Research Advances on Calf Pathogenic Diarrhea and Vaccine

Calf diarrhea is a kind of digestive tract disease caused by a variety of pathogenies, which has a great impact on the survival, growth and development of calves. Escherichia coli, bovine rotavirus, bovine coronavirus and other pathogens often cause diarrhea in calves, in addition, the secondary infection and mixed infection also occurre in different pathogens, which lead to great difficulty for prevention of calf diarrhea. A variety of vaccines have been developed for the prevention and treatment of calf diarrhea at home and abroad. Now, except only minor commercial calf diarrhea vaccines have been found in abroad, there is no one multivalent commercial calf diarrhea vaccine in China. Based on previous study, the progress of pathogens and vaccines for calf diarrhea were elaborated in the study, which could provide exploitation references for the commercial calf diarrhea vaccine in China.     

犊牛病原性腹泻及疫苗研究进展

犊牛腹泻是一种由多种病因引起的消化道疾病,对犊牛的成活、生长、发育等有较大影响,给奶牛和肉牛产业造成巨大经济损失。牛大肠杆菌、轮状病毒、冠状病毒等均可引起犊牛腹泻,且各种病原间还会发生继发感染和混合感染,给防控工作带来较大困难。国内外开发出各种疫苗用于防控犊牛腹泻病,但除了国外有少数商品化疫苗外,目前国内还没有一种针对由多种病原引起的犊牛腹泻病的商品化疫苗。文章就犊牛腹泻病原及疫苗的研究进展进行了阐述,以期为国内开发商品化犊牛腹泻病疫苗提供参考。     

犊牛病原性腹泻流行情况及综合防控研究概述

犊牛病原性腹泻是新生犊牛的一种常见问题,对养牛业危害很大,且病原较为复杂,不同地区该病的流行情况、临床症状和死亡率都不尽相同。大批文献从不同角度对该病进行了报道,本文对引起犊牛腹泻的主要病原、病原性犊牛腹泻在我国的流行情况以及主要的防控手段进行了总结,以期为临床有效防控犊牛病原性腹泻提供参考。     

A bovine virus diarrhea calfhood vaccination trial in a persistently infected herd: effects on titres, health and growth.

A controlled calfhood vaccination trial to prevent bovine virus diarrhea was conducted in a 100 head cow-calf operation with a three year history of annual calf losses due to enteric bovine virus diarrhea (persistently infected herd). Approximately 50% of the calves were vaccinated at six, 12 and 24 weeks of age. Paired serum samples and growth data were collected on three occasions for comparison between vaccinates and controls. Three vaccinated calves died of enteric bovine virus diarrhea in the first year of the trial and one nonvaccinated calf died in the second year. Two of the three vaccinated calves had developed bovine virus diarrhea virus neutralization antibody titres of 2048 or greater before developing clinical signs. The control and third vaccinated calf failed to seroconvert before dying of enteric bovine virus diarrhea. Approximately 90% of the vaccinated calves seroconverted compared to approximately 40% of the controls. Paired serum samples collected from 75% of the cows in the spring, summer and fall of each year of the trial, showed persistent high bovine virus diarrhea virus neutralization titres in all samples. Calf vaccination before 12 weeks of age had little effect on seroconversion due to high levels of passive antibody to bovine virus diarrhea. Growth data showed that there was no improvement in weight gain or rate of growth in the vaccinated calves.     

产志贺毒素大肠杆菌流行病学及主要毒力因子研究进展

产志贺毒素大肠杆菌(Shiga toxin-producing Escherichia coli,STEC) 是一类能引起包括水样腹泻、出血性结肠炎、尿毒综合症等一系列人体疾病的人畜共患肠道致病菌,其感染在世界范围内包括中国都有过暴发流行。文章阐述了STEC O157血清型和非O157血清型的分布特征及流行趋势,同时还对该病的主要毒力因子进行了综述,以期为该病的防控提供科学依据。     

Biosecurity for neonatal gastrointestinal diseases.

Infectious diarrhea is an important cause of neonatal calf morbidity and mortality that results in significant economic losses in the beef and dairy industries. Although numerous risk factors related to the occurrence of neonatal diarrhea have been identified, they can all be categorized into those that are related to the calf, the pathogens involved, or the environment of the calf. The immune status of calves, specifically the level of passively acquired immunity through colostrum, is the major risk factor related to the calf and the occurrence of diarrhea. Although numerous pathogens have been implicated in the occurrence of neonatal diarrhea, only a relatively limited number are commonly involved. Most should be viewed as secondary opportunists rather than primary pathogens, because none are extraordinarily virulent, and with the exception of Salmonella spp., most are present within the gastrointestinal tract of many healthy, mature cattle. Important risk factors related to pathogens involved in neonatal calf diarrhea involve the size of the inoculum and the occurrence of multiple infections. Finally, when considering the environment and housing conditions in which beef and dairy calves may reside, it is clear that tremendous variations exist. Despite these variations, the risk factors associated with the environment of the calf are also those that are the most amenable to the implementation of general environmental control and monitoring strategies as well as specific biosecurity measures.     

肉牛繁育场哺乳犊牛腹泻探讨

哺乳犊牛腹泻由多种原因造成,是犊牛养殖中相对常见的问题,在发病初期如得不到及时控制将造成严重损失,笔者结合牧场实践与现实情况,重点阐述了肉牛繁育场哺乳犊牛腹泻发病原因,同时分析、总结相关问题,针对性的提出肉牛繁育场哺乳犊牛腹泻管控方案,为行业内养殖者在处理哺乳犊牛腹泻时提供参考依据。     

Serologic evidence of coronavirus infection in New York and New England dairy cattle with winter dysentery.

Acute and convalescent sera were collected from 8 dairy herds with classic clinical features of winter dysentery. An enzyme-linked immunosorbent assay was used to measure coronavirus antibody titers, employing calf diarrhea coronavirus as antigen. Twenty-two of the 35 animals tested (63%) showed a greater than or equal to 4-fold seroconversion. Adult cattle in all 8 herds seroconverted. These findings complement previously reported immunoperoxidase and electron microscopic evidence, suggesting an etiologic role for an enteric coronavirus in this disease.     

Coronavirus as agent of neonatal calf diarrhea in southern Chile

Neonatal calf diarrhea is one of the most serious problems of cattle industry all over the world. Although the aetiology is complex, it is possible to assess that viruses play a very important role. During an investigation to study the importance of Rotavirus in enteric problems in calves and piglets, it was possible to demonstrate the presence, for the first time in southern Chile, of Coronavirus-like particles in a faecal sample of a 15 day old calf by means of electron microscopy. The importance of this diagnosis and some clinical characteristics of the disease are briefly discussed. Finally, the need for more research on this complex subject is recognized.     

Experimental Diagnosis,Prevention and Treatment of Calf Diarrhea Caused by Salmonella

This study was aimed to explore the pathogenesis of calf diarrhea in a large scale dairy farm in Shanxi province and the correspond comprehensive prevention and control measures. By investigating the incidence of calf diarrhea in the field, rotavirus, coronavirus,E. coli F5 (K99),Cryptosporidium parvum, coccidia and Salmonella were detected through experimental diagnosis, and the suspicious pathogenic bacteria was isolated and cultivated,which was identified with morphology and serology, simultaneously sensitive antibiotics were screened according to the antibiotic susceptibility tests, which contained 18 kinds of common antibiotics. The results showed that the clinical diagnosis and laboratory tests basically ruled out the possibility of E. coli F5 (K99), rotavirus, coronavirus, Cryptosporidium parvumand coccidia infection, and the isolated suspected bacteria had Salmonella colony characteristics and bacterial morphology, which showed positive reaction to Salmonella O polyvalent A-F serum, so we had identified that it was Salmonella diarrhea.The antibiotic susceptibility tests results showed that Salmonella was highly sensitive to ceftriaxone, gentamicin, cephradine and amikacin, which could be recommended for clinical treatment. Above all, this study proposed the specific prevention and treatment of the disease, and better control effect was achieved. This study initially provided a reference for the diagnosis and treatment of Salmonella of calf diarrhea, with great clinical significance in the early diagnosis and treatment of pathogens of calf diarrhea.     

由沙门氏菌引起的犊牛腹泻病的实验室诊断及防治

为了探究山西某规模化奶牛场犊牛腹泻病的发病原因及相应的综合防治措施,本研究通过对该场犊牛腹泻病发病情况进行调查,同时对可疑病原轮状病毒、冠状病毒、大肠杆菌F5（K99）、小球隐孢子虫、沙门氏菌进行实验室检测,分离并培养了可疑病原菌,并对该病原菌进行形态学和血清学鉴定,选取18种常见抗生素,通过药敏试验筛选对该菌敏感的抗生素。结果显示,经临床诊断和实验室检测基本排除大肠杆菌F5（K99）、轮状病毒、冠状病毒、小球隐孢子虫和球虫感染的可能性,分离的可疑菌具有沙门氏菌的菌落特征和细菌形态,并与沙门氏菌O多价血清A-F呈现阳性反应,确诊该病原主要为沙门氏菌。药敏试验结果显示,所分离的沙门氏菌对头孢曲松、庆大霉素、头孢拉定、阿米卡星等药物高度敏感,可推荐用于临床治疗。结合以上结果,本研究提出该病的具体防治措施,并取得了较好的防治效果。本研究初步为犊牛腹泻病中沙门氏菌病的诊断和防治提供了参考,对犊牛腹泻病病原的早期诊断和治疗具有重要的临床意义。     

A reliable, practical, and economical protocol for inducing diarrhea and severe dehydration in the neonatal calf.

Fifteen healthy, colostrum-fed, male dairy calves, aged 2 to 7 d were used in a study to develop a diarrhea protocol for neonatal calves that is reliable, practical, and economical. After instrumentation and recording baseline data, diarrhea and dehydration were induced by administering milk replacer [16.5 mL/kg of body weight (BW), PO], sucrose (2 g/kg in a 20% aqueous solution, p.o.), spironolactone and hydrochlorothiazide (1 mg/kg, PO) every 8 h, and furosemide (2 mg/kg, i.m., q6h). Calves were administered sucrose and diuretic agents for 48 h to induce diarrhea and severe dehydration. Clinical changes after 48 h were severe watery diarrhea, severe depression, and marked dehydration (mean, 14% BW loss). Cardiac output, stroke volume, mean central venous pressure, plasma volume, thiocyanate space, blood pH and bicarbonate concentration, base excess, serum chloride concentration, and fetlock temperature were decreased. Plasma lactate concentration, hematocrit, and serum potassium, creatinine, phosphorus, total protein and albumin concentrations were increased. This non-infectious calf diarrhea protocol has a 100% response rate, while providing a consistent and predictable hypovolemic state with diarrhea that reflects most of the clinicopathologic changes observed in osmotic/maldigestive diarrhea caused by infection with rotavirus, coronavirus or cryptosporidia. Limitations of the protocol, when compared to infectious diarrhea models, include failure to induce a severe metabolic acidosis, absence of hyponatremia, renal instead of enteric loss of chloride, renal as well as enteric loss of free water, absence of profound clinical depression and suspected differences in the morphologic and functional effect on intestinal epithelium. Despite these differences, the sucrose/diuretic protocol should be useful in the initial screening of new treatment modalities for calf diarrhea. To confirm their efficacy, the most effective treatment methods should then be examined in calves with naturally-acquired diarrhea.     

口鼻污染引起犊牛腹泻的防范

新生犊牛腹泻发病率及死亡率较高,给牧场造成了严重的经济损失。新生犊牛口鼻污染是导致1～14日龄犊牛腹泻的主要诱发因素之一。从生产管理角度出发防控口鼻污染引发的犊牛腹泻是防止新生犊牛腹泻的关键措施。接助产的规范管理是防范该病的重要一环,产前准备、分娩过程的干预,新生犊牛的护理等环节的管理不当都可能引起新生犊牛口鼻污染引发的腹泻的发病率的升高。此外,犊牛舍和牧场的环境卫生管理、犊牛饮食管理和牧场工作人员管理等其他方面也可能导致该病的高发。本文将从这几个方面阐述如何防范新生犊牛口鼻污染。     

Yersinia pseudotuberculosis infection in a suckler calf in the United Kingdom: a case report

Enterocolitis caused by Yersinia pseudotuberculosis was identified by bacterial culture and histopathology in a 5-month old suckler calf. No other significant enteric pathogens were detected. Diagnosis of this condition can be missed if selective media are not used for bacteriology and if histopathology is not attempted or the alimentary tract is unsuitable for examination. This is the first case report of Y. pseudotuberculosis infection in a calf in the United Kingdom.     

Dairy calf rearing unit and infectious diseases: diarrhea outbreak by bovine coronavirus as a model for the dispersion of pathogenic microorganisms

Dairy calf rearing unit is a management system that is only recently being implemented by some milk producer’s cooperatives in southern Brazil. However, aspects related to the health profile of the heifer calves that arrive in the rearing unit as well as about biosecurity practices and microbiological challenges have not yet been evaluated in this rearing system in a tropical country. Diarrhea is the main and most frequent consequence of enteric infections in newborn calves. This study, through some etiological and epidemiological characteristics of an outbreak of neonatal diarrhea, has the aim to alert to the possibility of pathogenic microorganism spread in a dairy heifer calf rearing unit. The diarrhea outbreak presented some non-regular characteristics observed in bovine coronavirus (BCoV) enteric infections in dairy calves. The spread of infection was extremely rapid (1 week); the attack rate (>?50%) was much higher than that observed in calves subjected to conventional rearing; and the age range (5 to 90 days) of the affected heifer calves was much broader than that often observed in the BCoV diarrhea worldwide. These unusual epidemiological characteristics observed in this BCoV diarrhea outbreak raise awareness of the health threat present in calf rearing units as well as of the easy and rapid viral spread in a population of young animals from different dairy herds and, therefore, with very distinct immunological status.

     

A Case of Viral Neonatal Calf Diarrhea in a Québec Dairy Herd

This report is concerned with a consistent problem of neonatal calf diarrhea (NCD) in a dairy herd in which, for nearly two years, the morbidity had approached 100% and the mortality had varied from 20% to 45%. Generally, diarrhea appeared at three days of age. By the fluorescent antibody tissue section technique the two Nebraska NCD viruses (reo-like and corona-like) were detected in the cytoplasm of many absorptive cells of the small intestine from a calf submitted for necropsy. Reo-like virus antigen was not detected in the absorptive and crypt cells of the colon but coronavirus-like antigen was. An adenovirus was also isolated from the small intestine of this calf. The disease was reproduced experimentally in a two day old colostrum deprived calf with a bacteria free intestinal homogenate obtained from the naturally infected calf. Both Nebraska NCD viruses were demonstrated in this experimental animal. However, the adenovirus was not re-isolated. Histological lesions observed in the small and large intestines of the naturally and experimentally infected calves were similar and because of their good correlation with the immunofluorescent findings, a combination of the two Nebraska NCD viruses was thought to be a major cause of the neonatal calf diarrhea problem afflicting this dairy herd.     

Nonruminant Nutrition Symposium: Involvement of gut neural and endocrine systems in pathological disorders of the digestive tract

The functioning of the gastrointestinal tract is under the control of the most extensive system of peripheral neurons in the body, the enteric nervous system, and the largest endocrine system of the body, the GEP endocrine system. The enteric nervous system in large mammals contains 500 million neurons, and the GEP endocrine system produces more than 30 hormones. Numerous enteric neuropathies affecting both humans and animals have been described and digestive disorders affect commercially important species, such as horses and cattle. The most severe enteric neuropathies (e.g., lethal white syndrome in horses or Hirschsprung's disease in humans) can be fatal. Also, horses with ileus or other digestive disorders are commonly euthanized. In this review we discuss examples of enteric neuropathies that affect agricultural animals and humans: prion disease, postoperative ileus, distal enteric aganglionosis, and infective diarrhea. Enteric neurons and glia are a location of prion proteins and are involved in transmission of the infection from gut to brain and brain to gut. Postoperative ileus is a complex disorder involving the local inhibitory effects of sympathetic nervous system activation and the release of opioids, presumably from enteric neurons. Intestinal inflammation, especially of the external muscle that includes enteric ganglia, also occurs in ileus. Congenital distal bowel aganglionosis, responsible for lethal white syndrome in horses, Hirschsprung's disease in humans, and similar conditions in mice and rats, is a fatal condition if untreated. Mutations of the same genes can cause the condition in each of these species. The only effective current treatment is surgical removal of the aganglionic bowel. Infectious diarrheas involve activation of enteric secretomotor neurons by pathogens and the toxins they produce, which causes substantial fluid loss. Strategies to target enteric neurons in the treatment of secretory diarrheas have not been developed. Disorders of enteroendocrine cells, other than GEP endocrine tumors, are less well documented. However, evidence for the involvement of gut endocrine cells in a subset of patients with irritable bowel syndrome, and in the symptomology of celiac disease, has been demonstrated. Further investigation of the involvement of enteric neural and endocrine signaling systems in digestive disorders, especially in agricultural and companion animals, may lead to diagnostic and therapeutic advances.     

中西医结合治疗犊牛腹泻

犊牛腹泻是犊牛最为常见的疾病,一年四季都可发生,多因饲养管理不当引起。该病如不及时治疗或治疗不当,邪气渐盛,正气不足以拒邪,轻者,影响食欲,皮毛松乱,抗病力差,生长发育受阻;重者,食欲废绝,粪便失禁,严重脱水死亡。笔者采用中西医结合治疗犊牛腹泻78例,治愈75例,疗效满意。