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Clinical Characteristics

The original description by Hughes in 1897 remains the best: "an endemic disease of long duration, characterized by a fever which is continuous, remittent and intermittent in type, in most cases an enlarged spleen, profuse perspiration, sudamina, constipation, relapses almost invariably, accompanied by pain of a rheumatic or neuralgic character, sometimes swelling of joints or orchitis, ending almost always in complete recovery. In fatal cases, enlargement and softening of the spleen, congestion of the duodenum and the upper part of the jejunum, no swelling or ulceration of Peyer's glands, and a constant occurrence in various organs of a species of micrococcus."

The most common clinical error at the start of the illness, is to misdiagnose it as influenza. The symptoms include weakness, anorexia, chills, and generalized aches and pains. Many patients are nervous and mentally depressed, with gross tremors of the hands and fingers, irritability, and emotional instability. Some may even be referred to psychiatrists! Headaches are common and often severe and constant, involving the frontal and temporal regions. There can be a wide variety of neurological syndromes.

Pain in the spine is an early and constant symptom, either in the neck or over the lumbar area. Spinal tenderness may be elicited clinically in 50% of all patents; there is often muscle spasm limiting spinal movement. Cord compression with paraplegia or other motor or sensory disturbances may occur in up to 12% of cases, but referred pain from involvement of the nerve roots is more frequent, occurring in as many as 60% of all patients. More than half of those with spinal disease are in the 40 to 60-year age group, and less than 1% are under the age of 20 years. The lumbar spine is affected more frequently than the thoracic and cervical regions.
When the disease affects the peripheral joints, it is usually in children under the age of 10 years; it is more frequent in the hips, knees and sacroiliac joints, but wrists, elbows, sternoclavicular, and costochondral joints may also be affected. Any joint which has been previously damaged, such as by degenerative changes in elderly people, is more liable to infection.

Twenty percent of patients complain of abdominal tenderness, which is often associated with enlargement of the liver and/or the spleen. Hepatomegaly is less common than splenomegaly, but occurs more often in those in whom there is bacteriologically proven disease compared with patients from whom the organism cannot be isolated. Clinical examination also demonstrates lymphadenopathy, particularly in the cervical and axillary nodes, which are soft and remain discrete and slightly tender. If the abdominal pain is in the right lower quadrant, resulting from mesenteric adenitis, it may be mistaken for acute appendicitis. Urinary infections occur but have no distinguishing features. Pyelo- and glomerulonephritis may develop. Brucella organisms may be found in the urine. Orchitis and epididymitis are not infrequent. Older patients may develop congestive cardiac failure. Pericardial effusions can occur. Other patients complain of a nonproductive, hacking cough. Brucella lung infection is uncommon and may only occur when there has been inhalation. A papular skin rash, skin ulcers, and soft tissue abscesses may all occur. Retinal thrombophlebitis, uveitis, and keratitis have been reported.

Fever is an almost constant finding (hence the name "undulant fever"), but otherwise there is great individual variation in the acuteness and severity of the disease. Some reports emphasize that Br. melitensis is most common in children under the age of 10, affecting both sexes equally. Others suggest that Br. abortus affects mainly adult males, and that Br. suis causes a more severe disease than the others but is less common. Regrettably, there is no consistency about the reports from various parts of the world, nor does it seem clinically possible to differentiate the three types of the disease. All agree that all Brucella infections run a lengthy course but that most of the patients recover. However, the infection should not be taken lightly and cardiac complications of any variety worsen the prognosis and are a frequent cause of death.

It is known that Brucella organism may survive in man for many years and remain dormant, only to erupt unexpectedly; it can be difficult to be sure that a cure has been finally effected.

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