Antigenic and genetic characterization ofTheileria sergenti

Tropical Animal Health and Production -     

Comparison of some characteristics ofTheileria sergenti andTheileria annulata

Tropical Animal Health and Production -     

Studies on the diagnosis ofTheileria annulata infection by ELISA

Tropical Animal Health and Production -     

Rapid quantitative assessment ofTheileria infection in ticks

A simplified method for methyl green pyronin staining is described for Theileria parva and T. annulata in whole salivary glands of Rhipicephalus appendiculatus and Hyalomma anatolicum subspecies respectively. The stain gives results comparable with Feulgen staining and can be used after the ticks have been in cold storage for 3 days. There is considerable variability in the rate and intensity of infection of these ticks with theilerial parasites and it is concluded that the method permits large samples (60 ticks per person per day) to be examined to overcome this variability when assessing infection quantitatively.     

Control of Leptospira hardjo infection in beef cattle by whole-herd vaccination.

A whole-herd vaccination programme to control Leptospira hardjo infection was applied to a closed herd of approximately 800 beef cattle on the island of Luing in Scotland. An experimental vaccine was produced and the herd was vaccinated annually for five years. Progress was monitored by means of a catalytic model using data for age-specific serological prevalences and geometric mean titres. Any cattle introduced to the herd were subject to antibiotic treatment and quarantine, and at the end of the trial the whole herd was treated prophylactically with antibiotics to minimise the risk of residual infection. There was a progressive right shift in age-specific serological prevalences, and by the end of the trial all young stock entering the breeding herd were seronegative. The age-specific geometric mean titres demonstrated the cessation of an endemic cycle of hardjo infection in the herd. Birth cohort analysis supported the serological evidence of a high level of control, and bacteriological monitoring at the end of the trial indicated that hardjo had been eliminated from the herd.     

Slow infection control by vaccination: paratuberculosis

Classical causality models for infectious diseases have fulfilled an important role in the progress of medical sciences, however, new forms of association where weakly pathogenic agents cause widespread infections that mostly do not progress to disease, but that if they do so, cause protracted clinical courses where the host resources are exhausted fit better with the slow infection concept proposed over half a century ago. This model could show an infectious cause behind some diseases that have never fulfilled the conventional criteria. While new mechanisms of causation are defined, these diseases still need to be controlled to allow sustainable animal production. Here, I discuss the case of paratuberculosis control by vaccination as an example of the benefits of using a theoretically preventive treatment to modify the course of infection towards preventing clinical disease even though the infection itself might not be fully controlled.     

鸡球虫病的免疫控制

球虫一旦感染鸡并在其体内定居,就处于宿主免疫系统的监测下并设法建立寄生生活。球虫在鸡体内最长可持续生存14天,且几乎都位于宿主肠壁深层的细胞内,并完全依赖于宿主营养,最多可进行4代生长、增殖(无性生殖)的过程。鸡在感染后数小时即对球虫产生反应,大约4天即可产生特异性的保护性免疫反应,且足以限制再感染。免疫反应强度与许多因素有关,如感染剂量及感染虫种的特性等,但通常一次摄入少量卵囊即足以诱导能充分抵御再感染的免疫反应。虽然认为免疫接种是控制鸡球虫病的实用方法已有50多年,但在化学治疗的鼎盛时代,疫苗使用常被忽略,仅…     

通过接种疫苗减少致病性大肠杆菌感染

禽致病性大肠杆菌（Avian pathogenic Ecoli,APEC）是影响全球肉鸡生产行业的最具经济意义的疾病综合征。APEC是许多疾病的病因,主要作为条件致病菌出现于免疫抑制及随后的呼吸道病毒性感染之后,它既能感染种鸡又可影响商品肉鸡群。     

Assessment of criteria for improvement in Theileria orientalis sergenti infection tolerance

We examined the relationships between calf productivity, anemia and Theileria orientalis sergenti infection from records of 109 Japanese shorthorn calves during a grazing period and we quantified the relative importance of the T. orientalis sergenti infection‐resistance criteria used. A decrease in average parasitemia (AvePara) and an increase in average packed cell volume (AvePCV) would cause a decrease in the number of drug treatments. An increase in AvePCV would decrease the number of drug treatments more efficiently than a decrease in AvePara. An increase in AvePCV would cause an increase in dairy gain, while a decrease in AvePara would cause a decrease in dairy gain. Therefore, an improvement in the capacity to control anemia development would improve T. orientalis sergenti infection resistance more efficiently than an improvement in the capacity to control parasitemia development.     

Control of coccidiosis in chickens by vaccination

Control of coccidiosis in chickens has relied upon managerial measurements and the prophylactic use of coccidiostatic drugs. With the emergence of Eimeria strains that are resistant to these drugs the use and number of commercially available vaccines has increased. In this review various aspects that contribute to the development of coccidiosis are discussed, and an overview of the currently marketed coccidiosis vaccines is presented. Three groups of vaccines can be distinguished based on the characteristics of the Eimeria species included in the products: vaccines based on live virulent strains, vaccines based on live attenuated strains, and vaccines based on live strains that are relatively tolerant to the use of ionophores. These latter vaccines combine the early protective effect of ionophore treatment with the late protective effect of vaccination. The impact of future developments such as recombinant-DNA vaccines and changes in consumer's attitude towards broiler production are discussed.     

Specific DNA probe for the detection of Theileria sergenti infection in cattle

A simple procedure was developed for detection of Theileria sergenti infection on the basis of hybridization of parasite DNA with a specific probe. A genomic DNA library of T. sergenti constructed in pUC-18 was screened to detect clones containing the parasite's DNA sequences by colony and Southern hybridizations. Two positive DNA inserts were purified from the recombinant plasmids and used as probes labelled with 32P or non-isotopic reagent, biotin-11-dUTP. 32P-radiolabelled and non-radioactive probes appear to be sensitive enough to detect 15 pg (equivalent to 1,200 parasites) and 125 pg (equivalent to 10,000 parasites) of purified T. sergenti DNA, and in diluted T. sergenti-infected red blood cells, they are able to detect 8,000 parasites and 16,000 parasites, respectively.