Early history of bovine brucellosis eradication in Australia

The first Australian bovine brucellosis eradication campaign on a state-wide basis was initiated and established in Tasmania. The procedures involved in drawing up a suitable scheme together with a summary of the difficulties encountered in setting up and operating the scheme are described, leading to the successful eradication of brucellosis from Tasmania. Our observations that milk was not a major factor in the transmission of brucellosis infection from cattle to man are recorded. Recognition is accorded to veterinarians, some eminent in the profession, who, in the absence of Australian research into the disease, gave freely of their advice in helping to pioneer the eradication program. Within one year of commencing the scheme 4 herds had been accredited; by 3 years 85 herds had been accredited.     

Control of warble fly in Great Britain and the European Community

The costs of warble fly in cattle have been estimated at 35 million pounds for Great Britain in 1985 and $85 million for Italy in 1982. Control measures within the European Community vary from one country to another and from the voluntary application of systemic products by individual farmers to comprehensive national eradication schemes backed by legislation. Of the countries opting for national eradication measures, Denmark has been successful and the Federal Republic of Germany, the Netherlands, the Republic of Ireland, Northern Ireland and Great Britain have reduced the incidence of the disease to very low levels. In Great Britain in 1978, 38 per cent of cattle were found to be affected in a survey of selected fatstock markets by the Meat and Livestock Commission. In 1985 the incidence had fallen to 0.01 per cent. Seven hundred and five affected herds were found in Great Britain when the disease was made notifiable in 1982, falling to 419 affected herds in 1985. Treatment of all cattle over 12 weeks old is required in affected herds. Since 1982 parts of Great Britain where the disease has persisted or where there is evidence of a recrudescence have been designated 'infected areas' in which all cattle over 12 weeks old have been required to be treated within specific dates. In addition to statutory measures the control measures in Great Britain include the inspection of cattle at auction markets and on farms. Work on the application to field conditions of an ELISA test is in progress, with encouraging results. It is considered that Great Britain is now well placed to eradicate warble fly.     

The transmissible spongiform encephalopathies: disease risks for North America.

Transmissible spongiform encephalopathies exotic to North America (BSE and associated diseases) are unlikely to be introduced or to persist should they be introduced into the United States [2]. Domestic TSEs (scrapie, CWD, and TME) seem to be relatively restricted in their host range, and none of these diseases is known to naturally cause disease in cattle. It is important that surveillance for TSEs continues, however, particularly in cattle because of the extreme consequences to the livestock industries, and potentially, public health, if BSE becomes established. Because the TSEs have implications beyond effects on their natural host species, adequate surveillance, control, and even eradication of these diseases should be goals for the livestock industries, wildlife managers, and animal health agencies in the United States.     

Theoretical basis and empirical implications of the bovine brucellosis market slaughter testing program in the United States

With reductions in federal funding, the Market Slaughter Testing (MST) surveillance system might once again become the primary bovine brucellosis surveillance system for the beef-cow population in the United States. Thus, understanding the weaknesses and/or strengths of the MST surveillance system will be crucial in determining the most effective program in a limited funding control/eradication program.An estimation of a hypergeometric distribution used in previous studies to describe the effectiveness of the MST system is employed and parameters of this distribution are estimated from secondary data. Results analyzed by herd size, and within-herd infection level yield a distinct herd size bias in the MST surveillance system. For example, the probability of detection in a 9-cow herd is 24% compared to 85.4% for a 645 cow herd after 1 year of infection. This herd size bias implies that secondary testing may be efficiently u used by concentrating testing in the smaller herds when funds for secondary testing are limited.MST detection probabilities can vary 30% between the build-up and liquidation phases of the cattle cycle, i.e., secular upswings and downswings in cattle inventory numbers. First Point of Concentration testing (FPC) of purchased replacements can partially offset the effects of the cattle cycle. A 95% herd vaccination level can reduce the probability of detection as much as 40% when compared to a similar herd that is not vaccinated.     

Paratuberculosis eradication programs in Northrhine-Westfalia

Since 1993 a voluntary eradication program for bovine paratuberculosis is established in Northrhine-Westfalia. After an effectivity control of the serological diagnostics it is combined with the fecal culture since August of 2000. Parallel use of both methods is necessary for a successful eradication. It could be monitored that a high percentage of the newly bought cattle in the herds participating in the eradication program was considered positive. Since paratuberculosis eradication is time and cost extensive besides intensive eradication programs the spread of the disease must be stopped.     

Risk associated with animals moved from herds infected with brucellosis in Northern Ireland

The movement of cattle from herds infected with Brucella abortus was investigated in order to assess the control measures for eradication of brucellosis from the cattle population of Northern Ireland. Using recorded cattle movement data, a historical cohort study was designed and carried out to quantify the risk of seropositivity in bovine animals moved from herds infected with brucellosis. The study found that 3.1% of animals, moved in the 6-month period prior to disclosure of infection in the source herd and subsequently tested, were interpreted as seropositive in their destination herds. The odds of seropositivity were approximately 19 (95% confidence interval: 7.8-46.4) times higher in this cohort compared with animals from herds with no history of infection. A multivariate logistic regression model was constructed to examine factors influencing the risk of seropositivity in the exposed cohort of animals, identifying maternal status (whether the dam had been a brucellosis reactor) and age at leaving the infected herd as the main risk factors.     

Early removal of cows with Brucellosis and the effect in strain 19 vaccinated cattle herds

The effect of early removal of cows excreting pathogenic Brucella abortus following Strain 19 vaccination of beef cattle herds was determined by comparing cumulative incidence (CI) of brucellosis reactors post-vaccination (p.v.). Adult female cattle in six herds were tested, reactors removed, and vaccinated with 3×10⁹ colony-forming units of B. abortus Strain 19. Cattle were tested at 2 months p.v. and culture-positive cattle were removed from a principal cohort of three herds at approximately 3 months p.v., and removal from a control cohort of three herds delayed until approximately 7 months p.v. Neither CI nor time to eliminate brucellosis was significantly different between cohorts.A review of the parturition data revealed that more of the infected cows in the principal cohort herds terminated gestation before removal. These data suggest that stage of gestation plus diagnostic and management alternatives to prevent parturition of infected cattle in the herd are more important factors in herd plans than early removal of postparturient infected cows following whole-herd Strain 19 vaccination.     

OBSERVATIONS ON SINGLE BRUCELLOSIS REACTORS IN LARGE HERDS

Over a 3 year period specimens were collected from single reacting cattle to the complement fixation test for brucellosis from large herds in north Queensland. Twenty-four such reactors were destroyed for culture, and Brucella abortus was isolated on 3 occasions. The existence of such low levels of Br. abortus in large herds should not be overlooked in the eradication campaign. Explanations were found for 17 of the single reactors, and included introduction of cattle to the herd, exposure to adjoining infected herds or vaccination with Strain 19.     

Control of BVDV-infection on common grassland--the key for successful BVDV-eradication in Lower Austria

A bovine viral diarrhea/mucosal disease (BVD/MD) control and eradication program was introduced in Lower Austria in 1996, according to the Swedish model. At present 9800 out of 17,000 herds are part of this program. An important risk factor for BVDV-transmission under local conditions is communal grazing. Approximately 3-4% of livestock share common pastures, in which susceptible pregnant cattle may be mixed with unrecognised persistently infected (PI) animals. Rules and regulations were defined to allow only herds free from BVDV-infection on to common grassland. At the moment, 5067 herds are certified free from BVDV. The percentage of BVDV-free herds in regions with intensive pasture utilisation is higher (57.3%) than in the other regions (43.0%) of Lower Austria. With a reliable system for identification of PI-animals and a high certainty of prevention of PI-animals on common grassland, the main transmission of BVDV infection can be stopped, even if the animals are derived from infected herds and transiently infected animals cannot be excluded.     

Brucellosis in the European Union and Norway at the turn of the twenty-first century

Control and eradication programs of brucellosis in cattle, sheep, goats and pigs have been more or less successfully implemented within the Member States (MS) of the European Union (EU) and Norway after Word War II. As a result, the epidemiological situation of animal brucellosis is extremely diverse among different MS or regions within a MS and among the different animal species. Some MS, mainly North European countries, and Norway are declared “officially bovine brucellosis free” and/or “officially ovine and caprine (Brucella melitensis) free”. The situation is less favorable in Southern European countries, particularly as far as sheep and goat brucellosis are concerned. This situation has important zoonotic consequences as reflected in the number of human brucellosis cases due to B. melitensis that are still encountered in those countries. Brucellosis in swine has re-emerged as a result of spillover from the wild boar brucellosis (Brucella suis biovar 2) reservoir, particularly in outdoor reared pigs. Besides the actual challenge to eradicate brucellosis, further issues have to be addressed: (1) the management of false positive serological results that occur in the course of brucellosis testing, particularly in cattle; (2) the impact of wildlife brucellosis, particularly wild boar brucellosis in domestic animals; and (3) the importance of B. melitensis infection in cattle that are in contact with infected sheep.     

Applied serology in the latter stages of the eradication of bovine brucellosis

Late in the program to eradicate bovine brucellosis from Western Australia, Rose Bengal test (RBT) and complement fixation test (CFT) results on the serums from 2,307 cattle (from herds where infection was still present after a minimum of 3 complete herd tests) showed that 327 were positive in the CFT and 246 were positive in the RBT (p less than 0.001). Subsequent testing by the RBT, CFT and the indirect haemolysis test (IHLT) of 722 serums from cattle slaughtered as part of infected herds showed that of 177 cattle positive on culture, 138 were positive in all 3 tests, 9 were negative in all 3 tests and no animal positive on culture had a reaction only in the RBT. In the 177 cattle from which B. abortus was isolated, positive reactions in the CFT occurred in the serums of 159 of them. Application of the RBT as a screening test followed by a confirmatory CFT would have resulted in 149 of the 177 cattle being positive and application of the CFT/IHLT (double test) on the serums of all cattle in the herds would have resulted in 168 or the 177 being regarded as positive.     

Diseases and parasites of cattle in Vanuatu

A study of cattle diseases was carried out in Vanuatu from 1971 to 1981. Tuberculosis was discovered in 4 herds and eradication was completed by 1981. The number of farms with brucellosis reactors increased from 2 in 1976 to 7 in 1978 despite eradication measures. Antibodies to serovars Leptospira icterohaemorrhagiae, australis, sejroe and canicola were demonstrated by the microscopic agglutination test. Antibodies were demonstrated against infectious bovine rhinotracheitis/infectious pustular vulvovaginitis and bovine virus diarrhoea/mucosal disease complexes. Of the 18 parasites identified, Haemaphysalis longicornis, Haemonchus, sp, Oesophagostomum phlebotomum and Neoascaris vitulorum were the most prevalent. As brucelossis is the only serious disease present, Vanuatu is in a favourable situation with regard to cattle diseases.     

The existing and potential importance of brucellosis and tuberculosis in canadian wildlife: a review

As the campaign to eradicate bovine brucellosis (Brucella abortus) and tuberculosis (Mycobacterium bovis) in Canadian livestock nears completion, the importance of extraneous sources of these diseases increases. This review summarizes the literature on brucellosis and tuberculosis in Canadian wildlife species to determine existing and potential hosts. Canadian caribou (Rangifer tarandus) are reservoirs of Brucella suis biotype 4 which is pathogenic in caribou, humans and muskoxen but reportedly nonpathogenic in livestock. Bison (Bison bison) and elk (Cervus canadensis) are significant reservoirs of B abortus and M. bovis. The bison in and around Wood Buffalo National Park have both diseases and are the only wildlife reservoir in Canada. Free-ranging elk are important reservoirs of brucellosis in Wyoming, and captive elk initiated the recent outbreak of bovine tuberculosis in 20 American states which has also involved bison and cattle herds. If bison and elk ranching continues to develop in Canada, the industry will have to be monitored to prevent the introduction and spread of infectious diseases like brucellosis and tuberculosis. This requires the evaluation and / or development of effective diagnostic methods for use in these animals.     

Isolation of brucella abortus from two dogs in contact with bovine brucellosis.

On a farm where several cattle were serologically positive for bovine brucellosis, three dogs were found to have titres greater than 400 i.u. to Brucella abortus. The titres persisted until the dogs were killed over two months later. Two male dogs were necropsied. B. abortus was isolated from the spleen of both dogs. While farm dogs are not thought to be a major reservoir of bovine brucellosis they may be considered as possible carriers in imfected herds and should be considered during the investigation and eradication of bovine brucellosis.     

Control of bovine viral diarrhea/mucosal disease in the district of Kamenz on a voluntary basis--ways, successes, limitations

In 69 dairy and beef herds in the district of Kamenz, Saxony, with a total number of 21,783 and 89.6% of the district's cattle, a voluntary BVDV eradication protocol was implemented from 2000 to 2007. The aim was to achieve eradication as comprehensive as possible and to prepare the herds for the mandatory eradication program. Essential preconditions for the accreditation of a herd as "free of BVD virus" were the antigen test of all cattle and their offspring for 12 months including completeness check and a negative serological random sampling of young cattle. Mean eradication period of infected herds lasted 45.6 months, herd size, and the number of newly purchased cattle were found to have a significant influence. In five infected farms calf losses significantly decreased after termination of the eradication. further examination of the 126 antigen test positive animals from 15 herds resulted in 87 persistently infected (PI) and 15 transiently infected (TI) individuals, 24 animals missed the second test. Furthermore, out of the 87 PI's 30 individuals (34%) had antibodies against BVDV. Eight farms vaccinated their whole herd, seven only the young stock before first breeding, and 54 herds did not vaccinate, respectively. Concluding from this study, the epidemiological particularities of the farms should be taken in account. Testing of all cattle in a minimum of time including, official monitoring of immediate culling of PI's, immediate epidemiological research, and serological monitoring of the eradication process is necessary.     

Eradication of bovine brucellosis in the 10th Region de Los Lagos,Chile

The process of Bovine Brucellosis Eradication that began in 1996 in the 10th Region de Los Lagos of Chile will be reviewed. The region comprises the most important dairy area of the country and it has the largest concentration of brucellosis infected herds. Based on the information gathered by an epidemiological surveillance system, the results of the eradication process for the years 1996 till 2001 are presented as rates of Milk Ring Test (MRT) positive dairies, rates of brucellosis reactors (bovines) in livestock markets and slaughterhouses, and the annual incidence and prevalence of brucellosis infected herds.

During the period the rates of positive dairies, bovine reactors in livestock markets and slaughterhouses, and the annual incidence and prevalence of infected herds have experienced a decrease, while the rate of bovine reactors in slaughterhouses has remained stable. Data on the preventive measures taken, such as vaccination of female bovines and Certification of Brucellosis Free Herds, are also shown. The surveillance system has allowed the detection of infected herds, while the measures of prevention and cleaning of infected herds have allowed a reduction in the incidence and prevalence of the infection by Brucella abortus.     

Brucellosis in Ontario: a case control study.

Data from cattle herds infected with brucellosis and from control (noninfected) herds were collected and analyzed using case control techniques. It appeared that herds located close to other infected herds and those herds whose owners made frequent purchases of cattle had an increased risk of acquiring brucellosis, particularly those who made purchases from other herds or from cattle dealers. Infected herds had a lower level of vaccination than noninfected herds. However, the percentage vaccinated was highly variable in each group. Vaccination per se did not appear to adversely influence the interpretation of serological test results nor did it appear to protect the individual animal. Once infected, the time required to become free of brucellosis was increased by large herd size and/or loose housing. Closed herds also took longer to become brucellosis free than more open herds. The percentage of animals removed from the herd was increased by active abortion. Those herds with multiple serological reactors (positives and questionables) at the first herd test after the imposition of quarantine had the highest percentage of cattle removed.     

Cattle brucellosis in traditional livestock husbandry practice in Southern and Eastern Ethiopia,and its zoonotic implication

Background

Cattle brucellosis has significant economic and zoonotic implication for the rural communities in Ethiopia in consequence of their traditional life styles, feeding habits and disease patterns. Hence, knowledge of brucellosis occurrence in traditional livestock husbandry practice has considerable importance in reducing the economic and public health impacts of the disease.

Methods

A total of 1623 cattle sera were serially tested using the rose Bengal test as screening and complement fixation test as confirmatory tests. The Stata survey command was used to establish prevalences for the overall and individual variables, while potential risk factors for seropositivity were analyzed using a multivariable logistic regression analysis.

Results

The results showed that 3.5% (95% CI = 2.4, 4.5%) of the animals and 26.1% (95% CI = 18.6, 33.7) of the herds tested had antibodies against Brucella species. Village level seroprevalence ranged from 0% to 100%. A higher seroprevalence was observed in pastoral system than mixed farming although this variable was not significant in the final model. The final logistic regression model identified herd size; with large (odd ratio (OR) = 8.0, 95% CI = 1.9, 33.6) and medium herds (OR = 8.1, 95% CI = 1.9, 34.2) showing higher risk of Brucella infection when compared to small herds. Similarly, the odds of Brucella infection was higher in cattle aged above 4 years when compared to age groups of 1-2 (OR = 5.4, 2.1, 12.9) and 3-4 years (OR = 3.1, 95% CI = 1.0, 9.6). Herd level analysis of the risk factors revealed that large and medium herds as well as herds kept with multiple livestock species were at higher risk of acquiring Brucella infection. Brucellosis in traditional livestock husbandry practices certainly poses a zoonotic risk to the public, in consequence of raw milk consumption, close contact with animals and provision of assistance during parturition. Due to lack of diagnostic facilities and information on its occurrence, human brucellosis is most likely misdiagnosed for other febrile diseases prevailing in the areas and treated empirically.

Conclusions

The results of this study demonstrated that bovine brucellosis is widely prevalent in the study areas particularly in pastoral production system. Hence, the study suggests the need for implementing control measures and raising public awareness on prevention methods of brucellosis.     

Economic consequences of control programs for paratuberculosis in midsize dairy farms in the United States

OBJECTIVE: To evaluate the epidemiologic efficacy and economic efficiency of current and potential future control programs for paratuberculosis (Johne's disease) on midsize dairy herds in the United States. DESIGN: Stochastic dynamic computer simulation model. SAMPLE POPULATION: Data on prices and other input variables collected from various sources were used to represent a population of midsize US dairy herds infected with paratuberculosis. PROCEDURE: The simulation model was modified to reflect management and production characteristics of midsize dairy herds in the United States. The model was validated by use of field data and expert opinion. Various control strategies then were simulated and compared on an epidemiologic basis and on the basis of economic efficiency. RESULTS: Test-and-cull strategies and vaccination against paratuberculosis were not able to decrease the mean prevalence of disease in the United States. Typically, only vaccination was economically attractive. Improved management strategies decreased the prevalence of paratuberculosis considerably and had high economic benefits. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of results of this study suggests that test-and-cull strategies alone do not reduce the prevalence of paratuberculosis in cattle and are costly for producers to pursue. Vaccination did not reduce the prevalence but was economically attractive. Finally, improved calf-hygiene strategies were found to be critically important in every paratuberculosis control program and most were economically attractive programs for midsize US dairy farms with the disease.     

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.