Brucellosis, an infectious disease caused by bacteria of the genus Brucella, is a highly contagious bacterial disease in cows that significantly affects their reproductive health. Caused primarily by Brucella abortus, this zoonotic disease poses serious economic and public health concerns across India and the world. Recognizing its symptoms early and implementing effective prevention strategies are vital for controlling its spread in dairy herds.

Brucella abortus mainly affects the reproductive system, leading to abortions, infertility, reduced milk yield, and long calving intervals. The disease is not only a threat to animal health and productivity but also to human health, as it can be transmitted through direct contact with infected animals or consumption of unpasteurized dairy products.

In India, bovine brucellosis is considered endemic and continues to be a major obstacle in improving cattle productivity. The Government of India has implemented the National Animal Disease Control Programme (NADCP) to address this, focusing on mass vaccination and disease surveillance.

How Does Brucellosis Spread?

Brucellosis spreads through:

• Ingestion of contaminated feed, water, or milk
• Contact with aborted fetuses, placenta, or uterine discharges
• Artificial insemination with infected semen
• Calving areas and milking sheds contaminated with infected materials

The bacteria can survive in the environment for weeks under cool and moist conditions, increasing the chances of herd infection.

Symptoms of Brucellosis in Cows

The clinical signs of brucellosis in cows often go unnoticed in the early stages. However, as the infection progresses, certain key symptoms emerge:

1. Abortion

• Most common sign, typically occurring during the last trimester
• Often followed by retained placenta and uterine infections

2. Infertility

• Irregular estrus cycles
• Difficulty in conceiving even after multiple attempts

3. Decreased Milk Production

• Infected cows may show a sudden drop in milk yield
• Milk may appear normal but can harbor the bacteria

4. Lameness or Joint Swelling

• Swollen joints, especially knees and hocks, may occur in chronic cases

5. Stillbirths and Weak Calves

• Calves may be born weak, fail to thrive, or die shortly after birth

In bulls, brucellosis can cause orchitis (inflammation of the testicles) and infertility, although they often remain asymptomatic carriers.

Diagnosis of Brucellosis

Since brucellosis symptoms can be confused with other reproductive disorders, laboratory testing is essential. Common diagnostic tests include Rose Bengal Plate Test (RBPT), Serum Agglutination Test (SAT), and Enzyme-Linked Immunosorbent Assay (ELISA)

Veterinarians may also take samples from aborted fetuses, placenta, or vaginal swabs for bacterial culture or PCR testing.

Prevention and Control of Brucellosis in Cows

Preventing brucellosis in cattle requires a combination of vaccination, biosecurity, and proper herd management practices.

1. Vaccination

• Brucella S19 vaccine is commonly used in heifer calves between 4-8 months of age
• Under the NADCP, mass vaccination is being implemented across India for disease eradication
• Vaccination is crucial to build herd immunity and prevent outbreaks

2. Regular Testing and Culling

• Periodic serological testing helps detect infected animals early
• Infected animals should be culled or isolated to prevent spread within the herd

3. Good Biosecurity Measures

• Maintain hygiene in calving and milking areas
• Properly dispose of aborted materials and placentas by incineration or deep burial
• Use personal protective equipment (PPE) while handling animals, especially during parturition

4. Quarantine New Animals

• New animals must be tested for brucellosis before being introduced into the herd

5. Avoid Unpasteurized Milk

• Educate farm workers and the community about the risks of drinking raw milk or handling infected animals

Human Health Risk

Brucellosis is a zoonotic disease, meaning it can be transmitted to humans. In humans, it is often called undulant fever, characterized by:

• Intermittent fever
• Joint and muscle pain
• Weakness
• Loss of appetite

People working closely with cattle, like veterinarians, dairy workers, and farmers, are at higher risk. Hence, brucellosis control in animals directly contributes to public health safety.

Role of Farmers and Veterinarians

Farmers should be trained to recognize early symptoms and report abortions or reproductive failures to local veterinary authorities. Veterinarians play a key role in diagnosis, vaccination, and educating farmers about brucellosis prevention and zoonotic risk management.

Brucellosis in cows is a serious reproductive disease that leads to economic losses, reduced animal productivity, and public health risks. With effective prevention strategies such as vaccination, biosecurity practices, and regular testing, India can move towards eliminating bovine brucellosis under national disease control initiatives.

Investing in livestock health not only improves milk production and cattle welfare but also ensures the safety of farmers and consumers. Timely action and awareness are our best tools to combat this silent threat in the dairy industry.