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PubMed2005

Disseminated intravascular coagulation in cattle with abomasal displacement.

The purpose of the study was to evaluate haemostatic function in cattle with abomasal displacement (AD) and to reflect the occurrence of disseminated intravascular coagulation (DIC). Ten adult cattle with left displacement of abomasum (LDA) (group I), 10 adult cattle with right displacement of abomasum with volvulus (RDA) (group II) and 10 clinically healthy adult cattle (control group) were used as material. Numbers of platelets (PLT) and coagulation tests (activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), serum fibrin/fibrinogen degradation products (FDPs), fibrinogen) were measured before the surgical treatment of cattle with LDA and RDA. APTT was prolonged only in group II compared with the control and group I (p<0.05). However, when the individual values of coagulation profiles of each cow were evaluated, two cattle in group I and three cattle in group II had at least three abnormal coagulation profiles, which reflect the occurrence of DIC. These cattle died after surgical treatment. The two cattle with LDA had abnormal APTT, FDPs and PLT values; three cattle with RDA had abnormal APTT, PT, TT, FDPs and PLT values. APTT (5 cases), FDPs (5 cases) and thrombocytopenia (5 cases) were the three most common abnormal tests on coagulation profile in the cattle with LDA and RDA. The results of the study indicate that cattle with AD had a spectrum of haemostatic dysfunction and that DIC was a significant risk factor for mortality.

Abomasum↗

PubMed1999

Effect of breed of cattle on innate resistance to infection with Anaplasma marginale transmitted by Boophilus microplus.

OBJECTIVE: To assess the innate resistance of and transmission in naive Bos taurus cross Bos indicus and purebred Bos indicus cattle when placed in a paddock with cattle infected with Anaplasma marginale and carrying Boophilus microplus ticks. DESIGN: A group of 49 purebred B indicus, and 48 B indicus cross B taurus (50%, F1 generation) 24-month-old steers were kept in the same paddock with cattle artificially infected with a virulent isolate of A marginale and Boophilus microplus. The cattle were seronegative for A marginale at the start of the trial but had previously been exposed to Babesia bovis and B bigemina. PROCEDURE: Cattle were inspected twice weekly for 118 days. Whole blood, blood smears and serum samples were collected from the cattle on day 37 after exposure and then at regular intervals to day 83 after exposure to measure packed-cell volumes, parasitaemias and antibody titres to A marginale. Any animals that met preset criteria were treated for anaplasmosis. On day 83 all cattle were treated with an acaricide and cattle infected with A marginale were removed from the rest of the group. RESULTS: A marginale was detected in blood smears from 14 crossbred and 9 B indicus steers between days 56 and 72 after exposure. Five and two of the infected crossbred and B indicus steers required treatment, respectively. One of the Bos indicus cattle died as a result of the A marginale infection despite treatment. Antibodies to A marginale were detected in the 23 infected cattle. The mean packed-cell volume depression was 40 and 37% in the affected crossbred and Bos indicus groups, respectively. There was no significant difference detected in susceptibility between these two groups. CONCLUSIONS: Innate resistance of purebred B indicus and crossbred cattle was not significantly different. The results confirm that purebred B indicus and crossbred cattle are sufficiently susceptible to warrant the use of vaccination against Anaplasma infections.

Anaplasma↗

PubMed2004

Cytokine gene expression in peripheral blood mononuclear cells and tissues of cattle infected with Mycobacterium avium subsp. paratuberculosis: evidence for an inherent proinflammatory gene expression pattern.

In cattle and other ruminants, infection with the intracellular pathogen Mycobacterium avium subsp. paratuberculosis results in a granulomatous enteritis (Johne's disease) that is often fatal. The key features of host immunity to M. avium subsp. paratuberculosis infection include an appropriate early proinflammatory and cytotoxic response (Th1-like) that eventually gives way to a predominant antibody-based response (Th2-like). Clinical disease symptoms often appear subsequent to waning of the Th1-like immune response. Understanding why this shift in the immune response occurs and the underlying molecular mechanisms involved is critical to future control measures and diagnosis. Previous studies have suggested that M. avium subsp. paratuberculosis may suppress gene expression in peripheral blood mononuclear cells (PBMCs) from infected cows, despite a continued inflammatory reaction at sites of infection. In the present study, we tested the hypothesis that exposure to M. avium subsp. paratuberculosis suppresses a proinflammatory gene expression pattern in PBMCs from infected cows. To do this, we examined expression of genes encoding interleukin-1alpha (IL-1alpha), IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p35, IL-16, and IL-18, as well as genes encoding gamma interferon (IFN-gamma), transforming growth factor beta (TGF-beta), and tumor necrosis factor alpha (TNF-alpha), in PBMCs, intestinal lesions, and mesenteric lymph nodes of cattle naturally infected with M. avium subsp. paratuberculosis. Cytokine gene expression in these cells and tissues was compared to expression in similar cells and tissues from control uninfected cattle. Our comprehensive results demonstrate that for most cytokine genes, including the genes encoding IFN-gamma, TGF-beta, TNF-alpha, IL-1alpha, IL-4, IL-6, IL-8, and IL-12p35, differential expression in PBMCs from infected and control cattle did not require stimulation with M. avium subsp. paratuberculosis. In fact, stimulation with M. avium subsp. paratuberculosis tended to reduce the differential expression observed in infected and uninfected cows for genes encoding IFN-gamma, IL-1alpha, and IL-6. Only IL-10 gene expression was consistently enhanced by M. avium subsp. paratuberculosis stimulation of PBMCs from subclinically infected cattle. In ileal tissues from M. avium subsp. paratuberculosis-infected cattle, expression of the genes encoding IFN-gamma, TGF-beta, IL-5, and IL-8 was greater than the expression in comparable tissues from control uninfected cattle, while expression of the gene encoding IL-16 was lower in tissues from infected cattle than in control tissues. Mesenteric lymph nodes draining sites of M. avium subsp. paratuberculosis infection expressed higher levels of IL-1alpha, IL-8, IL-2, and IL-10 mRNA than similar tissues from control uninfected cattle expressed. In contrast, the genes encoding TGF-beta and IL-16 were expressed at lower levels in lymph nodes from infected cattle than in tissues from uninfected cattle. Taken together, our results suggest that cells or other mechanisms capable of limiting proinflammatory responses to M. avium subsp. paratuberculosis develop in infected cattle and that a likely place for development and expansion of these cell populations is the mesenteric lymph nodes draining sites of infection.

Animals↗

PubMed1983

Use of a fluorometric immunoassay to determine antibody response to Pasteurella haemolytica in vaccinated and nonvaccinated feedlot cattle.

A retrospective study of the antibody response to Pasteurella haemolytica was conducted by using sera from 368 feedlot cattle divided among five experiments. In three experiments, live vaccines or a bacterin were administered to some of the cattle and others were left as nonvaccinated controls. In two experiments, cattle were not vaccinated. Clinical signs of disease with subsequent recovery developed in 48.0% of the cattle, and 10.3% of the cattle died. Vaccination had no apparent effect on morbidity or mortality. At the time of purchase, 78% of the cattle had low antibody titers (less than 25) as measured by a quantitative fluorometric immunoassay. In most groups of cattle (both vaccinated and nonvaccinated), there was a significant rise in mean antibody titers between the time of purchase and days 28 to 32 in the feedlot. The antibody titers at the time of shipment and health status of cattle. The antibody ratios were significantly greater for cattle that became sick and then recovered compared with those of cattle that remained healthy. Although significance could not be established, antibody titers at the time of shipment were higher for cattle that remained healthy compared with cattle that became sick and then recovered.

Animals↗

PubMed2006

Different prion disease phenotypes result from inoculation of cattle with two temporally separated sources of sheep scrapie from Great Britain.

BACKGROUND: Given the theoretical proposal that bovine spongiform encephalopathy (BSE) could have originated from sheep scrapie, this study investigated the pathogenicity for cattle, by intracerebral (i.c.) inoculation, of two pools of scrapie agents sourced in Great Britain before and during the BSE epidemic. Two groups of ten cattle were each inoculated with pools of brain material from sheep scrapie cases collected prior to 1975 and after 1990. Control groups comprised five cattle inoculated with sheep brain free from scrapie, five cattle inoculated with saline, and for comparison with BSE, naturally infected cattle and cattle i.c. inoculated with BSE brainstem homogenate from a parallel study. Phenotypic characterisation of the disease forms transmitted to cattle was conducted by morphological, immunohistochemical, biochemical and biological methods. RESULTS: Disease occurred in 16 cattle, nine inoculated with the pre-1975 inoculum and seven inoculated with the post-1990 inoculum, with four cattle still alive at 83 months post challenge (as at June 2006). The different inocula produced predominantly two different disease phenotypes as determined by histopathological, immunohistochemical and Western immunoblotting methods and biological characterisation on transmission to mice, neither of which was identical to BSE. Whilst the disease presentation was uniform in all scrapie-affected cattle of the pre-1975 group, the post-1990 inoculum produced a more variable disease, with two animals sharing immunohistochemical and molecular profile characteristics with animals in the pre-1975 group. CONCLUSION: The study has demonstrated that cattle inoculated with different pooled scrapie sources can develop different prion disease phenotypes, which were not consistent with the phenotype of BSE of cattle and whose isolates did not have the strain typing characteristics of the BSE agent on transmission to mice.

Animals↗

PubMed1975

Occurrence of gastrointestinal parasites in Georgia cattle.

A survey of gastrointestinal nematodes in Georgia cattle was conducted from 1968 through 1973 from actual worm counts from viscera of 145 slaughtered beef cattle or from egg counts made from fecal samples from 3,273 beef and 100 dairy cattle. Beef cattle were grouped as calves, yearlings, and cows. Dairy cattle were grouped as calves, replacement heifers, and cows. Results of fecal examinations positive; 99.5, 99.3, 99.6, and 41.2% of the calves, yearlings, drylot calves, and cows, respectively, were infected with nematodes. Seventy-four percent of the eggs counted were of the Cooperia-Ostertagia - Trichostrongylus complex (C-O-T) and 21% were of the Haemonchus-Oesophagostomum complex (H-O). Sixty-nine percent of the infective larvae recovered from coprocultures made from composite samples were of Ostertagia ostertagi. Moniezia (tapeworm) eggs were seen in 16% of all the samples, more predominantly in the calves (24%) and less in the cows (smaller than 1%). Oocysts of Eimeria spp were detected in 61% of the cattle, more predominantly in younger cattle. All cattle necropsied were infected with O ostertagi. Other nematodes present, in order of decreasing frequency, were Trichostrongylus axei (97%), Haemonchus placei (66%), Cooperia punctata (63%), Cooperia oncophora (61%), Oesophagostomum radiatum (61%), Bunostomum phlebotomum (55%), Trichostrongylus colubriformis (36%), Cooperia pectinata (28%), Trichuris spp (17%), Nematodirus spathiger (9%), and Capillaria bovis (4%). Tapeworms were also recovered from 19% of the cattle at necropsy. Seventy-eight percent of the dairy cattle were positive; 98% of the calves, 80% of the heifers, and 58% of the cows. Cooperia-Ostertagia-Trichostrongylus eggs were detected in 78% and H-O eggs in 38% of the cattle. Eimeria oocysts were detected in 71% of all the dairy cattle, and Moniezia eggs were in 10% of the calves and 7% of the heifers.

Animals↗

PubMed1991

Mass screening of cattle sera against 14 infectious disease agents, using an ELISA system for monitoring health in livestock.

Mass screening ELISA methods were developed for testing cattle serum for antibodies against 14 common livestock diseases simultaneously. The absorbance values were transformed to a %ELISA (spectrophotometric antibody end point) by a computer interfaced with a microplate reader. A histogram indicating a cutoff point and a report for the veterinarian also was generated. The computer program produced a print-out of the antibody profile for each animal tested, the antibody concentration against each disease, and a histogram (antibody profile) showing the prevalence of each disease in the herd. Serum samples were obtained from 1,953 cattle, including 880 dairy cattle from 10 herds and 1,073 beef cattle from 20 herds. These samples were obtained from June 1988 through June 1989. The highest antibody prevalence was against bluetongue virus. Of the 1,953 cattle tested, 1,223 (63%) were seropositive for bluetongue virus, including 502 (57%) of the dairy cattle and 721 (67%) beef cattle. Other antibody prevalences, in descending order, were: rotavirus (44%), Pasteurella spp (25%), Leptospira spp and Haemophilus spp (22%), Mycoplasma spp (18%), parainfluenza virus (17%), Campylobacter spp (16%), Anaplasma marginale (15%), bovine leukosis virus (13%), Brucella spp (8%), Mycobacterium paratuberculosis (8%), bovine viral diarrhea virus (3%), and infectious bovine rhinotracheitis virus (3%). Major differences in antibody prevalence between dairy and beef cattle were that only 4% of the dairy cattle were seropositive for A marginale, compared with 25% of the beef cattle, and conversely, 29% of the dairy cattle were seropositive for bovine leukosis virus, compared with 1% of the beef cattle.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1981

Comparative lymphocyte stimulation studies on whole blood from vaccinated and nonvaccinated cattle with paratuberculosis.

The lymphocyte stimulation test was evaluated in the diagnosis of bovine paratuberculosis, using whole blood samples from cattle. These samples were incubated with a purified protein derivative of Mycobacterium paratuberculosis. Samples from vaccinated and nonvaccinated cattle from paratuberculosis-free herds and from paratuberculous herds were used. Vaccinated and nonvaccinated groups from the paratuberculous herds each included fecal culture-positive cattle, fecal culture-negative cattle, and calves. All groups included some cattle with a stimulation index (SI) greater than or equal to 2, and all groups except 2 of the 4 vaccinated groups had some cattle with a SI less than or equal to 2. In paratuberculosis-free herds, 16% of the nonvaccinated cattle had a SI greater than or equal to 2, and 0.7% had a SI greater than or equal to 4. In paratuberculous herds, 42% of the nonvaccinated cattle that were negative on fecal culture had a SI greater than or equal to 2 and 24% had a SI greater than or equal to 4. Vaccinated cattle greater than 1 year old could not be distinguished from infected cattle by means of the lymphocyte stimulation test. If a SI of 2 or 4 had been used as a basis to cull individual animals, some paratuberculous cattle would have been identified incorrectly as noninfected, and some paratuberculosis-free cattle would have been identified incorrectly as infected.

Animals↗

PubMed1995

Repeat laparotomy for gastrointestinal disorders in cattle: 57 cases (1968-1992).

A study was conducted to investigate indications for, typical findings during, and outcome of repeat laparotomies in 57 cattle with gastrointestinal disorders. Cattle were grouped according to the reason the initial laparotomy had been performed. Group-1 cattle (n = 46) had had left or right displacement of the abomasum (LDA or RDA) or right volvulus of the abomasum. Group-2 cattle (n = 10) had had ruminal, reticular, or abomasal obstruction or perforation. Group-3 cattle (n = 7) had had obstruction, volvulus, distention, or perforation of the small or large intestine. Median interval between laparotomies was 1 month (range, 1 day to 38 months). Intraoperative findings during repeat laparotomy in group-1 cattle included LDA (n = 18), RDA (9), right volvulus of the abdomen (5), pneumoperitoneum (1), diffuse abdominal adhesions (1), cecal adhesions (1), adhesions of the rumen to the body wall (1), abscess in the cranial portion of the abdomen (1), reticular adhesions (1), localized necrosis (1), and idiopathic rumen distention (1). Intraoperative findings during repeat laparotomy in group-2 cattle included abscess in the cranial portion of the abdomen (4), no abnormalities (1), distended rumen (1), ruptured abomasum (1), recurrent abomasal impaction (1), diffuse abdominal adhesions (1), and pyloric fat necrosis (1). Intraoperative findings during repeat laparotomy in group-3 cattle included LDA (3), RDA (1), cecal volvulus (1), anastomotic rupture (1), and impacted colocolostomy (1). Seven cows and 1 calf underwent additional repeat laparotomies. Forty-four (77%) of the 57 cattle were discharged following final laparotomy. Fourteen of the 20 group-1 cattle, 1 of the 6 group-2 cattle, and 2 of the 3 group-3 cattle for which follow-up information was available were productive after repeat laparotomy.

Abomasum↗

PubMed1996

Coronavirus isolation from nasal swab samples in cattle with signs of respiratory tract disease after shipping.

OBJECTIVE: To monitor the prevailing viral respiratory tract infections in cattle after transportation to feedlots. ANIMALS: 100 cattle with signs of respiratory tract disease on arrival at 2 feedlots. PROCEDURES: Nasal swab samples were obtained from each animal and were used for inoculation of defined cell culture systems that detected bovine viruses known to cause respiratory tract infections, as well as viruses previously not recognized as respiratory pathogens for cattle. RESULTS: Bovine respiratory coronaviruses were isolated from 38 of the 100 cattle, including 6 of 50 cattle from California, 22 of 31 cattle from Oklahoma, 6 of 11 cattle from Texas, and 4 of 8 cattle of unknown origin. Parainfluenza 3 viruses also were isolated from 5 California cattle, but other bovine viruses were not detected. CLINICAL IMPLICATIONS: The high rate of coronavirus isolations from feedlot cattle with signs of respiratory tract disease implied wide distribution and high susceptibility among cattle to this infection, which had not been detected by use of viral isolation systems in previous etiologic evaluations of feedlot cattle affected with bovine respiratory disease complex.

Animals↗

PubMed1994

Oviposition and development of face flies in dung from cattle on herbage and supplemented herbage diets.

Dung was collected from Angus cattle (Bos taurus L.) fed (ad libitum) hays of endophyte-free (EF) and endophyte (Acremonium coenophialum Morgan-Jones and Gams) infected (EI) tall fescue (Festuca arundinacea Schreb.), smooth bromegrass (Bromus inermis Leyss.), red clover (Trifolium pratense L.), alfalfa (Medicago sativa L.), and alfalfa-smooth bromegrass (1:1 w/w) and green-chopped Kentucky bluegrass (Poa pratensis L.). Samples of dung were subsequently collected from the same animals offered the same herbage diets supplemented each day with ground maize (Zea mays L.) kernels at 0.35 kg per body weight. Dung from both sources were used in bioassays to establish oviposition preferences of face flies (Musca autumnalis De Geer). When offered dung from herbage diets, face flies deposited 38.3% of their eggs on dung derived from EF tall fescue diets, 9.9% on dung from EI tall fescue diets, 21.0% on dung from alfalfa diets, 7.4% on dung from red clover diets and 22.8% on dung from alfalfa-bromegrass diets. Face flies avoided ovipositing in dung from cattle ingesting bromegrass hay and Kentucky bluegrass green-chop. Supplements increased oviposition preference of face flies for dung from cattle ingesting Kentucky bluegrass greenchop to 19.1% at the expense of oviposition on dung from cattle ingesting alfalfa hay diets (4.5%), otherwise, they had little effect on oviposition preference ranking. Growth and development of first instar larvae of face flies was also measured in bioassays of dung from cattle on herbage and supplemented herbage diets. The presence of endophyte reduced pupation in dung from cattle on tall fescue hay diets from 86.3 to 79.8% and from 90.1 to 73.2% in dung from cattle on supplemented tall fescue hay diets. Pupal liveweights averaged 27.5 mg on dung from cattle on EF tall fescue diets, 22.1 mg from dung of cattle on EI tall fescue diets, 22.2 mg from dung of cattle on supplemented EF tall fescue diets and 24.0 mg from dung of cattle on supplemented EI tall fescue diets. Eclosion and the sex ratio of adults were not affected by dung from cattle on different source diets.

Animal Feed↗

PubMed1999

Analysis of erythropoietin and erythropoietin receptor genes expression in cattle during acute infection with Trypanosoma congolense.

Acute Trypanosoma congolense infection induced moderate, transient anemia in N'Dama cattle (trypanotolerant) and severe anemia in Boran cattle (trypanosusceptible). Erythropoietin receptor (EpoR) was cloned and sequenced from the two breeds of cattle. A single position mutation of Tyr in the Boran to His in the N'Dama predicted amino acid sequence was revealed. The mRNA transcription of erythropoietin (Epo) in kidneys and EpoR in the bone marrow of infected cattle was determined by competitive reverse transcription and the polymerase chain reaction (RT-PCR). Though Epo mRNA transcription increased in the kidneys during infection, the increase was not significantly different (p>0.05) between the two breeds of infected cattle. The level of EpoR transcripts in the bone marrow of infected N'Damas was significantly higher (p<0.05) than that detected in the marrows from infected Boran cattle. While infection seem to increase levels of transcription of IL-1alpha and beta, and TNFalpha in kidneys from both Boran and N'Dama cattle, no significant difference was detected in the level of mRNAs of these cytokines in the kidney from the two breed of cattle. The amount of IFNgamma mRNA transcripts were not changed with infection in N'Dama cattle, while on the contrary a significant higher levels of IFNgamma was found in kidneys from infected Boran cattle as compared to the other groups. A significant (p<0.05) increase in the levels of IL-1alpha and beta, and IFNgamma mRNA transcripts were detected in the marrows of infected Borans as compared to the infected N'Dama cattle. In this study the increase in the level of TNFalpha mRNA in the marrows of the two infected breeds was not different. This implies there is no negative effect of TNFalpha on hematopoiesis during acute infection. These findings suggest that the levels of Epo and EpoR in the infected Boran cattle were inadequate for their degree of anemia, which might be due in part to high expression of IFNgamma during acute infection with T. congolense.

Acute Disease↗

PubMed1988

Immunization of cattle using varying infective doses of Theileria parva lawrencei sporozoites derived from an African buffalo (Syncerus caffer) and treatment with buparvaquone.

A Theileria parva lawrencei isolate in the form of a sporozoite stabilate, derived by feeding clean Rhipicephalus appendiculatus nymphal ticks on an African buffalo (Syncerus caffer) captured in the Laikipia District, Kenya, was inoculated into groups of cattle at dilutions between 10(0) and 10(-3). Groups of 3 cattle infected with 1 ml inocula at 10(0), 10(-1) and 10(-2) dilutions were treated with 2.5 mg/kg body weight of buparvaquone on day 0 and similar groups were left untreated to act as controls. An additional group, given 10(0) dilution of the stabilate, was treated with buparvaquone on day 8 post-inoculation. It was found that all control cattle inoculated with the stabilate at dilutions between 10(0) and 10(-2) became infected, but only 2 out of 3 cattle developed patent infections at 10(-3) dilution. All 3 control cattle receiving 10(0) dilution died of theileriosis, 2 at 10(-1) and 10(-2) dilutions, and 1 at 10(-3) dilution died. Buparvaquone treatment on day 0 at 10(0) dilution resulted in the survival of 2 of 3 cattle and all the cattle at 10(-1) and 10(-2) dilutions. All the surviving cattle eventually developed a significant serological response against T. parva in the indirect fluorescent antibody test, except 1 in the 10(-3) dilution group, and were immune to homologous challenge when tested 3 months later with a lethal inoculum of stabilate, except 2 cattle in the 10(-3) dilution group. As a result of a theileriosis problem at about day 60 after inoculation in 2 cattle given 10(-2) dilution of stabilate and buparvaquone treatment on day 0, an additional 5 cattle were given 10(-2) dilution of stabilate and developed a good immunity after buparaquone treatment. None was shown to develop the carrier state. Treatment with buparvaquone on day 8 after infection with 10(0) dilution of stabilate was not successful since 2 died. The stabilate used was shown to produce reproducible infection in cattle at different dilutions.

Animals↗

PubMed1989

Theilerial parasites isolated from carrier cattle after immunization with Theileria parva by the infection and treatment method.

Groups of cattle were immunized with 10(-2) dilutions of sporozoite stabilates of Theileria parva lawrencei derived from African buffaloes either alone or in combination with Theileria parva parva derived from cattle and concomitant treatment with either long or short-acting formulations of oxytetracyline. At 90 or 120 days after infection, uninfected Rhipicephalus appendiculatus nymphal ticks were applied to individual immunized cattle and the resultant adults ticks were applied to individual susceptible cattle. Theilerial infection developed from ticks fed on 6 out of 11 animals investigated for evidence of a carrier state. Two additional animals were shown by cell-culture isolation to have persistent theilerial infections. Nine cattle infected with the parasites from carrier animals were treated with paravaquone and 7 recovered. These recovered cattle were then challenged with the original immunizing stabilates at 10 degrees dilution together with the original immunized and carrier cattle. Six out of 7 cattle which had recovered from carrier-derived infection succumbed to this challenge and died but none of the original immunized cattle showed theilerial reactions. When a carrier-derived sporozoite stabilate was used to challenge cattle immune to the original immunizing parasite, they proved to be immune. Cattle immune to the carrier-derived parasites were all immune to challenge with the original parasite. A monoclonal antibody profile against T. parva schizonts isolated by cell culture from samples of the experimental animals did not appear to be sensitive enough to determine the antigenic differences between the carrier-derived parasite and the original immunizing parasite. Indications are that the carrier state is not likely to produce new antigenic strains which would be dangerous to immunized cattle.

Animals↗

PubMed2000

The use of skin delayed-type hypersensitivity as an adjunct test to diagnose brucellosis in cattle: a review.

Brucellosis, caused by bacteria of the genus Brucella, is a contagious disease that causes economic loss to owners of domestic animals due to loss of progeny and milk yield. Because cattle, sheep, goats, and to a lesser extent pigs are considered to be the source of human brucellosis, serological tests have been used to screen domestic animals for antibodies against Brucella. Although the serological tests helped to eradicate brucellosis in many countries, serological tests are not always adequate to detect latent carriers of Brucella. Therefore, the use of the skin delayed-type hypersensitivity (SDTH) test, which is independent of circulating antibodies, might improve the diagnosis of brucellosis. In the literature, however, there are conflicting reports as to the value of the SDTH test for the diagnosis of brucellosis. Some studies consider the test unreliable, whereas others advocate its use because it detects brucellosis earlier than serological tests. The objectives of this study were therefore to assess the characteristics of the SDTH test, to select a Brucella strain that will yield a suitable brucellin for use in the field, and to determine whether the use of serological tests in combination with the SDTH test improves the detection of brucellosis. The results of this study clearly show that the SDTH test detects latent carriers of Brucella and confirms brucellosis in cattle with ambiguous serological test results. Brucellins prepared from smooth or mucoid strains of Brucella are better suited for use in the field than brucellins prepared from rough strains because they detect brucellosis in cattle with acute as well as chronic infection. The SDTH test is highly specific (99.3% specificity), and repeated testing of naive cattle or cattle infected with microorganisms that serologically cross-react with Brucella does not sensitize cattle to subsequent SDTH tests. However, it is possible that some naive cattle may serologically react to the injection of brucellin. The effect of these serological reactions on the sero-diagnosis of brucellosis is limited, because cattle may only now and then react serologically either with the serum agglutination test (SAT) or the complement fixation test (CFT). Nevertheless, cattle infected with microorganisms that serologically cross-react with Brucella may test seropositive for brucellosis 4 to 7 weeks after injection of brucellin, depending on the cross-reacting microorganism. The value of the SDTH test for the diagnosis of brucellosis was demonstrated after an outbreak of brucellosis. When the SDTH test was used in combination with SAT and CFT at diagnostic threshold > or =2 mm or > or =1 mm (increase in skinfold thickness), respectively, 39/44 (88%) or 42/44 (95%) of the infected cattle were detected compared with only 27/44 (61%) when SAT and CFT were used. When cattle in areas of low prevalence or in areas free from brucellosis are tested with the SDTH test an increase > or =2 mm in skinfold thickness should be considered indicative of infection. When the control and eradication of brucellosis is based on test-and-slaughter, an increase of > or =1 mm in skinfold thickness should be considered indicative of infection. Repeated serological testing complemented with the SDTH test in this programme will shorten the quarantine (movement control) period of a suspect herd, limiting the financial loss incurred during outbreaks of the disease. Consequently, since the SDTH test usually does not interfere with the serological diagnosis and can safely be used to establish the infection status of cattle in a suspect herd, it is opportune to consider adding the SDTH test to the procedure currently used to diagnose brucellosis in individual animals.

Animals↗

PubMed2004

Could insecticide-treated cattle reduce Afrotropical malaria transmission? Effects of deltamethrin-treated Zebu on Anopheles arabiensis behaviour and survival in Ethiopia.

Anopheles arabiensis Patton (Diptera: Culicidae) is the most widespread vector of malaria in the Afrotropical Region. Because An. arabiensis feeds readily on cattle as well as humans, the insecticide-treatment of cattle--as employed to control tsetse (Diptera: Glossinidae) and ticks (Acari: Ixodidae)--might simultaneously affect the malaria vectorial capacity of this mosquito. Therefore, we conducted field experiments in southern Ethiopia to establish whether Zebu cattle (Bos indicus L.) treated with a pour-on pyrethroid formulation of 1% deltamethrin, widely used to control ticks and tsetse, would be effective against An. arabiensis or cause the female mosquitoes to feed more frequently on humans, due to behavioural avoidance of insecticide-treated cattle. Contact bioassays (3 min exposure) showed that the insecticide remained effective for about 1 month (kill rate > 50%) against mosquitoes feeding on the flanks of treated cattle. A novel behavioural assay demonstrated that An. arabiensis readily fed on insecticide-treated cattle and were not deflected to human hosts in the presence of treated cattle. DNA-fingerprinting of bloodmeals revealed that An. arabiensis naturally feeds most frequently on older animals, consistent with the established practice of applying insecticide only to older cattle, while allowing younger untreated animals to gain immunity against infections transmitted by ticks. These encouraging results were tempered by finding that > 90% of An. arabiensis, An. pharoensis and An. tenebrosus females feed on the legs of cattle, farthest from the site of pour-on application along the animal's back and where the treatment may be least residual due to weathering. Observations of mosquitoes feeding naturally on insecticide-treated cattle showed that the majority of wild female anophelines alighted on the host animal for less than 1 min to feed, with significantly shorter mean duration of feeding bouts on insecticide-treated animals, and the effective life of the insecticide was only 1 week. Thus the monthly application of deltamethrin to cattle, typically used to control tsetse and ticks, is unlikely to be effective against An. arabiensis populations or their vectorial capacity. Even so, it seems likely that far greater impact on anopheline mosquitoes could be achieved by applying insecticide selectively to the legs of cattle.

Animals↗

PubMed2003

Forage feeding to reduce preharvest Escherichia coli populations in cattle, a review.

Although Escherichia coli are commensal organisms that reside within the host gut, some pathogenic strains of E. coli can cause hemorrhagic colitis in humans. The most notable enterohemorrhagic E. coli (EHEC) strain is O157:H7. Cattle are asymptomatic natural reservoirs of E. coli O157:H7, and it has been reported that as many as 30% of all cattle are carriers of this pathogen, and in some circumstances this can be as high as 80%. Feedlot and high-producing dairy cattle are fed large grain rations in order to increase feed efficiency. When cattle are fed large grain rations, some starch escapes ruminal microbial degradation and passes to the hind-gut where it is fermented. EHEC are capable of fermenting sugars released from starch breakdown in the colon, and populations of E. coli have been shown to be higher in grain fed cattle, and this has been correlated with E. coli O157:H7 shedding in barley fed cattle. When cattle were abruptly switched from a high grain (corn) diet to a forage diet, generic E. coli populations declined 1000-fold within 5 d, and the ability of the fecal generic E. coli population to survive an acid shock similar to the human gastric stomach decreased. Other researchers have shown that a switch from grain to hay caused a smaller decrease in E. coli populations, but did not observe the same effect on gastric shock survivability. In a study that used cattle naturally infected with E. coli O157:H7, fewer cattle shed E. coli O157:H7 when switched from a feedlot ration to a forage-based diet compared with cattle continuously fed a feedlot ration. Results indicate that switching cattle from grain to forage could potentially reduce EHEC populations in cattle prior to slaughter; however the economic impact of this needs to be examined.

Animal Feed↗

PubMed2004

Escherichia coli O157:H7 excretion by commercial feedlot cattle fed either barley- or corn-based finishing diets.

Effective preharvest control measures for Escherichia coli O157:H7 in cattle may significantly reduce the incidence of human disease caused by this organism. The prevalence and magnitude of fecal E. coli O157:H7 excretion was evaluated in 15 pens (300 to 500 cattle per pen) of commercial feedlot cattle fed a barley-based finishing ration and compared with that in 15 pens of cattle fed a corn-based ration. Average E. coli O157:H7 prevalence was 2.4% in barley-fed cattle and 1.3% in the corn-fed cattle (P < 0.05), and average magnitude of fecal E. coli O157:H7 excretion was 3.3 log CFU/g in the barley-fed cattle and 3.0 log CFU/g in the corn-fed cattle (P < 0.01). Corn-fed cattle had lower average fecal pH values (5.85) than did barley-fed cattle (6.51) (P < 0.01), and the average total generic fecal E. coli concentration in this group of animals (6.24 log CFU/g) was greater than that in the barley-fed cattle (5.55 log CFU/g) (P < 0.01). Specific feed ingredients may impact the frequency and magnitude of fecal excretion of E. coli O157:H7 by cattle.

Animal Feed↗