─ a genus of Gram-negative bacteria.They are small (0.5 to 0.7 by 0.6 to 1.5 µm), non-motile, non-encapsulated coccobacilli, which function as facultative intracellular parasites.<br />BRUCELLA<br />
<ul><li>Brucella is the cause of brucellosis(Rock fever; Cyprus fever; Undulant fever; Gibraltar fever; Malta fever; Mediterranean fever), which is a zoonosis. It is transmitted by ingesting infected food, direct contact with an infected animal, or inhalation of aerosols. Transmission from human to human, for example through sexual intercourse or from mother to child, is exceedingly rare, but possible.Minimum infectious exposure is between 10 - 100 organisms. Brucellosis primarily occurs through occupational exposure (e.g. exposure to cattle, sheep, pigs), but also by consumption of unpasteurized milk products.</li></li></ul><li><ul><li>There are a few different species of Brucella, each with slightly different host specificity. B. melitensis which infects goats and sheep, B. abortus which infects cattle, B. suis infects pigs, B. ovis infects sheep and B. neotomae. Recently new species were discovered, in marine mammals (B. pinnipedialis and B. ceti ), in the common vole Microtus arvalis (B. microti ), and even in a breast implant (B. inopinata ). One unnamed strain (Brucella sp. NVSL 07-0026) has been isolated from a baboon.
However, the new NCBI taxonomy has named all Brucella species Brucella melitensis. They include Brucella melitensis 16M and 5 other biovars: abortus, canis, neotomae, ovis, and suis.</li></li></ul><li>Epidemiology<br /><ul><li>United States</li></ul>Dairy herds in the USA are tested at least once a year with the Brucella Milk Ring Test (BRT). Cows that are confirmed to be infected are often killed. In the United States, veterinarians are required to vaccinate all young stock, thereby further reducing the chance of zoonotic transmission. This vaccination is usually referred to as a "calfhood" vaccination. Most cattle receive a tattoo in their ear serving as proof of their vaccination status. This tattoo also includes the last digit of the year they were born.<br />The first state–federal cooperative efforts towards eradication of brucellosis caused by Brucella abortus in the U.S. began in 1934.<br />
<ul><li>Greater Yellowstone area</li></ul>Wild bison and elk in the Greater Yellowstone Area (GYA) are the last remaining reservoir of Brucella abortus in the U.S. The recent transmission of brucellosis from elk to cattle in Idaho and Wyoming illustrates how the GYA is the last remaining reservoir in the United States, adversely affecting the livestock industry. Eliminating brucellosis from this area is a challenge, as there are many viewpoints on how to manage diseased wildlife.<br /><ul><li>Canada</li></ul>Canada declared their cattle herd brucellosis-free on September 19, 1985. Brucellosis ring testing of milk and cream, as well as testing of slaughter cattle, ended April 1, 1999. Monitoring continues through auction market testing, standard disease reporting mechanisms, and testing of cattle being qualified for export to countries other than the USA.<br />
<ul><li>Europe</li></li></ul><li><ul><li>Republic of Ireland</li></ul>Ireland was declared free of brucellosis on 1 July 2009. The disease had troubled the country's farmers and veterinarians for several decades.The Irish government submitted an application to the European Commission, which verified that Ireland had been liberated.Brendan Smith, Ireland's Minister for Agriculture, Fisheries and Food, said the elimination of brucellosis was "a landmark in the history of disease eradication in Ireland".Ireland's Department of Agriculture, Fisheries and Foodintends to reduce its brucellosis eradication programme now that eradication has been confirmed.<br />
Oceania<br /><ul><li>Australia</li></ul>Australia is at present free of cattle brucelosis, although it occurred in the past. Brucellosis of sheep or goats has never been reported. Brucellosis of pigs does occur. Feral pigs are the typical source of human infections.<br /><ul><li>New Zealand</li></ul>Brucellosis in New Zealand is limited to sheep (Brucella ovis). The country is free of all other species of Brucella.<br />
Transmission<br /><ul><li>B. abortus, B. melitensis, B. suis and B. canis are usually transmitted between animals by contact with the placenta, fetus, fetal fluids and vaginal discharges from an infected animal. Animals are infectious after either an abortion or full term parturition. Although ruminants are usually asymptomatic after their first abortion, they can become chronic carriers, and continue to shed Brucella in milk and uterine discharges during subsequent pregnancies. Dogs may also shed B. canis in later pregnancies, with or without symptoms. Entry into the body occurs by ingestion and through the mucous membranes, broken skin and possibly intact skin.</li></li></ul><li><ul><li>Most or all Brucella species are also found in semen. Males can shed these organisms for long periods or lifelong. The importance of venereal transmission varies with the species. It is the primary route of transmission for B. ovis. B. suis and B. canis are also spread frequently by this route. B. abortus and B. melitensis can be found in semen, but venereal transmission of these organisms is uncommon. Some Brucella species have also been detected in other secretions and excretions including urine, feces, hygroma fluids, saliva, and nasal and ocular secretions. In most cases, these sources seem to be relatively unimportant in transmission; however, some could help account for direct non-venereal transmission of B. ovis between rams.</li></li></ul><li><ul><li>Brucella can be spread on fomites including feed and water. In conditions of high humidity, low temperatures, and no sunlight, these organisms can remain viable for several months in water, aborted fetuses, manure, wool, hay, equipment and clothes. Brucella can withstand drying, particularly when organic material is present, and can survive in dust and soil. Survival is longer when the temperature is low, particularly when it is below freezing.
Accidental hosts usually become infected after contact with maintenance hosts. Although the ruminant udder is usually colonized during the course of an infection, it can also be infected by direct contact (for example, by bacteria on the hands of farm workers). </li></li></ul><li>This can result in the long-term shedding of species not normally found in ruminant milk, such as B. suis. Humans usually become infected by ingesting organisms or by the contamination of mucous membranes and abraded skin. In the laboratory and probably in abattoirs, Brucella can be transmitted in aerosols. Common sources of infection for people include contact with animal abortion products; ingestion of unpasteurized dairy products from cows, small ruminants or camels; ingestion of undercooked meat, bone marrow or other uncooked meat products; contact with laboratory cultures and tissue samples; and accidental injection of live brucellosis vaccines. Human to human transmission is rare, but has been reported after blood transfusion, bone marrow transplantation or sexual intercourse. Rare congenital infections seem to result from transplacental transmission or the ingestion of breast milk. Congenital infections might also occur if the infant is exposed to organisms in the mother’s blood, urine or feces during delivery.<br />
Incubation Period<br /><ul><li>The incubation period is difficult to determine in humans but has been estimated at five days to three months. Most infections seem to become apparent within two weeks. Aerosolization of bacteria in biological weapons could result in a shorter incubation period.</li></li></ul><li>Clinical Signs<br /><ul><li>Brucellosis is a multisystemic disease with a broad spectrum of symptoms. Asymptomatic infections are common. In symptomatic cases, the disease is extremely variable and the clinical signs may appear insidiously or abruptly. Typically, brucellosis begins as an acute febrile illness with nonspecific flu-like signs such as fever, headache, malaise, back pain, myalgia and generalized aches. Drenching sweats can occur, particularly at night. Splenomegaly, hepatomegaly, coughing and pleuritic chest pain are sometimes seen. Gastrointestinal signs including anorexia, nausea, vomiting, diarrhea and constipation occur frequently in adults but less often in children.</li></li></ul><li><ul><li>In many patients, the symptoms last for two to four weeks and are followed by spontaneous recovery. Others develop an intermittent fever and other persistent symptoms that typically wax and wane at 2 to 14 day intervals. Most people with this undulant form recover completely in three to 12 months. A few patients become chronically ill. Relapses can occur months after the initial symptoms, even in successfully treated cases. Hypersensitivity reactions can mimic the symptoms of brucellosis.
Complications are seen occasionally, particularly in the undulant and chronic forms. The most common complications are arthritis, spondylitis, epididymoorchitis and chronic fatigue. Neurological signs occur in up to 5% of cases. They may include personality changes, meningitis, encephalitis and peripheral neuropathy. Uveitis, optic neuritis and papilledema have been reported.</li></li></ul><li><ul><li>Endocarditis is one of the most serious complications, and is often the cause of death in fatal cases. Many other organs and tissues can also be affected, resulting in a wide variety of syndromes including nephritis, dermatitis, vasculitis, lymphadenopathy, deep vein thrombosis, granulomatous hepatitis, cholecystitis, osteomyelitis, anemia, leukopenia and thrombocytopenia. Abscesses can occur in internal organs.
The symptoms of congenital brucellosis are variable. Some congenitally infected infants are delivered prematurely, while others are born at full term. Common symptoms include low birth weight, fever, failure to thrive, jaundice, hepatomegaly and splenomegaly. Some newborns with congenital brucellosis have respiratory difficulty or severe respiratory distress, hypotension, vomiting and other signs of sepsis. Other infants may be asymptomatic or have only mild symptoms at birth. Whether brucellosis can lead to spontaneous abortion in humans is controversial.</li></li></ul><li>Communicability<br /><ul><li>Brucellosis is not usually transmitted from person to person. Rarely, bacteria have been transmitted by bone marrow transplantation, blood transfusion or sexual intercourse. Rare congenital infections have also been documented. In some cases, the infant appeared to be infected through the placenta, and in others by the ingestion of breast milk. Brucellosis was reported in an obstetrician who swallowed secretions while trying to clear a congenitally infected infant’s respiratory tract at birth.</li></li></ul><li>Signs and Tests<br /><ul><li>Blood culture
Meningitis</li></li></ul><li>Treatment<br /><ul><li>Antibiotics are usually the mainstay of treatment; longterm treatment may be required. Some forms of localized disease, such as endocarditis, may require surgery.</li></li></ul><li>Prevention<br /><ul><li>Drinking and eating only pasteurized milk and cheeses is the most important preventative measure. People who handle meat should wear protective glasses and clothing and protect skin breaks from infection. Detecting infected animals controls the infection at its source. Vaccination is available for cattle, but not humans.</li></li></ul><li>SymptomsAcute brucellosis may begin with mild flu-like symptoms or symptoms such as:<br /><ul><li>Fever
Weight loss</li></ul>Classically, high fever spikes occur every afternoon. "Undulant" fever derives its name from this up-and-down fever.<br /><ul><li>Additional symptoms that may be associated with this disease: