Biological Warfare (cont.)
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Brucellosis is an infection of domesticated and wild animals that can be transmitted to humans. It is caused by an organism of the genus Brucella. The organism infects mainly cattle, sheep, goats, and other similar animals, causing death of developing fetuses and genital infection. Humans, who usually are infected incidentally by contact with infected animals, may develop numerous symptoms in addition to the usual ones of fever, general illness, and muscle pain.
The disease often becomes long-term and may return, even with appropriate treatment. The ease of transmission through the air suggests that these organisms may be useful in biological warfare.
Each of six different species may tend to infect certain animal species. Four are known to cause illness in humans. Animals may transmit organisms during a miscarriage, at the time of slaughter, and in their milk. Brucellosis is rarely, if ever, transmitted from human to human.
Certain species can enter animal hosts through skin abrasions or cuts, the eye membranes, the respiratory tract, and the GI tract. Organisms grow rapidly and eventually go to the lymph nodes, liver, spleen, joints, kidneys, and bone marrow.
Signs and Symptoms
Victims may have a fever or a long-term infection or just a local inflammation. The disease may appear suddenly or develop slowly anywhere from three days to several weeks after exposure. Symptoms include fever, sweats, fatigue, loss of appetite, and muscle or joint aches. Depression, headache, and irritability occur frequently. In addition, infection of bones, joints, or the genitourinary tract may cause pain. Cough and chest pain also may be noted.
Symptoms often last three to six months and occasionally for longer than a year. Different species of the organism can cause different symptoms from skin sores to low back pain to liver disease.
The doctor will want to know about any exposure to animals, animal products, or environmental exposures in making the diagnosis. Military troops exposed to a biological attack and who have fever are likely candidates for this illness. Environmental samples may show the presence of this organism in the attack area. Laboratory tests and cultures of blood or body fluid samples including bone marrow may be performed.
Therapy with a single drug has resulted in a high relapse rate, so a combination of antibiotics should be prescribed. A six-week course of doxycycline along with streptomycin for the first two weeks is effective in most adults with most forms of brucellosis.
Animal handlers should wear appropriate protective clothing when working with infected animals. Meat should be well cooked, and milk should be pasteurized. Laboratory workers need to take appropriate cautions in handling the organism.
In the event of a biological attack, the standard gas mask should protect adequately from airborne species. No commercially available vaccine exists for humans. If the exposure is considered high risk, the CDC recommends treating with doxycycline and rifampin for three weeks.
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