PRESENCE OF BRUCELLA IN MILK AND DAIRY DERIVATIVES

PRESENCE OF BRUCELLA IN MILK AND DAIRY DERIVATIVES

 Sabahu Noor, Rabyia Javed

Abstract

Brucellosis is a zoonotic bacterial disease primarily caused by species of the genus Brucella, with Brucella melitensis, Brucella abortus, and Brucella suis being the most common. The disease poses a significant threat to both animal and human health worldwide. This chapter therefore focuses on the presence of Brucella spp. in milk and milk products, the transmission pathways, and preventive measures to mitigate the risk associated with these dairy products. A comprehensive understanding of brucellosis in milk and milk products is crucial for ensuring food safety and public health. Consuming dairy products without pasteurization, especially when produced without proper quality controls, poses a significant risk for highly contagious brucellosis.

Introduction

Dairy products are an essential part of our daily diet, providing us with essential nutrients like calcium and protein. However, the safety of these products is of paramount importance, as they can be a potential source of foodborne illnesses. It is of particular concern due to its potential impact on public health. Brucella has diverse transmission pathways from animals to humans. Firstly, it may be found in unpasteurized milk, dairy items, and undercooked meat sourced from infected animals. Secondly, direct exposure to diseased animals can result in transmission.  Brucella might be present in dust and airborne particles in areas where infected animals are housed or processed. Inhaling these particles can lead to bacterial infection. Researchers handling Brucella in laboratories risk accidental exposure through cuts or skin wounds. Additional routes of transmission include blood transfusions, tissue transplants, uncommon but direct contact with aborted materials, and venereal contact. Finally, in regions where Brucella is prevalent, individuals may encounter the bacteria through direct or indirect contact with their mouth, eyes, or respiratory system . This article delves into the detection of Brucella spp. in dairy products, the various transmission routes, and preventive measures essential for consumer protection.

Brucella in Dairy Products

The infection of animals used for the production of milk is closely related to the prevalence of Brucella in dairy products. Infected animals shed Brucella bacteria through their milk, urine, and reproductive fluids, introducing the bacteria into the dairy production process and resulting in contaminated products. Despite stringent hygiene measures aimed at minimizing the threat of contamination, the chance for Brucella to infiltrate the food supply chain remains. It is important to underscore that various stages of handling, storage, and production of cheese can expose it to species of Brucella. This risk is heightened when milk utilized in cheese production is contaminated, or if proper aseptic precautions are not maintained during handling . Additionally, specific types of aged cheese stored for prolonged durations have been linked with Brucella infections. Individuals who consume dairy products that are undercooked, like ice cream, butter, milk, whey, and yogurt, run the risk of getting Brucella infections. Notably, ice cream made from raw milk stands out as a significant source of infections. The survival of Brucella in milk is influenced by various factors, including factors like pH, temperature, and the existence of antimicrobials or disinfectants. Refrigerated unpasteurized or raw milk at 39°F can harbor Brucella for many days to weeks.  Study  revealed that when stored at 39°F and fermented with a yogurt starter culture, B. abortus could survive in milk for up to 22 days. Butter stored at 46.5°F can also host Brucella for as long as 142 days. Brucella can also linger in cheese at room temperature for up to 18 days and in ice cream kept at 32°F for up to 30 days . The introduction of Brucella into dairy products remains a challenge despite rigorous hygiene practices, emphasizing the significance of ongoing observation and precaution in the production and handling of dairy items.

 Risk factors

Health Risks to Consumers: Brucellosis in people can range from mild to severe, and in some cases, it can become chronic. The signs and symptoms may resemble other common illnesses, making it challenging to diagnose. This can lead to delayed treatment, potentially resulting in more severe health complications.

Economic Impact

Outbreaks of disease in livestock can have significant economic repercussions for the dairy industry. Infected animals may suffer from decreased milk production, abortions, and fertility issues, leading to financial losses for farmers.

 Regulatory Concerns

Regulatory bodies, like the FDA and USDA in the United States, have established guidelines and standards to limit the occurrence of Brucella in dairy products. Non-compliance with these standards can result in product recalls, fines, and reputational damage for dairy companies.

Methods for Identifying Brucella in Milk and Dairy Products
 In order to stop brucellosis from spreading to humans, milk and dairy products must be safe.

To accomplish this, various detection techniques have been developed to identify the incidence of Brucella species, enabling timely intervention and mitigation efforts.

Molecular Tests

Polymerase Chain Reaction: PCR, a robust molecular methodology, is employed to amplify and detect specific DNA sequences associated with Brucella. Targeting unique regions of the Brucella genome, PCR assays demonstrate high sensitivity and are applicable to both raw and pasteurized milk.

Real-Time PCR (qPCR)

Real-time PCR provides a quantitative assessment of Brucella DNA in a sample, facilitating rapid and accurate identification. This method works especially well for tracking how well brucellosis control initiatives are doing .

 Milk Ring Test (MRT)

A popular and reasonably priced serological test for identifying Brucella antibodies in both individual and bulk milk samples is the Milk Ring Test. A positive diagnosis of brucellosis is indicated by a discernible color shift in the presence of Brucella antibodies, which is produced by injecting a specific ring or well on a card with a colored indication. The MRT is well known for its effectiveness in dairy herds when it comes to early disease diagnosis

Cultural Methods

Isolation and Culture: Traditional methods involve isolating and culturing Brucella organisms from milk samples. Even though procedures take a while, these methods are nonetheless useful for verifying the existence of live Brucella bacteria.

Immunological Assays:

Enzyme-Linked Immunosorbent Assay (ELISA)

ELISA, a highly sensitive and specific immunological assay, is widely used for detecting Brucella antibodies in milk samples. Its rapid results make it suitable for large-scale screening in dairy animals, contributing to effective brucellosis surveillance.

Western Blotting:

Employed for confirmatory presence of Brucella antibodies, Western blotting is an immunological technique that separates and identifies specific proteins in a milk sample, offering high specificity and reliability.

Biosensor Technology

Biosensors, utilizing biological components, are evolving as advanced tools for detection of Brucella antigens or antibodies. These devices provide rapid results, good sensitivity, and the potential for on-site testing, showcasing promise for future applications in the dairy business.

Mass Spectrometry

Mass spectrometry methods, such as Matrix-assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS), enable the rapid identification of Brucella species based on their unique protein profiles. This technique offers accurate and quick identification of Brucella isolates. [8,9,4]

Preventive Measures

Efforts to prevent, control, and eliminate Brucella infection on a combination of strategies such as pasteurization of milk, depopulation, vaccination and rigorous testing to minimize infection reservoirs. Vaccinating cattle has shown to be very successful in protecting against the organism’s field strains. To ensure the success of these measures, a comprehensive understanding is essential among stakeholders, including livestock producers, veterinarians, field workers, local communities in endemic areas, and regulatory officials [10]. The effectiveness of these programs relies on well-defined rules tailored to specific regions or herds [11].

To lessen the risks of Brucella in dairy foods, preventive measures should be implemented throughout the supply chain. This includes

1.Strategies for Preventing Brucella Transmission via Milk and Dairy Products.

2.Efforts to combat Brucella infection center around key measures, such as pasteurization, depopulation, vaccination, and testing to reduce infection reservoirs.

3.Vaccinating cattle is particularly effective against the bacterium’s field strains. Success depends on stakeholders understanding these measures [11].

4.Strict adherence to tailored guidelines and rules is crucial for program success [12].

Pasteurization of Milk Products

Pasteurization is critical in endemic regions to ensure the safety of milk. Awareness about avoiding unpasteurized milk is crucial in preventing human brucellosis. The aim of pasteurization is to eliminate harmful microorganisms, making milk safe for consumption. However, rigorous monitoring is necessary, as Brucella species can persist if the process is not closely watched [13].

To guarantee the safety of milk and its by-products, molecular tests capable of detecting Brucella presence in both raw and pasteurized milk should be employed [14]. These tests are crucial for early detection and prevention of brucellosis outbreaks, emphasizing the importance of strict oversight and quality control measures in milk production.

Monitoring Brucella Species with the Milk Ring Test (MRT)

 The Milk Ring Test (MRT) plays a crucial role in brucellosis control by surveilling Brucella species in individual and bulk milk. This cost-effective and efficient method enables early disease detection, contributing to both animal and human health. Periodic MRTs, especially in endemic regions, aid in the early detection of infected animals, curbing disease spread [15].

Vaccination Program

In order to prevent brucellosis infections both within and between species, effective vaccination is essential. There are several vaccinations available, such as DNA-based vaccines, B. melitensis Rev.1, lysate vaccines, live vectored vaccines, S19, and RB51. Cattle are typically vaccinated against RB51 and B. abortus strain 19 [16,17]. To stop the spread of zoonotic illnesses like brucellosis, it is imperative that the public is informed about them. Public health campaigns, healthcare professional training programs, and educational initiatives in schools and communities are a few examples of initiatives. Key elements in preventing Brucella infection are regulatory compliance, routine inspections, and consumer education of the dangers of consuming raw dairy products.

Conclusion

The persistent public health concern of human brucellosis arising from the consumption of raw milk and milk products underscores the need for a comprehensive approach. This approach should encompass heightened public awareness regarding the risks associated with unpasteurized milk, the implementation of enhanced animal husbandry practices like vaccination programs and biosecurity measures, strict enforcement of regulations governing the sale of raw milk and its products, and the enhancement of surveillance and reporting systems. To effectively implement interventions that can reduce the prevalence of brucellosis and protect human health, collaboration among diverse stakeholders is crucial. This includes active involvement from farmers, veterinarians, medical professionals, and policymakers. Through collective efforts, we can make substantial strides in halting the transmission of brucellosis and ensuring the safety of our food supply.

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