Brucellosis Control Program Research Articles

Validation of enzyme-linked immunosorbent assays for the diagnosis of bovine brucellosis

The purpose of this study was to evaluate the performance of the indirect enzyme immunoassay (IELISA) and the competitive enzyme immunoassay (CELISA) for the diagnosis of bovine brucellosis in comparison to conventional serological tests routinely used in Argentina. Serum samples ( n = 3500), from Brucella-free herds, from vaccinated cattle and from naturally infected cattle, were tested by the following tests: buffered antigen agglutination test (BPAT), rose bengal test (RBT), 2-mercaptoethanol test (2-ME), complement fixation test (CFT), IELISA and CELISA. Sensitivity and specificity of the BPAT, RBT, IELISA and CELISA were determined relative to the 2-ME and the CFT. The CELISA was considered suitable for eliminating most serological reactions of vaccinated animals and was more specific than the other tests. The results indicate the potential use of the CELISA as a complementary assay in the brucellosis control and eradication program in Argentina and other countries, where Brucella abortusstrain 19 vaccination is mandatory.

Brucellosis in Saudi Arabia: Past, Present and Future

Brucellosis in Saudi Arabia: Past, Present and Future

Use of the enzyme-linked immunosorbent assay for screening cattle for Brucella antibodies in Nigeria.

The prevalence of Brucella antibodies in settled Fulani cattle herds in Kaduna State, Nigeria, was determined by using the enzyme-linked immunosorbent assay (ELISA) technique. Out of a total of 762 animals drawn randomly from 40 cattle herds in various areas of the state, 50 (6.6%) tested positive. There was no significant difference (P<0.01) in the number of reactors between male and female animals. Brucella antibodies were detected in animals in all areas of the state but prevalence was highest in Kaura area (26.8%) and was lowest in Zonkwa area (1.0%). Out of the 762 animals, 23 (3.0%) tested positive in the agglutination test (SAT) while 16 (2.1%) tested positive in the Rose-bengal plate test (RBTP). This study indicated that cattle in Nigeria have antibodies to Brucella tested by ELISA technique and that seropositive animals are located in distinct foci. The identification of these pockets of infection on a nation-wide basis will be crucial for future brucellosis control programmes.

Evaluation of trypanosomiasis and brucellosis control in cattle herds of Ivory coast

In 1978, treatment and vaccination programs were recommended to control bovine trypanosomiasis and brucellosis in Ivory Coast. A single trypanocidal treatment of young calves dramatically reduced their mortality rate. A preliminary demonstration project was carried out in a limited area by the government agency SODEPRA, followed by demonstrations on nearly all the farms. The costs were covered by SODEPRA as one of their development projects. Over a period of time the farmers took charge of the treatments, both financially and physically. In 1992, the trypanocidal treatments were still widely used. The reasons for this success could be its dramatic efficacy, the simple technology employed, the low cost that was progressively charged to the farmers, and the fact that this was a long term extension project with continuous farmer training. The brucellosis control program started with an initial vaccination of 1 to 10 year old females followed by an annual vaccination of 1 to 2 year old heifers. One year later, a 37% reduction in the abortion rate was observed. The vaccination were paid for and carried out by SODEPRA. The control program then stopped but, because of growing problems with brucellosis, vaccinations started again in 1992. There is still a question of how vaccinations will be accepted when the farmers are required to share the cost for the control of a largely inconspicuous disease.

Epidemiology of bovine anaplasmosis and babesiosis in Costa Rica

A serum bank created by the National Brucellosis Control Program during 1991 consisted of approximately 4000 sera collected from farms in each of the seven provinces in Costa Rica. Sera were used to determine the prevalence of antibodies directed against Anaplasma marginale, Babesia bigemina and Babesia bovis in Costa Rica and to study some geographical, ecological and management factors which could influence the epidemiology of the infection. The overall seroprevalence in bovines was 72.4%, 55.4% and 54.1% for A. marginale, B. bigemina and B. bovis, respectively. The Moran's index or spatial autocorrelation coefficient, which tests the significance of geographical patterns in disease distribution, indicated two foci of seropositivity in the country for B. bovis: one located mainly in the dry tropical forest and the other located in the tropical moist forest. Suggested foci were corroborated by a risk assessment using the random effects models.

Model for assessing the risk of introducing brucellosis into a brucellosis-free area.

A risk assessment model is presented, for use by local decision-makers to aid the evaluation of proposed changes in existing brucellosis eradication or control programmes. This model provides a format and structure for gathering and analysing data. The model uses data which are generally available and accessible, so that minimum time, expense and effort are required for collection. The use of this model enables an estimation of the risk of introduction of brucellosis into a non-infected population, based on the probability of importing the agent and subsequent spread, given the existence of specified surveillance and control measures. The model creates a point estimate of the risk associated with a given set of conditions.

Prevalence of Brucellosis Among Abattoir Workers in Saudi Arabia

The prevalence of brucellosis among abattoir workers in Saudi Arabia was determined through a randomised multi-stage sampling of 1200 abattoir workers. Diagnosis was made by both blood culture and standard tube agglutination test. The overall prevalence of brucellosis was 4.0% among abattoir workers. Infection was more common among butchers (8.9%), veterinarians and veterinary assistants (5.4%), and administrative personnel (1.1%). In order to reach optimum planning for a national brucellosis control programme in Saudi Arabia, ministerial co-ordination should be established with formulation of inter-governmental veterinary agreements between the Saudi government and the relevant authorities of animal exporting countries. A national survey on animal marketing is required.

Effects of live Brucella abortus strain 19 vaccine on reindeer

Twenty female and seven male reindeer (Rangifer tarandus) were vaccinated subcutaneously in the right shoulder with a 1-ml dose of approximately 1.2 x 108 colony forming units of Brucella abortus strain 19, the standard reduced dose for cattle. An additional three females and one male served as non-vaccinated sentinels. Brucella abortus strain 19 was isolated from two of three fetuses aborted by vaccinated females during the first of two fawning seasons. Serologic titers to brucellosis in the vaccinates peaked by 46 days post-vaccination. Shedding of B. abortus strain 19 by vaccinated animals was indicated by seroconversion of all four sentinels. Titers in the sentinels were low and sporadic. Brucella abortus strain 19 was isolated from the tissues and fetus of a pregnant female 51 days post-vaccination and from the carpal joint of another female 7 months post-vaccination. Based on these results and a previous challenge experiment, it was concluded that Brucella abortus strain 19 is not a suitable vaccine to use in a brucellosis control program in reindeer.

Role of predators in reindeer brucellosis in Alaska

Brucellosis caused by Brucella suis type 4 is endemic in Alaskan reindeer {Rangifer tarandus) herds. Predators and small mammals were collected on the fawning grounds of a known-infected herd during the springs of 1977 — 1984. Serologic reactions were detected in red foxes (Vulpes vulpes), arctic foxes (Alopex lagopus), grizzly bears (Ursus arctos) and arctic ground squirrels (Spermophilusparryii). Brucella suis type 4 was isolated from red and arctic foxes. Red foxes were orally challenged with B. suis type 4 in controlled experiments. Shedding of the organism was detected in fecal samples several days post-challenge. Antibody titers were detected up to several months post-challenge, and B. suis type 4 was isolated from several tissues at necropsy. Reindeer confined with infected foxes became infected. Transmission of brucellosis among reindeer and their predators needs to be addressed in a brucellosis control program.

Serological diagnosis of brucellosis.

Abstract Extract As the incidence of brucellosis is being reduced in many countries throughout the world, import requirements are becoming more stringent. Pressure is being applied in certain countries to establish regulations that will permit the import of cattle and meat products from brucellosis-free areas only. Countries such as New Zealand that have an important export trade in meat should be ready to comply with these import regulations when they come into effect. It is with this in mind that the New Zealand Department of Agriculture is undertaking a more extensive brucellosis control programme in the near future.

Application of Research to Bovine Brucellosis Control and Eradication Programs

Recent research on brucellosis has resulted in new developments in the broad areas of immunity, diagnosis, and Brucella characterization. Application of these developments is necessary to continue the progress of the control program toward the goal of eventual eradication of bovine brucellosis.Heifer calves vaccinated at three, four, or six months of age with Strain 19 developed an immunity against brucellosis equal to that in heifers vaccinated at eight months or older. Calves vaccinated at two months also developed a serviceable immunity. Application of vaccination at younger ages will practically eliminate persistent vaccinal titers that have caused some inaccuracies in interpretation of standard diagnostic tests.Specificity of several diagnostic tests has been increased considerably, thus increasing our ability to identify the infected animals. Most of these have been used to supplement the seroagglutination tests in problem herds. The card test is being evaluated further by applying it routinely in states that have not attained a modified certified status.Addition of Brucella phage and oxidative metabolic tests to the biochemic and serologic tests will enhance our capabilities of characterizing Brucella responsible for new outbreaks of brucellosis and our ability to contain such outbreaks.