Cystic Echinococcosis Control Research Articles

Molecular characterization and seroprevalence of Echinococcus granulosus in wild boars (Sus scrofa) in south-western Iran.

This study presents the first molecular and serological evaluation of Echinococcus granulosus infections in wild boars in Iran. Twenty five wild boars were collected in south-western Iran, during authorized hunting program, from March to October 2013, necropsied and examined for E. granulosus infection. Furthermore, seroprevalence of cystic echinococcosis in hunted boars was evaluated by an ELISA system. A fertile hydatid cyst due to E. granulosus was detected in the lung of one of the animals. Genotype analysis of the isolate was determined by analyzing a mitochondrial gene, cytochrome C oxidase subunit 1 (co1). DNA was extracted from the cyst sample and polymerase chain reaction amplification and DNA sequencing of the specific region of the co1 gene was performed. Molecular evaluation confirmed the presence of a sheep strain, the G1 genotype, in the wild boar in south-western Iran. This is the first report of the presence of G1 genotype of E. granulosus in wild boar in Iran. Serological evaluation of hydatid cyst by antigen-B ELISA revealed E. granulosus antibodies in 5 (20%) of 25 wild boars. A statistically significant difference was observed between the prevalence of E. granulosus antibodies and gender while the difference between the seroprevalence of E. granulosus and age was insignificant. Findings of this study might have important implications for the prevention and control of cystic echinococcosis.

Genome-wide sequencing of small RNAs reveals a tissue-specific loss of conserved microRNA families in Echinococcus granulosus.

BackgroundMicroRNAs (miRNAs) are important post-transcriptional regulators which control growth and development in eukaryotes. The cestode Echinococcus granulosus has a complex life-cycle involving different development stages but the mechanisms underpinning this development, including the involvement of miRNAs, remain unknown.ResultsUsing Illumina next generation sequencing technology, we sequenced at the genome-wide level three small RNA populations from the adult, protoscolex and cyst membrane of E. granulosus. A total of 94 pre-miRNA candidates (coding 91 mature miRNAs and 39 miRNA stars) were in silico predicted. Through comparison of expression profiles, we found 42 mature miRNAs and 23 miRNA stars expressed with different patterns in the three life stages examined. Furthermore, considering both the previously reported and newly predicted miRNAs, 25 conserved miRNAs families were identified in the E. granulosus genome. Comparing the presence or absence of these miRNA families with the free-living Schmidtea mediterranea, we found 13 conserved miRNAs are lost in E. granulosus, most of which are tissue-specific and involved in the development of ciliated cells, the gut and sensory organs. Finally, GO enrichment analysis of the differentially expressed miRNAs and their potential targets indicated that they may be involved in bi-directional development, nutrient metabolism and nervous system development in E. granulosus.ConclusionsThis study has, for the first time, provided a comprehensive description of the different expression patterns of miRNAs in three distinct life cycle stages of E. granulosus. The analysis supports earlier suggestions that the loss of miRNAs in the Platyhelminths might be related to morphological simplification. These results may help in the exploration of the mechanism of interaction between this parasitic worm and its definitive and intermediate hosts, providing information that can be used to develop new interventions and therapeutics for the control of cystic echinococcosis.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-736) contains supplementary material, which is available to authorized users.

A Monoclonal Antibody-Based Copro-ELISA Kit for Canine Echinococcosis to Support the PAHO Effort for Hydatid Disease Control in South America

Cystic echinococcosis is still a major concern in South America. While some regions show advances in the control of the disease, others have among the highest incidence in the world. To reverse this situation the Pan American Health Organization (PAHO) has launched a regional project on cystic echinococcosis control and surveillance. An early concern of the program was the lack of a standardized diagnostic tool to monitor infection in dogs, a key target of control programs. Under this premise, we have developed a new copro-ELISA test after extensive screening of a large panel of monoclonal antibodies (MAbs) and polyclonal sera, which performs with high standards of sensitivity (92.6%) and specificity (86.4%) as established by necropsy diagnosis of dogs. The key component of the test, MAbEg9 has a convenient IgG isotype and reacts with a periodate-resistant epitope found in high molecular weight components of the worm. Time-course analysis of experimentally infected dogs showed that even animals with a very low number of parasites could be detected as early as day 20 post infection. The test was formulated in a ready-to-use kit format with proven stability of each component for a minimum of 3 months at room temperature. This characteristic facilitates its standardized use and shipping to other laboratories, which was demonstrated by the identical results obtained by two different laboratories in Peru and our own laboratory when a large number of field samples were analyzed independently in a blind fashion.

Critical analysis of cystic echinococcosis control programs and praziquantel use in South America, 1974-2010

Cystic echinococcosis (CE) is one of the most prevalent zoonoses in Argentina, Brazil, Chile, Peru, and Uruguay. Control programs in South America were originally modeled after programs developed in insular territories, such as Tasmania and New Zealand. The advent and proven effectiveness of praziquantel, plus the experience of insular models, produced high expectations for rapid advances; however, after 30 years of praziquantel use, no endemic area in South America has obtained eradication. In fact, only modest gains in CE control have been made and impact on prevalence among humans has been slight. A major impediment has been the infrastructure needed to administer praziquantel to dogs in rural areas 8 times per year over numerous years, a requirement for rapid attack stage 1. Such an infrastructure has not been financially or politically sustainable in endemic areas, which tend to be the poorest. On the other hand, certain areas in Argentina have had success with simple and economically viable alternatives. Based primarily on continuous field work supported by the local community, these strategies have significantly decreased transmission to humans, the health sector's main objective. In addition, new possibilities and tools, such as the EG95 vaccine, are being evaluated; as are early detection and treatment of asymptomatic carriers.

El proyecto subregional cono sur de control y vigilancia de la hidatidosis

Southern Cone Sub-Regional Project on Cystic Echinococcosis Control and Surveillance: Argentina, Brasil, Chile and Uruguay, is a joint and collaborative tool with the aim of promoting the implementation or the strengthening of programs for disease control. The paper describes the background, the institutional aspects that regulates the structure and functions, as well as the guidelines defined in the technical and operational project. The article emphasize the achievements through Projects of Technical Cooperation among Countries, and the development of integrated and innovative approaches for prevention and control of the disease and training of human resources of the control programs. Some of the challenges are: to achieve the sustainability of the project, implementation of technical groups for analysis and assessment at request of the countries, improvement of the regional information systems, to continue training human resources of the control programs and to expand and strengthen the technical cooperation among countries.

Echinococcus granulosus Infection and Options for Control of Cystic Echinococcosis in Tibetan Communities of Western Sichuan Province, China

BackgroundHuman cystic echinococcosis (CE) is highly endemic in the Tibetan regions of Sichuan where most families keep guard dogs and where there are considerable numbers of ownerless/stray dogs. Strong Buddhist beliefs do not allow for elimination of stray dogs, and many strays are actually fed and adopted by households or monasteries. On account of the high altitude (3900–5000 m), pasturage is the major agricultural activity in this area. The harsh mountainous climate often leads to many grazing animals dying on the pasture at the end of a hard winter. The skin and some meat are taken, and the rest of the animal is left for scavenging birds and animals. The poor sanitation and hygiene, the Buddhist doctrine of allowing old livestock to die naturally, plus the unrestricted disposal of animal viscera post-slaughter may be responsible for the high prevalence of human CE in this setting.Methods and FindingsAs part of a large collaborative control program for CE in Ganzi County, situated in the west of Sichuan Province, surveillance for Echinococcus infection in domestic dogs using a coproantigen method and necropsy of unwanted dogs was carried out prior to (in 2000) and after (in 2005) dog anthelminthic treatment (5 mg/kg oral praziquantal at 6 month intervals) to determine the efficacy of the treatment for control. The prevalence of E. granulosus only in dogs by necropsy was 27% and 22%, and prevalence of both Echinococcus spp. by necropsy was 63% and 38%; prevalence of both Echinococcus spp. by coproantigen analysis was 50% and 17%. Necropsy of sheep/goats (age <1 to 12 years) (prevalence of E. granulosus in 1–6-year-old animals was 38% and in 10–12-year-old animals was 70%) and yaks (age 4 years) (prevalence of E. granulosus was 38%) was undertaken to determine the baseline transmission pressure. Protoscoleces were only found in very old sheep/goats and yaks. Necropsy of dogs in the Datangma district indicated that there was no apparent significant change in the overall prevalence of E. granulosus in unwanted dogs after 5 years of 6-month praziquantel treatment. However, this was likely due to the number of dogs available for necropsy being too small to reflect the real situation prevailing. There was a highly significant decrease in Echinococcus prevalence after the 5-year treatment program shown by coproantigen-ELISA. This indicated a decreasing but continuing risk for re-infection of domestic and stray dogs. Genotyping of E. granulosus samples obtained from necropsied sheep/goats and yaks and from locally infected humans at surgery was carried out to determine the strain of parasite responsible for human infection. DNA genotyping indicated that only the sheep strain (G1) of E. granulosus was present in the study area.ConclusionsConsiderable re-infection rates of E. granulosus among dogs indicated a high infection pressure from infected livestock in this region, most likely from older animals dying on the pasture. A combination of livestock vaccination with the Eg95 vaccine, which is effective against the sheep strain of E. granulosus, and dog anthelmintic treatment, thus targeting two critical points of the parasite life-cycle, would avoid the conflicts of religion or local culture and could achieve the goal of hydatid control in the long term.

Modelling the age variation of larval protoscoleces of Echinococcus granulosus in sheep

In autumn 2006, a study of the age-dynamics of Echinococcus granulosus cyst abundance was undertaken from an abattoir study of 1081 sheep slaughtered in Naryn Province in central Kyrgyzstan, an area endemic for echinococcosis. The results demonstrated approximately 64% of sheep were infected with the prevalence increasing markedly with age. The mean abundance was 3.8 cysts per sheep. From established models, an infection pressure of 1.33 cysts per year was estimated. In addition all cysts were recovered from infected sheep and the numbers of protoscoleces was evaluated in each cyst. A new model was developed that examined the variation in numbers of protoscoleces per infected sheep with age. This demonstrated that young sheep aged 1–2 years had very few protoscoleces, but there was a massive increase as the sheep aged. The best-fitting model assumed that the number of protoscoleces in a sheep was proportional to the volume of the cysts. In this model, the radius of the individual cyst increased linearly with the age of the cyst and hence the volume increased with the cube of the cyst age. This combined with the linear increase in numbers of cysts with age resulted in a massive accumulation of protoscoleces with the age of sheep. When the model was parameterised it demonstrated that 80% of protoscoleces were present in sheep aged 4 years and older and this represented just 28% sheep slaughtered. An average sheep at 6 or more years of age has an abundance of over 9700 protoscoleces, whilst in a young sheep of 1 year of age an average of just 16 protoscoleces could be found. The average for the sampled population across all ages was 1562 protoscoleces per sheep. The maximum number of protoscoleces in a single cyst was just 482 for sheep aged 1 year rising to 92,000 for sheep aged 6 years or older. The mean volume of cysts containing protoscoleces increased from approximately 0.7 ml at 1 year of age to 8.8 ml at 6 years of age. Cysts containing protoscoleces ranged from a diameter of 0.5–8 cm with a volume of fluid ranging from 0.2 to 50 ml. It is hypothesised that removal of old sheep through a culling programme could substantially improve the control of cystic echinococcosis.

Cystic Echinococcosis in Water Buffaloes from the Campania Region of Southern Italy

comprises several intraspecific variants (or strains) showing differencesin the sequence of some genes (in particular those of the mitochondrial DNA), that affecttheir life cycle pattern, host specificity, development rate, pathogenicity, antigenicity andsensitivity to chemotherapeutic agents, transmission dynamics, epidemiology and controlof cystic echinococcosis (Thompson and McManus, 2002).In total 10 distinct strains (genotypes) of

Mathematical models for the control of cystic echinococcosis

Cystic echinococcosis (CE) caused by Echinococcus granulosus is a global public health problem. In many areas the disease is being diagnosed in increasing numbers, whilst in other areas it is re-emerging due to the collapse of public health programmes associated with socio-economic changes. Mathematical models of the transmission dynamics between animals can have an important role to play in developing control options. In particular the parasite is highly endemic in many lower income countries where resources to undertake an intensive control programme that has been successful in wealthy countries, such as New Zealand, are not available. Data from dogs and livestock have been collected and modelled from a number of different countries and regions. In Australia and New Zealand transmission modelling was first developed and these models have been refined using data from the Middle East and central Asia. The model indicates that relatively intense anthelmintic treatment of the dog population will result in a substantial decrease in the parasite population over time and has been supported by the results of control programmes. However, if the newly developed sheep vaccine is included in the control programme, then it should be possible to treat dogs less frequently to achieve the same result. This is due to the potentiating effects of attacking the parasite at two places in its life cycle. This should result in considerable cost savings over the use intensive anthelmintic treatment as the sole method of control.

Impfen gegen Echinokokkose (?)

Two species of the genus Echinococcus occur sympatrically in central Europe, namely Echinococcus multilocularis, the causative agent of alveolar echinococcosis (AE), and E. granulosus, resulting in cystic echinococcosis (CE) in humans. The endemic area of Europe demonstrates an annual incidence of 0.02 to 1.4 new AE cases per 100000 inhabitants. The importance of the disease refers primarily to the high lethality observed in untreated cases. Therapeutically, radical surgical resection of hepatic lesions followed by continuous benzimidazole-therapy is anticipated. Recently, the strategic control of cystic echinococcosis in humans has considerably been improved by the development of an effective and efficient vaccine that will indirectly prevent humans from infection. The vaccine protects animal intermediate hosts (mainly farm ruminants), thus the lack of hydatid cysts in these animals will prevent dogs to become infected. This on the long-term will result in an abrogation of infection sources (Echinococcus eggs) for humans (and other intermediate hosts). Principally, it has been shown that a similar vaccination is also possible for E. multilocularis. Thus, a 14-3-3 and another Em95-vaccine have successfully been tested in the experimental murine model. As the parasite development mainly focuses on a wildlife cycle (wild rodents), a practical application of the vaccine can hardly be implemented. Nevertheless, AE is a very severe disease in humans, therefore one should discuss about the feasibility and the health-economic impact of large-scale vaccination of humans living in areas of high endemicity and thus being at high infection risk.

Epidemiological evaluations of the efficacy of slow-released praziquantel-medicated bars for dogs in the prevention and control of cystic echinococcosis in man and animals

To assess the epidemiological efficacy of type SRP III slow-released praziquantel-medicated bars for dogs in the prevention and control of cystic echinococcosis in man and livestock, praziquantel-medicated bars were implanted subcutaneously in over 90% of dogs in villages in north Xinjiang, China, where cystic echinococcosis is highly endemic. After implantation, infection rate of Echinococcus granulosus in dogs, specific antibodies in children and prevalence of echinococcosis in one-year-old lambs were observed for 3 years. Coproantigen of E. granulosus was positive in 41.2% of the dogs at the start of experiment. In the second and third year after medicated-bar implantation, coproantigen was undetectable in any dogs examined, while 3.0% of dogs were positive at the end of the fourth year. The antibody positive rate in 7-year-old pupils, that was 41.2% before the experiment, declined gradually and it was 5.4% in the fourth year, while children in the non-intervention control area showed 30.6% seropositivity. The prevalence of hydatid disease in children aged 7–16 years also declined significantly. The prevalence of hydatidosis in lambs one year of age was 44.8% in the first year, dropping to 10.7% in the fourth year, while in the non-intervention control area the level of infection was 46.4%. These results demonstrated not only that the slow released praziquantel-medicated bars efficiently blocked reinfection in dogs at least for 2 years, but also the measure was effective in preventing transmission of cystic echinococcosis to both man and livestock.

Progress in control of cystic echinococcosis in La Rioja, Spain: decline in infection prevalences in human and animal hosts and economic costs and benefits

The Autonomous Community of La Rioja is a region in the north of Spain where the mean annual number of surgical cases of cystic echinococcosis (CE) was 50 (19 per 100 000 inhabitants) during the years 1984–1987. This high clinical incidence prompted local authorities to implement a control program in 1986, whose methods and results are reported here. Initially, the program consisted in documenting the prevalence of CE in sheep and humans, communicating an awareness of the disease risks among the population, and treating all registered dogs with praziquantel at intervals of 45 days. Stray dogs were collected systematically, euthanized, and their intestines were examined for Echinococcus granulosus infection. Epidemiological data collected during the course of the program demonstrated that the major reservoirs of E. granulosus were the stray dogs, precisely the ones not receiving periodic praziquantel treatment. Therefore, the program emphasis was shifted to targeting critical points in the transmission of E. granulosus, including improved control of stray dogs, echinococcidal treatments of working sheep dogs, providing means for safe disposal of slaughtered sheep offal and safe disposal of dead sheep in sanitary pits. These measures led to a decline in prevalence of E. granulosus in dogs from 7.0% at the beginning of the program to 0.2% in 2000, i.e. a reduction of 97.2%. Prevalence of infection in adult sheep declined from 82.3 to 20.3%, i.e. a reduction of 75.4%, while the mean number of cysts per infected animal decreased from 6.5% to 0.58 (91% reduction). The rate of diagnoses of new cases in humans between these two dates dropped by 78.9%, from 19 to 4 per 100 000 population. In terms of economic costs, these reductions were estimated to yield an increasing cumulative cost/benefit balance that was already positive on year 8 of the program (1994), and that reached 1.96 in year 2000.

Canine echinococcosis: an alternative for surveillance epidemiology

The essential activities for programmes of cystic echinococcosis control are the census of all dogs from the program and identification of parasitised animals. Currently, in South America evaluations and epidemiological surveillance are based on the administration of arecoline hydrobromide. This method has the disadvantage of increasing environmental pollution and risk for operators and owners of treated dogs. A genus-specific ELISA capture method has been employed for recently issued faeces and the confirmation of positive examination was performed by dog autopsies. Our work presents an alternative method based on collection of dry field-dispersed faeces, followed by serological diagnosis by Copro-ELISA and confirmation by Copro-Western blot. If Copro-ELISA were used to define positive samples of dry faeces, the Copro-Western blot assay would provide 70% sensitivity and 100% specificity. Global efficiency of the system using dry faeces would reach 76%, allowing epidemilogical surveillance to be oriented to analysis of surface units instead of dog as measurement unit.