Brucellosis in Goats: Causes, Signs, Treatment & Control

Brucellosis (B. melitensis) is an infectious bacterial disease that can affect most domestic animals, with goats and sheep being particularly susceptible. It is the leading cause of Brucellosis in people worldwide, causing a severely debilitating disease.

Causes of Brucellosis Disease

Brucellosis is caused by bacteria belonging to the genus Brucella. The main pathogens responsible for brucellosis in goats are Brucella melitensis and Brucella ovis. Among these, Brucella melitensis is the most significant and pathogenic species affecting goats. There is also a less common species called Brucella intermedia, which can infect goats as well.

Note:

The gram-negative bacterium Brucella melitensis can have a spherical or rod-like body shape. It possesses distinct serological characteristics that enable its identification and differentiation from other Brucella species. Serological tests, such as the Rose Bengal Plate Test (RBPT) or serum agglutination assays, are commonly conducted to detect antibodies against Brucella species in animals suspected of having brucellosis.

The bacteria primarily affect the reproductive systems of goats, leading to reproductive issues like abortion, stillbirths, and reduced fertility. Infected goats can also shed the bacteria in their milk, thereby increasing the risk of human infection through the consumption of contaminated dairy products.

Preventing the transmission of infected animals, implementing strict biosecurity measures, and conducting regular testing are vital strategies for controlling and managing brucellosis in goat herds. Vaccination may also be employed in specific situations, although the availability and effectiveness of vaccines may vary depending on the specific Brucella species and regional regulations.

Transmission of Brucellosis

The spread of brucellosis occurs through consuming contaminated animal products or close contact with infected animals.

Direct contact: The bacteria responsible for brucellosis are shed in large numbers during abortion, and these organisms can survive for a short period in the environment. Transmission can occur through direct contact with aborted fetuses, fetal membranes, and vaginal discharges from infected animals. This includes handling such materials without appropriate protective measures.

Ingestion: The most common mode of transmission is through the consumption of contaminated food or drink. This can occur when people consume raw, unpasteurized milk or dairy products obtained from diseased animals. The germs enter the body through the mouth, throat, and digestive system mucous membranes.

Inhalation: Although less frequent, inhalation of aerosolized particles containing Brucella organisms can occur in settings with high exposure, such as slaughterhouses or laboratories handling the bacteria.

Conjunctival route: The conjunctiva, which is the mucous membrane covering the front surface of the eye and the inner surface of the eyelids, can also serve as an entry point for Brucella organisms. Direct contact with infected materials or contaminated surfaces, followed by eye contact, can lead to transmission.

Preventing the Transmission of Brucellosis in Goats

Preventing the introduction and spread of brucellosis in animal populations requires implementing biosecurity measures, maintaining proper hygiene, using protective gear (such as gloves), pasteurizing milk before consumption, and pasteurizing potentially contaminated objects. Routine testing and surveillance are essential for identifying and controlling infected animals, reducing the risk of infection spreading to both humans and other animals.

Typical Clinical Symptoms of Brucellosis in Goats

Abortion storm: Brucellosis often manifests as an abortion storm, where a significant number of animals in the herd experience abortion within a relatively short period. This is a characteristic feature of the disease.

Quiescent period: Following the abortion storm, there is usually a period of relative calm, with fewer animals aborting and the disease appearing less active. However, it's important to note that the infection persists, and the potential for future outbreaks remains.

Recurrence of abortions: After a quiescent period, the abortions may resurge after a couple of years, leading to another round of abortion storms. This cyclic pattern is a hallmark of brucellosis in goats.

Lameness and mastitis: In some cases, infected goats may exhibit lameness or mastitis (inflammation of the mammary gland). These signs can occur in the early stages of infection and pose a risk to humans through the consumption of milk from infected animals. Mastitis typically does not affect lactation, allowing infected goats to continue producing milk despite the infection.

Silent carriers: Kids (young goats) infected with Brucella organisms may not display any signs of illness. However, once they reach reproductive age and become pregnant, they may experience abortion, revealing their carrier status.

Male symptoms: Brucellosis can cause orchitis, an infection of the testicles, in males. However, the symptoms are often subtle and difficult to detect.

Note:

Currently, there are no effective treatments for animals with brucellosis. Once Brucella has been transmitted to an animal, the bacteria often remain in the body, particularly in the mammary glands and reproductive system. This makes the complete eradication of the infection through medical care alone challenging.

Prevention and Control Measures of Brucellosis in Goats

Hygiene and good management practices: Maintaining a clean and sanitary environment is crucial. This involves ensuring proper sanitation, regular facility cleaning, and disinfection of all materials and surfaces that come into contact with infected animals or their products. Special attention should be given to the proper disposal of aborted items, including fetuses, placentas, and vaginal secretions.

Separate quarters for kidding: Providing separate and clean quarters for kidding can help minimize the risk of disease transmission. Isolating newly born kids and their dams from the rest of the herd can prevent contact with potentially infected animals and reduce the spread of brucellosis.

Vaccination: Vaccination can play a role in controlling brucellosis, although the availability and effectiveness of vaccines may vary depending on the specific Brucella species and regional regulations. Both killed and attenuated vaccines have been used in certain situations. Consult with a veterinarian to determine your herd's most appropriate vaccination strategy.

Test and disposal procedures: Regular testing of animals is crucial for the early detection of infected individuals. Diagnostic tests, such as serological tests (e.g., Rose Bengal Plate Test, serum agglutination tests), can identify infected animals. Infected animals identified through testing should be culled from the herd to prevent further transmission. Proper disposal methods should be followed for culled animals or materials to prevent environmental contamination.

Biosecurity measures: Implementing biosecurity protocols is vital to prevent the introduction and spread of brucellosis. This includes quarantine procedures for introducing new animals, minimizing contact with other herds or wildlife that may carry the disease, and controlling the movement of animals and personnel.

Surveillance and monitoring: Regular surveillance and monitoring are necessary to detect new cases and track the progress of control measures. This may involve regular testing, record-keeping, and reporting of suspected or confirmed cases to the appropriate authorities.

Veterinary diagnosis: A veterinarian should make a definitive diagnosis of brucellosis in goats using various diagnostic tests. These may include blood tests, such as the Rose Bengal Plate Test (RBPT) or serum agglutination tests, to detect antibodies against Brucella species. Additional diagnostic methods, such as polymerase chain reaction (PCR), may be used to detect the presence of the bacteria.

Conclusion

In conclusion, brucellosis is a significant infectious bacterial disease that poses risks to both animal populations and human health. Goats, in particular, are highly susceptible to this debilitating disease caused by bacteria of the genus Brucella, with Brucella melitensis being the most pathogenic species affecting goats.

Preventing and controlling brucellosis in goat herds requires a multi-faceted approach. Strict biosecurity measures, proper hygiene practices, and the use of protective gear are essential to prevent the introduction and spread of the disease. Regular testing, surveillance, and veterinary diagnosis are crucial for early detection and identification of infected animals. Vaccination, where available and effective, can play a role in controlling brucellosis.