Brucellosis overview

# Overview
Brucellosis is an ancient zoonotic disease. It is caused by bacteria of the genus Brucella. It is usually acquired by consuming unpasteurized dairy or undercooked meat products. Patients with brucellosis usually present with undulant fever, night sweats and joint pain. Brucellosis can be easily treated with antibiotics. If left untreated, patients with brucellosis may progress to develop focal organ involvement, relapses or chronic brucellosis. Prognosis is good with treatment.

# Historial Perspective
According to some studies, there is evidence that Brucellosis occurred in animals 60 million years ago and 3 million years ago in human beings. In 450 BC, Hippocrates described a disease similar to Brucellosis.

# Pathophysiology
Brucellosis is a zoonotic disease. Humans could be infected by eating undercook meat or raw dairy products, inhalation of the bacteria and direct contact of bacteria with skin wounds or mucous membranes. Following transmission, white blood cells phagocyte the pathogen and transports it via hematologic or lymphatic route to different organs, specially to those of the reticuloendothelial system. Endotoxic lipopolysaccharide LPS plays an important role in: survival of bacteria inside monocytic cell, supressing phagosome-lysosome fusion and internalizing bacteria into endoplasmic reticulum.

# Causes
Human brucellosis is caused by four Brucellae species: B. abortus, B. canis, B. melitensis, and B. suis..

# Differentiating Brucellosis from other Diseases
Brucellosis must be differentiated from Typhoid fever, Malaria, Tuberculosis, Lymphoma, Dengue, Leptospirosis, Rheumatic disease, Epstein-barr virus, Toxoplasmosis, Cytomegalovirus, and HIV.

# Epidemiology and Demographics
Worldwide, the incidence of Brucellosis ranges from a low of 0.01 per 100,000 to high of 200 per 100,000 individuals. Case fatality rate is less than 2% when untreated. Brucellosis most commonly affects men in age group between 20 to 45 years old. Areas currently listed as high risk are the Mediterranean Basin (Portugal, Spain, Southern France, Italy, Greece, Turkey, North Africa), South and Central America, Eastern Europe, Asia, Africa, the Caribbean and the Middle East

# Risk Factors
Common risk factors in the development of brucellosis are: consuming unpasteurized dairy products or raw meat products, unsafe hunting practices and occupational risks.

# Screening
There are no guidelines for screening Brucellosis.

# Natural history, Complications and Prognosis
If left untreated, patients with brucellosis may progress to develop focal organal involvement, relapses or chronic brucellosis. Common complications of brucellosis include: granulomatous hepatitis, arthritis, sacroiliitis, meningitis, orchitis, epididymitis uveitis, and endocarditis. The prognosis of brucellosis is good with adequate treatment.

# Diagnosis

## Principles of Diagnosis
Diagnosis is based on history of potential exposure, presentation consistent with the disease, and supporting laboratory findings.

## History and Symptoms
Brucellosis can present with diverse clinical presentation which include systemic flu-like symptoms and symptoms due to focal involvement of organs.

## Physical Examination
Patients with brucellosis are usually well-appearing. Common physical examination observed include hepatomegaly, splenomegaly and lymphadenopathy.

## Laboratory Findings
The diagnosis of brucellosis can be confirmed by either a positive bacterial culture or a positive titre of anti-brucella antibodies on serological testings.

## Other Diagnostic Studies
There is no specific X-ray, CT or MRI finding associated with Brucellosis.

# Treatment

## Medical Therapy
The mainstay of therapy for brucellosis is antimicrobial therapy. The preferred regimen for uncomplicated brucellosis is a combination of Doxycycline and Streptomycin.  Rifampicin is the drug of choice for brucellosis in pregnancy. For children less than 8 years of age, the preferred regimen is either Gentamycin or a combination of Trimethoprim-sulfamethoxazole and Streptomycin.

## Prevention
Brucellosis can be prevented by not consuming unpasteurized dairy products or undercooked meat and having safe occupational practices.