Aka- Undulant fever, Malta fever & Mediterranean fever

Brucellae are small parasites that can cause acute and chronic disease in both animals and humans.

Brucellosis, highly contagious, is most often spread to humans by eating or drinking unsterilized milk, raw cheese (especially goat cheese), meat products from infected animals, or having close contact with their waste products.

Ticks have been known to pass the infection. Transmission from human to human (mother to infant, sexual transmission) is possible. A study by Rementsova listed 20 observations of Brucella detection in ticks. Brucella in ticks retained their virulence even after 2 years. [Rementsova MM. Brucellosis in Wild Animals. In: Galuzo and Gvozdev, editors. New Delhi: Oxonian Press (1987).]

Scanlan et al. infected gray foxes with Br. abortus in dog food. Seven of eight foxes became seropositive. Neiland and Miller infected six beagle dogs, two wolves (Canis lupus), one black bear (Ursus americanus), and two grizzly bears (Ursus arctos horribilis) with a strain of Br. suis biovar 4 isolated from a sled dog from Alaska. Their experiments demonstrated that canids and ursids are susceptible to the infection via intraperitoneal inoculation and through oral mucous membranes. SOURCE

Importantly, Brucella invaded salivary glands and probably also mammary glands and kidney, thus providing conditions for shedding the bacteria in saliva, milk, and urine. SOURCE

Tests on rats showed transmission of Br. abortus biovar 1 from infected male to uninfected female rats resulted from sexual intercourse. Vertical transmission of Br. abortus caused sterility in pregnant mice.

Guzman-Verri et al. cited the more likely modes of transmission of Br. ceti to be through sexual intercourse, maternal feeding, aborted fetuses, placental tissues, vertical transmission from mother to the fetus or through fish or helminth reservoirs. SOURCE

Brucellae have high viability and can survive in the environment for 3–21 days in spring-summer and for 151–233 days in winter-fall seasons. Brucellae maintain viability in carcasses (muscles, internal organs, and lymph nodes) at −7.2° to 38.4°C for 1–12 months (53). [Egorov IY, Kalinovskii AI, Maramovich AS, Chernyavskii VF. Problems of epidemiological surveillance of brucellosis under conditions of deer breeding in the North. Epidemiol Infekts Bolezni. (1997) 3:18–21.]

Some vaccines used in livestock, most notably B. abortus strain 19, also cause disease in humans if accidentally injected. Certain strains of Brucella, B. suis and B. canis, cause infection in pigs and dogs, respectively.

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.

NOTE- A newly discovered Brucella has been named Brucella microti. Be sure not to confuse it with Babesia microti. The names are both shortened in studies and articles to read- "B. microti".

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.

"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.[49] In some cases, consumption of undercooked game can result in exposure to the disease.[49]

Hunters can limit exposure while cleaning game through the use of precautionary barriers, including gloves and masks, and by washing tools rigorously after use.[46][50]" (Source- WIKI)

The bacteria, Brucellae, discovered in the 19th century, can be shed from an infected cow at or around the time of calving. Cattle can also harbor the bacteria in their reproductive tracts. Brucella can be transmitted to uninfected dogs through breeding and contact with fetuses of infected animals.

Dogs can harbor the bacteria in the genitals, eyes and kidneys. Symptoms of brucellosis in dogs include abortion in female dogs and scrotal inflammation in males. Fever is uncommon.

Brucellosis can infect humans that come in contact with infected aborted tissue or semen from dogs, cattle and other animals. As in humans, the disease is treated with antibiotics, but it is often difficult to cure.

**Patients who have had brucellosis should probably be excluded indefinitely from donating blood or organs.**


(Emphasis on muscular pain and night sweats)

Brucellae can cause chronic disease, which usually persists for life.

In humans symptoms may include day and night sweats with odors, headaches, fluctuating fevers, nervousness, weakness, anorexia, arthritis, chills, depression, malaise, joint pain, insomnia, constipation, impotence, and muscle pain.

FROM WIKI- "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.

Recent study links Brucella with Spondylodidcitis.

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." (Source- WIKI)

Later symptoms may include brain infection (encephalitis), hepatitis, endocarditis (heart), spondylitis, prostatitis, anaemia, leukopenia, thrombocytopenia, meningitis, uveitis, optic neuritis and neurological disorders.

"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." (Source- WIKI)

Testing for Brucellae

NOTE- Tests for Brucellosis can be false negative and are not standardized.

"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." (Source- WIKI)

"Other laboratory findings include normal peripheral white cell count, and occasional leucopenia with relative lymphocytosis. The serum biochemical profiles are commonly normal." (Source- WIKI)

QUEST LAB- Tests for Brucellae


Treatment can be difficult and is not always curative. Antibiotics, or combinations of antibiotics, are used to try to eliminate the infection.

"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." (Source- WIKI)

"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 seven days is an acceptable substitute when streptomycin is not available or contraindicated." (Source- WIKI)

"Another widely used regimen is doxycycline plus rifampin twice daily for at least six 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.[27]" (Source- WIKI)

"Doxycycline is able to cross the blood–brain barrier, but requires the addition of two other drugs to prevent relapse. Ciprofloxacinand co-trimoxazole therapy is associated with an unacceptably high rate of relapse." (Source- WIKI)

"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." (Source- WIKI)

Bioweapon- "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.[40] " (Source- WIKI)


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Last Updated- April 2019