Protection of sheep against Schistosoma bovis using cryopreserved radiation-attenuated schistosomula

Reaching the World Health Organization elimination targets for schistosomiasis: the importance of a One Health perspective

The past three years has seen the launch of a new World Health Organization (WHO) neglected tropical diseases (NTDs) roadmap, together with revised control and elimination guidelines. Across all, there is now a clear emphasis on the need to incorporate a One Health approach, recognizing the critical links between human and animal health and the environment. Schistosomiasis, caused by Schistosoma spp. trematodes, is a NTD of global medical and veterinary importance, with over 220 million people and untold millions of livestock currently infected. Its burden remains extremely high in certain regions, particularly within sub-Saharan Africa, despite over two decades of mass preventive chemotherapy (mass drug administration), predominantly to school-aged children. In Africa, in contrast to Asia, any zoonotic component of schistosomiasis transmission and its implications for disease control has, until recently, been largely ignored. Here, we review recent epidemiological, clinical, molecular, and modelling work across both Asia and Africa. We outline the evolutionary history and transmission dynamics of Schistosoma species, and emphasize the emerging risk raised by both wildlife reservoirs and viable hybridization between human and animal schistosomes. To achieve the 2030 WHO roadmap elimination targets, a truly multi-disciplinary One Health perspective must be implemented. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.

Schistosome Vaccines for Domestic Animals

Schistosomiasis is recognized as a tropical disease of considerable public health importance, but domestic livestock infections due to Schistosoma japonicum, S. bovis, S. mattheei and S. curassoni are often overlooked causes of significant animal morbidity and mortality in Asia and Africa. In addition, whereas schistosomiasis japonica is recognized as an important zoonosis in China and the Philippines, reports of viable schistosome hybrids between animal livestock species and S. haematobium point to an underappreciated zoonotic component of transmission in Africa as well. Anti-schistosome vaccines for animal use have long been advocated as part of the solution to schistosomiasis control, benefitting humans and animals and improving the local economy, features aligning with the One Health concept synergizing human and animal health. We review the history of animal vaccines for schistosomiasis from the early days of irradiated larvae and then consider the recombinant DNA technology revolution and its impact in developing schistosome vaccines that followed. We evaluate the major candidates tested in livestock, including the glutathione S-transferases, paramyosin and triose-phosphate isomerase, and summarize some of the future challenges that need to be overcome to design and deliver effective anti-schistosome vaccines that will complement current control options to achieve and sustain future elimination goals.

The role of nuclear technologies in the diagnosis and control of livestock diseases--a review

Nuclear and nuclear-related technologies have played an important role in animal health, particularly in relation to disease diagnosis and characterization of pathogenic organisms. This review focuses primarily on how and where nuclear technologies, both non-isotopic and isotopic methods, have made their impact in the past and where it might be expected they could have an impact in the future. The review outlines the extensive use of radiation attenuation in attempts to create vaccines for a multiplicity of pathogenic organisms and how the technology is being re-examined in the light of recent advances in irradiation techniques and cryopreservation/lyophilization that might obviate some of the problems of maintenance of viable, attenuate vaccines and their transport and use in the field. This approach could be used for a number of parasitic diseases where vaccination has been problematic and where investigations into the development of molecular vaccines have still failed to deliver satisfactory candidates for generating protective immune responses. Irradiation of antigens or serum samples also has its uses in diagnosis, especially when the samples need to be transported across international boundaries, or when handling the pathogens in question when carrying out a test presents serious health hazards to laboratory personnel. The present-day extensive use of enzyme immunoassays and molecular methods (e.g., polymerase chain reaction) for diagnosis and characterization of animal pathogens has its origins in the use of isotope-labeled antigens and antibodies. These isotopic techniques that included the use of 75Se, 32P, 125I, and 35S isotopes enabled a level of sensitivity and specificity that was hitherto unrealized, and it is prescient to remind ourselves of just how successful these technologies were, in spite of their infrequent use nowadays. Finally, the review looks at the potential for stable isotope analysis for a variety of applications--in the tracking of animal migrations, where the migrant are potential carriers of transboundary animal diseases, and where it would be useful to determine the origins of the carrier, e.g., Highly Pathogenic Avian Influenza and its dissemination by wild water fowl. Other applications could be in monitoring sequestered microbial culture (e.g., rinderpest virus) where in the case of accidental or deliberate release of infective culture it would be possible to identify the laboratory from which the isolate originated.

[Schistosoma mansoni: implantation of worms into the peritoneal cavity with a view to immunoprotection]

Tentou-se obter imunoproteção contra infecção cercariana pela inoculação de vermes vivos na cavidade peritoneal de camundongos. Embora os vermes sobrevivessem bem nestas condições e não ocorresse postura de ovos, não foi possível obter imunoproteção, Também a inoculação de ovos viáveis por via sangüínea e peritoneal não propiciou o aparecimento de imunoproteção nos camundongos com vermes na cavidade peritoneal.

Cryopreservation of Dictyocaulus viviparus third-stage larvae and Trichinella spiralis muscle larvae

In cryopreservation studies with third-stage larvae of Dictyocaulus viviparus, best results were achieved by incubating larvae in 0.05% NaOCl at 37 degrees C to remove the sheath, followed by cooling at a rate of 1 degree C min per min down to about 0 degree C. After an equilibration time of 10 min at +4 degrees C with or without 4% polyethylene glycol-400 as cryoprotectant, samples were frozen at the same cooling rate to an intermediate temperature of -20 degrees C, maintained at this temperature for 10 min and finally plunged into liquid nitrogen for storage. Three groups of 3 calves were infected with the following batches of third-stage larvae: (a) fresh, sheated; (b) fresh, exsheathed; (c) exsheathed, cryopreserved for 13 weeks in liquid nitrogen and subsequently thawed. Although 62% of group (c) were regarded as viable in vitro, their infectivity to calves was low and only an average of 0.08% of the inoculated larvae (3000 per animal) developed into adult lungworms (= infectivity rate). Average infectivity rates of fresh, sheathed (a) and fresh, exsheathed (b) larvae were much higher (38.3% and 29.7%) and not significantly different from each other. Two of the calves inoculated with previously frozen larvae and all of the calves infected with fresh larvae excreted first-stage larvae in their faeces, but the latter groups in higher quantities. The results show that cryopreservation of exsheathed third-stage larvae of D. viviparus is possible, but for strain maintenance infection doses greater than 3000 larvae should be used for inoculation of calves.(ABSTRACT TRUNCATED AT 250 WORDS)