A pilot study for control of hyperendemic cystic hydatid disease in China

A scoping review on control strategies for Echinococcus granulosus sensu lato

Background

Cystic echinococcosis (CE) is a widespread neglected zoonotic disease caused by Echinococcus granulosus sensu lato (EG) with a global burden of control in the billions of dollars. E. granulosus' life cycle involves definitive, intermediate, and humans as dead-end hosts. Echinococcosis control programs use strategies that focus on any of these hosts. We aimed to provide a comprehensive and up-to-date overview of the EG control interventions worldwide.

Methods

We conducted a scoping review by mapping all studies on interventions for EG control following the Arksey and O'Malley Framework. We screened identified articles, and charted and coded selected papers. We classified the data based on target host, type of study, and control mechanism. We described the efficacy or safety outcomes, and the associated barriers/facilitators for the intervention. Critical appraisal was conducted.

Results

From 7,853 screened studies, we analyzed 45: seven centered on human interventions, 21 on animals, and 17 on both. Studies on humans focused on educational strategies and human CE monitoring. The studies on animals were field trials and most were based on Praziquantel (PZQ) for dogs. Studies focused on both animals and humans had, in general, more participants, lasted longer, and covered larger geographical areas. Overall, the quality of studies was moderate to low.

Conclusions

Available evidence suggests that long-term interventions aimed at both animals and humans can achieve significant reduction in EG transmission, particularly when PZQ treatment for dogs is included. Higher quality evidence, standardization of methodologies, and better reporting on post-intervention outcomes are necessary for drawing stronger conclusions. Further evidence is needed to assess the sustainability and scalability of control measures. Nonetheless, an integrative One Health approach is essential for overcoming the multiple challenges associated with sustaining long-term control efforts for Echinococcosis.

Funding

RCN was supported by the National Institute of Allergy and Infectious Diseases (grant nos. K01AI139284 and R01AI168291). LOC, JAB, and RCN were supported by the Fogarty International Center (grant no. D43TW012741). TAD, CG and JAB were supported by the Fogarty International Center (grant no. D43TW001140).

Author Summary

Cystic echinococcosis is a disease caused by the parasite Echinococcus granulosus sensu lato . This parasite can be found in specific areas on all continents, especially in poverty-stricken regions, increasing costs and losses. Some countries have achieved control, but most are still in the process. Our review provides a clear picture of what we currently know about these control strategies and points out where more research is needed. It highlights how the findings can improve control practices by showing what works best and address practical challenges. The review also identifies gaps in current knowledge and suggests that comparing different control methods could help find the most effective and cost-efficient solutions. Key areas needing attention include increasing support and funding for echinococcosis, as the disease is often overlooked. More research from different fields is needed to better understand and manage the disease's complexities. Better and ongoing surveillance is crucial for maintaining effective control strategies. Finally, comprehensive reviews that bring together findings from different studies are needed to identify what works best and improve and combine future control efforts.

The economic evaluation of Cystic echinococcosis control strategies focused on zoonotic hosts: A scoping review

BACKGROUND

Cystic echinococcosis (CE) is a zoonotic neglected tropical disease (zNTD) which imposes considerable financial burden to endemic countries. The 2021-2030 World Health Organization's roadmap on NTDs has proposed that intensified control be achieved in hyperendemic areas of 17 countries by 2030. Successful interventions for disease control, and the scale-up of programmes applying such interventions, rely on understanding the associated costs and relative return for investment. We conducted a scoping review of existing peer-reviewed literature on economic evaluations of CE control strategies focused on Echinococcus granulosus zoonotic hosts.

METHODOLOGY/PRINCIPAL FINDINGS

Database searches of Scopus, PubMed, Web of Science, CABI Direct and JSTOR were conducted and comprehensively reviewed in March 2022, using predefined search criteria with no date, field or language restrictions. A total of 100 papers were initially identified and assessed for eligibility against strict inclusion and exclusion criteria, following the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. Bibliography review of included manuscripts was used to identify additional literature. Full review of the final manuscript selection (n = 9) was performed and cost data for control interventions were extracted.

CONCLUSIONS/SIGNIFICANCE

There are very little published data pertaining to the cost and cost effectiveness of CE control interventions targeting its zoonotic hosts. Data given for costs are often incomplete, thus we were unable to perform an economic analysis and cost effectiveness study, highlighting a pressing need for this information. There is much scope for future work in this area. More detailed information and disaggregated costings need to be collected and made available. This would increase the accuracy of any cost-effective analyses to be performed and allow for a greater understanding of the opportunity cost of healthcare decisions and resource allocation by stakeholders and policy makers for effective and cost-effective CE control.

High endemicity of alveolar echinococcosis in Yili Prefecture, Xinjiang Autonomous Region, the People's Republic of China: Infection status in different ethnic communities and in small mammals

Alveolar echinococcosis (AE) is a life-threatening disease in humans caused by the larval stage of Echinococcus multilocularis. The tapeworm is transmitted between small mammals and dogs/foxes in the Northern Hemisphere. In this study 286 AE cases were reported from eight counties and one city in Yili Prefecture, Xinjiang Autonomous Region, the People's Republic of China from 1989 to 2015 with an annual incidence (AI) of 0.41/100,000. Among the patients, 73.08% were diagnosed in the last 11 years. Four counties in the high mountainous areas showed higher AI (0.51-1.22 cases/100,000 residents) than the four counties in low level areas (0.19-0.29/100,000 residents). The AI of AE in Mongolian (2.06/100,000 residents) and Kazak (0.93/100,000 residents) ethnic groups was higher than the incidence in other ethnic groups indicating sheep-farming is a risk for infection given this activity is mainly practiced by these two groups in the prefecture. A total of 1411 small mammals were captured with 9.14% infected with E. multilocularis metacestodes. Microtus obscurus was the dominant species in the mountain pasture areas with 15.01% of the voles infected, whereas Mus musculus and Apodemus sylvaticus were the dominant small mammals in the low altitude areas. Only 0.40% of A. sylvaticus were infected with E. multilocularis. PCR amplification and sequencing analysis of the mitochondrial cox1 gene showed that E. multilocularis DNA sequences from the small mammals were identical to isolates of local human AE cases. The overall results show that Yili Prefecture is a highly endemic area for AE and that the high-altitude pasture areas favorable for M. obscurus may play an important role in its transmission in this region.

Cystic Echinococcosis in Three Locations in the Middle Atlas, Morocco: Estimation of the Infection Rate in the Dog Reservoir

A longitudinal study was carried out in Middle atlas, Morocco (locality of Had Oued Ifrane) in a population of 255 dogs from three localities, including two categories of dogs (owned and stray dogs). The dogs were investigated three times over a period ranging from 4 to 8 months between December and August. At each investigation, dogs were treated with arecoline, inducing defecation and allowing feces collection. Dogs were further treated with praziquantel to clear them from Echinococcus granulosus. Microscopic examination of feces was performed to assess the infection status of dogs at each investigation, and positive samples underwent copro-PCR to determine the circulating strain of E. granulosus. A high prevalence of infestation ranging from 23.5% to 38.8% and from 51.3% to 68.5% was, respectively, found in owned and in stray dogs. The PCR results revealed the presence of G1 strain in all positive samples. A logistic regression model was used to determine the incidence of infestation and showed that stray dogs underwent a significantly higher risk of infection (odds ratio = 14; 95% confidence interval: 6-30; p < 0.001) compared with owned dogs. Only anthelmintic treatment intervals of 2 months efficiently prevented egg shedding in owned and stray dogs. The seasonal effect was also significant, with the highest risk of reinfestation in winter and the lowest risk in summer. This study confirms that stray dogs undergo an increased risk of infestation by E. granulosus and indicate that infective pressure is influenced by season.

Knowledge, Attitudes, and Practices of 50 Patients with Surgically Treated Cystic Echinococcosis from Basrah Province, Iraq

Cystic echinococcosis (CE) is recognised worldwide as a neglected disease of public health concern, particularly in low- and middle-income countries. The objectives of this study were to describe, using a questionnaire survey, the characteristics, attitudes, knowledge, and practices of patients with CE from Basrah Province, Iraq. We interviewed 50 patients, 31 female and 19 male, of whom, 74% originated from rural areas. Approximately half (48%) of the participants reported slaughtering livestock at home for their families’ consumption; 78% indicated the presence of a large number of stray dogs roaming freely about their village; 86% reported that they never boiled water prior to drinking it; and 26% reported not washing vegetables prior to eating them. Although a large proportion of the participants (72%) had heard of hydatid disease prior to becoming ill, over half (57%) were not aware how the disease was transmitted from animals to humans. This study highlighted a gap in health education efforts regarding CE in Southern Iraq, with a lack of counselling of patients on how to prevent reinfection. An intensive control programme should be implemented and founded on health education to reduce CE disease in Basrah.

Prevalence and Molecular Characterization of Echinococcus granulosus Sensu Stricto in Northern Xinjiang, China

Echinococcus granulosus is an important zoonotic parasite globally causing cystic echinococcosis (CE) in humans and animals. In this study, prevalence of CE and variation of cox1 gene sequence were analyzed with isolates E. granulosus collected from different areas in northern Xinjiang, China. The survey showed that 3.5% of sheep and 4.1% of cattle were infected with CE. Fragment of cox1 was amplified from all the positive sheep and cattle samples by PCR. In addition, 26 positive samples across the 4 areas were included. The isolates were all E. granulosus sensu stricto (s.s.) containing 15 haplotypes (Hap1-15), and clustered into 2 genotypes, G1 (90.1%, 91/101) and G3 (9.9%, 10/101). Hap1 was the most common haplotype (48.5%, 49/101). Hap9 were found in humans samples, indicating that sheep and cattle reservoir human CE. It is indicate that E. granulosus may impact on control of CE in livestock and humans in the region.

Echinococcosis transmission on the Tibetan Plateau

Since the mid-1990s detailed studies and field investigations on the Tibetan Plateau have revealed human echinococcosis to be an under-reported major public health problem, particularly in the dominant pastoral communities in the eastern and central regions. Human prevalence surveys showed that cystic echinococcosis (CE, caused by Echinococcus granulosus) and alveolar echinococcosis (AE, caused by Echinococcus multilocularis) are co-endemic with higher burdens of each disease than other endemic world regions. Epidemiological investigations identified some major risk factors for human CE and AE including dog ownership, husbandry practices and landscape features. Dogs appear to be the major zoonotic reservoir for both E. granulosus and E. multilocularis, but the latter is also transmitted in complex wildlife cycles. Small mammal assemblages especially of vole and pika species thrive on the Plateau and contribute to patterns of E. multilocularis transmission which are influenced by landscape characteristics and anthropogenic factors. Tibetan foxes are a principal definitive host for both E. multilocularis and E. shiquicus. In 2006 a national echinococcosis control programme was initiated in Tibetan communities in northwest Sichuan Province and rolled out to all of western China by 2010, and included improved surveillance (and treatment access) of human disease and regular deworming of dogs with annual copro-testing. Control of echinococcosis in Tibetan pastoral communities poses a difficult challenge for delivery and sustainability.

Echinococcosis: Advances in the 21st Century

Echinococcosis is a zoonosis caused by cestodes of the genus Echinococcus (family Taeniidae). This serious and near-cosmopolitan disease continues to be a significant public health issue, with western China being the area of highest endemicity for both the cystic (CE) and alveolar (AE) forms of echinococcosis. Considerable advances have been made in the 21st century on the genetics, genomics, and molecular epidemiology of the causative parasites, on diagnostic tools, and on treatment techniques and control strategies, including the development and deployment of vaccines. In terms of surgery, new procedures have superseded traditional techniques, and total cystectomy in CE, ex vivo resection with autotransplantation in AE, and percutaneous and perendoscopic procedures in both diseases have improved treatment efficacy and the quality of life of patients. In this review, we summarize recent progress on the biology, epidemiology, diagnosis, management, control, and prevention of CE and AE. Currently there is no alternative drug to albendazole to treat echinococcosis, and new compounds are required urgently. Recently acquired genomic and proteomic information can provide a platform for improving diagnosis and for finding new drug and vaccine targets, with direct impact in the future on the control of echinococcosis, which continues to be a global challenge.

Molecular characterization of human echinococcosis in Sichuan, Western China

Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are highly co-endemic in Sichuan, a part of Qinghai-Tibet Plateau where is a typical Tibetan nomadic community living area. In order to better understand the Echinococcus spp. of human being infected origins in this area, 140 lesions were collected from echinococcosis patients who were received operations during the period of 2014-2016 in different geographic districts in this region. Partial DNA sequences of the mitochondrial cox1 gene were analyzed. The genetic characterization of the isolates from 3 different places including Ganzi, Aba and Liangshan were assessed. Of all the 140 samples, the great majority was identified as Echinococcus granulosus sensu stricto (n = 108). Echinococcus multilocularis was confirmed to be another important pathogen of the human infections (n = 31). Additionally, one Echinococcus canadensis (G6/7) isolate from Ganzi was confirmed. Comparing the clinical diagnosis with the sequencing results, 6.4% (9/140) of the cases were misdiagnosed between AE and CE, and another 8.6% (12/140) were unclassified to sub-type in echinococcosis. Higher rates of misdiagnosis and unclassified diagnosis were found in AE cases (12.9%, 4/31 and 16.1%, 5/31 respectively) compared to CE (4.6%, 5/109 and 6.4%, 7/109 respectively). In E.granulosus s.s., a total of 34 haplotypes were detected, and 4 haplotypes were inferred from E.multilocularis. The haplotype networks of the 2 species exhibited a similar star-shaped feature with a dominant haplotype in the center. Geographically specific haplotypes were observed in Ganzi and Aba respectively. This study provides insight into the current species causing human echinococcosis in the Tibetan districts of Sichuan. E.granulosus s.s. and E.multilocularis are confirmed to be the main causative agents, and the existence of E.canadensis (G6/7) is also observed in the region. Molecular diagnosis was proven to be essential for the confirmation of human echinococcosis in the area.

Neglected Zoonoses and the Missing Opportunities for One Health Education: The Case of Cystic Echinococcosis among Surgically Operated Patients in Basrah, Southern Iraq

Cystic echinococcosis (CE) is recognized as a neglected disease of public health significance throughout the world, particularly in low and middle-income countries. The objectives of this study were to describe the characteristics, attitudes, knowledge, and practices of some Basrah province residents diagnosed with CE. Using a questionnaire survey, we interviewed 50 surgically operated cases of CE from Basrah, south Iraq. The cases comprised of 31 females and 19 males, of which 74% originated from rural areas. The questionnaire contained 30 questions and focused on gathering the demographic characteristics of the patients and capturing their overall knowledge, attitudes, and practices toward CE. Approximately half of the participants reported slaughtering livestock at home for their families’ consumption, 78% indicated the presence of a large number of stray dogs roaming freely about their village, 86% reported that they never boiled water before drinking it, and 26% reported not washing vegetables before eating them. Although a large proportion of the participants (72%) had heard of hydatid disease before becoming sick, over half (57%) were not aware of how the disease can be transmitted from animals to humans. This study highlights a gap in One Health education efforts regarding CE in southern Iraq, with a lack of counselling of patients on how to prevent reinfection. An intensive One Health education program should be implemented in Basrah to reduce CE at the human–animal interface. Lack of awareness on zoonoses among medical professionals, who are supposed to disseminate advice on preventative measures to their patients, is a challenge to the public health system.

Dog vaccination with EgM proteins against Echinococcus granulosus

Background

Dogs play a pivotal role in the transmission of cystic echinococcosis (CE), a zoonosis caused by the tapeworm Echinococcus granulosus. We showed previously that dogs vaccinated with two E. granulosus adult-worm specific proteins, EgM9 and EgM123, emulsified with Freund’s adjuvants induced significant protective efficacy in terms of reduction in worm burden and egg production after 45 days post-infection. It was not known whether this protection can be sustained using adjuvants suitable for use in dogs.

Methods

Recombinant EgM9 and EgM123 were mixed with Quil A or ISCOMs for vaccinating dogs. After three vaccine injections, all the dogs were orally challenge-infected with 200 000 protoscoleces of E. granulosus. After 45 days of infection, all the dogs were euthanized and necropsied for collecting and counting E. granulosus worms. Immunoglobins, including the IgG subclasses IgG1 and IgG2, were detected in the sera of vaccinated dogs by ELISA. To determine whether the protection efficacy could be maintained after 45 days post-infection, we implemented a longevity trial to count eggs in dog faeces for 170 days after infection.

Results

The dogs vaccinated with EgM9 and EgM123 mixed with Quil A and ISCOMs showed similar protective efficacy as the proteins emulsified with Freund’s adjuvants in our previous study in terms of reduction of worms and eggs at 45 days post-infection. The longevity trial showed that EgM9 protein-vaccinated group released lower number of eggs per gram compared with the egg counts in the control dogs during the dog trial study.

Conclusion

EgM9 and EgM123 are thus suitable vaccine candidates against E. granulosus infection in dogs.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0425-4) contains supplementary material, which is available to authorized users.

Echinococcosis: Control and Prevention

Human cystic echinococcosis (CE) has been eliminated or significantly reduced as a public health problem in several previously highly endemic regions. This has been achieved by the long-term application of prevention and control measures primarily targeted to deworming dogs, health education, meat inspection, and effective surveillance in livestock and human populations. Human CE, however, remains a serious neglected zoonotic disease in many resource-poor pastoral regions. The incidence of human alveolar echinococcosis (AE) has increased in continental Europe and is a major public health problem in parts of Eurasia. Better understanding of wildlife ecology for fox and small mammal hosts has enabled targeted anthelmintic baiting of fox populations and development of spatially explicit models to predict population dynamics for key intermediate host species and human AE risk in endemic landscapes. Challenges that remain for echinococcosis control include effective intervention in resource-poor communities, better availability of surveillance tools, optimal application of livestock vaccination, and management and ecology of dog and wildlife host populations.

One Health and paradigms of public biobanking

In this paper, the authors consider the idea of the public biobank governance framework with respect to the innovative paradigm of One Health. The One Health initiative has been defined as an integrative and interdisciplinary effort to improve the lives and well-being of human beings and non-human animals, as well as to preserve the environment. Here, we use this approach as a starting presumption with respect to institutional design. We examine the theoretical and legal framework underlying the concept of biobanking that, being public orientated, is for the public good. We suggest that this account of research practice does not ethically correlate with One Health principles. Instead, we argue that One Health requires a model of biobanking that is based on universal goods, that is, goods that serve human beings as well as non-human animals and the environment, and which we define in detail. Our purpose is to begin a discussion on how One Health principles might be implemented in health initiatives.

Epidemiology and control of echinococcosis in central Asia, with particular reference to the People's Republic of China

At least 270 million people (58% of the total population) are at risk of cystic echinococcosis (CE) in Central Asia including areas of Mongolia, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan, Afghanistan, Iran, Pakistan and western China. The annual surgical incidence rate in Uzbekistan and Tadjikistan has been estimated to be as high as 25-27 cases/100,000 with the highest prevalence reaching 10% (range from 0.8 to 11.9%) in some Tibetan communities in western China. Echinococcus transmission in the region is largely associated with social factors including limited community knowledge of echinococcosis, small-scale household animal production, home killing of livestock, and the feeding of dogs with uncooked offal. Alveolar echinococcosis (AE) is also endemic in Central Asia and is recognized as a major problem in some Tibetan communities with up to 6% of villagers infected in some villages. In western China, 5-30% of the population are seropositive against E. granulosus antigens, indicating that a large number of individuals have been exposed to the parasite. Although echinococcosis control programs have been initiated in some countries in Central Asia, control efforts are generally fragmented and uncoordinated. Monthly deworming of dogs with praziquantel (PZQ), as a key measure to control the Echinococcus parasites, has been used in western China. However, the approach has proven difficult in local semi-nomadic communities. Additional control measures including health education, domestic livestock animal treatment/vaccination and dog vaccination are needed in CE-endemic areas to accelerate progress.

Dog population management for the control of human echinococcosis

Cystic and alveolar hydatid disease of humans caused by infection with Echinococcus granulosus or Echinococcus multilocularis are significant zoonoses in developing countries. For human infections, the main definitive host is the dog, and reduction in the population of unwanted dogs, together with anthelmintic treatment of wanted dogs, are recommended control procedures for these zoonoses. Both owned and unowned dogs have been shown to be a major source of Echinococcus spp. infection in developing countries. Unowned dogs are the most challenging category in dog population management for the control of major zoonotic diseases. Unowned dogs are those dogs that do not have an owner, and those dogs whose owner cannot readily be identified. Control of numbers of unowned dogs can be done in various ways if funds are available. Fertility control and humane euthanasia are likely to be the most effective procedures in developing countries. Fertility control requires significant funding, and where resources are scarce humane euthanasia may be the most effective option. Both procedures are ongoing events, with no predictable end point. This paper examines the sociology and technology for the population management of owned and unowned dogs, specifically for the reduction of human hydatid disease. Examples are given for developing and developed countries. Although a "One Health" approach is desirable, the technology for hydatid control is different from that for rabies, and FAO Animal Welfare recommendations for dog population management should be adjusted accordingly.

A comparison of loop-mediated isothermal amplification (LAMP) with other surveillance tools for Echinococcus granulosus diagnosis in canine definitive hosts

BACKGROUND

Cystic echinococcosis is highly prevalent in northwest China. A cost-effective, easy to operate diagnostic tool with high sensitivity and specificity would greatly facilitate the monitoring of Echinococcus infections in canine definitive hosts.

METHODS

The primers used in the LAMP assay were based on the mitochondrial nad5 gene of E. granulosus sensu stricto (E. granulosus s.s., or E.g.s.s.) and were designed using Primer Explorer V4 software. The developed LAMP assay was compared with a conventional PCR method, copro-ELISA and microscopy, using the faeces of dogs experimentally infected with E.g.s.s., and field-collected faeces of domestic dogs including 190 from Qinghai province highly endemic for E.g.s.s. and 30 controls from an area in Gansu, where a domestic dog de-worming program was in operation.

RESULTS

The positivity rates obtained for the field-collected faecal samples were 12.6%, 1.6% and 2.1% by the LAMP, PCR and copro-ELISA assays, respectively. All samples obtained from the control dogs were negative. Compared with the conventional PCR, the LAMP assay provided 88.8% specificity and 100% sensitivity. The higher sensitivity of the LAMP method was also shown by the fact that it could detect the presence of laboratory challenge dog infections of E. granulsous s.s. four days earlier than the PCR method. Three copro-samples shown positive by the commercial copro-ELISA were all negative by LAMP, PCR and microscopy, which suggests these samples may have originated from another infection rather than E. granulsous s.s., possibly E. shiquicus or E. Canadensis, which is also present in China.

CONCLUSIONS

We have developed a potentially useful surveillance tool for determining the prevalence of canine E. granulosus s.s. infections in the field. The LAMP assay may lead to a more cost-effective and practicable way of tracking Echinococcus infections in canids, especially when combined with the copro-ELISA.

Canine echinococcosis: global epidemiology and genotypic diversity

Canine echinococcosis is a potential zoonotic infection caused by the adult form of several cestode species belonging to the genus Echinococcus, of which E. granulosus sensu lato and E. multilocularis are the most epidemiologically relevant. Dogs infected with E. granulosus and E. multilocularis are widely regarded as the main source of infection for human cystic and alveolar echinococcosis, diseases that cause substantial morbidity and socio-economic burden in several regions of the world. Following our previous review on the global situation of cystic echinococcosis in livestock species (Cardona and Carmena. Vet. Parasitol. 2013;192:10-32), we summarize here current knowledge on the global epidemiology, geographical distribution and molecular diversity of Echinococcus spp. infection in dogs. We address relevant topics including the implications of the increasing urbanization of wildlife species such as foxes, coyotes, and dingoes in the establishment of urban cycles of Echinococcus spp., or the rising concerns regarding the role of unsupervised translocation of infected dogs in spreading the infection to Echinococcus-free areas. The involvement of wildlife species as natural reservoirs of disease to domestic animals and humans and the epidemiological significance of the sympatric occurrence of different Echinococcus species in the same geographical region are also debated. Data presented are expected to be useful for policy makers, educational and health authorities responsible for designing and implementing effective measures for disease control and prevention.

Research gaps for three main tropical diseases in the People's Republic of China

This scoping review analyzes the research gaps of three diseases: schistosomiasis japonica, malaria and echinococcosis. Based on available data in the P.R. China, we highlight the gaps between control capacity and prevalence levels, and between diagnostic/drug development and population need for treatment at different stages of the national control programme. After reviewing the literature from 848 original studies and consultations with experts in the field, the gaps were identified as follows. Firstly, the malaria research gaps include (i) deficiency of active testing in the public community and no appropriate technique to evaluate elimination, (ii) lack of sensitive diagnostic tools for asymptomatic patients, (iii) lack of safe drugs for mass administration. Secondly, gaps in research of schistosomiasis include (i) incongruent policy in the implementation of integrated control strategy for schistosomiasis, (ii) lack of effective tools for Oncomelania sp. snail control, (iii) lack of a more sensitive and cheaper diagnostic test for large population samples, (iv) lack of new drugs in addition to praziquantel. Thirdly, gaps in research of echinococcosis include (i) low capacity in field epidemiology studies, (ii) lack of sanitation improvement studies in epidemic areas, (iii) lack of a sensitivity test for early diagnosis, (iv) lack of more effective drugs for short-term treatment. We believe these three diseases can eventually be eliminated in mainland China if all the research gaps are abridged in a short period of time.

Developing plant-based vaccines against neglected tropical diseases: where are we?

Neglected tropical diseases (NTDs) impair the lives of 1 billion people worldwide, and threaten the health of millions more. Although vaccine candidates have been proposed to prevent some NTDs, no vaccine is available at the market yet. Vaccines against NTDs should be low-cost and needle-free to reduce the logistic cost of their administration. Plant-based vaccines meet both requirements: plant systems allow antigen production at low cost, and also yield an optimal delivery vehicle that prevents or delays digestive hydrolysis of vaccine antigens. This review covers recent reports on the development of plant-based vaccines against NTDs. Efforts conducted by a number of research groups to develop vaccines as a mean to fight rabies, cysticercosis, dengue, and helminthiasis are emphasized. Future perspectives are identified, such as the need to develop vaccination models for more than ten pathologies through a plant-based biotechnological approach. Current limitations on the method are also noted, and molecular approaches that might allow us to address such limitations are discussed.

Challenges for diagnosis and control of cystic hydatid disease

This paper is based on the experience of the authors, with the aim to define the challenges for Echinococcus granulosus (E.g./CE) diagnosis and control for those countries that may now or in the future be contemplating control of hydatid disease. A variety of methods are available for diagnosis in humans but a universal gold standard is lacking. Diagnosis in definitive hosts can avoid necropsy by the use of methods such as coproantigen detection but test performance is variable between populations. A sylvatic cycle adds challenges in some countries and the epidemiology of the parasite in these hosts is poorly understood. Control by solely administering praziquantel to dogs is not effective in developing countries where the disease is endemic. Additional avenues to pursue include the instigation of participatory planning, use of an existing vaccination for intermediate hosts and development of a vaccine and long-acting anthelmitic implants for definitive hosts. Promoting public acceptance of control of the dog population by humane euthanasia and reduced reproduction is also essential.

Cestode genomics - progress and prospects for advancing basic and applied aspects of flatworm biology

Characterization of the first tapeworm genome, Echinococcus multilocularis, is now nearly complete, and genome assemblies of E. granulosus, Taenia solium and Hymenolepis microstoma are in advanced draft versions. These initiatives herald the beginning of a genomic era in cestodology and underpin a diverse set of research agendas targeting both basic and applied aspects of tapeworm biology. We discuss the progress in the genomics of these species, provide insights into the presence and composition of immunologically relevant gene families, including the antigen B- and EG95/45W families, and discuss chemogenomic approaches toward the development of novel chemotherapeutics against cestode diseases. In addition, we discuss the evolution of tapeworm parasites and introduce the research programmes linked to genome initiatives that are aimed at understanding signalling systems involved in basic host-parasite interactions and morphogenesis.

Differential expressions of MHC-DQB1 mRNA in Chinese merino sheep infected with Echinococosus granuclosus

The purpose of the present study was to investigate the dynamic changes of MHC-DQB1 mRNA expression in sheep infected with Echinococosus granuclosus. A total of 14 healthy Chinese merino sheep were experimentally infected with E. granuclosus. The blood samples were collected on days 0 (initiation of the infection), 7, 21, 30, and 60 post-infection, respectively. On day 60 post-infection, when the experiment was terminated, all sheep were euthanized to make a diagnosis of cystic echinococcosis (CE) using routine meat inspection and microscopical examination, respectively. The sheep were then divided into two groups according to the diagnostic results: group A (n = 8) consisted of sheep which were diagnosed as CE infection, while group B (n = 6) comprised sheep diagnosed as self-cured or healthy controls. Blood samples obtained during the period of the study were correspondingly divided into groups A and B. The mRNA expression levels of DQB1 revealed significant alterations detected at different stages of E. granuclosus infection in the two groups. Results showed that in group A, DQB1 mRNA expression underwent a progressive increase from day 0 to day 21 post-infection (P = 0.073), and suddenly, suffered from a dramatic drop until day 30 post-infection, and then jumped rapidly and peaked on day 60 post-infection (P = 0.004). Meanwhile, in group B, DQB1 mRNA expression displayed a sharp increase from day 0 to day 7 post-infection (P = 0.000), which thereafter showed a marked decrease until day 30 post-infection, and experienced a plateau from day 30 to day 60 post-infection, remaining at or above that on day 0. It is concluded that DQB1 mRNA expression levels varied in different stages of E. granuclosus infection in sheep. In addition, it appears that the ability to eliminate the parasites possibly depends, at least in part, on the DQB1 expression in the early stage of infection, especially in the first week post-infection.