Centre for Disease Modeling, Department of Mathematics and Statistics, York University,Toronto, Ontario, Canada.
BMC Public Health. 2009 Nov 18;9 Suppl 1(Suppl 1):S9. doi: 10.1186/1471-2458-9-S1-S9.
With the world's largest population, HIV spread in China has been closely watched and widely studied by its government and the international community. One important factor that might contribute to the epidemic is China's numerous surplus of men, due to its imbalanced sex ratio in newborns. However, the sex ratio in the human population is often assumed to be 1:1 in most studies of sexually transmitted diseases (STDs). Here, a mathematical model is proposed to estimate the population size in each gender and within different stages of reproduction and sexual activities. This population profiling by age and gender will assist in more precise prediction of HIV incidences.
The total population is divided into 6 subgroups by gender and age. A deterministic compartmental model is developed to describe birth, death, age and the interactions among different subgroups, with a focus on the preference for newborn boys and its impact for the sex ratios. Data from 2003 to 2007 is used to estimate model parameters, and simulations predict short-term and long-term population profiles.
The population of China will go to a descending track around 2030. Despite the possible underestimated number of newborns in the last couple of years, model-based simulations show that there will be about 28 million male individuals in 2055 without female partners during their sexually active stages.
The birth rate in China must be increased to keep the population viable. But increasing the birth rate without balancing the sex ratio in newborns is problematic, as this will generate a large number of surplus males. Besides other social, economic and psychological issues, the impact of this surplus of males on STD incidences, including HIV infections, must be dealt with as early as possible.
中国拥有世界上最大的人口，其艾滋病病毒的传播情况一直受到政府和国际社会的密切关注和广泛研究。导致艾滋病在中国传播的一个重要因素可能是中国男性人口过剩，这是由于新生儿性别比例失衡造成的。然而，在大多数性传播疾病（STD）研究中，人类人口的性别比例通常假定为 1:1。在这里，提出了一个数学模型来估计每个性别和不同繁殖阶段和性活动中的人口规模。这种按年龄和性别划分的人口分布将有助于更准确地预测艾滋病发病率。
将总人口按性别和年龄分为 6 个亚组。建立了一个确定性的房室模型来描述出生、死亡、年龄以及不同亚组之间的相互作用，重点关注对新生男孩的偏好及其对性别比例的影响。使用 2003 年至 2007 年的数据来估计模型参数，并进行模拟预测短期和长期的人口分布。
中国的人口将在 2030 年左右进入下降轨道。尽管最近几年可能低估了新生儿的数量，但基于模型的模拟显示，到 2055 年，大约会有 2800 万男性在性活跃期没有女性伴侣。
中国的出生率必须提高以保持人口的生存能力。但是，在不平衡新生儿性别比例的情况下提高出生率是有问题的，因为这将产生大量的男性过剩。除了其他社会、经济和心理问题外，还必须尽早处理男性过剩对包括艾滋病病毒感染在内的性传播疾病发病率的影响。
