Brucellosis
A silent herd disease with two costs: it quietly wrecks breeding — abortions, dead calves, repeat services — and it is one of the most common infections that pass from farm animals to the people who keep them.
- Cause
- Brucella abortus / melitensis
- Main sign
- Abortion in late pregnancy
- Zoonotic
- Yes — undulant fever in people
- Control
- Test-and-remove + calfhood vaccine
Overview
Brucellosis in Indian livestock is caused mainly by Brucella abortus in cattle and buffalo and Brucella melitensis in goats and sheep. The bacteria concentrate massively in the placenta, the aborted foetus and the fluids and discharges of an animal that has aborted or calved. They also pass out in milk. An animal usually catches it by licking or sniffing an aborted foetus, afterbirth or contaminated ground, or through contaminated feed and water.
The hallmark in cattle and buffalo is abortion in the last third of pregnancy, often in a first pregnancy, followed by a retained placenta and a womb infection. After one or two abortions the cow may carry a calf to term but keeps shedding bacteria at every calving, and both cows and bulls can become permanently sub-fertile — "repeat breeders". In goats and sheep the pattern is abortion storms in late pregnancy and weak, dying kids and lambs.
There is no practical cure in animals; treatment does not clear the infection, so control is about testing, removing or isolating positive animals, and vaccinating young females. Brucellosis is a serious zoonosis: in people it causes undulant fever — weeks of rising-and-falling fever, drenching night sweats, joint and back pain and lasting fatigue — usually caught from handling birth material without protection or drinking unboiled milk.
This is a general guide, not a substitute for a veterinarian. Always call a vet for diagnosis, dosage and treatment of a sick animal.
Signs in the herd
- Abortion in the last 3 months of pregnancy, especially in heifers with their first calf; sometimes a full-term but weak or stillborn calf.
- Retained placenta (afterbirth not passed within 12 hours) and a persistent brownish womb discharge after aborting.
- Cows that come back into heat repeatedly and fail to hold to service — "repeat breeders".
- In goats and sheep: several does or ewes aborting in late pregnancy within a short period, and weak kids and lambs that die.
- In bulls: hot, swollen testicles (orchitis) and reduced fertility; swollen leg joints or hygroma in some adult cattle.
- Often no visible illness at all — infected animals look healthy between calvings while still shedding bacteria.
How it spreads
- Contact with the aborted foetus, afterbirth, and the fluids and discharges of an animal that has aborted or just calved — the main source, teeming with bacteria.
- Licking or sniffing contaminated ground, bedding, feed and water; the bacteria survive for weeks in cool, moist, shaded conditions.
- In the milk of infected animals — important for calves, kids and for people who drink it unboiled.
- Buying in infected replacement animals with no test — the commonest way a clean herd becomes infected.
- Natural service with an infected bull, shared or contaminated AI equipment, and on hands, boots and tools between animals.
Protecting people (zoonosis)
- Never handle an aborted foetus, afterbirth or a freshly calved animal with bare hands — wear rubber gloves, cover cuts, and wash and disinfect afterwards.
- Do not let children or dogs near abortion material; collect it and bury it deep with lime or burn it.
- Always boil milk before drinking or making curd, especially from a herd with any history of abortion; avoid raw-milk products.
- People at risk — farmers, herders, milkers, AI technicians, vets, abattoir and dairy workers — should ask a doctor for a brucellosis test if they get a long, up-and-down fever with night sweats and joint pain.
- Tell the treating doctor about animal contact — brucellosis in people is often missed and needs a specific, weeks-long course of antibiotics.
Control and vaccination
- Vaccinate all female calves of cattle and buffalo once with Brucella abortus S19 vaccine at 4–8 months of age (the strategy under the National Animal Disease Control Programme); goats and sheep are vaccinated with Rev-1 where used.
- Do not vaccinate adult pregnant animals with S19 — it can itself cause abortion and is best given only in the calfhood window.
- Blood-test breeding animals (RBPT screening, confirmed by ELISA); cull or permanently isolate positive animals and keep them out of the breeding herd.
- Test every animal before you buy it, and quarantine new arrivals until a second test 4–8 weeks later is also negative.
- Calve cows in a separate clean pen; remove and safely destroy all afterbirth; disinfect the pen before the next animal uses it.
- Keep a closed herd where possible, use AI from certified brucellosis-free bulls, and do not share a bull with infected herds.
Animals affected
Open an enterprise page for its full feeding, breed and vaccination-calendar guide.
Frequently asked questions
My cow aborted once and is now carrying normally. Is she cured?
No. An infected cow typically aborts once or twice, then carries calves to term — but she stays infected for life and sheds huge numbers of bacteria in the fluids and afterbirth at every calving. She is a permanent source of infection for the rest of the herd and for people, which is why test-positive animals are removed from breeding.
Can I catch brucellosis from milk?
Yes — drinking unboiled milk or eating products made from raw milk from an infected animal is a well-known way people get brucellosis. Boiling milk destroys the bacteria. The other main route is handling abortion material or a freshly calved animal without gloves.
Is there an injection or course that cures an infected cow?
No practical one. Antibiotics do not reliably clear Brucella from an animal, and treated animals keep shedding. Control is based on preventing new infections — calfhood vaccination, testing, and removing positives — not on treating infected adults.
Why can’t I just vaccinate my whole adult herd to fix it?
The S19 vaccine is designed for female calves aged 4–8 months. Given to adult or pregnant animals it can cause abortion and can make later blood tests hard to interpret. The right approach is to vaccinate every heifer calf in that window from now on, and test-and-remove among the adults.
Signs, prevention and treatment follow ICAR, DAHD and state veterinary-university practice; vaccine schedules are the commonly notified ones and may vary by region or outbreak status. Always confirm with a veterinarian before treating an animal. editorial policy.