Brucellosis: what is it, symptoms, human, canine, bovine, vaccine

Brucellosis, also called Bang’s disease, fever malta, Gibraltar fever, Mediterranean fever, Neapolitan fever and other names, is a disease caused by a bacterial infection.

Even with so many names, brucellosis is still not a disease so well known to people. However, it is quite understandable, considering the fact that it is a rare pathology that affects, in most cases, animals such as cows, pigs, horses and dogs.

Are you curious to know how this transmission can occur?


What is brucellosis?

Brucellosis is a contagious bacterial disease caused by bacteria of the genus Brucella . It is a zoonosis, that is, a disease that affects humans and is transmitted by contact with animals.

It can be known for a number of variations, such as Malta fever, Gibraltar fever, intermittent Mediterranean fever and several other nominations.

As some of the names above indicate, fever is one of the main symptoms of the disease. In addition, it causes sweating, tiredness , chills, abdominal pain, headache and back pain .

It is a more common disease in animals, but it also affects humans.

However, it is not considered a risk for the general population, and is therefore considered a professional disease.

In other words, it is related to professionals who work in contact with animals, such as veterinarians, biologists, farmers, milk producers, people who work in slaughterhouses, etc.

The treatment of brucellosis is done through the administration of antibiotics , in order to eliminate the bacteria from the patient’s body.

When the treatment is successful, the chances of the patient getting a cure are high. However, the disease may recur.

For humans, there is still no vaccine that can prevent contamination. Therefore, to avoid it, it is necessary to maintain some preventive measures and care with hygiene.

In the International Disease Code, ICD-10 , brucellosis is found by the code A23, and also in the following segments:

  • A23.0 : Brucellosis due to Brucella melitensis;
  • A23.1 : Brucellosis by Brucella abortus;
  • A23.2 : Brucellosis by Brucella suis;
  • A23.3 : Brucellosis by Brucella canis;
  • A23.8 : Other brucellosis;
  • A23.9 : Brucellosis, unspecified.

Cause: etiologic agent

Brucellosis is caused by infection by bacteria of the genus Brucella.

There are 9 species described within this genus, the main ones responsible for causing the disease in humans are B. melitensis, B. abortus and B. suis . Being B. melitensis can cause the most serious cases, but in Brazil this type is rarer.

Although they can be found in any animal group, normally the species of this bacterium have specific host groups. Are they:

  • B. unpredictable , humans;
  • B. melitensis : goats, sheep and camelids (camels, llamas, alpacas, etc.);
  • B. abortus : cattle and buffaloes;
  • B. suis : swine and wild mammals;
  • B. canis : dogs;
  • B. ovis : sheep;
  • B. neotomae : wild rats (from forests and deserts);
  • B. microti: roedores;
  • B. delphini, B. pinnipedia and B. ceti : marine animals, such as whales, dolphins and seals.


On wet soil and in water, these bacteria are able to stay alive for up to 10 weeks. But in the heat or in contact with products such as disinfectants, they are inactivated.

How does the transmission happen?

The transmission of brucellosis to humans occurs through some routes, the main ones being through direct contact with infected animals or ingestion of food or drinks contaminated by the bacteria.

The incubation period for human brucellosis varies from 5 to 60 days, and can last up to 2 years.

Check out some of the main forms of contamination:


People can become infected with the bacteria through ingestion of contaminated products, such as unpasteurized milk, raw or undercooked meat, and dairy products, such as cheese, butter, ice cream, etc.

In food, the time they remain active can vary. In unpasteurized milk at normal temperature, for example, the bacteria can survive for up to 17 days, in frozen milk it can live for long periods (more than 2 years).

In products such as butter, they remain active for up to 4 months, and in cheese for up to 6 months.

Read more: Leptospirosis: disease transmitted by rat pee during floods and in soda cans

Contact with infected animals

It is a transmission that occurs more frequently among people who work in contact with animals that can be hosts (cattle, sheep, pigs, horses, dogs, etc.).

This contamination occurs through contact with the animal’s blood, urine and secretions, but also through contact with aborted fetuses and placental remains, with the injured skin and mucosal regions of the animal (such as gums).


Transmission can occur through the respiratory tract, when, in contaminated environments, the bacteria is able to enter the patient’s body through inhalation. It can occur in people who work in places with infected animals, such as stables, kennels, laboratories, slaughterhouses, etc.

Other forms of transmission

There are some forms of transmission from person to person that are extremely rare, but that can also occur, such as by accident in the animal vaccination application, during sexual intercourse, in pregnancy (vertical transmission), blood transfusion and transplants.

Risk groups for human brucellosis

Because it is a zoonosis, people working with animals are among the risk groups, who become more vulnerable to contamination and develop the disease, such as farmers, veterinarians, professionals working in slaughterhouses, microbiologists, milk producers, etc.

In general, men are more affected by brucellosis than women, being 2 times more vulnerable to the disease. As for age, the age group most affected is between 55 and 64 years old.

As for the period of transmission, it is in the months between April and July that more cases are observed, due to the period being marked by the greater number of births of the animals and greater production of milk.

Symptoms in humans

Brucellosis, in some patients, can be asymptomatic. When it causes symptoms, they can be nonspecific at the onset of the disease. The most characteristic symptom of the disease is high fever (above 38 ºC).

Other signs of the disease also resemble a flu condition , as the patient may experience malaise, tiredness, weakness, chills and, in some cases, weight loss.

High fever

In brucellosis, patients have fever as a characteristic symptom, but it can manifest in several ways. The patient may fluctuate in temperature throughout the day, and may be a higher fever throughout the afternoon and evening and may have remission in the morning.


In this infection, the patient ends up also having pains in the body, such as headache, in the joints, abdomen, back and muscles.

Excessive sweat

In addition to fever and pain, the patient presents, together, sweating, an excessive sweat and more common during the night. This manifestation, in some cases, can cause an unpleasant odor.

Brucellosis in pregnancy

Brucellosis in pregnant women is a risk, but transmission to the baby is very rare. This vertical transmission, as it is called, can cause abortion.

In the first trimester of pregnancy, the risk is even more pronounced, and it is extremely important to seek medical help in case of any symptoms of the disease and correctly maintain the routine of consultations and prenatal care.

The earlier the diagnosis of brucellosis, the better the response to the treatment of the disease. Thus, the health risks of the mother and baby are also reduced.


The diagnosis of brucellosis is not always easy, as the symptoms are nonspecific and can be interpreted as a flu or other illness. Thus, only with an analysis of the symptoms, it is not possible to have an accurate diagnosis.

Considering this difficulty, it is important that doctors conduct an interview with the patient to identify whether they have had contact with an infected animal or ingested any product that may be contaminated.

However, to confirm the disease it is also necessary to do laboratory tests, such as bacterial culture, PCR and serology, which can be done after collecting the patient’s blood.

Bacteria culture

This is a technique used to control and grow certain bacteria, so that it is easier to assess, identify and study the species, which helps in the treatment of the patient.

It is done with the collection of tissue samples or fluids, such as saliva.


The PCR (C-reactive protein) test is performed from the collection of a blood sample.

This protein is an indicator of inflammatory processes and necrosis in the body, especially in cases of bacterial infections. It is an important technique to investigate the risk of cardiac complications.


Typically, the test is used to investigate whether the patient has been infected with a virus or other microorganism, indicating whether there is a specific antibody in the blood.

Does brucellosis have a cure?

Yes , brucellosis is curable. In humans, with the correct drug treatment and early diagnosis, the disease can be treated and the patient has a complete remission of the infection. However, in some cases, the disease can reoccur, which requires treatment to be done again.


Brucellosis is treated with the use of antibiotics, which are drugs that help fight bacterial infection in the body. After diagnosing the symptoms and carrying out tests, the doctor should prescribe the use of these remedies.

It is important that the patient follows the treatment to the letter, as the use of antibiotics for a longer or shorter period than prescribed can interfere with the treatment and cure of the disease.

In the Unified Health System (SUS), the treatment of human brucellosis is available free of charge.

Remembering that the time of treatment, medications and doses may vary according to the type of bacteria present in the patient’s body and the age group.

In addition to medication, patients must also remain at rest and with good hydration.

Read more: Misuse of antibiotics creates superbugs that can kill


Some of the antibiotics that can be used to treat human brucellosis are:

  • Gentamicin ;
  • Doxycycline ;
  • Tetracycline ;
  • Streptomycin ;
  • Ciprofloxacin .


NEVER self-medicate or stop using a medication without first consulting a doctor. Only he will be able to tell which medication, dosage and duration of treatment is the most suitable for his specific case. The information contained on this site is only intended to inform, not in any way intended to replace the guidance of a specialist or serve as a recommendation for any type of treatment. Always follow the instructions on the package insert and, if symptoms persist, seek medical or pharmaceutical advice.


Brucellosis is rarely a lethal or chronic disease. Although it is possible to relapse, it can be treated and cured with antibiotics without leaving sequelae.

However, when left untreated, it can develop into serious health problems that can lead to death.

Relapses of the disease can occur in up to 10% of patients who received treatment. This return of the disease occurs, on average, after 2 to 3 months after the treatment of the first manifestation.

The patient suffers from the same symptoms, but more pronounced or intense.

This can occur either because of treatment failure or because of the bacteria’s resistance to medications.


When the patient does not receive these drugs, the disease can become chronic and cause more serious complications.

In this condition, the patient may present with fever as a constant symptom. You may also experience weight loss, anemia and chronic joint pain.

In addition, brucellosis can progress to other, even more serious, diseases that affect the nervous system. However, they are rare cases, because with antibiotic treatment, the patient tends to have a total improvement of the disease, without damage to the organism.

The main complications that can occur in cases of untreated brucellosis are:


The arthritis is an inflammation that occurs in the joints, which can be due to several factors. One of the causes is bacterial infection.

In this condition, the patient has constant pain, swelling, difficulty in movement and redness of the skin in the region of the joints.


The endocarditis is a serious complication that affects the lining of the heart, in most cases causing damage to heart valves.

In patients with untreated brucellosis, endocarditis can occur due to the presence of bacteria in the bloodstream, which can reach the heart and cause this inflammation.

Patients with this disease can have heart failure, infarction and damage to other vital organs, which can be lethal.


It occurs when the brucellosis bacteria cause an inflammation in the patient’s liver. With this disease, the person manifests characteristic symptoms of hepatitis, such as when the skin and the white part of the eyes become more yellow.

Bacterial meningitis

The meningitis is an inflammation that affects the meninges, the membrane protecting the brain region. It is a serious complication, which can lead the patient to death and cause serious sequelae.


Infection is a risk for pregnant women as it can cause an abortion, especially in the first trimester of pregnancy.

As of the 6th gestational month, brucellosis is associated with premature birth and retention of the placenta, a condition in which the placenta is retained in whole or in part in the uterus for periods longer than 12 hours after delivery.

How to prevent?

The transmission of brucellosis from person to person is very rare, but contamination from animals to humans, which is the most frequent, can be prevented. Some prevention guidelines include:

Use safety equipment

Professionals who work in direct contact with animals should use equipment that helps to prevent contamination by infectious agents, such as gloves, goggles, masks and aprons.

These precautions are especially indicated when an animal shows symptoms of this or another disease, in childbirth or when dealing with a dead animal.

After using this safety equipment, it is important that it is properly disposed of or sanitized.

Do not consume unpasteurized food

It is important to be very careful with the consumption of milk, cheese or other products derived from homemade milk, which have not undergone a pasteurization process. This is one of the main ways of preventing brucellosis for humans.

Stay away from contaminated animals or environments

Brucella sp bacteria can remain in water and moist soil for long periods, but it is inactivated by heat and cleaning products such as disinfectants. Therefore, it is important to be careful with environments in which cases of brucellosis have been recorded and to keep them clean.

Avoid eating undercooked meat.

The bacterium does not survive when it undergoes pasteurization or cooking processes, so it is important to cook food well before consuming it, as is the case with meat.

At a cooking temperature of 60 ºC, these bacteria can survive for 10 minutes. At higher temperatures, such as 71 ºC, they can be inactivated in a matter of seconds.

Vaccinate animals

Because it is a zoonosis, it is known that one of the main forms of prevention is to eradicate the disease in animals. In cattle, the disease is quite common and, in their case, there is a vaccine to prevent brucellosis.

In many cases, the infection of these animals requires that they be sacrificed, so it is essential that there is prevention with immunization.

Brucellosis vaccine

Although there is no vaccination against brucellosis for humans, fortunately, it exists for animals of other species, which, consequently, helps to contain the spread of the disease among humans as well.

Vaccination in animals, therefore, is mandatory for all females aged between 3 and 8 months, called B19. It is applied in a single dose, with the ability to offer prolonged protection in 70 to 80% of the animals.

Another measure to contain the disease is the certification of free or monitored properties that are protected from the disease through immunization.

How old are you to vaccinate against brucellosis?

The animals must be vaccinated with the B19 immunizer when they are aged between 3 and 8 months. This application is done in a single dose and only in females. In calves, the vaccine is recommended to be applied no later than 6 months, to reduce the risk of adverse reactions.

Canine brucellosis

As seen, dogs are also not free to suffer from this infection. In pets, the disease is caused by the species of bacteria B. canis , which can affect males and females in the same way.

In females, canine brucellosis can cause miscarriage, being one of the signs of the disease in the animal.

It can also cause symptoms such as hair failure, anemia, apathy, joint pain and lethargy, a condition in which the dog even awake appears to be unconscious.

The diagnosis in dogs is usually made through serological tests, but they can have false positive results and, in cases of chronic canine brucellosis, they can point out false negatives.

In such cases, to confirm the diagnosis, a bacterial isolation test may be necessary.

Treatment is done with antibiotic drugs, however, in many cases it is not enough to fight these bacteria in the animal’s body.

Among dogs, the bacterium is transmitted during sexual intercourse, it can also be spread through infections in the nasal mucosa, through injured skin, during delivery and through feces.

Why is brucellosis an occupational disease?

Brucellosis is an occupational disease because the contamination is also related to the work environment.

That is precisely why workers from specific areas are among the risk groups, such as veterinarians, milk producers, biologists, farmers, people who work in slaughterhouses, etc. In all of these areas there is a risk of bacterial infection from contact with animals.

Although it is a zoonosis and transmission from man to man is rare, it is important to know what brucellosis is and the complications that this bacterial infection can cause.

Now that you are well informed about this disease, how about sharing this article so that more people can get to know and know about ways of prevention? Thanks for reading!