A case-control study of risk factors in light Taenia saginata cysticercosis in Danish cattle.

Risk factors in light T. saginata cysticercosis in cattle herds were investigated in a case-control study. The case group consisted of farms from which cattle with low-grade cysticercosis had been detected at slaughter. The control group consisted of farms where no cases were detected during the same period. The major risk factor identified was allowing cattle access to drink from streams carrying effluent from sewage treatment plants (odds ratio = 3.6). Spreading of septic tank sludge through deliberate or accidental mixing with animal slurry, deposition of sewage sludge, and proximity to railways, camping sites or sewage treatment plants seemed to be of minor importance.     

Serum antibody levels to Taenia saginata in cattle grazed on Scottish pastures

The serum antibody levels to Taenia saginata of three groups of cattle were assessed by an enzyme-linked immunosorbent assay (ELISA). The first group of cattle were from four farms which had a confirmed T saginata cysticercosis outbreak, all of which had cattle classed as infected by ELISA. The second group were from four farms where sewage sludge had been applied to pasture subsequently grazed by the cattle. One of these farms had cattle classed as infected by ELISA. The control cattle, which were all classed as uninfected by ELISA, came from five farms whose pasture had not been treated with sewage sludge. In a wider survey, involving sera from 47 additional farms, the majority could not be distinguished from the control farms in the earlier survey. However, samples from three of the farms had a similar number of positives to two of the known infected farms in the initial survey. Since the ELISA assay may indicate infected herds, farms such as these warrant further investigation.     

Taenia saginata cysticercosis in an Ohio cattle feeding operation

In January to March 1981, 37 slaughter cattle from a single Ohio feeding operation were determined, at postmortem inspection, to be infected with Taenia saginata cysticerci. A subsequent outbreak on this same farm in March 1983 involved 7 slaughter cattle. An epidemiologic investigation was conducted of possible sources of the T saginata ova; these included leakage of raw sewage onto the pasture after a flood in 1980, municipal sewage sludge application on the farm, defecation in feed or water by farm workers, and other off-farm sources. Temporal and spatial observations implicated raw sewage contamination of pastures as the most likely source of infection in the 1981 outbreak. The outbreak in 1983 was more likely associated with sludge application. The possibility of an infected worker exposing the cattle to infected feces was not excluded definitely as a possible source.     

PRELIMINARY OBSERVATIONS ON THE REMOVAL OF TAENIA SAGINATA EGGS FROM SEWAGE USING VARIOUS TREATMENT PROCESSES

SUMMARY Cattle were grazed for four months on pasture irrigated by effluent from activated sludge plants, a trickling filter plant, from a lagooning process or with raw sewage, and then killed and their heart, diaphragm, tongue, and muscles of their head and one forelimb were sliced and examined for Cysticercus bovis. None of the cattle grazed on pasture irrigated with effluent from lagooning were infected compared with 3.3% from the trickling filter plant, 9.0% and 12.5% from the two activated sludge plants and 30.0% of cattle on pastures irrigated with raw sewage. Of the 40 control calves killed at the time the test calves were placed on the various pastures, 2.5% were infected. It appears that modern sewage purification methods do not efficiently remove Taenia saginata from the final effluent and that prolonged settling is necessary before effluent is used to irrigate cattle pastures if C. bovis infection is to be reduced to very low levels.     

Very low helminth infection in sheep grazed on pastures fertilised by sewage sludge or cattle slurry

Helminth infection acquired by lambs grazing on pastures fertilised either by urban sewage sludge or cattle slurry were studied in temperate Central Western France. The aim was to assess the risk of larval cestodoses in lambs after sewage application and of digestive tract nematode infection following the slurry application. Twenty-six sheep were allocated on two paddocks of 0.7 ha, one fertilised with sludge and the other with cattle slurry. The delay between application and actual grazing was 6 weeks; grazing on these paddocks extended from mid July to beginning of November 2002. The herbage biomass was slightly increased in the sludge paddock but it did not result in an increase of lamb live weight, compared with the slurry paddock. The lambs did not acquire cysticercosis or any other larval cestodoses in the sewage sludge group and only very limited infections with Cooperia spp. and Nematodirus spp. were observed in the slurry group. It was concluded that in our conditions the helminth risk was extremely low and was not a cause of restriction of the use of these biowastes.     

Investigation of an outbreak of Taenia saginata cysts (cysticercus bovis) in dairy cattle from two farms

The paper describes the epidemiological investigation carried out on two dairy farms with cattle infected with Taenia saginata cysts. On the first affected farm it was estimated using Bayesian techniques that approximately 65% of 1400 mixed-age cattle were infected with Taenia saginata cysts. The investigation aimed to determine potential exposure pathways of cattle to Taenia saginata with a view to finding the human source of infection and to describe the epidemiology of the outbreak on the affected farms. In order to determine potential exposure pathways, investigation was centred on how feed or water could have been contaminated with eggs. The plausibility of pathways was determined by examining the spatial and temporal association between factors related to the pathway and the prevalence of infection in cattle strata. We describe the investigation carried out on affected farms.     

The use of urban sewage sludge on pastures: the cysticercosis threat

Urban sewage production is increasing and its agronomical use as a fertiliser has been advocated. Considerable defiance is prevalent in consumers and among farmers on the use of such fertilisers due to unknown pathological or environmental risks. The aim of the present review was to consider which pathological risk is major. Cysticercosis due to Taenia saginata appears to be one of the major pathological threats when sewage sludge is used to fertilise cattle pastures in temperate areas. The situation is different in Africa (Taenia solium and T. saginata are both highly prevalent) and Asia (Taeniasaginata-like are prevalent). The processing of sludge and the delay between its application onto a pasture and grazing are probably major risk factors. Little data are available on the influence of processing, delay between processing and the use of sludge on the pathogenic risk. Producers and consumers will be more confident on the use of sludge if objective data are gained on risk. Most of the cases of cysticercosis (North America, United-Kingdom, Germany or Denmark) are related to poor human hygiene or accidental overflooding of sewage plants onto pastures. The standard application of sludge on pastures is apparently at low risk. This low risk does not mean that surveillance should cease since outbreaks of cysticercosis have been reported. Future investigations should concentrate on the most sustainable means of reducing risk (length of storage before use, composting, other treatments).     

Evaluation of an enzyme-linked immunosorbent assay (ELISA) for detection of Taenia saginata cysticercosis in cattle.

Serum IgG response of cattle with cysticercosis caused by Taenia saginata was studied in an enzyme-linked immunosorbent assay (ELISA) where a T. saginata metacestode surface extract was used as antigen. In experimentally infected calves, a sharp rise in specific antibody levels was found 3-4 weeks after the infection followed by a logical level of detection corresponded to about 25 cysts. The ELISA was employed in cattle herds where cysticercosis outbreaks had occurred and also in supposedly uninfected herds. Significantly increased antibody levels were found in the herds with massive cysticercosis cases. The test was not adapted for individual diagnosis as some animals of the uninfected herds, especially within the older age groups, had elevated antibody values. The ELISA was, however, useful in the investigation of outbreaks to determine the extent and pattern of the infection in the herd. The rate of decline in antibody levels in these herds was studied by follow up sampling. The increased antibody levels in the infected herds were also reflected in colostrum-fed calves. This observation was employed to estimate the time of infection.     

Diagnosis of naturally occurring Fasciola hepatica infections in cattle with an enzyme-linked immunosorbent assay

Sera from 100 herds of cattle located in the state of Washington were examined with an enzyme-linked immunosorbent assay for antibody to Fasciola hepatica in a screening procedure that included 5 to 10 samples/herd. Twenty-eight herds contained infected cattle and F hepatica was most prevalent in 3 distinct geographic areas. Subsequent retesting of all sera available from 14 herds (mean of 109 samples/herd) revealed that the screening procedure correctly detected 7 of 7 operations in which greater than 40% of samples were positive or suspect and 3 of 3 operations in which 12% to 13% of the samples were positive or suspect. One of 3 herds considered negative after screening was found to contain a few (7%) positive samples and 1 herd considered possibly infected was negative on retest. These results were compared with those obtained by fecal examination for F hepatica eggs in 9 of the 14 herds. A good correlation (5 of 5) was found in which a high percentage (48% to 85%) of sera were positive or suspect. Fasciola eggs were not found in samples from 2 herds with few (7% to 12%) positive or suspect sera or in 2 herds that were negative by an enzyme-linked immunosorbent assay.     

Brucellosis in Ontario: a case control study.

Data from cattle herds infected with brucellosis and from control (noninfected) herds were collected and analyzed using case control techniques. It appeared that herds located close to other infected herds and those herds whose owners made frequent purchases of cattle had an increased risk of acquiring brucellosis, particularly those who made purchases from other herds or from cattle dealers. Infected herds had a lower level of vaccination than noninfected herds. However, the percentage vaccinated was highly variable in each group. Vaccination per se did not appear to adversely influence the interpretation of serological test results nor did it appear to protect the individual animal. Once infected, the time required to become free of brucellosis was increased by large herd size and/or loose housing. Closed herds also took longer to become brucellosis free than more open herds. The percentage of animals removed from the herd was increased by active abortion. Those herds with multiple serological reactors (positives and questionables) at the first herd test after the imposition of quarantine had the highest percentage of cattle removed.     

Evaluation of bovine spongiform encephalopathy (BSE) infection risk of cattle via sewage sludge from wastewater treatment facilities in slaughterhouses in Japan

Scattered SRM residues from BSE-infected cattle are possible to contaminate sewage during the slaughtering process in slaughterhouses. A proportion of the sludge discharged from wastewater treatment facilities at slaughterhouses has historically been processed into fertilizer. We therefore investigated the associated risk of BSE infection to cattle via sludge-derived fertilizer. Each stage of the process associated with BSE exposure was qualitatively evaluated and quantitative evaluations were subsequently performed using infectious dose as a unit of concern. Results of these qualitative evaluations indicated that installation of filter(s) at the drains to the wastewater treatment facilities has been undertaken by many slaughterhouses and has decreased the likelihood of SRM contamination of sewage. The level of sludge-derived fertilizer ingested by cattle was considered to be very low since the fertilizer is mixed with the ground soil, and the amount of soil ingested by cattle is likely to be small. Results from the quantitative analysis indicated the total infectious dose ingested by cattle in Japan from an infected cow has been estimated to be 5.5 x 10(-3) ID(50). Preventing scattering of SRM during the slaughtering process, installing filters to the drains with the removal of residues from the drain water and preventing the application of sludge-derived fertilizer to pasturelands would be effective to reduce the risk. Although the limited extent of available information, this study should provide useful indication for the development of an inclusive risk assessment for slaughterhouse sludge in the future.     

Evaluation of a 'dipstick' immunoassay to detect cysticercosis in experimentally infected cattle

A 'dipstick' immunoassay for bovine cysticercosis, using an antigen isolated from Taenia hydatigena cyst fluid, was evaluated in cattle experimentally infected with Taenia saginata. The assay correctly identified six out of seven infected cattle, including an animal in which only 12 living cysticerci were found. Cattle became seropositive as early as 3 weeks post-infection. A false-negative reaction was found for one very lightly infected animal, from which only four living cysticerci were recovered at necropsy. The assay was also used to detect circulating antibodies in experimentally infected cattle before and after therapeutic treatment with anthelminthics. The results suggest that praziquantel-treated animals gradually revert to being seronegative after the cysticerci are killed.     

苜蓿施用污泥效果的研究Ⅱ对土壤理化性质及元素含量的影响

将兰州市七里河污水处理厂生活污泥施用于苜蓿人工草地，探讨其对土壤环境的影响，结果表明，施用污泥，改善了土壤理化性质，增加了土壤肥力，土壤中有机质，全N和全P的含量增加，土壤容重下降，污泥施用量与土壤有机质，全氮含量呈极显著正相关（P＜0．01），与土壤容得呈极显著负相关（P＜0．01），当污泥施用量在4kg/m^2以上时，0－20cm土层Fe和Ca的含量显著增加，施用量8kg/m^2时，Cu和Zn的含量显著高于对照，而K，Mn和重金属元素Ni,Pb,As,Hg的含量与对照无显著差异，且各元素都未向土壤下层迁移，没有对土壤环境造成污染。     

Taenia saginata in Europe

In spite of the EU directives that regulate meat inspection for bovine cysticercosis, Taenia saginata is still present in Europe and causes economic losses due to condemnation, refrigeration and downgrading of infected carcasses. The main reasons for this persistence include the low sensitivity of current meat inspection protocols, the dissemination and survival of eggs in the environment and cattle husbandry systems, which allow grazing on pastures and drinking from water streams. It is assumed that water streams and surface water are potentially contaminated with T. saginata eggs. Furthermore, current wastewater management not only fails to halt, but rather contributes to the dissemination of eggs in the environment. Here, the authors discuss an integrated approach for control of this food-borne zoonosis, as well as the potential use of serological methods as a way of improving detection of bovine cysticercosis.     

A Case–Control Study of Risk Factors for Bovine Cysticercosis in Danish Cattle Herds

Bovine cysticercosis (BC) is a zoonotic, parasitic infection in cattle. Under the current EU meat inspection regulation, every single carcass from all bovines above 6 weeks of age is examined for BC. This method is costly and makes more sense in countries with higher number of BC‐infected animals than in countries with few lightly infected cases per year. The aim of the present case–control study was to quantify associations between potential herd‐level risk factors and BC in Danish cattle herds. Risk factors can be used in the design of a risk‐based meat inspection system targeted towards the animals with the highest risk of BC. Cases (n = 77) included herds that hosted at least one animal diagnosed with BC at meat inspection, from 2006 to 2010. Control herds (n = 231) consisted of randomly selected herds that had not hosted any animals diagnosed with BC between 2004 and 2010. The answers from a questionnaire and register data from the Danish Cattle Database were grouped into meaningful variables and used to investigate the risk factors for BC using a multivariable logistic regression model. Case herds were almost three times more likely than control herds to let all or most animals out grazing. Case herds were more than five times more likely than control herds to allow their animals access to risky water sources with sewage treatment plant effluent in proximity. Case herds were also more likely to share machinery or hire contractors than control herds. The risk decreased with increasing herd size probably because the larger herds generally tend to keep cattle indoors in Denmark. The results are useful to guide future data recording that can be supplied by the farmer as food chain information and then be used for differentiated meat inspection in low‐ and high‐risk groups, enabling development of risk‐based meat inspection systems.     

Biotypes of Brucella abortus and their value in epidemiologic studies of infected cattle herds.

Four Texas cattle herds containing cows infected with either Brucella abortus biotype 1, 2, or 4 were studied to determine the probability of transmission of Brucella between adjacent cattle herds, the most probable means by which Brucella was introduced into the herds, and the relative frequency of strain 19 isolation from vaccinated cattle. A total of 1,935 cattle in the four herds were tested for brucellosis; 339 reactors were identified, and isolations of B abortus were made from 143. The biotype of B abortus was used to determine that purchased cattle or reentry of bred heifers into the herds was probably responsible for introducing B abortus and that the biotype was not readily transmitted to adjacent herds. Three (9%) of 32 B abortus isolations from adult-vaccinated cattle were strain 19. The data supported the hypothesis that biotypes can be useful in determining the source of B abortus for cattle and in differentiating field and vaccine strain infections in adult-vaccinated cattle.     

Emergence of fasciolosis in cattle in East Anglia

Liver fluke (Fasciola hepatica) infection caused weight loss, diarrhoea, decreased milk yield and occasionally death in cattle in East Anglia during the winters of 2001 to 2003. The condition had previously been limited mainly to stock imported into this part of Britain from endemically infected areas. In composite faecal samples collected by 16 farm animal veterinary practices in Norfolk, Suffolk and Essex, fluke eggs were found in 15 (28.8 per cent) of 52 previously unaffected suckler herds and 10 (16.7 per cent) of 60 dairy herds. Antibodies to F hepatica were detected by elisa in 32 (53.3 per cent) of the bulk milk samples from these 60 dairy herds, including the 10 in which fluke eggs were found. The emergence of fasciolosis in East Anglia was attributed to recent higher summer rainfall, which favoured the intermediate snail host Lymnaea truncatula and the free-living stages of F hepatica, the increased influx of sheep from endemic fluke areas for seasonal grazing, and the wetter grazing conditions associated with the Environmentally Sensitive Area scheme.     

A modeling study on the sustainability of a certification-and-monitoring program for paratuberculosis in cattle

Certification-and-monitoring programs for paratuberculosis are based on repetitive herd testing to establish a herd's health status. The available tests have poor sensitivity. Infected but undetected herds may remain among certified "paratuberculosis-free" herds. The objective was to determine if truly free herds acquire a certified status and keep it over time when infected but undetected herds remain. The Dutch program was used as a basis to construct a mechanistic deterministic model of the evolution over 25 years of the number of herds per health status. Three health states for herds were defined: not detected as infected in the certification process to obtain a free status; not detected as infected by any of the repetitive tests for monitoring the certified free status; detected as infected. Among undetected herds, two types were defined: truly free versus undetected but infected. Transitions between states were due to the purchase of an infected animal, infection via the environment, clearance via culling or sales, detection of an infected animal, and certification. A sensitivity analysis was carried out. We showed that--for a 100% specific test only--most of the truly free herds at the beginning of the program got a certified free status and kept it over time. Most infected herds were either detected as infected or cleared. The number of certified truly free herds increased with a decrease in the animal-level prevalence or in the risk of purchasing an infected cattle, for example by restricting purchases to cattle from herds at the highest level of certification.     

脑多头蚴病研究进展

脑多头蚴病是由多头带绦虫的中绦期幼虫脑多头蚴寄生于绵羊、山羊、黄牛、牦牛等有蹄动物的脑及脊髓中引起的一种人兽共患寄生虫病,人可因误食虫卵而感染此病。该病在宿主出现典型临床症状后如果得不到治疗,多以死亡为转归,给畜牧业生产造成了巨大的经济损失。论文就脑多头蚴病的病原学、生活史、流行病学、临床症状、诊断、治疗及免疫预防等方面的研究进展进行了综述。