Brucellosis is an infectious disease characterized by recurring waves of fever with intervening apyrexial period, transient painful swelling of the joints, splenomegaly, weight loss and toxaemia. It is of world wide distribution but has become uncommon in developed countries like U.K., USA because of better hygienic measures. All ages and both sexes are equally susceptible.

Brucellosis is caused by a small, non-motile, non-capsulated gram negative cocco-bacilli. There are four species of Brucella. B. abortus is responsible for infection in cattle, B. melitensis in goats and sheep, B. suis in pigs and B. canis in dogs. Of these the first three are important as far as infection in humans is concerned.

Humans acquire the disease by drinking infected goats milk or contaminated animal food products. It is found mostly in farmers, veterinarians, abattoir workers. Butchers •and laboratory workers who come in contact with the infected material. Organism gains entry into the human body through wounds, abrasions or orally and uncommonly via the respiratory tract.

According to the Brucellosis history, the disease causing agent Brucella was discovered in the year 1887. David Bruce first discovered the bacteria in the sleeps of British soldiers who were fatally infected while they were stationed in the Malta Island. The brucellosis history dates back to centuries when sections of the infected patients spleen were tested with Grams method and also with methylene blue, thus revealing large number of micro coccus.

According to the brucellosis history, another four cases showed bits of spleen tissue that were inoculated into tubes containing the nutrient agar and small round colonies that appeared after incubation at 37 degrees centigrade for sixty eight hours.

Upon examination of the stained smears under very high power, numerous micrococci were again visualized. Thus, in the second presentation, David Bruce described the presence of similar bacteria in another fatal case with various organisms measuring from 0.0008 to 0.001 mm in diameter, singly and in pairs that were scattered in the organs.


According to the history, later reports revealed the pathology of the disease in humans and it was compared to typhoid fever and malaria, and thus, the bacteria were classified as gram negative. After the initial diagnosis of the disease, M.Louis Hughes published a monogram that contained detailed information about the disease that was present in enlarged spleens of very rare fatally infected humans.

Although there was no pathological evidence of the disease, the main cause was identified as lack of proper sanitary conditions. When the natural history was defined, it marked the end of centuries of effort that started from the first clinical presentation of the disease.

The citation of such descriptions is often considered sufficient evidence that the disease had existed for long periods of time before its identity was established by an isolation of the etiological agent. According to Hughes, a disease pattern that was compatible with it was described by Hippocrates.

However, according to the history, during the eighteenth and nineteenth centuries several medical writers related cases of intermittent fever suggestive of brucellosis. A large number of descriptions of the disease include intermittent typhoid, typho malarial fever, remittent fever, Mediterranean gastric remittent fever.

The history reveals that it was also known as Mediterranean fever, rock or Gibraltar fever, Malta fever Neapolitan fever, Cyprus fever and undulant fever. Most authorities agree that the first accurate description of it in the history as a disease entity was given by Marston in the year 542 when he was an assistant Surgeon in the British Army Medical Department, who wrote during the year 1860 on the description of the Mediterranean gastric Remittent Fever.

There were many other accounts in the history that was caused due to the etiological agent known as Micrococcus Melitensis and there was also a presentation of the clinical discussion. Thus, it is known to exist for over a century now and it is found in cattle’s ass well as human beings. Various vaccinations have been developed in order to prevent the spread.


After ingestion brucella organism is phogocytized by polymorphonuclear leucocytes and macrophages. Some are killed while other reach via lymphatics to regional lymph nodes. In severe cases bacteremia develops. The spleen gets enlarged as well as liver, kidneys and lungs which show congestion: Granulomas are formed in liver and other reticulo endothelial organs but there is no caseation. These may coalesce, and suppurate to form a chronic. source of bacteremia but eventually, these heal with fibrosis and uncommonly calcification.


Brucellosis undulant fever is a contagious that is caused by bacteria of the genus brucella. The disease is referred to as Brucellosis and it is known to affect animals as well as human beings. When an individual is infected with it he may show sign of undulant fever. Major symptoms include rising and falling fevers that show a wavy pattern and thus the name undulant fever. The individual may also show a sign of excessive sweating that is associated with malaise.

The patient may also complain of weakness and fatigue and there may be symptoms of anorexia. Sometimes, there are headaches and muscular pains, and backaches are also seen in patients suffering from undulant fever.

It is transmitted through ingestion of it causing bacteria that is present in the various types of animal products that are consumed by humans. In some cases, the infection may also result due to contact with an infected animal. Brucellosis fever is very common in veterinary doctors and laboratory workers who may have come in contact with an animal.

Brucellosis fever and excessive sweating is the major sign for recognizing it. The disease causing bacteria may be transmitted when the individual ingests contaminated unpasteurized milk produced from infected animal.

It is also transmitted through direct contact with animal carcass that may be containing the bacteria. If the aborted fetus from an infected animal is not discarded, it can also be the cause of infection. Therefore, proper precaution must be taken when dealing with an animal.

Clinical features

The incubation period of the disease is variable ranging from 1-3 weeks (average 14 days). Clinically it has been divided into Acute, Chronic, Malignant form and Localized Brucellosis.

Chronic brucellosis

It is characterized by ill health, myalgia, easy fatiguability and occasional bouts of fever. Generally these symptoms persist for many months even going upto a year. There is anaemia and splenomegaly.

According to a medical journal, a detailed survey of the symptoms of chronic brucellosis was conducted based on observations of veterinary surgeons working in different regions. The observations were mainly conducted based on the symptoms during observation of cattle that were infected with brucella.

The common symptoms observed in chronic type included excessive sweating and weakness. Most of the patients show symptoms of malaise and irritability and depression. In case of chronic brucellosis, there were signs of rheumatism and arthritis.

The veterinary doctors also reported the presence of backache which was very significant in the case of people suffering with chronic type. It was also found that common symptoms related to the alimentary canal were very much prevalent in all patients that had it.

Headache and insomnia were found in chronic presentation of the disease. Furthermore, it was found that there was a high level of serological brucella antibody titers found in asymptomatic persons that were suffering with chronic type.

In fact, it was found that a large number of surgeons show symptoms of the disease within a period of five years. Therefore, proper precautionary measures must be applied when dealing with infected cattle.

It is known to be transmitted to human beings when it is ingested in the form of unpasteurized milk that may contain the bacteria. It can also be transferred when the veterinary surgeon or other workers come in contact with the body fluid or meat from the cattle showing symptoms.

The individual handling cattle must wear gloves and other gear that is used for protection in order to avoid direct contact with the carcass. After the procedure is completed, the gloves and all other gear must be burned in order to avoid spread of the disease.

Acute Brucellosis

The onset is generally insidious with a wide variety of symptoms. Bouts of fever (low or high grade remittent or intermiltent) lasting 2 or 3 weeks alternate with periods of remission producing the typical Undulant Fever chart. There is profuse sweating, chills, malaise weakness, debility and transient painful swellings of joints.

Lymphadenopathy, splenomegaly, Hepatomegaly and neuralgic pains involving the spine are common. Tongue is coated and furred. There is abdominal discomfort and anorexia. Despile all these complaints, physical findings are not prominent.

Localised Brucellosis

It is not very common and is more like complications in a case of it. It may involve any system ranging from skeletal system (osteomyelitis suppurative arthritis) Neurological (meningitis, Radiculitis, Neuropathy, Encephalitis), Pulmonary (Pneumonia pleural effus ions) Cardiovascular (Endocarditis, Myocarditis) Genito urinary (Epididymoorchitis, urinary tract infection, Prostatis) to splenic abscess. In females, menorrhagia, abortion or premature labour may occur.

The symptoms produced by these may range from Palpilation, Breathlessness, Dizziness, ‘Tinnitus, Arthralgia, visual disturbances etc and shall depend on the system involved.

Malignant form. This is a very severe form but uncommon where person is attacked all of a sudden with high fever, generalized pains, diarrhoea and vomiting. Pulmonary and cardiac complications predominate with hyperpyrexia. This may be a terminal event.

Brucellosis epidemiology

According to the epidemiology, it is commonly found in cattle and is major cause of concern in the United States of America. In most cases, the risk of transmission is always there as the disease causing agent can be transmitted from the infected fetus. This usually occurs when the fetus is exposed to susceptible host.

However, research shows that the brucellosis epidemiology occurs when the disease causing agent is ingested by the cattle. This can be transmitted to other cattle through the process of reproduction. In this case, the semen is responsible for spreading.

In many cases, the infected animal may not show any symptoms. Thus, the epidemiology continues to propagate through contaminated milk that is produced by the cattle.

This milk is a major cause of infection in calves as well as humans who ingest the milk. The main form of transmission occurs when the healthy animal comes in contact with infected tissue of the fetus, or when it comes in contact with fluids that are expelled from the body of the animal during the birth process.

It is also available in the uterine fluids or in the form of vaginal discharges from suffering animals. In case the female cow is suffering, the epidemiology leads to the abortion of the first pregnancy. In some case, the brucellosis epidemiology is confined to the lymph nodes and the tissue is found in the udder of the female cow. Thus, the calves could also become infected by feeding on milk produced by the suffering cow.

Brucellosis Transmission to Humans

Its transmission occurs when causing bacteria spreads from animals to humans. Some of the most common mode of brucellosis transmission includes contact infection, food borne infection, and air borne infection.

The disease causing brucella genus bacteria are present in the tissue and body fluids and transmission occurs when the individual comes in direct contact with the bacteria. In most cases, the brucellosis transmission is done by contact with tissues of the infected animal.

It could also occur when the individual comes in contact with the animal’s blood or urine. The infection is very common in the case of veterinary doctors and their assistants who may be involved in direct contact with vaginal discharge, aborted fetus and placenta of the animal during the process of childbirth.

The bacteria may penetrate through the mucosa or conjunctiva and invade other organs. This type of infection is very commonly found in individuals involved in slaughterhouses. If there is a food borne infection, then transmission may occur due to ingestion of contaminated unpasteurized milk or other dairy products that are made from the raw milk.

It has been found that fresh vegetables may also be a major source of infection as they may collect bacteria from the manure that is used to fertilize the soil. Contaminated water may also be a major source of infection as it may contain the excreta of animals leading to transmission to humans. Brucellosis disease transmission could also spread when the individual inhales dust or aerosols containing the disease causing agent leading to it in humans.

Diagnosis of Brucellosis in Humans

Brucellosis is a contagious disease that affects cattle, goats, dogs and pigs. The disease causing bacteria can also spread to the humans, especially those that come in close contact with infected animals. The bacteria of genus brucella lodge themselves in the tissues and body fluids and thus one must be very careful when handling tissue and milk produced by animals. The bacteria may transmit through mucous membranes and lodge themselves in the lymph nodes and spleen.

If the individuals ingest contaminated unpasteurized milk and milk products, it could lead to the spread of it to the animals. It has been found that the diagnosis of it is very rare in the United States of America.

Brucellosis is very prevalent as almost 200 to 300 cases are being reported on an annual basis. Moreover, people who are in contact may contract the disease when they come in contact with animals or infected meat. The individuals may be slaughterhouse workers, farmers, and even the veterinary doctors are also at a high risk.

The diagnosis of it includes mild flu like symptoms like fever, abdominal pain and back pain. There may be excessive sweating associated with undulant fevers in the patient suffering from it. The diagnosis of it in some cases also showed symptoms of fatigue, headache, loss of appetite, weakness and weight loss.

A major problem with the diagnosis of it is that most physicians are unable to identify the symptoms in the patients due to lack of information. This is important for the eradication of brucellosis in the cattle available in the herd.


1. Brucdlla Agglutination Thst (STA) is the most commonly used. A titre greater than 1: 160 is considered positive. A four fold increase is considered diagnostic.

2. Blood cultures are positive in acute phase of disease in 50% of patients; Bone Marrow cultures give higher positivity.

3. An elevated 1gM antibody titre is seen in first week of infection, IgG antibodies appear 2- 3 weeks after onset of illness and their persistence indicates continuing infection.

Use of 2-mercaptoethanol (2-ME) destroys the agglutination activity of 1gM antibodies and thus allows measurement of only IgG antibodies, indicating a recent infection.

4. Brucella skin test. It is not of much use and is only a measure of past infection.


A combination of Tetracycline (30mg/kg per day in four divided doses) for 3 to 6 weeks plus Inj. Streptomycin IG I/M for 3 weeks, is the treatment of choice, A variety of other dmgs like Rifampacin, Doxycyclin, and gentamicin have also been employed.

Prevention from brucellosis in humans is by adopting hygienic measures like avoiding unboiled milk and infected meat products. People who are at high risk must take proper precautions. No vaccine for use in humans is available. Species of Brucella group of Organisms

Organism Natural Host

1. B. Abortus Cattle

2. B. Mellitensis Goats, Sheep, camel

3. B. Suis Pig

4. B. Canis Dogs

Brucellosis in horses

Brucellosis in horses is caused by the disease causing brucella Abortus or Brucella Suis. It is also known as supportive bursitis that is most commonly recognized as fistulus withers or poll evil is the most common clinical presentation in Horses.

In rare cases, abortion has been reported when there is brucellosis in horses. Also, it has been found that there are no known cases where it has been transmitted to other horses, or other animals or even humans. The disease occurs when the bacteria is ingested by the horse while feeding in areas that lack proper sanitary conditions. The disease can be identified by testing the aborted fetus of the infected horses.

It is also known to reduce fertility in the horses. Therefore, proper precautionary measure must be taken when bringing the horse back from an animal fair or exhibition. The horse must be quarantined and tested for any infection before it is reintroduced in the herd. Thus proper preventive measures must be taken while buying horses and they must be tested for brucellosis in horses.

It is also common in other significant animals like goats, pigs, sheep and other cattle found in the farm. It is also found in human beings, especially those who are in contact with the infected livestock. This includes veterinary doctors, assistants, laboratory workers and others who are in contact with the infected horses. If any animal is identified with it, it is slaughtered in order to eradicate the disease causing agent.

Symptoms of Swine Brucellosis

Brucellosis is common in all forms of domesticated animals including cattle, sheep, pigs and goats. Swine Brucellosis is an infectious one that is commonly found in pigs. The disease is caused by bacteria that are from the brucella suis strain and it has been spreading at a fast pace.

The infection can be caused due to any form of contact with the secretions that are produced from the animal. In most cases, the symptoms are caused by semen that may be infected and is transmitted during breeding.

The symptoms are caused due to the spread causing bacteria from the milk or other reproductive fluids that are formed from the pig. Placenta, aborted fetuses and urine from the infected pig can also cause the spread of the symptoms.

Inhalation or eye contact with the pig that is infected can also lead to chronic illnesses. If the pig has a genetic tendency where it has a reduced response, it may also result in chronic brucellosis.

When symptoms occur in adult pigs, it leads to non specific infertility and in other cases, there is an increased incidence of abortions in the pigs and the animals also show a lack of sexual drive. Wild Boars may also show signs of the disease that is indicated by symptoms like arthritis, lameness, and posterior paralysis.

In spite of all the advancements in the technology, research is still going on as there are no available vaccines for the disease. On the other hand, there is no cure for the symptoms of swine brucellosis.

Wild boars can cause serious infections in pigs and the most commonly found is known as swine brucellosis. The disease causing bacteria is very similar to that found in cows, horses, dogs or sheep. When it occurs in cattle, it is major cause of concern and proper precautions must be taken in order to curb the spread. Clinical presentation includes abortions in sows and is identified when tests are conducted on the aborted fetus.

In the case of wild boars, swine brucellosis causes infertility. The bacteria can continue to exist in the pigs for a long period of time without showing any symptoms. But when swine brucellosis occurs in the cattle it can be very debilitating for the business as it causes a decrease in profits.

The swine bacteria are transmitted through body fluids, especially those that are expelled from the uterus at the time of birth. These are also found in the semen of wild boars and in the infected sows. The most common method to eradicate the disease is by culling the animals. Proper care must be taken when handling infected wild boars.

One must wear gloves and disposable plastic when handling the carcass of the wild boars. One must make sure to properly dispose off all gloves and other gear used while handling the pigs. When bringing the pigs back from an affair, one must follow proper precautionary measures and isolate the animal in order to observe any signs of swine brucellosis in the pigs.

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