Water buffalo as sentinel animals for schistosomiasis surveillance

Schistosoma transmission: scaling-up competence from hosts to ecosystems

In a One-Health context, it is urgent to establish the links between environmental degradation, biodiversity loss, and the circulation of pathogens. Here we review and literally draw a general vision of aquatic environmental factors that interface with Schistosoma species, agents of schistosomiasis, and ultimately modulate their transmission at the ecosystem scale. From this synthesis, we introduce the concept of ecosystem competence defined as 'the propensity of an ecosystem to amplify or mitigate an incoming quantity of a given pathogen that can be ultimately transmitted to their definitive hosts'. Ecosystem competence integrates all mechanisms at the ecosystem scale underlying the transmission risk of a given pathogen and offers a promising measure for operationalizing the One-Health concept.

Sentinel animals for monitoring the environmental lead exposure: combination of traditional review and visualization analysis

In nature, certain animals share a common living environment with humans, thus these animals have become biomonitors of health effects related to various environmental exposures. As one of the most toxic environmental chemicals, lead (Pb) can cause detriment health effects to animals, plants, and even humans through different exposure pathways such as atmosphere, soil, food, water, and dust, etc. Sentinel animals played an "indicative" role in the researches of environmental pollution monitoring and human health. In order to comprehend the usage of sentinel animals in the indication of environmental Pb pollution and human Pb exposure completely, a combination of traditional review and visualization analysis based on CiteSpace literature was used to review earlier researches in this study. In the first instance, present researches on exposure sources and exposure pathways of Pb were summarized briefly, and then the studies using sentinel animals to monitor environmental heavy metal pollution and human health were combed. Finally, visualization software CiteSpace 5.8.R3 was used to explore and analyze the hotspots and frontiers of lead exposure and sentinel animals researches at home and abroad. The results showed that certain mammals were good indicators for human lead exposure. Sentinel animals had been widely used to monitor the ecological environment and human lead exposure. Among them, the blood lead levels of small mammals, particularly for domestic dogs and cats, had a significant correlation with the blood lead levels of human living in the same environment. It indicated that certain biological indicators in animals can be used as surrogates to monitor human body exposure to heavy metals. This study also explored the challenges and perspectives that may be faced in sentinel animal research, in order to provide a certain theoretical basis and train of thought guidance for future research.

High prevalence of Schistosoma japonicum by perfusion in naturally exposed water buffalo in a region of the Philippines endemic for human schistosomiasis

In the past decade, ecological surveys emphasized rats and dogs as the most significant animal reservoirs for Schistosoma japonicum (S.j) in the Philippines. However, recent studies demonstrated 51-91% prevalence of schistosomiasis among water buffalo using qPCR in the Sj endemic regions in the Philippines. In order to resolve the inconsistency of reported surveys regarding Sj endemicity among carabao, a domestic water buffalo that is the most important draught animal, we introduced 42 schistosome negative water buffalo to Macanip, Jaro municipality, Leyte, the Philippines, a subsistence rice-farming village that has been the focus of schistosomiasis japonica studies of our group for the past 20 years. We conducted perfusion to the remaining 34 buffalo that survived 10 months of nature exposure and Typhoon Haiyan. Thirty-three water buffalo were found to be positive with at least 1 pair of worms from the mesenteric vein. The infection rate is 97%, with the worm burden of 94 (95% confidence interval, 49-138 worms) worms. To our knowledge, this is the first report about S. japonicum worm burden in naturally infected water buffalo in the Philippines. The fact that with less than one-year of exposure, in this human schistosomiasis endemic area, only 1 out of 34 water buffalo was uninfected is striking. Urgent attention is needed for a cost-effective technique for monitoring Sj infection in animals and humans. Meanwhile, intervention implementation, including water buffalo treatment and vaccination, should be taken into consideration.

Prevalence of Schistosoma japonicum in bovines and Oncomelania hupensis quadrasi from ricefields surrounding Lake Mainit, Philippines

Schistosomiasis is a parasitic disease caused by blood flukes of the genus Schistosoma and involves bovines and snails as a reservoir and intermediate hosts, respectively. This disease is endemic in Lake Mainit, Philippines, as early as 1947. The study was conducted to determine the prevalence of Schistosoma infection in ricefields adjacent to Lake Mainit by collecting Oncomelania hupensis quadrasi snails and bovine fecal samples which are then subjected to laboratory examination and analysis. A total of 345 O. quadrasi individuals and 32 bovine fecal samples were collected from six barangay rice field stations adjacent to Lake Mainit from February and July 2020. Among the six barangays, Alipao had the highest prevalence of Schistosoma in O. quadrasi (39.71%), followed by San Isidro (28.3%), Matin-ao (18%), Poblacion (15%), and Magpayang (2.5%). No Oncomelania snails were collected in the ricefields of Cuyago. Schistosoma japonicum had an overall prevalence of 14.71% in all the bovines sampled, where Cuyago had the highest prevalence (50.0%) followed by Alipao (33.33%). The intensity of infection of Schistosoma eggs per gram (MPEG = 0.70) among bovines is categorized as light. Bovine contamination index calculations revealed that, on average, infected bovines in Lake Mainit excrete ~ 55,000 S. japonicum eggs per day. The study confirms the important role of bovines as a reservoir host for schistosomiasis. The presence of both infected bovines and O. quadrasi in ricefields makes this agricultural venue an important nidus of S. japonicum emergence in Lake Mainit. An integrated approach of mass drug administration (MDA) of praziquantel, implementation of a bovine vaccine-directed control program, and providing farmers with mechanized farm equipment are highly recommended to minimize the risk of exposure and infection to schistosomiasis in rice fields adjacent to the lake.

Prevalence and distribution of livestock schistosomiasis and fascioliasis in Côte d'Ivoire: results from a cross-sectional survey

BACKGROUND

Schistosoma and Fasciola are zoonotic parasites of public health and veterinary importance. However, while the epidemiology of schistosomiasis in humans is well studied, little is known about fascioliasis and schistosomiasis in livestock in Côte d'Ivoire. This study aimed to determine the prevalence and the distribution of livestock schistosomiasis and fascioliasis across Côte d'Ivoire. In 2018, we conducted a cross-sectional survey in abattoirs and farms in 13 departments of Côte d'Ivoire. In abattoirs, the mesenteric veins and livers of slaughtered cattle, sheep and goats were examined for adult Schistosoma and Fasciola flukes. Faeces from live cattle, goats and sheep were collected and examined for Schistosoma and Fasciola eggs using a sedimentation technique.

RESULTS

A total of 386 cattle, 174 goats and 151 sheep from abattoirs and 435 cattle, 22 goats and 176 sheep from farms were sampled. The observed prevalence of schistosomiasis was higher in slaughtered animals. Fascioliasis was more prevalent in farm animals. The prevalence of schistosomiasis in slaughtered cattle varied between 5.9% (95% confidence interval (CI): 0.7-19.7%) and 53.3% (95% CI: 37.9-68.3%) with the highest prevalence observed in Ouangolodougou in the North. Cattle from farms had a relatively low prevalence of schistosomiasis, with the highest prevalence found in Ouangolodougou (2.4%, 95% CI: 0.7-6.1%). The prevalence of fascioliasis varied considerably from one department to another, ranging from nil (95% CI: 0.0-18.5%) to 50.8% (95% CI: 43.4-58.2%), with the highest prevalence found in farm cattle in Dikodougou in the North. Sheep and goats had a lower prevalence of schistosomiasis and fascioliasis than cattle. In slaughtered animals, cattle aged 4 years and older were at highest risk for schistosomiasis (odds ratio (OR): 2.4; 95% CI: 1.0-5.6) and fascioliasis (OR: 2.1; 95% CI: 1.1-3.9). In farm animals, male cattle had higher odds of being infected with Schistosoma (OR: 4.3; 95% CI: 0.7-26.9) than females.

CONCLUSIONS

Our study confirms that schistosomiasis and fascioliasis are endemic in livestock across Côte d'Ivoire. A strategic control programme should be considered, especially for cattle, including providing drinking water in troughs to reduce faecal contamination of water sources by cattle.

Field Evaluation of Recombinant Antigen ELISA in Detecting Zoonotic Schistosome Infection Among Water Buffaloes in Endemic Municipalities in the Philippines

In this study, we investigated the use of recombinant antigens thioredoxin peroxidase-1 (rSjTPx-1) and tandem repeat rSj1TR in evaluating the antibody positivity rates of Schistosoma japonicum infection among water buffaloes from four endemic areas in the Philippines, two municipalities with high endemicity (Calatrava, Negros Occidental and Catarman, Northern Samar) and two municipalities nearing elimination with no cases of human schistosomiasis (Talibon and Trinidad, Bohol). These recombinant antigen ELISA assays were compared with other diagnostic tests including SEA-ELISA, FECT, and fecal-based PCR. Results showed that rSj1TR-ELISA has the highest agreement with PCR in all study areas. Furthermore, significant positivity rates among water buffaloes were seen in Talibon and Trinidad, indicating that water buffaloes are maintaining the schistosome parasites in transmission areas even in the absence of human infection. Hence, serological assay using a more sensitive and specific rSj1TR-ELISA can be used for animal surveillance to prevent emergence and re-emergence of human schistosomiasis.

Humoral responses to Schistosoma japonicum soluble egg antigens in domestic animals in Lindu Subdistrict, Central Sulawesi Province, Indonesia

Background and Aim: Schistosomiasis japonica, a disease caused by Schistosoma japonicum, is a public health problem in the Philippines, the Republic of Indonesia, and the People's Republic of China. The disease is known as zoonotic, meaning other than humans, animals are involved as the reservoirs. In Indonesia, schistosomiasis surveillance in animals is not continuous. Thus, the study to determine the prevalence of the disease in animals is needed. The study was aimed to determine the seroprevalence of S. japonicum infection among four species of domestic animals in the Lindu Sub-district, Central Sulawesi Province of Indonesia. Materials and Methods: Blood samples of domestic animals were collected and analyzed for the presence of anti-S. japonicum immunoglobulin G antibodies against S. japonicum soluble egg antigens using the indirect hemagglutination assay. Animal stool samples were collected, and the miracidia-hatching assay was used for the detection of S. japonicum infection. Additional data concerning the animal identity and the management practices were obtained through a questionnaire used in surveys and interviews. Results: A total of 146 sera from 13 cattle, 24 buffaloes, 54 pigs, and 55 dogs were collected. The overall schistosomiasis seroprevalence was 64.4%. The serology prevalence in cattle, buffalo, pig, and dog was 100.0%, 41.7%, 74.1%, and 56.4%, respectively. Domestic animals in all of five villages have previous exposure with S. japonicum as seropositive animals detected in every village. A total of 104 animal stool samples from 146 animals sampled were obtained. The overall schistosomiasis prevalence determined by the miracidia hatching assay was 16.35%. The sensitivity and specificity of indirect hemagglutination assay (IHA) in the current study were 88.24% and 41.37%, respectively, with miracidia hatching assay as the gold-standard method. Conclusion: This study has shown a high seroprevalence of schistosomiasis japonica among domestic animals in the Lindu Subdistrict. IHA can be used as the screening method for the detection of S. japonicum infection in domestic animals. Chemotherapy and animal livestock grazing management programs to reduce the parasite burden and Schistosoma egg contamination in the environment must be implemented as part of one health approaches, in addition to other control measures.

Currently Available Monitoring and Surveillance Systems for Taenia spp., Echinococcus spp., Schistosoma spp., and Soil-Transmitted Helminths at the Control/Elimination Stage: A Systematic Review

An increasing global focus on neglected tropical diseases (NTDs) has resulted in the set up of numerous control and elimination activities worldwide. This is partly true for Taenia solium taeniasis/cysticercosis, the most important foodborne parasitic infection. Despite substantial progress, adequate monitoring and surveillance (M&S) are required to sustain a status of control/elimination. This is often lacking, especially for T. solium. Therefore, the objective was to conduct a systematic literature review of the currently available M&S systems at the control/elimination stage of the four top-ranked helminth NTDs. Specifically, Taenia spp., Echinococcus spp., Schistosoma spp., and soil-transmitted helminths (STHs) were considered to determine if there are any similarities between their M&S systems and whether certain approaches can be adopted from each other. The systematic review demonstrated that rigorous M&S systems have been designed for the control/elimination stage of both STHs and schistosomiasis, particularly in China. On the other hand, a concept of M&S for Taenia spp. and Echinococcus spp. has not been fully developed yet, due to a lack of epidemiological data and the fact that many endemic countries are far away from reaching control/elimination. Moreover, accurate diagnostic tools for all four diseases are still imperfect, which complicates proper M&S. Finally, there is an urgent need to develop and harmonize/standardize M&S activities in order to reliably determine and compare the epidemiological situation worldwide.

Blood lymphocyte subpopulations in healthy water buffaloes (Bubalus bubalis, Mediterranean lineage): Reference intervals and influence of age and reproductive history

There is an increasing interest toward infectious diseases and mechanisms of immune response of water buffaloes, mainly because of the growing economic impact of this species and of its high-quality milk. However, little is known about the immune system of these animals in physiological conditions. Recently, a wide number of antibodies cross reacting with buffalo antigens has been validated for use in flow cytometry (FC), allowing detailed characterization of the lymphocytic population in this species. The aim of the present study was to describe the lymphocyte subpopulations in a large number of healthy water buffaloes, providing reference intervals (RIs), and to assess whether the composition of blood lymphocyte population significantly varied with age and reproductive history. Our final aim was to lay the ground for future studies evaluating the role of host immune response in water buffaloes. One-hundred-twelve healthy buffaloes from four different herds in the South of Italy were included in the study. All animals had been vaccinated for Infectious Bovine Rhinotracheitis (IBR), Salmonellosis, Colibacillosis and Clostridiosis, and all herds were certified Brucellosis- and Tuberculosis-free. Venous blood collected into EDTA tubes was processed for FC, and the percentage of cells staining positive for the following antibodies was recorded: CD3, CD4, CD8, CD21, TCR-δ-N24, WC1-N2, WC1-N3 and WC1-N4. Absolute concentration of each lymphoid subclass was then calculated, based on automated White Blood Cell (WBC) Count. Reference Intervals were calculated according to official guidelines and are listed in the manuscript. The composition of the lymphocyte population varied with age and reproductive history, with animals <2-years-old and heifers having higher concentration of most of the subclasses. The present study provides RIs for the main lymphocytic subclasses in healthy water buffaloes, highlighting gross differences between young and old animals. Establishment of age-specific RIs is recommended in water buffaloes. The data we present may be useful as a basis for further studies concerning mechanisms of immune response toward infectious agents in water buffaloes.

Asian Schistosomiasis: Current Status and Prospects for Control Leading to Elimination

Schistosomiasis is an infectious disease caused by helminth parasites of the genus Schistosoma. Worldwide, an estimated 250 million people are infected with these parasites with the majority of cases occurring in sub-Saharan Africa. Within Asia, three species of Schistosoma cause disease. Schistosoma japonicum is the most prevalent, followed by S. mekongi and S. malayensis. All three species are zoonotic, which causes concern for their control, as successful elimination not only requires management of the human definitive host, but also the animal reservoir hosts. With regard to Asian schistosomiasis, most of the published research has focused on S. japonicum with comparatively little attention paid to S. mekongi and even less focus on S. malayensis. In this review, we examine the three Asian schistosomes and their current status in their endemic countries: Cambodia, Lao People's Democratic Republic, Myanmar, and Thailand (S. mekongi); Malaysia (S. malayensis); and Indonesia, People's Republic of China, and the Philippines (S. japonicum). Prospects for control that could potentially lead to elimination are highlighted as these can inform researchers and disease control managers in other schistosomiasis-endemic areas, particularly in Africa and the Americas.

Some facts on south asian schistosomiasis and need for international collaboration

In this review, we are discussing South Asian schistosomiasis; more specifically species which are responsible for schistosomiasis in India or South Asia -Schistosoma indicum, S. spindale, S. nasale, S. incognitum, S. gimvicum (S.haematobium), Bivitellobilharzia nairi, Orientobilharzia bomfordi, O. dattai, O. turkestanicum and O.harinasutai, their survival strategies such as mild pathology to the host, producing low egg number and utilizing fresh water snails (Indoplanorbis exustus and Lymnaea luteola) in stagnant water bodies like ponds, lakes, ditches, low laying areas, marshy lands and rice fields. Presently, correct identification of blood fluke species, their immature stages, male schistosomes and their intermediate host details like strain variations, susceptibilities, ecologies are not well studied. Species like B. nairi, O. bomfordi, O. harinasutai (Lymnaea rubiginosa intermediate host for O.harinasutai in Thailand) are also not well studied. Moreover, snail species like Oncomalania spp are not from South Asia, but species of Tricula or Neotricula are reported from this geography, which gives indications of S. mekongi like blood fluke presence in the area. Although in humans, cercarial dermatitis is rampant in rural population with occasional reporting of schistosome eggs in stools, human schistosomiasis is considered absent from this region, despite finding a foci (now dead) of urinary schistosomiasis in Gimvi village of Ratnagiri district, Maharashtra, India. There is great difficulty in diagnosing the infection in man and animals due to low egg production, hence development of a single step antigen detection test is the need of the hour. Interestingly, lethal effect of praziquantel was seen against S.haematobium and S.mansoni. However, this drug failed to cause significant reduction of S. incognitum and S. spindale experimentally suggesting some differences in the biology of two groups of the schistosomes. Triclabendazole showed adulticidal effect at a dose rate of 20 mg/kg body against female schistosome worms, but at lower dose (10 mg/kg body wt) of the drug, a dose that is used in treating bovine fascioliasis, it is providing chances of drug resistance of the persisting schistosomes against triclabendazole. Though the South Asian institutes have all the facilities to tackle issues related to existing schistosomes, it is recommended to develop an international collaboration by establishing an international centre on schistosomiasis in India.

Schistosoma mansoni and other intestinal parasitic infections in schoolchildren and vervet monkeys in Lake Ziway area, Ethiopia

Objective

To assess Schistosoma mansoni and other intestinal parasitic infections in schoolchildren and vervet monkeys (Chlorocebus aethiops) in Bochessa Village, Ziway, Ethiopia.

Results

Fecal specimens from selected schoolchildren and droppings of the vervet monkeys were collected and microscopically examined for intestinal parasites using the Kato-Katz thick smear and formol-ether concentration techniques. The prevalences of S. mansoni, Trichuris trichiura, Ascaris lumbricoides, Enterobius vermicularis, hookworms, Hymenolepis nana and Taenia species among the children were 35.7, 26.9, 24.1, 2.1, 2.1, 1.07 and 2.1%, respectively (by Kato-Katz) and 39.3, 36.1, 35.6, 2.9, 10.0, 4.3, and 2.9%, respectively (by formol-ether concentration). Prevalence of S. mansoni in vervet monkeys ranged from 10 to 20%. B. pfeifferi snails were exposed to S. mansoni miracidia from vervet origin, shed cercariae were then used to infect lab-bred albino mice. Adult worms were harvested from the mice 5 weeks post-exposure to cercariae to establish the schistosome life cycle and confirm the infection in the vervet monkeys. The natural infection of S. mansoni in vervet monkeys suggests that the non-human primate is likely to be implicated in the local transmission of schistosomiasis. Further epidemiological and molecular studies are needed to fully elucidate zoonotic role of non-human primate in the area.

iTRAQ-Based Comparative Proteomic Analysis of Adult Schistosoma japonicum from Water Buffalo and Yellow Cattle

Schistosomiasis japonicum is one of the most severe zoonotic diseases in China. Water buffalo and yellow cattle are important reservoir hosts and the main transmission sources of Schistosoma japonicum in endemic areas. The susceptibility of these two hosts to schistosome infection is different, as water buffaloes are less susceptible to S. japonicum than yellow cattle. In this study, iTRAQ-coupled LC-MS/MS was applied to compare the protein expression profiles of adult schistosomes recovered from water buffalo with those of yellow cattle. A total of 131 differentially expressed proteins (DEPs) were identified, including 46 upregulated proteins and 85 downregulated proteins. The iTRAQ results were confirmed by Western blotting and quantitative real-time PCR. Further analysis indicated that these DEPs were primarily involved in protein synthesis, transcriptional regulation, protein proteolysis, cytoskeletal structure and oxidative stress response processes. The results revealed that some of the differential expression molecules may affect the development and survival of schistosomes in these two natural hosts. Of note, this study provides useful information for understanding the interplay between schistosomes and their final hosts.

Host immunity, nutrition and coinfection alter longitudinal infection patterns of schistosomes in a free ranging African buffalo population

Schistosomes are trematode parasites of global importance, causing infections in millions of people, livestock, and wildlife. Most studies on schistosomiasis, involve human subjects; as such, there is a paucity of longitudinal studies investigating parasite dynamics in the absence of intervention. As a consequence, despite decades of research on schistosomiasis, our understanding of its ecology in natural host populations is centered around how environmental exposure and acquired immunity influence acquisition of parasites, while very little is known about the influence of host physiology, coinfection and clearance in the absence of drug treatment. We used a 4-year study in free-ranging African buffalo to investigate natural schistosome dynamics. We asked (i) what are the spatial and temporal patterns of schistosome infections; (ii) how do parasite burdens vary over time within individual hosts; and (iii) what host factors (immunological, physiological, co-infection) and environmental factors (season, location) explain patterns of schistosome acquisition and loss in buffalo? Schistosome infections were common among buffalo. Microgeographic structure explained some variation in parasite burdens among hosts, indicating transmission hotspots. Overall, parasite burdens ratcheted up over time; however, gains in schistosome abundance in the dry season were partially offset by losses in the wet season, with some hosts demonstrating complete clearance of infection. Variation among buffalo in schistosome loss was associated with immunologic and nutritional factors, as well as co-infection by the gastrointestinal helminth Cooperia fuelleborni. Our results demonstrate that schistosome infections are surprisingly dynamic in a free-living mammalian host population, and point to a role for host factors in driving variation in parasite clearance, but not parasite acquisition which is driven by seasonal changes and spatial habitat utilization. Our study illustrates the power of longitudinal studies for discovering mechanisms underlying parasite dynamics in individual animals and populations.

Cross-species prophylactic efficacy of Sm-p80-based vaccine and intracellular localization of Sm-p80/Sm-p80 ortholog proteins during development in Schistosoma mansoni, Schistosoma japonicum, and Schistosoma haematobium

Schistosomiasis remains a major global health problem. Despite large-scale schistosomiasis control efforts, clear limitations such as possible emergence of drug resistance and reinfection rates highlight the need for an effective schistosomiasis vaccine. Schistosoma mansoni large subunit of calpain (Sm-p80)-based vaccine formulations have shown remarkable efficacy in protecting against S. mansoni challenge infections in mice and baboons. In this study, we evaluated the cross-species protective efficacy of Sm-p80 vaccine against S. japonicum and S. haematobium challenge infections in rodent models. We also elucidated the expression of Sm-p80 and Sm-p80 ortholog proteins in different developmental stages of S. mansoni, S. haematobium, and S. japonicum. Immunization with Sm-p80 vaccine reduced worm burden by 46.75% against S. japonicum challenge infection in mice. DNA prime/protein boost (1 + 1 dose administered on a single day) resulted in 26.95% reduction in worm burden in S. haematobium-hamster infection/challenge model. A balanced Th1 (IFN-γ, TNF-α, IL-2, and IL-12) and Th2 (IL-4, IgG1) type of responses were observed following vaccination in both S. japonicum and S. haematobium challenge trials and these are associated with the prophylactic efficacy of Sm-p80 vaccine. Immunohistochemistry demonstrated that Sm-p80/Sm-p80 ortholog proteins are expressed in different life cycle stages of the three major human species of schistosomes studied. The data presented in this study reinforce the potential of Sm-p80-based vaccine for both hepatic/intestinal and urogenital schistosomiasis occurring in different geographical areas of the world. Differential expression of Sm-p80/Sm-p80 protein orthologs in different life cycle makes this vaccine potentially useful in targeting different levels of infection, disease, and transmission.

Vaccination with recombinant paramyosin in Montanide ISA206 protects against Schistosoma japonicum infection in water buffalo

BACKGROUND

Schistosomiasis japonica is a zoonosis and presents significant public health problems in China and the Philippines. Vaccines targeting domestic animals constitute attractive control measures.

METHODS

We conducted three vaccine trials to evaluate the protective efficacy of recombinant full-length paramyosin (rSj97) in water buffalo. Animals were immunized with 3 doses of rSj97 adjuvanted with ISA206 at 250μg/dose or 500μg/dose at 4wk intervals before challenge with 1000 Schistosoma japonicum cercariae. The primary outcome was worm burden assessed by portal perfusion 8-10weeks post challenge. Safety measures included weight, temperature, body condition score, hemogram and routine assays for hepatic and renal function.

RESULTS

The three-dose regimen was well tolerated in all three trials. In the first trial, vaccinated buffalo had 51.5% lower worm burden post challenge compared to controls. In the second trial, buffalo immunized with 500μg/dose of rSj97 had 57.8% lower worm burden compared to controls (p=0.026). A similar but not significant reduction (60.9%) was observed with animals administered with 250ug rSj97/dose. In the third trial, buffalo immunized with a 500μg/dose of rSj97 had 57.8% lower worm burden compared to controls (p=0.014).

CONCLUSIONS

These findings indicated that rSj97 is a safe and promising vaccine candidate for schistosomiasis japonica in water buffalo.