Brucellosis, also called undulant fever, or Malta fever, is a highly contagious zoonosis caused by ingestion of unsterilized milk or meat from infected animals, or close contact with their secretions. The disease now called brucellosis, under the name “ Mediterranean fever ” , first came to the attention of British medical officers in Malta during the Crimean War in the 1850s. The causal relationship between organism and disease was first established by Dr. David Bruce in 1887.
Brucellosis is caused by the bacterial genus Brucella. Brucella spp. are small, gram-negative , non-motile, non-spore-forming rods, which function as facultative intracellular parasites that cause chronic disease, which usually persists for life. These organisms localize in the reproductive organs of host animals, causing abortions and sterility. They are shed in large numbers in the animal ’ s urine, milk, placental fluid, and other fluids. Exposure to infected animals and animal products causes the disease in humans.
Classification The traditional classification of Brucella species is based largely on the preferred hosts. South America, Southeast Asia, United States . Pigs (biotype 1-3) . B . suis Worldwide . Cows, buffalo, camels, yaks . B . abortus Mediterranean, Asia, Latin America, parts of Africa and some southern European countries . Goats, sheep, camels . B . melitensis Geographic Distribution Animal Reservoir Organism
Classification Geographic Distribution Animal Reservoir Organism Recent case reports describing some human cases (mainly neurobrucellosis) . Marine animals, minke whales, dolphins, seals . B . pinnipediae and B . cetaceae Not known to cause human disease . Rodents . B . neotomae No known human cases . Sheep . B . ovis Cosmopolitan . Canines . B . canis
Ingestion of unpasteurized goat milk and related dairy products is the main route of B . melitensis transmission to humans.
Brucellosis causes more than 500,000 infections per year worldwide. The heaviest disease burden lies in countries of the Mediterranean basin and Arabian Peninsula, and the disease is also common in India, Mexico, and South and Central America.
Human brucellosis carries a low mortality rate (<5%), mostly secondary to endocarditis, which is a rare complication of brucellosis. However, brucellosis can cause chronic debilitating illness with extensive morbidity.
The diseases most frequently confused with brucellosis are a nkylosing s pondylitis and u ndifferentiated s pondyloarthropathy , i nfluenza , c ryptococcosis , l eptospirosis , viral h epatitis, m alaria , h istoplasmosis , t uberculosis , i nfectious m ononucleosis , i nfective e ndocarditis , t yphoid f ever , c ollagen vascular disease , c hronic fatigue syndrome , m alignancy , and o steomyelitis .
The goal of medical therapy is to control patient symptoms as quickly as possible to prevent complications and relapses. Multidrug antimicrobial regimens are the mainstay of therapy because of high relapse rates reported with monotherapeutic approaches.
Inform persons with occupational risk about the use of protective devices (masks, gloves) to avoid exposure to aerosols, body fluids, and inadvertent vaccine exposure. Inform travelers to endemic areas about appropriate dietary hygiene.
Although initial symptoms may be debilitating, if the symptoms are treated appropriately and within the first few months of onset, this disease is easily curable with a low risk of relapse or chronic disease. The prognosis is poor in persons who present with congestive heart failure due to endocarditis, with a mortality rate approaching 85%.