Pig-shed air polluted by α-haemolytic cocci and ammonia causes subclinical disease and production losses

There is mounting evidence that bacteria originating from pigs degrade the environment of the pig shed and adversely affect the health of the animals and the pig-shed workers. α-haemolytic cocci (AHC) occur in pig-shed environments, but are regarded as commensals. Ammonia is also a component of the pig-shed environment, and is known to damage upper respiratory tract epithelia. The aim of this study was to determine whether polluted air in pig sheds adversely affected performance indicators in pigs. Modelling revealed a direct effect of AHC on voluntary feed intake and hence AHC are not commensal. No direct effect of ammonia on the pigs was detected, but the combination of AHC and ammonia stimulated the immune system in a progressive manner, and there were direct effects of immune stimulation on food intake and growth resulting in poorer feed-conversion efficiency, even though the effects remained subclinical. The authors conclude that exposure of the respiratory epithelia of pigs to viable AHC in the presence of ammonia redirects nutrients away from production and towards the immune system, explaining the impact of poor pig-shed hygiene on production parameters.

Helminth control using local resources in smallholder production systems of Asia

Practical helminth control in smallholder systems needs to match technical options with local knowledge, locally available animal and feed resources and the needs of both producers and consumers. Despite extensive research over many decades the uptake of new technology in these systems has been slow and limited to few farmers with access to good technical support. Investment by small holders is constrained by lack of regular market signals for livestock and livestock products. Examples of effective helminth control in cattle, buffalo, sheep, goat and pig systems show that effective control is possible using local resources and knowledge. Livestock systems in Asia are changing rapidly through industrialisation of production and consolidation of supply chains and retail markets, but smallholder systems, which are resilient and multipurpose, will remain important in rural areas and in peri-urban environments. They also provide a significant pathway for the poor to build assets and generate income. Helminth control in these systems will always vary greatly between farmers and systems and will need to be relatively simple and tailored to locally available resources. The public sector will continue to provide advice on appropriate genetics, to regulate drug importation, use and quality, and ensure novel helminth control options are investigated for local application and promotion to livestock producers. The private sector has the complementary role to develop clear market signals for livestock and livestock products, and make anthelmintics available in appropriate packages. Improved helminth control has the potential to increase the profitability and sustainability of all components of the livestock sector.

Carcinomas of the female genital tract occurring after pelvic irradiation: a report of 15 cases

The concept of postradiation sarcoma is widely appreciated, however carcinomas arising in previously irradiated fields, the putative "postradiation carcinoma," are less well understood. Fifteen patients who developed gynecological malignancies after pelvic radiation therapy were studied. Five of these patients had HPV-related tumors both pre- and post- irradiation. Ten were irradiated for cervical cancer, one for endometrial carcinoma, one for vulvar carcinoma, one for colon cancer and 2 for benign conditions. The mean and median latent periods from the initiation of radiation therapy to the development of the second malignancy were 22.8 and 19 years, respectively (22.4 and 19.5 years, respectively, for non-HPV-related cancers; 24 and 18 years for HPV-related cancers). The "postradiation" malignancies included 2 ovarian carcinomas, 5 vaginal carcinomas (3 invasive, 2 in situ), 4 endometrial carcinomas, one cervical carcinoma, one vulvar carcinoma, one distal urethral carcinoma, and one pelvic carcinoma of unclear primary site. Gynecological carcinomas may occur many years after pelvic irradiation. Although the evidence for a causative role is circumstantial, these tumors appear to have a similar latent period as postradiation sarcomas.

Treatment of sarcoptic mite infestation and mite hypersensitivity in pigs with injectable doramectin

Thirty-two pigs were infested experimentally with Sarcoptes scabiei var suis and allocated randomly to a medicated group (injected intramuscularly with 300 micrograms doramectin/kg) or an unmedicated group (injected intramuscularly with 1 ml saline/33 kg). They were observed daily for 15 minutes for signs of pruritus, and the ear lesions were assessed and skin scrapings examined for mites on days 7, 14, 21 and 28 after treatment. In the 16 pigs treated with doramectin the ear lesions resolved completely within 14 days, no mites were recorded on 15 of them on day 7 or on any of them on days 14, 21 and 28; pruritus was greatly reduced from day 7 onwards (range 0 to 0-62 rubbing episodes per pig per day) and papular skin lesions were absent from 15 of the pigs at slaughter on day 28. In comparison, the ear lesions in the 16 unmedicated pigs failed to resolve in 15 of them. Mites were present on 15 of them at different times during the experiment; the numbers of rubbing episodes ranged from 0.88 to 4.65 per pig per day and all the pigs had papular skin lesions at slaughter. In the unmedicated pigs, both the degree of pruritus and the presence and severity of papular skin lesions at slaughter were greater in those with zero or low mite counts than in those with high mite counts.

Humoral and cell-mediated immune responses in non-pregnant heifers following infection and vaccination with Brucella abortus

Humoral and cell-mediated-immune responses to Brucella abortus were observed in non-pregnant heifers following infection alone; infection followed by vaccination; vaccination followed by infection; and vaccination alone. The humoral responses, as measured by the Rose Bengal test (RBT), complement fixation test (CFT), indirect haemolysis test (IHLT) and the enzyme-linked immunosorbent assay (ELISA) tended to be immediate and transient following infection alone, infection following vaccination and vaccination alone. However, when vaccination was superimposed on infection, reactions were maintained for at least 2 years. The cell-mediated-immune (CMI) responses were assessed by the lymphocyte stimulation test. The responses occurred after the humoral responses had peaked and were present for periods of 6-22 weeks. However, the level of stimulation was greater following infection than following vaccination, and the response when vaccination was superimposed on infection was present for less than 6 months.

Evaluation of an enzyme linked-immunosorbent assay for the diagnosis of Brucella ovis infection in rams

A simple enzyme linked immunosorbent assay (ELISA) was developed for the serological diagnosis of Brucella ovis infections in rams. Serums from brucellosis accredited-free flocks and flocks known to be infected with B. ovis were tested and the results correlated with warm complement fixation (CF) test and bacteriological examination of semen. Both the ELISA and the CF test detected 0.5% false positive reactions in rams from clinically negative flocks. However the ELISA detected significantly more positive reactors in infected flocks and the CF test failed to detect some rams excreting B. ovis. The ELISA proved to be a valuable test in eradicating brucellosis from infected flocks.

Use of an enzyme-linked immunosorbent assay in a bovine brucellosis eradication program

An enzyme-linked immunosorbent assay (ELISA) was developed and was compared with the complement fixation test (CFT) in a bovine brucellosis eradication program. The ELISA detected significantly more reactors than the CFT in both strain 19 vaccinated infected herds (1.79% versus 1.14%) and non-vaccinated infected herds (4.2% versus 3.59%) but not in either vaccinated or non-vaccinated brucella-free herds. The specificity for both tests in brucella-free herds was greater than 0.998. The specificity and sensitivity of the ELISA were compared with those of 3 other tests (the Rose Bengal test; the indirect haemolysis test [IHLT] and the CFT) on serum from 151 animals cultured at slaughter. The calculated specificity of the ELISA in this infected group was lower than for both the CFT and the IHLT (0.58 versus 0.67 versus 0.75). The sensitivity however was much greater (1.0 versus 0.73 versus 0.71). The value of the ELISA when used in an eradication program is discussed.

Serological and bacteriological survey of three horse studs for contagious equine metritis

A bacteriological and serological survey for evidence of contagious equine metritis (CEM) was made during the 1980 breeding season on 3 horse studs in South Australia with a history of previous infection. Swabs from the clitoral sinus and the cervix were cultured for Haemophilus equigenitalis and serum was screened for antibody using the complement fixation test (CFT) and the enzyme-linked immunosorbent assay (ELISA). The specificity of both tests was greater than 0.99 but the ELISA was more sensitive in detecting antibody in infected mares. On the evidence presented it was concluded that H. equigenitalis is no longer present in the horse studs investigated.

Serological studies of Australian and Papua New Guinean cattle and Australian sheep for the presence of antibodies against bluetongue group viruses

Following isolation of a virus (CSIRO19) from insects in Australia and its identification as bluetongue virus serotype 20 (BTV20), a nationwide survey of antibodies in cattle and sheep sera was undertaken. Initial studies using the serum neutralization (SN) test showed that the distribution of BTV20 antibodies in cattle was confined to the northern part of Australia. Group-reactive antibody tests (agar gel diffusion precipitin, AGDP, and complement-fixation, CF) showed group-reactive cattle sera south of the BTV20 zone (northern Australia), and southwards from Queensland to New South Wales. Very few group-reactive sheep sera (45 out of 16213) were found and these were of doubtful epidemiological significance. Some of these BTV group-reactive, BTV20-negative, sera were tested in SN tests against BTV1 to 17 and Ibaraki (IBA) virus. The results indicated that BTV1, or a closely related orbivirus, was active in cattle in Queensland, northern Western Australia, and New South Wales, and that antibody to BTV15 was present in some of the cattle sera in northern Western Australia and the Northern Territory. Antibody to IBA virus was present in some cattle sera in Queensland, northern Western Australia and New South Wales. SN antibody titres greater than or equal to 60 were also found to a number of other BTV serotypes in cattle sera in northern Western Australia and Queensland (principally, BTV2 and BTV7). Low level reactions were commonly observed against these and a number of other BTV serotypes, often in the same serum samples. Further, 22% of the group-reactive cattle sera did not react with any of the viruses in the SN tests. Such results were difficult to interpret in terms of known Australian BTV or BTV-related isolates.

Protection of pregnant swine by vaccination against Leptospira infection

The protection conferred on pregnant gilts by 2 commercially available leptospira interrogans serovars pomona and tarassovi bacterins was evaluated. Gilts vaccinated either 3, 6 or 12 months prior to natural challenge with L. interrogans serovar pomona had significantly lower abortion rates (2% vs 69%) and foetal mortality rates (14% vs 57%) than unvaccinated controls. One vaccine was significantly superior to the other and contained approximately twice the number of L. interrogans serovar pomona organisms per vaccine dose. Neither vaccine protected against renal colonisation but vaccination reduced urinary excretion of leptospires. Both vaccines reduced agglutinating antibody response to infection, as measured by the microscopic agglutination (MA) test. This may prevent the detection of a carrier animal by serology. Foetal pigs did not develop specific MA titres. Cultural methods were not reliable in making a diagnosis of foetal infection. Histopathology of foetal liver and kidneys helped in making a diagnosis of foetal infection.