The results of the present investigation are presented in Table 1 and Fig 1. A total of 50 unvaccinated buffalo serum samples collected from a livestock farm were tested by a commercially procured competitive enzyme-linked immunosorbent assay kit (cELISA) in the present study. Some of these buffaloes at a farm experienced abortion and also a drop in milk production during the year, mid-2015. This history of the animals pointed towards possible infection of the
Brucella organisms and hence in that year in the late-2015 collected serum samples from these buffaloes were received for initial testing by plate agglutination tests at the laboratory at Dr. Ambedkar Nagar-Mhow. However, one set of serum samples was stored in the deep freezer for future testing and research purposes at the laboratories located at Dr. Ambedkar Nagar-Mhow. There are several tests available for the diagnosis of Brucellosis in cows and buffaloes by using various clinical specimens namely isolation of the
Brucella organisms, serological testing and advanced molecular detections
(Brahmabhatt et al., 2009; Madhukar et al., 2014;
Upadhyay et al., 2019; Bohre et al., 2021). Isolation of the agent is considered the gold standard for the diagnosis of Brucellosis but this can be a time-consuming and laborious process besides posing a risk of infection to laboratory personnel. That’s why serological tests are generally preferred (Niranjan
et al., 2015). In previous studies, high as well as lower percentages of Anti-
Brucella Antibodies (2.5%-38.5%) from randomly collected or suspected/infected cases of bovines were reported in India and abroad by using different diagnostic tests
(Amin et al., 2005; Islam et al., 2018; Priyanka et al., 2018;
Priyantha et al., 2021). Bovine Brucellosis in Madhya Pradesh was reported as early as 1969 (
Kataria and Verma, 1969) and continued to be reported from the state
(Gupta et al., 2017; Verma et al., 2019b; Audarya et al., 2024). The cELISA test with high specificity is capable of detecting all immunoglobulin classes
(Quinn et al., 2011). The cELISA kit employed in the study detects Antibodies specific to
B. abortus,
B. melitensis,
B. ovis and
B. suis in bovine, ovine, caprine or swine from serum/plasma/milk samples.
The present study reported a higher seroconversion rate (48%) by cELISA testing of buffaloes with a history of abortion at the livestock farm due to the
Brucella species infection. Higher seroconversion could be due to the presence of infected aborted buffaloes and shedding of bacteria in large quantities and the transmission of the organisms to susceptible buffalo populations that were in close contact. Further, samples from the same area were not tested due to vaccination in the herd and no report of an outbreak. However, Brucella infection is being detected in swine, small and large ruminant populations of the state
(Gupta et al., 2017; Yadav, 2022;
Audarya et al., 2024). An overall seropositivity of 18.36% was reported when samples from the outbreak were tested by rose Bengal test
(Audarya et al., 2024). So, cELISA is more sensitive in detecting seropositivity to
Brucella infection than the rose Bengal test. Brucellosis is responsible for more than double the economic loss in an infected buffalo compared to an infected cow
(Jadav et al., 2022). Hence, it is important to assess the status of infection at a farm especially when unvaccinated buffaloes are experiencing abortion. All the positive samples in the plate agglutination test (10) were also evaluated as positive in cELISA (Table 1). A total of 24 serum samples tested positive out of 50 buffalo serum samples in cELISA even when these serum samples were stored at deep freezing conditions for the long-term for more than 6 years indicating the robustness of both the test and Anti-
Brucella Antibodies. On finding positive samples in initial studies, it was advised to farm authorities to send and test those samples at the Indian Veterinary Research Institute, Izatnagar-243 122, Bareilly, Uttar Pradesh for further confirmation of individual animals by ELISA due to the unavailability of an ELISA kit at the laboratory at that time. Results of which were not made available to the authors hence studies regarding deterioration of antibody titers/positivity and negativity in corresponding samples could not be made in respect to ELISA studies. However, those samples that tested positive in the plate agglutination test were also evaluated as positive in the present investigation. Hence, stored serum samples were of diagnostic value even after storage at long cold conditions. So, in the present investigation, 48% of buffalo serum samples tested positive in a cELISA at a livestock farm indicating an outbreak of Brucellosis in the buffaloes of the farm. At least one male buffalo was positive for the infection in the study. Some animals even after abortion may act as carriers and transmit the infection to othe in-contact healthy animals. Hence, further bacterial isolation and molecular studies will be planned
(Gokmen et al., 2019). Prevention and control of Brucellosis is done by following standard biological practices related to the quarantine of infected/diseased animals from healthy animals and vaccinations of the remainder. Eradication and control of the disease are achieved elsewhere by following testing and slaughter of infected animals and vaccinations to susceptible livestock populations including buffaloes
(Puran et al., 2013) to minimize economic losses to livestock owners. Brucellosis is also a zoonotic disease hence screening manpower at farms and being involved with related activities and treatment of affected individuals if any is necessary
(Madhukar et al., 2014; Nagappa et al., 2018).
The study findings also highlight the importance of vaccinations to the country’s buffalo and other susceptible livestock populations as envisioned in the Government of India policies to contain the losses incurred due to Brucellosis.
