Nasty Infectious Diseases You Want To Avoid - Leptospirosis

This is a bacterial disease characterized by a skin rash and flulike symptoms caused by a spirochete bacterium excreted by rodents. Also known as autumn fever, there are about 100 cases and a few deaths reported in the United States each year. Leptospirosis is considered to be a disease that is reemerging in this country and is possibly the most common disease that rats carry and transmit to humans in the United States. There are several strains of the organism; infection with one usually provides immunity to that organism alone, but not to other strains.

Although the disease is not new in the United States, it is hard to diagnose and its prevalence may be unknown. Those especially at risk are urban patients who complain of flulike symptoms (especially during the summer) and who could have been exposed to rat urine or to pools of infected water in alleys and parks of the inner city.

Unrecognized leptospirosis might be common in city dwellers; one recent Baltimore study found 16 percent of blood samples taken at an STD clinic were positive for leptospirosis. An earlier study found that about a third of children tested in Detroit also had been exposed. None of the inner-city patients had been diagnosed with leptospirosis.

Cause - The infectious disease is caused by the spirochete Leptospira interrogans transmitted in the urine of wild or domestic animals, especially rats, livestock, and dogs. People get the disease when broken skin or mucous membranes contact the infected urine or water, soil, or vegetation. The bacteria survive best in warm water (72 degrees F) that is stagnant; most cases have been reported from swimming, wading, or splashing in pools, streams, or puddles that were contaminated with animal urine. In addition to urban dwellers, leptospirosis is an occupational disease of farmers, sewer workers, or others whose job requires contact with animals (especially rats). Most victims are male teenagers and young adults. Leptospirosis is not usually transmitted from person to person.

Symptoms - Leptospirosis has two phases. After an incubation period of up to three weeks, the first phase begins with an acute illness of sudden headache, fever and chills, severe muscle aches, and skin rash appears. Up to 10 percent of infected patients develop a serious systemic form of the illness, called Weil's syndrome. This phase starts a few days after the fever drops; fever will return and bacteria may spread to the brain, causing meningitis. Other serious symptoms include jaundice, confusion, depression, or decreased urine. The kidneys are often affected, and liver damage is common. People infected with this potentially fatal form of leptospirosis are usually very ill and are often hospitalized. Leptospirosis is often mistaken for viral meningitis or hepatitis, but its two distinct phases separate it from those infections.

Diagnosis - The disease is diagnosed using specific blood, urine, or fluid tests available through state public health laboratories. If positive, they are sent to the Centers for Disease Control and Prevention lab for confirmation. However, it takes up to a month to get a final determination. A physician must request such testing; it is not routinely done, and local labs do not ordinarily perform these tests.

Treatment - Tetracycline and erythromycin are effective, and in about one third of cases patients improve rapidly. Fluid replacement is essential if jaundice or other signs of severe illness occur. Kidney dialysis may be needed in some cases.

Complications - Untreated patients may develop Weil's syndrome, a severe form of leptospirosis that can cause permanent kidney and liver damage; most patients recover, but sometimes the disease is fatal.

Prevention - The disease can be prevented by good sanitation practices, including using boots and gloves in hazardous places and practicing rodent control. It is common practice to immunize livestock and dogs against the disease, but even vaccinated animals can shed the bacteria in urine for a long time and infect humans.

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