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Other namesundulant fever, undulating fever, Mediterranean fever, Malta fever, rock fever (Micrococcus Melitensis) [1]
Brucella spp.JPG
Specialty Infectious disease

Brucellosis [2] [3] is a highly contagious zoonosis caused by ingestion of unpasteurized milk or undercooked meat from infected animals, or close contact with their secretions. [4] It is also known as undulant fever, Malta fever, and Mediterranean fever. [5]

Zoonosis infectious disease that is transmitted between species (sometimes by a vector) from animals other than humans to humans or from humans to other animals

Zoonoses are infectious diseases caused by bacteria, viruses and parasites that spread between animals and humans.

Pasteurization or pasteurisation is a process in which certain packaged and non-packaged foods are treated with mild heat, usually less than 100 °C (212 °F), to eliminate pathogens and extend shelf life. The process is intended to stabilize foods by destroying or inactivating organisms and enzymes that contribute to spoilage, including vegetative bacteria but not bacterial spores. Since Pasteurization is not sterilization, and does not kill spores, a second "double" pasteurization will extend the quality by killing spores that have germinated.

Milk white liquid produced by the mammary glands of mammals

Milk is a nutrient-rich, white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for infant mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to its young and can reduce the risk of many diseases. It contains many other nutrients including protein and lactose. Interspecies consumption of milk is not uncommon, particularly among humans, many of whom consume the milk of other mammals.


Brucella species are small, Gram-negative, nonmotile, non-spore-forming, rod-shaped (coccobacilli) bacteria. They function as facultative intracellular parasites, causing chronic disease, which usually persists for life. Four species infect humans: B. abortus, B. canis, B. melitensis, and B. suis. B. abortus is less virulent than B. melitensis and is primarily a disease of cattle. B. canis affects dogs. B. melitensis is the most virulent and invasive species; it usually infects goats and occasionally sheep. B. suis is of intermediate virulence and chiefly infects pigs. Symptoms include profuse sweating and joint and muscle pain. Brucellosis has been recognized in animals and humans since the 20th century.

<i>Brucella</i> genus of bacteria

Brucella is a genus of Gram-negative bacteria, named after David Bruce (1855–1931). They are small, nonencapsulated, nonmotile, facultatively intracellular coccobacilli.


A coccobacillus is a type of bacterium with a shape intermediate between cocci and bacilli. Coccobacilli, then, are very short rods which may be mistaken for cocci.

Parasitic plant type of plant that derives some or all of its nutritional requirements from another living plant

A parasitic plant is a plant that derives some or all of its nutritional requirement from another living plant. They make up about 1% of angiosperms and are in almost every biome in the world. All parasitic plants have modified roots, called haustoria, which penetrates the host plants, connecting them to the conductive system – either the xylem, the phloem, or both. For example, plants like Striga or Rhinanthus connect only to the xylem, via xylem bridges (xylem-feeding). Alternately, plants like Cuscuta and Orobanche connect only to the phloem of the host (phloem-feeding). This provides them with the ability to extract water and nutrients from the host. Parasitic plants are classified depending on where the parasitic plant latches onto the host and the amount of nutrients it requires. Some parasitic plants are able to locate their host plants by detecting chemicals in the air or soil given off by host shoots or roots, respectively. About 4,500 species of parasitic plant in approximately 20 families of flowering plants are known.

Signs and symptoms

A graph of the cases of brucellosis in humans in the United States from the years 1993-2010 surveyed by the Centers for Disease Control and Prevention through the National Notifiable Diseases Surveillance System BrucellosisGraph.png
A graph of the cases of brucellosis in humans in the United States from the years 1993–2010 surveyed by the Centers for Disease Control and Prevention through the National Notifiable Diseases Surveillance System

The symptoms are like those associated with many other febrile diseases, but with emphasis on muscular pain and night sweats. The duration of the disease can vary from a few weeks to many months or even years.

Fever common medical sign characterized by elevated body temperature

Fever, also known as pyrexia and febrile response, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using values between 37.5 and 38.3 °C. The increase in set point triggers increased muscle contractions and causes a feeling of cold. This results in greater heat production and efforts to conserve heat. When the set point temperature returns to normal, a person feels hot, becomes flushed, and may begin to sweat. Rarely a fever may trigger a febrile seizure. This is more common in young children. Fevers do not typically go higher than 41 to 42 °C.

In the first stage of the disease, bacteremia occurs and leads to the classic triad of undulant fevers, sweating (often with characteristic foul, moldy smell sometimes likened to wet hay), and migratory arthralgia and myalgia (joint and muscle pain). Blood tests characteristically reveal a low number of white blood cells and red blood cells, show some elevation of liver enzymes such as aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and demonstrate positive Bengal Rose and Huddleston reactions. Gastrointestinal symptoms occur in 70% of cases and include nausea, vomiting, decreased appetite, unintentional weight loss, abdominal pain, constipation, diarrhea, an enlarged liver, liver inflammation, liver abscess, and an enlarged spleen.

Bacteremia is the presence of bacteria in the blood. Blood is normally a sterile environment, so the detection of bacteria in the blood is always abnormal. It is distinct from sepsis, which is the host response to the bacteria.

Arthralgia literally means joint pain. Specifically, arthralgia is a symptom of injury, infection, illness, or an allergic reaction to medication.

Myalgia, or muscle pain, is a symptom of many diseases and disorders. The most common causes are the overuse or over-stretching of a muscle or group of muscles. Myalgia without a traumatic history is often due to viral infections. Longer-term myalgias may be indicative of a metabolic myopathy, some nutritional deficiencies or chronic fatigue syndrome.

This complex is, at least in Portugal, Israel, Syria, and Jordan, known as Malta fever. During episodes of Malta fever, melitococcemia (presence of brucellae in blood) can usually be demonstrated by means of blood culture in tryptose medium or Albini medium. If untreated, the disease can give origin to focalizations or become chronic. The focalizations of brucellosis occur usually in bones and joints, and osteomyelitis or spondylodiscitis of the lumbar spine accompanied by sacroiliitis is very characteristic of this disease. Orchitis is also common in men.

Osteomyelitis bone inflammation disease that has material basis in infection located in bone or located in bone marrow

Osteomyelitis (OM) is an infection of bone. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The long bones of the arms and legs are most commonly involved in children, while the feet, spine, and hips are most commonly involved in adults.

Spondylodiscitis is a combination of discitis and spondylitis, the latter generally involving the areas adjacent to the intervertebral disc space.

Sacroiliitis (say-kroe-il-e-I-tus) is a medical condition caused by any inflammation within one, or both, of the sacroiliac joints. Sacroiliitis is a feature of spondyloarthropathies, such as axial spondyloarthritis, psoriatic arthritis, reactive arthritis or arthritis related to inflammatory bowel diseases, including ulcerative colitis or Crohn's disease. It is also the most common presentation of arthritis from brucellosis.

Diagnosis of brucellosis relies on:

  1. Demonstration of the agent: blood cultures in tryptose broth, bone marrow cultures. The growth of brucellae is extremely slow (they can take up to two months to grow) and the culture poses a risk to laboratory personnel due to high infectivity of brucellae.
  2. Demonstration of antibodies against the agent either with the classic Huddleson, Wright, and/or Bengal Rose reactions, either with ELISA or the 2-mercaptoethanol assay for IgM antibodies associated with chronic disease.
  3. Histologic evidence of granulomatous hepatitis on hepatic biopsy.
  4. Radiologic alterations in infected vertebrae: the Pedro Pons sign (preferential erosion of the anterosuperior corner of lumbar vertebrae) and marked osteophytosis are suspicious of brucellic spondylitis.

The consequences of Brucella infection are highly variable and may include arthritis, spondylitis, thrombocytopenia, meningitis, uveitis, optic neuritis, endocarditis, and various neurological disorders collectively known as neurobrucellosis.

Arthritis form of joint disorder that involves inflammation of one or more joints

Arthritis is a term often used to mean any disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In some types other organs are also affected. Onset can be gradual or sudden.

Spondylitis is an inflammation of the vertebra. It is a form of spondylopathy. In many cases spondylitis involves one or more vertebral joints as well, which itself is called spondylarthritis.

Thrombocytopenia A blood platelet disease characterized by a low platelet count in the blood.

Thrombocytopenia is a condition characterized by abnormally low levels of thrombocytes, also known as platelets, in the blood.


Granuloma and necrosis in the liver of a guinea pig infected with Brucella suis Brucella granuloma.jpg
Granuloma and necrosis in the liver of a guinea pig infected with Brucella suis

Brucellosis in humans is usually associated with consumption of unpasteurized milk and soft cheeses made from the milk of infected animals—primarily goats, infected with B. melitensis and with occupational exposure of laboratory workers, veterinarians, and slaughterhouse workers. [7] Some vaccines used in livestock, most notably B. abortus strain 19, also cause disease in humans if accidentally injected. Brucellosis induces inconstant fevers, miscarriage, sweating, weakness, anaemia, headaches, depression, and muscular and bodily pain. The other strains, B. suis and B. canis, cause infection in pigs and dogs, respectively.

Overall findings support that brucellosis poses an occupational risk to goat farmers with specific areas of concern including weak awareness of disease transmission to humans and lack of knowledge on specific safe farm practices such as quarantine practices. [8]


Definite diagnosis of brucellosis requires the isolation of the organism from the blood, body fluids, or tissues, but serological methods may be the only tests available in many settings. Positive blood culture yield ranges between 40% and 70% and is less commonly positive for B. abortus than B. melitensis or B. suis. Identification of specific antibodies against bacterial lipopolysaccharide and other antigens can be detected by the standard agglutination test (SAT), rose Bengal, 2-mercaptoethanol (2-ME), antihuman globulin (Coombs’) and indirect enzyme-linked immunosorbent assay (ELISA). SAT is the most commonly used serology in endemic areas. [9] [10] An agglutination titre greater than 1:160 is considered significant in nonendemic areas and greater than 1:320 in endemic areas.

Due to the similarity of the O polysaccharide of Brucella to that of various other Gram-negative bacteria (e.g. Francisella tularensis , Escherichia coli , Salmonella urbana , Yersinia enterocolitica , Vibrio cholerae , and Stenotrophomonas maltophilia ), the appearance of cross-reactions of class M immunoglobulins may occur. The inability to diagnose B. canis by SAT due to lack of cross-reaction is another drawback. False-negative SAT may be caused by the presence of blocking antibodies (the prozone phenomenon) in the α2-globulin (IgA) and in the α-globulin (IgG) fractions.

Dipstick assays are new and promising, based on the binding of Brucella IgM antibodies, and are simple, accurate, and rapid. ELISA typically uses cytoplasmic proteins as antigens. It measures IgM, IgG, and IgA with better sensitivity and specificity than the SAT in most recent comparative studies. [11] The commercial Brucellacapt test, a single-step immunocapture assay for the detection of total anti-Brucella antibodies, is an increasingly used adjunctive test when resources permit. PCR is fast and should be specific. Many varieties of PCR have been developed (e.g. nested PCR, realtime PCR, and PCR-ELISA) and found to have superior specificity and sensitivity in detecting both primary infection and relapse after treatment. [12] Unfortunately, these are not standardized for routine use, and some centres have reported persistent PCR positivity after clinically successful treatment, fuelling the controversy about the existence of prolonged chronic brucellosis.

Other laboratory findings include normal peripheral white cell count, and occasional leucopenia with relative lymphocytosis. The serum biochemical profiles are commonly normal. [13]



According to a study published in 2002, an estimated 10–13% of farm animals are infected with Brucella species. [14] Annual losses from the disease were calculated at around 60 million dollars. Since 1932, government agencies have undertaken efforts to contain the disease. Currently, all cattle of ages 3–8 months must receive the Brucella abortus strain 19 vaccine. [15]


Australia is free of cattle brucellosis, 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. [16] [17]


On 19 September 1985, the Canadian government declared its cattle population brucellosis-free. Brucellosis ring testing of milk and cream, and testing of cattle to be slaughtered ended on 1 April 1999. Monitoring continues through testing at auction markets, through standard disease-reporting procedures, and through testing of cattle being qualified for export to countries other than the United States. [18]


Disease incidence map of B. melitensis infections in animals in Europe during the first half of 2006
never reported
not reported in this period
confirmed clinical disease
confirmed infection
no information B.melitensis in Europe.svg
Disease incidence map of B. melitensis infections in animals in Europe during the first half of 2006
  never reported
  not reported in this period
  confirmed clinical disease
  confirmed infection
  no information


Until the early 20th century, the disease was endemic in Malta to the point of it being referred to as "Maltese fever". Since 2005, due to a strict regimen of certification of milk animals and widespread use of pasteurization, the illness has been eradicated from Malta. [19]

Republic of Ireland

Ireland was declared free of brucellosis on 1 July 2009. The disease had troubled the country's farmers and veterinarians for several decades. [20] [21] The Irish government submitted an application to the European Commission, which verified that Ireland had been liberated. [21] Brendan Smith, Ireland's then Minister for Agriculture, Food and the Marine, said the elimination of brucellosis was "a landmark in the history of disease eradication in Ireland". [20] [21] Ireland's Department of Agriculture, Food and the Marine intends to reduce its brucellosis eradication programme now that eradication has been confirmed. [20] [21]

New Zealand

Brucellosis in New Zealand is limited to sheep (B. ovis). The country is free of all other species of Brucella. [22]

United States

Dairy herds in the USA are tested at least once a year to be certified brucellosis-free. [23] with the Brucella milk ring test. [24] Cows confirmed to be infected are often killed. In the United States, veterinarians are required [ citation needed ] to vaccinate all young stock, to further reduce the chance of zoonotic transmission. This vaccination is usually referred to as a "calfhood" vaccination. Most cattle receive a tattoo in one of their ears, serving as proof of their vaccination status. This tattoo also includes the last digit of the year they were born. [25]

The first state–federal cooperative efforts towards eradication of brucellosis caused by B. abortus in the U.S. began in 1934.

Brucellosis was originally imported to North America with non-native domestic cattle (Bos taurus), which transmitted the disease to wild bison (Bison bison) and elk (Cervus canadensis). No records exist of brucellosis in ungulates native to America until the early 19th century. [26]


Antibiotics such as tetracyclines, rifampin, and the aminoglycosides streptomycin and gentamicin are effective against Brucella bacteria. However, the use of more than one antibiotic is needed for several weeks, because the bacteria incubate within cells.

Surveillance using serological tests, as well as tests on milk such as the milk ring test, can be used for screening and play an important role in campaigns to eliminate the disease. Also, individual animal testing both for trade and for disease-control purposes is practiced. In endemic areas, vaccination is often used to reduce the incidence of infection. An animal vaccine is available that uses modified live bacteria. The World Organisation for Animal Health Manual of Diagnostic Test and Vaccines for Terrestrial Animals provides detailed guidance on the production of vaccines. As the disease is closer to being eliminated, a test and eradication program is required to completely eliminate it.

The gold standard treatment for adults is daily intramuscular injections of streptomycin 1 g for 14 days and oral doxycycline 100 mg twice daily for 45 days (concurrently). Gentamicin 5 mg/kg by intramuscular injection once daily for 7 days is an acceptable substitute when streptomycin is not available or contraindicated. [27] Another widely used regimen is doxycycline plus rifampin twice daily for at least 6 weeks. This regimen has the advantage of oral administration. A triple therapy of doxycycline, with rifampin and co-trimoxazole, has been used successfully to treat neurobrucellosis. [28]

Doxycycline is able to cross the blood–brain barrier, but requires the addition of two other drugs to prevent relapse. Ciprofloxacin and co-trimoxazole therapy is associated with an unacceptably high rate of relapse. In brucellic endocarditis, surgery is required for an optimal outcome. Even with optimal antibrucellic therapy, relapses still occur in 5 to 10% of patients with Malta fever.

The main way of preventing brucellosis is by using fastidious hygiene in producing raw milk products, or by pasteurizing all milk that is to be ingested by human beings, either in its unaltered form or as a derivative, such as cheese.


The mortality of the disease in 1909, as recorded in the British Army and Navy stationed in Malta, was 2%. The most frequent cause of death was endocarditis. Recent advances in antibiotics and surgery have been successful in preventing death due to endocarditis. Prevention of human brucellosis can be achieved by eradication of the disease in animals by vaccination and other veterinary control methods such as testing herds/flocks and slaughtering animals when infection is present. Currently, no effective vaccine is available for humans. Boiling milk before consumption, or before using it to produce other dairy products, is protective against transmission via ingestion. Changing traditional food habits of eating raw meat, liver, or bone marrow is necessary, but difficult to implement.[ citation needed ] Patients who have had brucellosis should probably be excluded indefinitely from donating blood or organs. Exposure of diagnostic laboratory personnel to Brucella organisms remains a problem in both endemic settings and when brucellosis is unknowingly imported by a patient. [29] After appropriate risk assessment, staff with significant exposure should be offered postexposure prophylaxis and followed up serologically for 6 months. [30] Recently published experience confirms that prolonged and frequent serological follow-up consumes significant resources without yielding much information, and is burdensome for the affected staff, who often fail to comply. The side effects of the usual recommended regimen of rifampicin and doxycycline for 3 weeks also reduces treatment adherence. As no evidence shows treatment with two drugs is superior to monotherapy, British guidelines now recommend doxycycline alone for 3 weeks and a less onerous follow-up protocol. [31]


David Bruce (centre), with members of the Mediterranean Fever Commission (Brucellosis) The members of the Mediterranean Fever Commission. Wellcome L0022610.jpg
David Bruce (centre), with members of the Mediterranean Fever Commission (Brucellosis)
The lab in which Sir Themistocles Zammit and the Mediterranean Fever Commission carried out research about brucellosis from 1904 to 1906 is located within the Castellania in Valletta, Malta. Sir Temi Zammit laboratory.jpeg
The lab in which Sir Themistocles Zammit and the Mediterranean Fever Commission carried out research about brucellosis from 1904 to 1906 is located within the Castellania in Valletta, Malta.

Under the name "Malta fever", the disease now called brucellosis first came to the attention of British medical officers in the 1850s in Malta during the Crimean War. Jeffery Allen Marston (1831–1911) described his own case of the disease in 1861. The causal relationship between organism and disease was first established in 1887 by David Bruce. [32] [33] The agent that Bruce identified was classed as a coccus.

In 1897, Danish veterinarian Bernhard Bang isolated a bacillus as the agent of heightened spontaneous abortion in cows, and the name "Bang's disease" was assigned to this condition. At the time, no one knew that this bacillus had anything to do with the causative agent in Malta fever.

Maltese scientist and archaeologist Dr Themistocles Zammit identified unpasteurized goat milk as the major etiologic factor of undulant fever in June 1905. [34]

In the late 1910s, American bacteriologist Alice C. Evans was studying the Bang bacillus and gradually realized that it was virtually indistinguishable from the Bruce coccus. [35] The short-rod versus oblong-round morphologic borderline explained the leveling of the erstwhile bacillus/coccus distinction (that is, these "two" pathogens were not a coccus versus a bacillus but rather were one coccobacillus). [35] The Bang bacillus was already known to be enzootic in American dairy cattle, which showed itself in the regularity with which herds experienced contagious abortion. [35] Having made the discovery that the bacteria were certainly nearly identical and perhaps totally so, Evans then wondered why Malta fever was not widely diagnosed or reported in the United States. [35] She began to wonder whether many cases of vaguely defined febrile illnesses were in fact caused by the drinking of raw (unpasteurized) milk. [35] During the 1920s, this hypothesis was vindicated. Such illnesses ranged from undiagnosed and untreated gastrointestinal upset to misdiagnosed [35] febrile and painful versions, some even fatal. This advance in bacteriological science sparked extensive changes in the American dairy industry to improve food safety. The changes included making pasteurization standard and greatly tightening the standards of cleanliness in milkhouses on dairy farms. The expense prompted delay and skepticism in the industry, [35] but the new hygienic rules eventually became the norm. Although these measures have sometimes struck people as overdone in the decades since, being unhygienic at milking time or in the milkhouse, or drinking raw milk, are not a safe alternative.

In the decades after Evans's work, this genus, which received the name Brucella in honor of Bruce, were found to contain several species with varying virulence. The name "brucellosis" gradually replaced the 19th-century names Mediterranean fever and Malta fever. [36]

In 1989, neurologists in Saudi Arabia discovered "neurobrucellosis", a neurological involvement in brucellosis. [37] [38]

These obsolete names have previously been applied to brucellosis: [39] [40]

Biological warfare

Brucella species were weaponized by several advanced countries by the mid-20th century. In 1954, B. suis became the first agent weaponized by the United States at its Pine Bluff Arsenal near Pine Bluff, Arkansas. Brucella species survive well in aerosols and resist drying. Brucella and all other remaining biological weapons in the U.S. arsenal were destroyed in 1971–72 when the American offensive biological warfare program was discontinued by order of President Richard Nixon. [41]

The experimental American bacteriological warfare program focused on three agents of the Brucella group:

Agent US was in advanced development by the end of World War II. When the United States Air Force (USAF) wanted a biological warfare capability, the Chemical Corps offered Agent US in the M114 bomblet, based on the four-pound bursting bomblet developed for spreading anthrax during World War II. Though the capability was developed, operational testing indicated the weapon was less than desirable, and the USAF designed it as an interim capability until it could eventually be replaced by a more effective biological weapon.

The main drawback of using the M114 with Agent US was that it acted mainly as an incapacitating agent, whereas the USAF administration wanted weapons that were deadly. Also, the stability of M114 in storage was too low to allow for storing it at forward air bases, and the logistical requirements to neutralize a target were far higher than was originally planned. Ultimately, this would have required too much logistical support to be practical in the field.

Agents US and AA had a median infective dose of 500 organisms/person, and for Agent AM it was 300 organisms/person. The time-of-incubation was believed to be about 2 weeks, with a duration of infection of several months. The lethality estimate was based on epidemiological information at 1 to 2%. Agent AM was believed to be a somewhat more virulent disease, with a fatality rate of 3% being expected.

Other animals

Species infecting domestic livestock are B. abortus (cattle, bison, and elk), B. canis (dogs), B. melitensis (goats and sheep), B. ovis (sheep), and B. suis (caribou and pigs). Brucella species have also been isolated from several marine mammal species (cetaceans and pinnipeds).


B. abortus is the principal cause of brucellosis in cattle. The bacteria are shed from an infected animal at or around the time of calving or abortion. Once exposed, the likelihood of an animal becoming infected is variable, depending on age, pregnancy status, and other intrinsic factors of the animal, as well as the number of bacteria to which the animal was exposed. [42] The most common clinical signs of cattle infected with B. abortus are high incidences of abortions, arthritic joints, and retained placenta.

The two main causes for spontaneous abortion in animals are erythritol, which can promote infections in the fetus and placenta, and the lack of anti-Brucella activity in the amniotic fluid. Males can also harbor the bacteria in their reproductive tracts, namely seminal vesicles, ampullae, testicles, and epididymes.


The causative agent of brucellosis in dogs, B. canis , is transmitted to other dogs through breeding and contact with aborted fetuses. Brucellosis can occur in humans who come in contact with infected aborted tissue or semen. The bacteria in dogs normally infect the genitals and lymphatic system, but can also spread to the eyes, kidneys, and intervertebral discs. Brucellosis in the intervertebral disc is one possible cause of discospondylitis. Symptoms of brucellosis in dogs include abortion in female dogs and scrotal inflammation and orchitis in males. Fever is uncommon. Infection of the eye can cause uveitis, and infection of the intervertebral disc can cause pain or weakness. Blood testing of the dogs prior to breeding can prevent the spread of this disease. It is treated with antibiotics, as with humans, but it is difficult to cure. [43]

Aquatic wildlife

Brucellosis in cetaceans is caused by the bacterium B. ceti . First discovered in the aborted fetus of a bottlenose dolphin, the structure of B. ceti is similar to Brucella in land animals. B. ceti is commonly detected in two suborders of cetaceans, the Mysticeti and Odontoceti. The Mysticeti include four families of baleen whales, filter-feeders, and the Odontoceti include two families of toothed cetaceans ranging from dolphins to sperm whales. B. ceti is believed to transfer from animal to animal through sexual intercourse, maternal feeding, aborted fetuses, placental issues, from mother to fetus, or through fish reservoirs. Brucellosis is a reproductive disease, so has an extreme negative impact on the population dynamics of a species. This becomes a greater issue when the already low population numbers of cetaceans are taken into consideration. B. ceti has been identified in four of the 14 cetacean families, but the antibodies have been detected in seven of the families. This indicates that B. ceti is common amongst cetacean families and populations. Only a small percentage of exposed individuals become ill or die. However, particular species apparently are more likely to become infected by B. ceti. The harbor porpoise, striped dolphin, white-sided dolphin, bottlenose dolphin, and common dolphin have the highest frequency of infection amongst ondontocetes. In the mysticetes families, the northern minke whale is by far the most infected species. Dolphins and porpoises are more likely to be infected than cetaceans such as whales. With regard to sex and age biases, the infections do not seem influenced by the age or sex of an individual. Although fatal to cetaceans, B. ceti has a low infection rate for humans. [44]

Terrestrial wildlife

The disease in its various strains can infect multiple wildlife species, including elk (Cervus canadensis), bison (Bison bison), African buffalo (Syncerus caffer), European wild boar (Sus scrofa), caribou (Rangifer tarandus), moose (Alces alces), and marine mammals (see section on aquatic wildlife above). [45] [46] While some regions use vaccines to prevent the spread of brucellosis between infected and uninfected wildlife populations, no suitable brucellosis vaccine for terrestrial wildlife has been developed. [47] This gap in medicinal knowledge creates more pressure for management practices that reduce spread of the disease. [47]

Wild bison and elk in the greater Yellowstone area are the last remaining reservoir of B. abortus in the US. The recent transmission of brucellosis from elk back to cattle in Idaho and Wyoming illustrates how the area, as the last remaining reservoir in the United States, may adversely affect the livestock industry. Eliminating brucellosis from this area is a challenge, as many viewpoints exist on how to manage diseased wildlife. However, the Wyoming Game and Fish Department has recently begun to protect scavengers (particularly coyotes and red fox) on elk feedgrounds, because they act as sustainable, no-cost, biological control agents by removing infected elk fetuses quickly. [48] Purebred bison in the Henry Mountains of southern Utah are free of brucellosis. [49]

The National Elk Refuge in Jackson, Wyoming asserts that the intensity of the winter feeding program affects the spread of brucellosis more than the population size of elk and bison. [45] Since concentrating animals around food plots accelerates spread of the disease, management strategies to reduce herd density and increase dispersion could limit its spread. [45]

Effects on hunters

Hunters may be at additional risk for exposure to brucellosis due to increased contact with susceptible wildlife. Exposure can occur through contact with open wounds or by directly inhaling the bacteria while cleaning game. [50] In some cases, consumption of undercooked game can result in exposure to the disease. [50] Hunters can limit exposure while cleaning game through the use of precautionary barriers, including gloves and masks, and by washing tools rigorously after use. [47] [51] By ensuring that game is cooked thoroughly, hunters can protect themselves and others from ingesting the disease. [50] Hunters should refer to local game officials and health departments to determine the risk of brucellosis exposure in their immediate area and to learn more about actions to reduce or avoid exposure.

See also

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Major-General Sir David Bruce was a Scottish pathologist and microbiologist who investigated Malta fever and African trypanosomiasis. He discovered a protozoan parasite transmitted by insects, later named Trypanosoma brucei after him. Working in the Army Medical Service and the Royal Army Medical Corps, his major scientific collaborator was his microbiologist wife Mary Elizabeth Bruce, with whom he published more than thirty technical papers.

<i>Brucella melitensis</i> species of bacterium

Brucella melitensis is a Gram-negative coccobacillus bacterium from the Brucellaceae family. The bacterium causes ovine brucellosis, along with Brucella ovis. It can infect sheep, cattle, and sometimes humans, and it can be transmitted by the stable fly. It is zoonotic, unlike B. ovis, causing Malta fever or localized brucellosis in humans.

Swine brucellosis Human disease

Swine brucellosis is a zoonosis affecting pigs, caused by the bacterium Brucella suis. The disease typically causes chronic inflammatory lesions in the reproductive organs of susceptible animals or orchitis, and may even affect joints and other organs. The most common symptom is abortion in pregnant susceptible sows at any stage of gestation. Other manifestations are temporary or permanent sterility, lameness, posterior paralysis, spondylitis, and abscess formation. It is transmitted mainly by ingestion of infected tissues or fluids, semen during breeding, and suckling infected animals.

Blackleg (disease) infectious bacterial disease

Blackleg, black quarter, quarter evil, or quarter ill is an infectious bacterial disease most commonly caused by Clostridium chauvoei, a Gram-positive bacterial species. It is seen in livestock all over the world, usually affecting cattle, sheep, and goats. It has been seen occasionally in farmed bison and deer. The acute nature of the disease makes successful treatment difficult, and the efficacy of the commonly used vaccine is disputed.

Bovine malignant catarrhal fever cattle disease

Bovine malignant catarrhal fever (BMCF) is a fatal lymphoproliferative disease caused by a group of ruminant gamma herpes viruses including Alcelaphine gammaherpesvirus 1 (AlHV-1) and Ovine gammaherpesvirus 2 (OvHV-2) These viruses cause unapparent infection in their reservoir hosts, but are usually fatal in cattle and other ungulates such as deer, antelope, and buffalo. In Southern Africa the disease is known as snotsiekte, from the Afrikaans.

Brucella abortus is a Gram-negative proteobacterium in the family Brucellaceae and is one of the causative agents of brucellosis. The rod-shaped pathogen is classified under the domain Bacteria. The prokaryotic B. abortus is non-spore-forming, nonmotile and aerobic.

<i>Anaplasma phagocytophilum</i> species of bacterium

Anaplasma phagocytophilum is a Gram-negative bacterium that is unusual in its tropism to neutrophils. It causes anaplasmosis in sheep and cattle, also known as tick-borne fever and pasture fever, and also causes the zoonotic disease human granulocytic anaplasmosis.

Alice Catherine Evans American microbiologist

Alice Catherine Evans was a pioneering American microbiologist. She became a researcher at the US Department of Agriculture. There she investigated bacteriology in milk and cheese. She later demonstrated that Bacillus abortus caused the disease Brucellosis in both cattle and humans.

Ehrlichia chaffeensis is an obligate intracellular gram-negative species of rickettsiales bacteria. It is a zoonotic pathogen transmitted to humans by the lone star tick. It is the causative agent of human monocytic ehrlichiosis.

African tick bite fever spotted fever that has material basis in Rickettsia africae, which is transmitted by ticks

African tick bite fever (ATBF) is a bacterial infection spread by the bite of a tick. Symptoms may include fever, headache, muscles pains, and a rash. At the site of the bite there is typically a red skin sore with a dark center. Onset usually occur 4–10 days after the bite. Complications are rare, however may include joint inflammation. Some people do not develop symptoms.

Yellowstone Park bison herd

The Yellowstone Park bison herd in Yellowstone National Park is probably the oldest and largest public bison herd in the United States. Yellowstone is known for its geothermal activity and large mammals, especially elk, timber wolves, bison, bears, pronghorns, moose and bighorn sheep. The Yellowstone Park bison herd was estimated in 2015 to be 4,900 bison The bison in the Yellowstone Park bison herd are American bison of the Plains bison subspecies. Yellowstone National Park may be the only location in the United States where free-ranging bison were never extirpated, since they continued to exist in the wild and were not re-introduced, as has been done in most other bison herd areas. Other large free-ranging, publicly controlled herds of bison in the United States include the Tallgrass Prairie Preserve in Kansas, Wind Cave bison herd, the Antelope Island bison herd, the Henry Mountains bison herd in Utah, and the National Bison Range herd near Flathead Lake, Montana.

<i>Brucella ceti</i> species of bacterium

Brucella ceti is a gram negative bacterial pathogen that causes brucellosis in cetaceans. Brucella ceti has been found in both classes of cetaceans, mysticetes and odontocetes. Brucella ceti was first isolated in 1994 when an aborted dolphin fetus was discovered. Only a small portion of those with Brucella ceti have overt clinical signs of brucellosis indicating that many have the bacteria and remain asymptomatic or overcome the pathogen. Serological surveys have shown that cetacean brucellosis may be distributed worldwide in the oceans. The likely transmission route for the bacterial pathogen is through mating or reproduction and lactation of a cetacean. Brucellosis in some dolphins and porpoises can result in serious clinical signs including fetal abortions, male infertility, neurobrucellosis, cardiopathies, bone and skin lesions strand events, and death. 

Brucella pinnipedialis is a species of bacteria. It causes infections and related diseases primarily in pinnipeds and cetaceans.

Remittent fever

Remittent Fever is a type or pattern of fever in which temperature does not touch the baseline and remains above normal throughout the day. Daily variation in temperature is more than 1°C in 24 hours, which is also the main difference as compared to continuous fever. Fever due to most infectious diseases is remittent. Diagnosis is based upon clinical history, blood tests, blood culture and chest X-ray.


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Further reading

External resources