Epidemiological study of enzootic bovine leukosis in Brazil

Tropical Animal Health and Production -     

Clinical forms of enzootic pneumonia in calves and their effects on respiration]

Enzootic pneumonia was diagnosed in 160 of 225 bullocks in a livestock fattening unit. Within the first 10 weeks, 51 of those affected contracted the disease a second time after the symptoms had vanished. Acute catarrhal bronchopneumonia were most common (49.3%) during the first outbreak, whereas acute catarrhal purulent bronchopneumonia (39.2%) and chronic pneumonia (29.4%) were most common during the second. Arterial blood gas analysis was undertaken for 33 clinically healthy bullocks and 100 bullocks with clinically diagnosed acute bronchitis, acute catarrhal bronchopneumonia, acute catarrhal purulent bronchopneumonia and chronic pneumonia. The pO2, SATO2 and A-aDO2 levels found in blood from the abdominal aorta of all diseased animals differed significantly from those of healthy animals. The values for animals with distinct catarrhal bronchopneumonia and catarrhal purulent bronchopneumonia showed the greatest differences.     

兰州地区犊牛轮状病毒性腹泻的流行病学调查

为明确甘肃省兰州地区犊牛轮状病毒性腹泻的流行动态,从该区的3个大型奶牛场采集1月龄以内的犊牛粪便样品19份,利用轮状病毒酶标诊断试剂盒检测技术对粪便进行检测,并对粪便特征和防治药物进行调查分析.结果表明:该地区犊牛轮状病毒性腹泻的发病率为36.84%;腹泻犊牛粪便颜色多为黄白或浅黄绿色水泻样;防治药物以抗生素为主(占60%),辅助治疗药物占24%,中药制剂占16%.     

河南省部分地区乳牛隐孢子虫病的流行病学调查

为进一步掌握乳牛隐孢子虫病在河南省的流行动态,从河南省郑州、开封、济源和鹤壁4个地区9个奶牛场采集12月龄以内的乳牛粪便样品582份,用饱和蔗糖溶液漂浮法和改良抗酸染色法进行检测。结果显示,隐孢子虫总感染率为26．12％（152／582）。其中,断乳前犊牛（5日龄至2月龄）隐孢子虫感染率为30．91％（51／165）,断乳后犊牛（3～12月龄）感染率为24．22％（101／417）。依据形态数值初步鉴定为2种隐孢子虫,即微小隐孢子虫和安氏隐孢子虫。微小隐孢子虫在断乳前犊牛阳性样品中的比率为50．98％（26／51）,在断乳后乳牛阳性样品中的比率为9．90％（10／101）。另外,饲养方式（断乳前犊牛单独隔离饲养和未隔离饲养）对断乳前犊牛2种隐孢子虫的感染率有显著影响。     

The colonization of the upper respiratory tract and the bacteremic phases of enzootic pneumonia of calves

Twenty calves, following their re-accommodation on a calf raising unit, were tested twelve days for presence of Pasteurellae and mycoplasms on the mucosa of the nasal pharynx and in blood. The same microorganisms were searched for in another 65 calves, yet, only at the beginning of pneumonia. Tests were applied to 19 calves for presence of chlamydia in the blood. The nasopharynx of all 20 calves was colonised by Pasteurellae, whereas mycoplasms were detected only in few cases. Neither Pasteurellae nor mycoplasms were isolated by blood culturing, though chlamydia were found in concomitance with pneumonia in three of 13 evaluable cases.     

Salmonella infections in neonatal dairy calves.

To estimate herd prevalence of Salmonella spp, fecal specimens were obtained for culture from neonatal calves of 47 Ohio dairy herds. Of the 452 calves tested, 10 calves from 7 farms were culture-positive. Salmonella serotypes isolated were S dublin, S typhimurium, S enteritidis, S agona, S mbandaka, and S montevideo. Bulk tank milk filters from these dairies were also submitted for culture. Salmonella sp was isolated from 1 of the 50 filters, and 2 calves from this herd were found to be shedding Salmonella sp of the same serotype.     

Early damages to lung capillaries in enzootic pneumonia of rabbits.

The present study is part of a series of investigations aimed at characterizing the "enzootic pneumonia" phenomenon in rabbits, both from the clinical-epidemiological and the pathophysiological point of view. All affected rabbits included in this study showed an acute injury to pulmonary microvasculature, similar to changes reported in pulmonary infections caused by Gram-negative bacteria. Similar alterations were not found in the control rabbits. The clinical and morphological findings revealed certain similarities between the Enzootic Pneumonia Syndrome of rabbits and Adult Respiratory Distress Syndrome (ARDS) of man. Therefore, it is suggested that, just as in the human syndrome, heterophils (PMN) are directly involved in the pathogenesis of the process. Many of the similarities noted between the two syndromes would make it possible to postulate the natural disease in rabbits as an eventual animal model suitable for extrapolating data to humans.     

Colostrum management for dairy calves.

Colostrum management is the single most important management factor in determining calf health and survival. Unfortunately, a significant proportion of North American dairy calves suffer from failure of passive transfer of antibodies from colostrum, contributing to excessively high preweaning mortality rates and other short- and long-term losses associated with animal health, welfare, and productivity. A successful colostrum management program requires producers to consistently provide calves with a sufficient volume of clean, high-quality colostrum within the first few hours of life. This article reviews the process of colostrogenesis and discusses important components of colostrum. The key components of delivering and monitoring a successful colostrum management program are discussed.     

Longitudinal prevalence study of diarrheagenic Escherichia coli in dairy calves

A longitudinal study (cohort study) elaborating 1,224 rectal swabs from 221 calves aging between 1 and 12 weeks was conducted on 11 dairy farms (i) to ascertain associations between diarrhea and shedding of diarrheagenic E. coli and (ii) to facilitate the zoonotic potential assessment of E. coli strains shed by young calves. Calves were screened weekly by PCR of swab cultures for shedding of enterotoxigenic E coli [ETEC; by detection of heat stable (est) and heat labile enterotoxin genes (elt)], diffusely adhering E. coli [DAEC; diffuse adhesion (daa)], typical enteropathogenic E. coli [EPEC; bundle-forming pili (bfpA) and intimin (eae)] as well as enterohemorrhagic E. coli [EHEC, intimin (eae) and Shiga toxin (stx)]. In addition, EHEC-hemolysin- (Hly(EHEC)) and alpha-hemolysin- (alpha-Hly) producing E. coli were detected by inoculation of blood agar plates. Within the 221 calves, prevalences were 69.7% (25.2% of the 1,224 samples) for Hly(EHEC)-producing E. coli, 55.3% (19.3%) for eae, and 18.2% (4.5%) for stx. E. coli strains exhibiting an alpha-Hly phenotype were detected in 66.5% of the calves and 21.9% of fecal samples. The est gene was detectable in 31.7% of the calves from only 9 of 11 herds and in 7.8% of the samples. Calves shedding DAEC or typical EPEC were not identified. The detection frequency of virulence traits significantly depended on the calves' age and shedding dynamics differed between the traits. A significant correlation between calf diarrhea and shedding of EHEC virulence traits was determined for several postnatal periods (1 week: Hly(EHEC); 1st & 10th week: eae; 4th week stx). Shedding of ETEC (est) was associated with diarrhea in newborn calves (1st week) only. Hly(EHEC)- and alpha-Hly-producing E. coli were shed significantly more frequently by diarrheic calves in 1st and 8th week of life, respectively. The knowledge gained in this study highlights the high prevalence of zoonotic E. coli already in calves.The age-dependent shedding dynamic of the various E. coli pathovars has to be considered regarding prophylaxis as well as planning intervention studies, both for calves and humans.