The Brucellosis is a group of diseases caused by bacteria belonging to the genus called Brucella . It is an anthropozoonotic disease, that is, it is a disease that can be transmitted to humans by various vertebrate animals. It could be said that the human being is not actually the target of this group of bacteria, but that its infection is an accident in the epidemiological chain (path followed by the pathogen from its natural habitat to the susceptible host), since its host Other mammals are usually common (sheep, cattle, goats, pigs, dogs, cetaceans, etc.).

In humans there have been cases of infection with B. melitensis , which originally affects mainly goats and sheep, and which is responsible for most of the cases observed in Spain. B. abortus , which affects cattle; in humans it usually presents as an asymptomatic pathology. And B. suis appears in sheep and pigs; the percentage of infection in humans is quite low.

How brucellosis is contracted

The spread of brucellosis (also known as Maltese or Mediterranean fever, undulating fever or Bang’s disease) is usually caused by contact with fluids from an infected animal (blood, urine, feces, vaginal fluids, aborted fetuses, placenta ) and due to the consumption of infected animal products, mainly raw milk or dairy products made with raw milk.

In general, cases of person-to-person transmission do not occur, they have only been detected in certain circumstances such as transplants with infected organs, sexual contact with a sick individual, or a nursing baby breastfed by an infected mother.

The routes of contagion, that is, the place where the bacteria enters the body once it has established contact with the individual, are usually the mouth, nose, eyes and injured areas on the skin (cuts, wounds, etc.). Eating an infected product is usually the most common form of infection unrelated to the workplace.

Brucellosis symptoms

The incubation period for brucellosis can be very variable, from five days to several months. The most common is that the first symptoms begin to be observed between 10 and 30 days after exposure to the pathogen.

The symptoms of brucellosis can be very different in each individual, even asymptomatic cases.

The path that the bacterium follows after penetrating the body has its first stop in the lymph nodes; if at this point the individual’s defenses are unable to eliminate the pathogen, it will multiply and pass into the bloodstream. At this time the typical symptoms of the acute stage of the disease can be observed. The most common and characteristic of this stage is the appearance of fever of up to 38ºC that lasts for several days, after which it decreases, later appearing in waves and accompanied by profuse sweating, disproportionate to the feverish state and usually at night, and pain articular, muscular or neurological. The patient can present a state of continuous tiredness and, in many occasions, constipation. To this can be added unspecific symptoms such as fatigue,

Once in the blood, the bacteria will have access to various organs and tissues of the body, acquiring focal locations:

• Orchiepididymitis: inflammation of the testicle and epididymis (a tube that connects the testicle to the vas deferens). It occurs in five out of every 100 male patients.
• Focal affections of the osteoarticular system :
• Sacroiliitis: inflammation of the sacroiliac joint, joint located between the sacrum and the ilium of the coxal bone, in the final part of the back.
• Spondylitis – inflammation of the joints of the spine. It gives rise to low back pain, stiffness, etc.
• Bursitis: inflammation of the bursa, a structure located between the bones, tendons and muscles, and whose function is to facilitate the movement of these structures, avoiding friction between them.
• Tenosynovitis: inflammation of the sheath that lines a tendon.
• Hepatic granulomatosis: inflammatory lesion that gives rise to a mass or granuloma formed by the accumulation of cells of the immune system.
• Brucellosis pneumopathy: set of lung disorders that can include various symptoms.

The arrival of bacteria in the central nervous system and endocarditis (inflammation of the endocardium, inner wall of the heart) are the most serious complications of brucellosis ; These, like cases of dermatological lesions, are quite rare and usually occur mainly in individuals who are continuously exposed to the pathogen due to their occupational occupation.

Brucellosis has a high tendency to produce recurrences (reappearance of symptoms), especially in the three months after the disease and in cases that have not been treated. Some individuals may suffer from ailments derived from the disease for years, leading to a chronic condition that will lead to a decrease in skeletal muscle function, neurovegetative disorders, paresthesia (altered sensation of the senses that manifests as tingling, numbness , etc.) and joint pain.

Diagnosis of brucellosis

Given the wide variety of symptoms that brucellosis can produce , detection of the disease is not always easy. The data provided by the patient about his occupation and the area where he lives or works can be very helpful in determining the diagnosis . In endemic areas, health professionals are familiar with this type of case and, therefore, the diagnosis is usually quick and accurate. This localized distribution of the disease is a disadvantage in areas where brucellosis does not appear routinely, since differential tests for this condition are not routinely performed, and cases tend to be detected when the disease is already well advanced.

Laboratory analysis is an essential test in the search for signs of brucellosis, since it will make it possible to know for sure which is the causative agent of the pathology (if this is a bacterial agent). The procedure consists of taking a blood sample and performing a culture with it, that is, keeping the sample in specific conditions that allow the growth of the bacteria. This allows, first of all, to determine the presence / absence of bacteria in the blood.

If colonies appear (groups of bacteria that appear in the medium when there is growth), it will be possible to determine if these belong to Brucella , according to their color and shape characteristics. Subsequently, a sample of the cultured bacteria can be taken and their morphology can be observed under a microscope, which will be compared with that of the suspected pathogen. In addition, a series of biochemical tests can be performed that will provide additional data to confirm the diagnosis of brucellosis.

Brucellosis Treatment

The treatment of brucellosis consists of the administration of a combination of antibiotics . No antibiotic alone clears the infection effectively. Before applying any treatment, the doctor must identify the extent of the infection, that is, he must assess the presence of focal locations and complications such as meningoencephalitis or endocarditis ; In the latter case, treatment with the usual medication (rifampicin and doxycycline) will be added with a treatment with a third antibiotic (usually tetracycline or an aminoglycoside).

The objective of the treatment is, in addition to reducing the symptomatic period of the disease, avoiding the appearance of complications such as the focal location of the pathology, and minimizing the appearance of recurrences.

The recommended duration of treatment for brucellosis is a minimum of six weeks ; in cases with focal locations, it may be prolonged somewhat more depending on the evolution of symptoms.

Like all long-term treatments, brucellosis presents the problem of abandonment. It is of utmost importance to carry out the complete process since, if this disease already has a high rate of recurrence, an incomplete follow-up of the treatment will be practically equivalent to its absence.

In patients who comply with the prescribed doses and period, the appearance of recurrences depends mainly on the presence of focal locations. The medication to be applied in the event of a recurrence will be the same as that of the initial treatment, given that Brucella has the characteristic (at least for the time being) of not presenting resistance to any of the antibiotics used to combat it (in Bacteria sometimes become resistant to antibiotics to which they have been previously exposed.)