Fromont Emmanuelle Gilot, Riche Benjamin, Rabilloud Muriel
Laboratoire de Biométrie et Biologie Evolutive, Equipe Ecologie Evolutive des Populations, UMR5558, CNRS, Villeurbanne, France.
BMC Infect Dis. 2009 May 28;9:76. doi: 10.1186/1471-2334-9-76.
Toxoplasma gondii, the agent of toxoplasmosis, has a complex life cycle. In humans, the parasite may be acquired either through ingestion of contaminated meat or through oocysts present in the environment. The importance of each source of contamination varies locally according to the environment characteristics and to differences concerning human eating habits and the presence of cats; thus, the risk factors may be determined through fine-scale studies. Here, we searched for factors associated with seropositivity in the population of two adjacent villages in Lorraine region, France.
All voluntary inhabitants filled out a questionnaire and gave a blood sample. The seroprevalence was estimated globally and according to the inhabitants' ages using a cubic spline regression. A mixed logistic regression model was used to quantify the effect of individual and household factors on the probability of seropositivity.
Based on serological results from 273 persons, we estimated seroprevalence to be 47% (95% confidence interval: 41 to 53%). That seroprevalence increased with age: the slope was the steepest up to the age of 40 years (OR = 2.48 per 10-year increment, 95% credibility interval: [1.29 to 5.09]), but that increase was not significant afterwards. The probability of seropositivity tended to be higher in men than in women (OR = 2.01, 95% credibility interval: [0.92 to 4.72]) and in subjects eating raw vegetables at least once a week than in the others (OR = 8.4, 95% credibility interval: [0.93 to 72.1]). These effects were close to statistical significance. The multivariable analysis highlighted a significant seroprevalence heterogeneity among households. That seroprevalence varied between 6 and 91% (5th and 95th percentile of the household seropositivity distribution).
The major finding is the household effect, with a strong heterogeneity of seroprevalence among households. This effect may be explained by common exposures of household members to local risk factors. Future work will quantify the link between the presence of oocysts in the soil and the seroprevalence of exposed households using a spatial analysis.
弓形虫是弓形体病的病原体，具有复杂的生命周期。在人类中，寄生虫可通过摄入受污染的肉类或环境中存在的卵囊而感染。根据环境特征、人类饮食习惯差异以及猫的存在情况，每种污染来源的重要性在当地各不相同；因此，风险因素可通过精细尺度研究来确定。在此，我们在法国洛林地区两个相邻村庄的人群中寻找与血清阳性相关的因素。
所有自愿参与的居民填写了一份问卷并提供了血样。使用三次样条回归对总体血清阳性率以及根据居民年龄的血清阳性率进行了估计。采用混合逻辑回归模型来量化个体和家庭因素对血清阳性概率的影响。
基于273人的血清学结果，我们估计血清阳性率为47%（95%置信区间：41%至53%）。血清阳性率随年龄增长而升高：在40岁之前斜率最陡（每10年增加的比值比为2.48，95%可信区间：[1.29至5.09]），但之后这种升高并不显著。男性血清阳性的概率往往高于女性（比值比为2.01，95%可信区间：[0.92至4.72]），且每周至少食用一次生蔬菜的受试者血清阳性概率高于其他人（比值比为8.4，95%可信区间：[0.93至72.1]）。这些效应接近统计学显著性。多变量分析突出显示家庭间血清阳性率存在显著异质性。血清阳性率在6%至91%之间（家庭血清阳性分布的第5和第95百分位数）。
主要发现是家庭效应，家庭间血清阳性率存在强烈异质性。这种效应可能是由于家庭成员共同暴露于当地风险因素所致。未来的工作将通过空间分析来量化土壤中卵囊的存在与暴露家庭血清阳性率之间的联系。
