Climate change effects on trematodiases,with emphasis on zoonotic fascioliasis and schistosomiasis

The capacity of climatic conditions to modulate the extent and intensity of parasitism is well known since long ago. Concerning helminths, among the numerous environmental modifications giving rise to changes in infections, climate variables appear as those showing a greater influence, so that climate change may be expected to have an important impact on the diseases they cause. However, the confirmation of the impact of climate change on helminthiases has been reached very recently. Only shortly before, helminthiases were still noted as infectious diseases scarcely affected by climate change, when compared to diseases caused by microorganisms in general (viruses, bacteriae, protozoans). The aim of the present paper is to review the impact of climate change on helminthiases transmitted by snails, invertebrates which are pronouncedly affected by meteorological factors, by focusing on trematodiases. First, the knowledge on the effects of climate change on trematodiases in general is reviewed, including aspects such as influence of temperature on cercarial output, cercarial production variability in trematode species, influences of magnitude of cercarial production and snail host size, cercarial quality, duration of cercarial production increase and host mortality, influence of latitude, and global-warming-induced impact of trematodes. Secondly, important zoonotic diseases such as fascioliasis, schistosomiasis and cercarial dermatitis are analysed from the point of view of their relationships with meteorological factors. Emphasis is given to data which indicate that climate change influences the characteristics of these trematodiases in concrete areas where these diseases are emerging in recent years. The present review shows that trematodes, similarly as other helminths presenting larval stages living freely in the environment and/or larval stages parasitic in invertebrates easily affected by climate change as arthropods and molluscs as intermediate hosts, may be largely more susceptible to climate change impact than those helminths in whose life cycle such phases are absent or reduced to a minimum. Although helminths also appear to be affected by climate change, their main difference with microparasites lies on the usually longer life cycles of helminths, with longer generation times, slower population growth rates and longer time period needed for the response in the definitive host to become evident. Consequently, after a pronounced climate change in a local area, modifications in helminth populations need more time to be obvious or detectable than modifications in microparasite populations. Similarly, the relation of changes in a helminthiasis with climatic factor changes, as extreme events elapsed relatively long time ago, may be overlooked if not concretely searched for. All indicates that this phenomenon has been the reason for previous analyses to conclude that helminthiases do not constitute priority targets in climate change impact studies.     

A recombinant-based ELISA evaluating the efficacy of netobimin and albendazole in ruminants with naturally acquired fascioliasis

The therapeutic efficacy of albendazole and netobimin in ruminants with naturally occurring fascioliasis was investigated using a recombinant-based ELISA. The variation in the IgG response against a 2.9-kDa recombinant protein (FhrAPS), termed efficacy index (EI) 1, and the egg-output changes, termed EI 2, were used to evaluate drug efficacy.The values of EI 1 ranged between 0% and 50% in sheep, and between 0% and 30% in cattle after treatment with albendazole and netobimin. Similar EI 2 values were observed in sheep receiving albendazole or netobimin, but the highest values were found in cattle treated with netobimin. The significant reduction in the IgG response to FhrAPS found in this study shows promise in terms of developing alternative methods for evaluating the efficacy of chemotherapy against Fasciola hepatica in grazing ruminants.     

Development and Application of Sandwich ELISA for Diagnosis of Fascioliasis gigantica in Early Stage

To establish a method for the diagnosis of Fascioliasis gigantica in early stage, five hybridoma cell lines were recovered and used for preparation of monoclonal antibodies.7D2 was used as a capture antibody and 7D1 as detection antibody.Coating antibody dilution was 1:6 400 (0.208 μg/mL), 5% nonfat milk was used as blocking solution and detection antibody dilution was 1:10 000 (0.200 μg/mL).The detection limit of the sandwich ELISA was 1:3 200 (0.156 μg/mL), with good specificity and stability, and there was no cross reaction with other kinds of parasite antigen.The results showed that the method provided the important conditions and theoretical basis for the diagnosis of Fascioliasis gigantica in early stage. This would save unnecessary economic losses to the livestock, and it had clinical application value.     

山羊肝片吸虫病致胆管病变的病理形态学研究

为了进一步了解肝片吸虫病致羊胆管的病变,眼观及组织病理学研究结果表明,肝片吸虫所致胆管病变可分为4类：单纯慢性增生性胆管炎、腺体增生性胆管炎、腺体瘤样增生性胆管炎以及管壁的机械损伤。胆管的病变类型与肝片吸虫病的病程似无明显的对应关系。此外,在胆管的病变中还可见玻璃滴细胞。并讨论了胆管病变发生的机理。     

Prevalence of bovine fascioliasis in a new-emerging focus of human fascioliasis in BoyerAhmad district,southwest of Iran

BackgroundThe prevalence of fascioliasis in a population of cattle in a new-emerging focus of human fascioliasis in Boyer-Ahmad District, in the southwest of Iran, was investigated, using an ELISA system and coprological methods.MethodsBlood, as well as stool samples, were collected from 150 dairy cattle consisted of 82 (54.7%) males and 68 (45.3%) females, aged from 1 to 8 years, selected from different pastures. The stool samples were evaluated by direct wet mount microscopic examination as well as sedimentation methods. Moreover, modified Telemann was used for detecting of Fasciola eggs. Anti-Fasciola antibodies in the cattle sera samples were determined, using a Fasciola excretory-secretory antigen-specific ELISA.ResultsAnti-Fasciola antibodies were detected in 64 (42.4%) of the subjects by ELISA. Out of 64 seropositive cases, 29 (45.3%) were female and 35 (54.6%) were male. No significant association was found between sex and seropositivity to fascioliasis. Considering the age of the cattle, the highest prevalence of fascioliasis (23%) was found in the 5-year old age group. However, the difference between the age of the cattle and seropositivity to fascioliasis was not statistically significant (P > 0.05). Fasciola eggs were not detected in fecal samples of any of the studied cattle, while Paramphistomide, as well as Dicrocoelium dendriticum eggs, were detected in 6 (4%) and 17 (11.3%) of the subjects, respectively.ConclusionFindings of the current study provide basic information about bovine fascioliasis in a new focus of human fascioliasis in Iran, which is needed for effective control of this parasitic infection in such areas.     

《羚牛1号》对金毛羚牛肝片形吸虫病的疗效试验

肝片形吸虫病是一种人畜共患的寄生虫病 ,对反刍类动物有很大的危害。金毛羚牛属于我国一级保护动物 ,由于长期生活在西北干旱地区 ,对肝片形吸虫的抗性很差 ,进入肝片形吸虫疫区后 ,危害变得更严重。为了有效的控制金毛羚牛的肝片形吸虫病 ,需寻找一种高效低毒的驱虫药物 ,同时为防治金毛羚牛肝片形吸虫病提出防治程序     

Fasciola hepatica infections in livestock flock, guanacos and coypus in two wildlife reserves in Argentina

Between autumn and spring 2006, a coprological survey was performed in two wildlife reserves located in the north of Argentine Patagonia to determine the prevalence of Fasciola hepatica and the number of parasite eggs per gram (epg) of feces in wild guanacos (Lama guanicoe), coypus (Myocastor coypus), and locally born and raised goats and sheep. Snails of the Family Lymnaeidae were collected in freshwater habitats, identified taxonomically and analyzed parasitologically.Prevalence of patent infection was 100% in sheep (n = 69) and coypus (n = 9), 84% in goats (n = 20) and 0.5% in guanacos (n = 224). No significant differences in epg were found among animals, but the median epg of coypus (160) and sheep (160) was higher than that of goats (80). For guanacos and goats, a negative binomial model estimating the population egg-count frequency could be fitted, while for coypus and sheep parasite egg-count frequencies trended toward a normal distribution, indicative of a more even, and much less aggregated distribution across sampled hosts. All snails (n = 175) were Lymnaea truncatula and none of them was found infected. This is the first report of fascioliasis in free-ranging guanacos in Argentina. Coypu appears to be a major wildlife reservoir of F. hepatica, which was presumably introduced locally by livestock.     

片形吸虫病的免疫诊断概况

片形吸虫病是牛羊等反刍动物的最重要寄主虫病之一,常引起严重的经济损失。近年来,片形吸虫病的研究主要集中在免疫及免疫诊断等问题上,目前,学者已研究了片形吸虫的成虫粗制抗原,ＥＳ抗原等的提纯,并将其用于片形吸虫病的诊断之中,另外,随着免疫学和生物学的不断发展,片形吸虫病的免疫诊断技术的敏感性和特异性也有所提高,现研制出了许多特异性的免疫诊断技术,如ＥＬＩＳＡ,Ｄｏｔ－ＥＬＩＳＡ,ＡＢＣ－ＥＬＩＳＡＴＦ     

肝片吸虫病诊断与防治研究进展

肝片吸虫病是反刍运物常发的一种慢性消耗性疾病,给畜牧业生产带来巨大的经济损失。本文就该病的常规诊断方法、血清学诊断方法和分子生物学诊断方法,以及疫苗预防和药物防治方法进行了综述。     

碘醚柳胺的研制及其对肝片吸虫的驱虫试验

以３,４－二氯硝基苯为起始原料,经醚化、还原、卤化、缩合等四步反应合成抗肝片吸虫新药碘醚柳胺,用红外光谱、质谱和元素分析等对化学结构进行了确证。建立高效液相色谱法测定绵羊血药浓度及组织残留量。色谱条件：ＯＤＳ柱,流动相为甲醇,检测波长２８３ｎｍ,吸收度与浓度的线性关系范围０～５０μｇ／ｍｌ。碘醚柳胺小鼠骨髓微核试验结果为阴性。驱虫试验表明牛羊按７．５ｍｇ／ｋｇ口服或３ｍｇ／ｋｇ皮下注射对牛羊肝片吸虫的驱虫率和虫卵减少率均达１００％,无任何毒副作用。