的重新定位和细胞间的偶然关系。我们假设艾滋病毒在1975年在2010年流行>10%的地区存在。我们根据国家和地区级别的患病率估计对模型进行了校准。
■达到全国流行率要求所有成年人在1990年之前每年至少有22次随意性行为。模型二,如果排除地区之间的关系，则III和V在一定程度上再现了2010年患病率的地理异质性（模型II；4.9％-21.1％）。长途休闲伙伴关系的混合大大减轻了患病率的差异（模型III中，2010年各地区的范围为4.1％-18.9％；模型V中的4.0％-17.6％）；随着国际移民，差异消失了（模型IV；2010年各地区的范围为6.9％-13.3％）。到2030年，全国患病率下降到5%。
■较早将HIV引入马拉维南部地区可能会导致HIV流行程度的异质性。社会行为特征等其他因素可能会产生重大影响，需要进行调查。
■我们开发了一种灵活的基于个体的HIV传播数学模型，该模型包括空间表示和个体水平的决定因素。我们通过将其校准到马拉维的HIV流行来测试该模型，并探索是否可以复制HIV流行率的异质性。我们运行了1975-2030年的模型，对地理结构和流动性进行了五种替代实现：（I）没有地理结构；28个行政区，包括（II）仅永久性的区际搬迁，(三)区际永久搬迁和随意的性关系，或（IV）地区之间以及往返国外和地区间随意性行为的永久迁移；（V）10×10km2单元的网格，永久的重新定位和细胞间的偶然关系。我们假设艾滋病毒在1975年在2010年流行>10%的地区存在。我们根据国家和地区级别的患病率估计对模型进行了校准。
■达到全国流行率要求所有成年人在1990年之前每年至少有22次随意性行为。模型二,如果排除地区之间的关系，则III和V在一定程度上再现了2010年患病率的地理异质性（模型II；4.9％-21.1％）。长途休闲伙伴关系的混合大大减轻了患病率的差异（模型III中，2010年各地区的范围为4.1％-18.9％；模型V中的4.0％-17.6％）；随着国际移民，差异消失了（模型IV；2010年各地区的范围为6.9％-13.3％）。到2030年，全国患病率下降到5%。
■较早将HIV引入马拉维南部地区可能会导致HIV流行程度的异质性。社会行为特征等其他因素可能会产生重大影响，需要进行调查。
