Soler Paula, Gurevitz Juan Manuel, Morales Juan Manuel, Larroza Marcela
Grupo de Salud Animal, Instituto Nacional de Tecnología Agropecuaria (INTA), San Carlos de Bariloche, Río Negro, Argentina.
INTA-CONICET, Instituto de Investigaciones Forestales y Agropecuarias Bariloche (IFAB), Río Negro, Argentina.
PeerJ. 2024 Dec 20;12:e18648. doi: 10.7717/peerj.18648. eCollection 2024.
The trematode parasite (liver fluke) can infect livestock, wild mammals, and humans, generating serious economic losses worldwide. Aquatic or amphibious snails of the Lymnaeidae family are the intermediate host of this parasite. Both snail population dynamics and parasite development are closely associated with temperature, although most field studies have recorded air temperature rather than water temperature. Our aim was to statistically model the population dynamics of lymnaeid snails and their infection by under natural environmental conditions in Northwest Andean Patagonia.
For two years, we sampled snails monthly in four bodies of water, while registering water and air temperature hourly, and assessing infection in snails. Hierarchical Bayesian modeling allowed us to estimate the functional relationship between water temperature and population growth, the probability of detecting snails, and infection by .
A total of 1,411 snails were collected, identified, and analyzed for infection. All sites showed seasonal variation in the number of snails collected and in water temperature as well as sharp variations in snail counts between surveys adjacent in time. The hierarchical model revealed that water temperature acts, at least, at two different time scales: water temperature at the time of sampling determines snail detection probability, whereas the average water temperature between sampling dates affects lymnaeid population growth. We found maximum prevalences in snails of 40% (2/5 and 4/10), followed by 33% (65/197). These are the highest prevalences recorded in populations in Argentina to date. Our modeling evidenced that the positive effects of water temperature on infection probability increases with snail size and prevalence on the previous survey, while previous prevalence strongly enhances the effects of snail size.
Our results underscore the high temporal and spatial variability in the population of snails and the prevalence of , as well as the major impact temperature has on detecting snails. Our models provide quantifications of the effects of water temperature on the population growth of , its detection, and infection under natural field conditions. These are crucial steps towards generating mechanistic models of transmission that would facilitate the design and simulation of potential interventions based on treatments and on environmental and livestock management, taking into account the specific characteristics of each region.
吸虫寄生虫（肝吸虫）可感染家畜、野生哺乳动物和人类，在全球造成严重的经济损失。椎实螺科的水生或两栖蜗牛是这种寄生虫的中间宿主。蜗牛种群动态和寄生虫发育都与温度密切相关，尽管大多数实地研究记录的是气温而非水温。我们的目的是在安第斯山脉西北部巴塔哥尼亚的自然环境条件下，对椎实螺的种群动态及其感染情况进行统计建模。
两年来，我们每月在四个水体中采集蜗牛样本，同时每小时记录水温和气温度，并评估蜗牛的感染情况。分层贝叶斯建模使我们能够估计水温与种群增长、检测到蜗牛的概率以及感染之间的函数关系。
共收集、鉴定并分析了1411只蜗牛的感染情况。所有地点采集到的蜗牛数量和水温均呈现季节性变化，且相邻调查之间蜗牛数量变化剧烈。分层模型显示，水温至少在两个不同的时间尺度上起作用：采样时的水温决定蜗牛检测概率，而采样日期之间的平均水温影响椎实螺种群增长。我们发现蜗牛的最高感染率为40%（2/5和4/10），其次是33%（65/197）。这些是迄今为止阿根廷肝吸虫种群中记录到的最高感染率。我们的建模证明，水温对感染概率的积极影响随着蜗牛大小和上一次调查中的感染率而增加，而上一次感染率强烈增强了蜗牛大小的影响。
我们的结果强调了蜗牛种群和肝吸虫感染率在时间和空间上的高度变异性，以及温度对检测蜗牛的主要影响。我们的模型量化了水温对肝吸虫种群增长、检测和感染的影响，这些是在自然野外条件下生成肝吸虫传播机制模型的关键步骤，有助于基于治疗以及环境和家畜管理设计和模拟潜在干预措施，同时考虑每个地区的具体特征。
