Department of Parasitology, Faculty of Pharmacy, University of Granada.
Departamento de Parasitología, Facultad de Farmacia, Campus Universitario de Cartuja, 18.071, Granada, Spain.
Acta Trop. 2021 Jan;213:105749. doi: 10.1016/j.actatropica.2020.105749. Epub 2020 Nov 7.
Leishmaniasis is a vector-borne disease transmitted by sand flies. A dozen species have been involved in the transmission of Leishmania infantum in the Mediterranean region. Climate change may alter sand fly distribution at particular altitudes and latitudes. The objective of this study was to interrogate the existence of stable populations of sand flies in high-altitude ecosystems and evaluate if these populations are enough to support autochthonous transmission of leishmaniasis. These altitudinal conditions can be found in Sierra Nevada (southern Spain). Therefore, we have determined the sand fly population dynamics in different biotopes located at elevations above 1,300 m a.s.l. and searched for evidence of leishmaniasis transmission. Five collecting sites above 1,300 m a.s.l. containing large livestock concentrations were selected. Sand flies were caught using CDC light traps from May to November, annually from 2008 to 2013, and these were morphologically identified. Association between sand fly density or presence and temperature/humidity was estimated by linear and logistic regression, respectively. Leishmania infantum detection in female sand flies was performed by PCR. Diagnosis of canine leishmaniasis (CanL) was carried out by indirect immunofluorescence and PCR. A total of 2,973 specimens of 5 sand fly species were collected from June to October. Phlebotomus perniciosus was the most frequent (100%), abundant (80.1%) and densest species (9.8 sand flies/trap). The minimum temperature on the day of capture was the most important variable factor for sand fly presence and P. perniciosus density. An increase in altitude showed a negative effect over the sand fly diversity and activity period, driving changes in seasonal dynamics similar to those reported by latitudinal changes. CanL prevalence was 23%, a similar rate to previous surveys carried out on randomly selected dogs from towns in southern Spain. A successful host-vector-pathogen network was found at this altitude characterised by 9.9% L. infantum infection rate in non-blood fed P. perniciosus and Phlebotomus ariasi females and high CanL prevalence that entails an increase in the leishmaniasis risk area driven by sand fly colonization.
利什曼病是一种由沙蝇传播的媒介传播疾病。在地中海地区，有十几种沙蝇参与了利什曼原虫的传播。气候变化可能会改变沙蝇在特定海拔和纬度的分布。本研究的目的是探讨高海拔生态系统中沙蝇稳定种群的存在，并评估这些种群是否足以支持利什曼病的本地传播。这些海拔条件可以在内华达山脉（西班牙南部）找到。因此，我们已经确定了位于海拔 1300 米以上的不同生境中的沙蝇种群动态，并寻找了利什曼病传播的证据。选择了海拔 1300 米以上的五个大型牲畜集中的采集点。使用 CDC 诱捕器从 2008 年到 2013 年，每年从 5 月到 11 月收集沙蝇，并对其进行形态学鉴定。通过线性和逻辑回归分别估计了沙蝇密度或存在与温度/湿度之间的关系。通过 PCR 检测雌性沙蝇中的利什曼原虫。通过间接免疫荧光和 PCR 检测犬利什曼病（CanL）。共收集了 5 种沙蝇的 2973 个标本，从 6 月到 10 月。珀氏无角亚属是最常见的（100%）、丰富的（80.1%）和最密集的物种（9.8 只沙蝇/诱捕器）。捕获当天的最低温度是沙蝇存在和珀氏无角亚属密度的最重要变量因素。海拔升高对沙蝇多样性和活动期有负面影响，导致季节动态的变化类似于纬度变化所报告的变化。CanL 患病率为 23%，与在西班牙南部随机选择的城镇的随机选择的狗进行的先前调查相似。在这个海拔高度发现了一个成功的宿主-媒介-病原体网络，特征是未吸血的珀氏无角亚属和 Phlebotomus ariasi 雌性中利什曼原虫感染率为 9.9%，以及高 CanL 患病率，这导致了沙蝇定殖驱动的利什曼病风险区域的增加。
