Bovine ostertagiasis: a changing epidemiological pattern?

An unusual epidemiological pattern in bovine ostertagiasis is described in which clinical ostertagiasis occurred in calves grazed on a silage aftermath from late July. The calves were treated with the anthelmintic levamisole prior to grazing the aftermath and the latter had not been grazed since the previous autumn. Analysis of the herbage larval counts suggests that delayed emergence of overwintered Ostertagia ostertagi L3 from the soil was the most likely source of the infection.     

Bovine spongiform encephalopathy: a review

Transmissible Spongiform Encephalopathies are a group of chronic, always fatal diseases affecting the central nervous system of humans and animals. They occur in all species and are probably caused by agents called prions. In this minireview, a first part provides an overview of the various disease forms, a second part is devoted to the molecular biology of transmissible spongiform encephalopathies, and a last part deals with the specific problems of the Bovine Spongiform Encephalopathy.     

Bovine ephemeral fever: a review

Bovine ephemeral fever is a viral disease of cattle and buffaloes besides subclinical involvement of a variety of ruminant species. The subtropical and temperate regions of Africa, Asia and Australia have experienced the major epidemic of the bovine ephemeral fever but the occurrence in the tropics can not be overlooked. Although the substantial role played by the vectors viz., mosquitoes and culicoides in bovine ephemeral fever perpetuation and dissemination, other vector involvement if any should be extensively studied. The clinical severity of the disease is not apparent and the mortality is low. However, high morbidity, enormous economic losses in terms of significant reduction in production, disruption of national and international trade and finally a variety of complications resulting from the disease have drawn appreciable attention from the researchers around the world to resolve the unsolved questions in this area. In this review, detailed informations of all the aspects of the disease has been provided in a simple, lucid and easily understandable manner.     

Bovine uterine defense mechanisms: a review

Bovine uterine defense mechanisms during physiological and pathological conditions have been reviewed in this article. The initial uterine defense against bacterial infection is phagocytosis by uterine leucocytes (mainly neutrophils). The reported literature showed that very little work has been done on immunoglobulins and their role in the bovine uterine defense mechanisms; however, some investigators have found a positive correlation between gamma-globulin and the development of uterine infection after calving. Many explanations exist for the difference in susceptibility of the uterus to infection during the different phases of estrous cycle; however, most of the reports agreed that the uterine defense mechanism is inadequate during diestrus. The abnormal puerperium effects uterine defense mechanisms adversely and prolongs the time to complete uterine involution. Future treatment may utilise natural antimicrobial substances such as proteins or peptides derived from PMN, chemoattractant substances such as E. coli lipopolysaccharide or a bacteria-free filtrate of streptococci. Specific hyperimmunserum could also be used as opsonin for refractory cases of uterine bacterial infections.     

Bovine sole ulcer: a literature review

Sole ulcers are the most frequently encountered lesion in lame cattle. They are of growing concern to the dairy industry since the incidence of ulcers is increasing. Ulcers cause financial losses, the animal's wellbeing is disturbed to a high degree and they harm the image of the industry in general. Biomechanic factors and laminitis are of particular significance in the pathogenesis of the sole ulcer. The development of sole contusions and ulcers is assumed to occur in 3 phases (Sinking theory). In the first phase there is a general disturbance in the vascular system of the corium. The second phase follows when the structures that suspend the claw bone within the horn shoe give way. The locus minoris resistentiae has yet to be identified. The claw bone sinks and causes various lesions when it pinches the underlying sole or heel corium. The third phase begins when haemorrhages become visible on the horn surface of the sole or when the sole ulcerates; socalled third phase lesions. The relationship between the development of sole ulcers and anatomical structures such as the claw bone's tuberculum flexorium or the fat bodies under the bone are unclear. Epidemiological studies have shown that sole ulcers have a high rate of recurrence. The healing processes and the factors that influence them have hitherto not been studied.     

Bovine postparturient hemoglobinuria: a review of the literature

Predisposing causes of bovine post-parturient hemoglobinuria are summarized along with suspected pathogeneses, clinical signs, laboratory findings, clinical management and early experimentation.     

Bovine respiratory syncytial virus (BRSV): a review

Bovine respiratory syncytial virus (BRSV) infection is the major cause of respiratory disease in calves during the first year of life. The study of the virus has been difficult because of its lability and very poor growth in cell culture. However, during the last decade, the introduction of new immunological and biotechnological techniques has facilitated a more extensive study of BRSV as illustrated by the increasing number of papers published. Despite this growing focus, many aspects of the pathogenesis, epidemiology, immunology etc. remain obscure. The course and outcome of the infection is very complex and unpredictable which makes the diagnosis and subsequent therapy very difficult. BRSV is closely related to human respiratory syncytial virus (HRSV) which is an important cause of respiratory disease in young children. In contrast to BRSV, the recent knowledge of HRSV is regularly extensively reviewed in several books and journals. The present paper contains an updated review on BRSV covering most aspects of the structure, molecular biology, pathogenesis, pathology, clinical features, epidemiology, diagnosis and immunology based on approximately 140 references from international research journals.     

Bovine leukocyte adhesion deficiency (BLAD): a review

Bovine leukocyte adhesion deficiency (BLAD) in Holstein cattle is an autosomal recessive congenital disease characterized by recurrent bacterial infections, delayed wound healing and stunted growth, and is also associated with persistent marked neutrophilia. The molecular basis of BLAD is a single point mutation (adenine to guanine) at position 383 of the CD18 gene, which caused an aspartic acid to glycine substitution at amino acid 128 (D128G) in the adhesion molecule CD18. Neutrophils from BLAD cattle have impaired expression of the beta2 integrin (CD11a,b,c/CD18) of the leukocyte adhesion molecule. Abnormalities in a wide spectrum of adherence dependent functions of leukocytes have been fully characterized. Cattle affected with BLAD have severe ulcers on oral mucous membranes, severe periodontitis, loss of teeth, chronic pneumonia and recurrent or chronic diarrhea. Affected cattle die at an early age due to the infectious complications. Holstein bulls, including carrier sires that had a mutant BLAD gene in heterozygote were controlled from dairy cattle for a decade. The control of BLAD in Holstein cattle by publishing the genotypes and avoiding the mating between BLAD carriers was found to be successful. This paper provides an overview of the genetic disease BLAD with reference to the disease in Holstein cattle.     

Control strategies for ostertagiasis

There are currently four major options for control of ostertagiasis and other ruminant gastrointestinal parasites. These are the traditional, suppressive, integrated and strategic approaches. Strategic dosing is the most realistic and beneficial approach for most regions of the world, including the U.S.A. It is effective, practical, labor-saving and can yield big economic returns. Today this approach is even more appropriate because of important advances in the technology of controlled release and pulse-release devices. Top priority in worm control programs should be given to dairy replacement heifers in their first year at pasture and to beef calves in the immediate post-weaning period. This is preferable to recommendations for blanket treatment of all beef and dairy cattle, regardless of age, immune status or pasture infectivity. An anthelmintic overkill is both wasteful and potentially harmful in that it increases the selection pressure for drug resistance. It is suggested that better dissemination of information is needed to make producers aware of the benefits of strategic dosing programs. This would eliminate much of the confusion about parasite control and focus attention on simple and effective programs that could significantly reduce current losses to the livestock industries.     

Drug resistance in ostertagiasis

Benzimidazole- and levamisole-resistant Ostertagia circumcincta from sheep have been reported from several countries, but there are no reports of anthelmintic-resistant O. ostertagi in cattle, where resistance has been confirmed in controlled trials. The reasons for this may include (1) the biology of the worm, (2) avoidance of drug action by inhibition, (3) host metabolism of drugs, (4) less anthelmintic used in cattle than in sheep, (5) high costs of controlled trials, (6) lack of adequate in vitro tests to detect resistant worms and (7) lack of reporting of anthelmintic failures. Reduced efficacy of the anthelmintics levamisole and thiabendazole to adult O. ostertagi and of modern benzimidazoles to the inhibited L4 larvae has been reported in cattle. This latter effect might, in part, represent a stage-specific expression of resistance. Although anthelmintic resistance in O. ostertagi is not known to be a problem at present, it could potentially become a serious issue.     

Preliminary report: immunodiagnosis of pre-type II ostertagiasis

Ostertagia ostertagi soluble antigens were prepared by gel electrophoresis and electrophoretic transfer onto nitrocellulose for enzyme-linked immunosorbent assays with serum probes. Serologic responses to L3-derived antigen of approximately 32 kDa may be unique and diagnostic for cattle harboring inhibited larvae, or pre-Type II ostertagiasis. Specificity was evaluated by comparing sera from pre-Type II cattle to sera from Type I, uninfected, Fascioloides magna infected, Fasciola hepatica infected or Cooperia oncophora infected cattle.     

Bovine brucellosis – a comprehensive review

Brucellosis is a zoonotic disease of great animal welfare and economic implications worldwide known since ancient times. The emergence of brucellosis in new areas as well as transmission of brucellosis from wild and domestic animals is of great significance in terms of new epidemiological dimensions. Brucellosis poses a major public health threat by the consumption of non-pasteurized milk and milk products produced by unhygienic dairy farms in endemic areas. Regular and meticulous surveillance is essentially required to determine the true picture of brucellosis especially in areas with continuous high prevalence. Additionally, international migration of humans, animals and trade of animal products has created a challenge for disease spread and diagnosis in non-endemic areas. Isolation and identification remain the gold standard test, which requires expertise. The advancement in diagnostic strategies coupled with screening of newly introduced animals is warranted to control the disease. Of note, the diagnostic value of miRNAs for appropriate detection of B. abortus infection has been shown. The most widely used vaccine strains to protect against Brucella infection and related abortions in cattle are strain 19 and RB51. Moreover, it is very important to note that no vaccine, which is highly protective, safe and effective is available either for bovines or human beings. Research results encourage the use of bacteriophage lysates in treatment of bovine brucellosis. One Health approach can aid in control of this disease, both in animals and man.