Brucellosis

The Brucellosis is a disease of animals and humans caused by a bacillus called Brucella.

This disorder is very common and appears in practically all countries. Has been called in many ways, depending on the geographical regions where it was or its symptoms, and other names are fever Mediterranean, Malta fever, fever Gibraltar fever Cyprus fever undulant, or typhoid fever intermittent, for their similar to typhoid fever.

It produces varied symptoms, although the most frequent is fever and it can end up producing a large number of complications in different organs if adequate treatment is not established. Formerly it produced high mortality rates, although since antibiotics have been known, death from this disorder is quite rare.

Why is it produced?

Brucellosis is caused by brucella, which is an aerobic, gram-negative, immobile, capsule-free bacteria.

There are four different species:

• Brucela melitensis: it is the most common in the world and is transmitted by goats, camels and sheep.
• Brucela abortus: Found in cattle
• Brucela suis: Appears in pigs
• Brucela canis: Found in the dog.

Brucella can remain alive for up to 40 days on dry land with remains of urine, feces, vaginal secretions or products of conception from infected animals. If the ground is wet, it survives longer.

It is not destroyed by freezing but by boiling or pasteurization of milk or its derivatives, which are the main source of contagion to humans.

The bacteria live in infected animals and from these they are transmitted to man. The main route of transmission is the consumption of fresh milk or dairy derivatives without any type of preparation, it is also acquired if raw meat or bone marrow of infected animals is consumed.

Another form of transmission is by inhalation during contact with animals, especially in children and workers in slaughterhouses, farms and laboratories. In addition, workers in these industries can suffer transmission by skin abrasions, autoinoculation and splashes to the eyes. In addition, transmission from person to person through the placenta or through breastfeeding has been seen.

Once the bacteria enter the body, an immune system response is produced through antibodies and lymphocytes, which develop inflammation in the brucella replication site, which are the lymph nodes and tissues of the reticuloendothelial system, which can lead to necrosis of these areas and abscess formation. On other occasions, the infection is spread through the blood, thus affecting different organs.

Symptoms of brucellosis

The clinical manifestations are highly variable, from mild forms with few general symptoms to very severe forms.

The incubation period, from when infection occurs until symptoms develop, varies from one to three weeks, although sometimes it lasts for several months.

Symptoms appear abruptly (one to two days), or gradually (a week or more), the most common being fever, which is usually higher in the afternoon and at night, chills, sweating, headaches, muscle, joint, loss of appetite and weight, fatigue, pharyngitis and dry cough . Sometimes the symptoms are much more serious with paleness, poor general appearance, lymphadenopathy, enlargement of the liver and spleen, joint inflammation, testicular inflammation, meningitis , heart murmurs or pneumonia.

The complications that can appear as a consequence of this infection are highly variable, encompassing almost all organs:

• Skeletal system : It can cause septic arthritis , although the most frequent is the appearance of reactive arthritis to the general affectation, without the presence of infection in the affected joints (usually several at the same time), which show an increase in size with swelling and pain. It occurs mostly on the knees, hips, and shoulders. Sometimes infection occurs inside the bones, mainly in the lumbar vertebrae.
• Cardiovascular system: Brucella can cause infective endocarditis , pericarditis, and abscesses of the aortic arch. Endocarditis appears on previously damaged valves or on healthy valves.
• Respiratory system: It is common to cause a picture similar to a cold with pharyngitis or tonsillitis and a dry cough. Sometimes more complications appear such as pneumonia and lung abscesses.
• Digestive system : They are usually mild, such as diarrhea, nausea, vomiting and abdominal pain. More serious complications are enlargement of the liver and spleen, jaundice, and the formation of abscesses in the liver and spleen.
• Urogenital system: It can lead to unilateral or bilateral orchiepideymitis, prostatitis , cystitis , infections and abscesses in the tubes and ovaries, and acute pyelonephritis . Brucella infection during pregnancy can cause the death of the fetus.
• Nervous system : Neurological involvement is rare but very serious if it occurs, with meningitis, encephalitis and brain abscesses.
• Organs of the senses: Splashes of brucella in the eye can cause conjunctivitis , corneal ulcers and retinal detachment .
• Skin: May cause a generalized rash, ulcers, and skin abscesses.

How is it diagnosed?

A feverish syndrome, with sweating, joint pain and lymphadenopathy or an enlarged spleen should make us think about this infection, although its diagnosis requires confirmation by the laboratory. For this, two methods can be used, either isolating the germ or demonstrating the existence of antibodies in the body against it.

Brucella can be found in different products such as blood, urine, sputum, CSF, bone marrow, etc. The cultivation of all these materials can demonstrate the existence of the germ, although the most profitable one is hemoculture (blood culture) in enriched media at 37ºC for at least one month if no bacterial growth has occurred before. To be effective, the patient should not be under treatment with antibiotics.

There are several serological techniques to demonstrate the existence of brucellae by detecting antibodies, the best known being the so-called Rose Bengal, which offers a quick result.

In addition to these diagnostic techniques, different tests will be needed to diagnose possible complications such as chest X-rays for pneumonia, bone X-rays, MRI or scintigraphy for bone infection, ultrasound for abdominal complications, etc.

Treatment for brucellosis

There are several treatment guidelines, although all of them use combinations of several antibiotics since only one has been associated with high rates of resistance of the germ and with treatment failures and recurrences of the condition. In addition, the duration of treatment must be greater than six weeks to be effective.

The most commonly used combination is doxycycline with streptomycin, gentamicin, or netilmicin for 4 to 8 weeks. An alternative is doxycycline plus rifampin for 8 to 12 weeks.
Rifampin plus trimethoprim-sulfamethoxazole is administered in pregnancy, as in children. If there is neurological involvement, doxycycline is administered with rifampin and streptomycin, although third-generation cephalosporins that penetrate better into the CNS must also be administered at times. If endocarditis exists, the treatment is the same, although surgical intervention is sometimes necessary to replace the damaged valve.

At 4 to 14 days after starting treatment, the fever disappears and the general symptoms, the liver and spleen recover between 2 and 4 weeks.

Sometimes when starting antibiotic treatment there is a flare of symptoms that is temporary and should not cause treatment to be suspended. Patients whose symptoms have apparently healed should not be trusted and should undergo clinical and serological follow-up.

How can I avoid brucellosis?

It is essential to avoid the transmission of the disease, for this you must immunize cattle and consume pasteurized milk and its derivatives, since the consumption of milk and fresh cheese is the main source of infection, in addition to eating cooked meat. A vaccine has been tested in workers in the meat and dairy industries in China, Russia and France, reducing the infection rate, the vaccination must be renewed every two years. It is not yet widespread throughout the world.

Prolonged fever, especially affecting the general state or associated with other symptoms, should always be a reason to consult a doctor, since although it may be due to trivial processes such as colds or flu , on other occasions it is due to more serious conditions.

Joint inflammations or the symptoms of more serious problems such as meningitis, endocarditis or pyelonephritis should also urge us to go to our doctor urgently to request the pertinent tests to reach a diagnosis.