Acute sensorineural deafness in Lassa fever

Article Abstract:

Lassa fever is an endemic virus-induced fever that was first identified in northeastern Nigeria. The disease is spread by the urine of a rat and perhaps by person-to-person contact. The incubation period of the virus ranges from 7 to 18 days. It is estimated that there are approximately 250,000 human infections yearly and 5,000 deaths per year. Lassa fever accounts for more than one third of hospital deaths in eastern Sierra Leone in West Africa. Cases have now been reported from the United States, Canada, Europe, Israel, and Japan. The disease's symptoms include headache, malaise, painful joints, inflammation of the pharynx, chest pain beneath the sternum (breast bone), vomiting, small-vessel hemorrhages, abdominal soreness, decreased blood pressure (hypotension), and bleeding from the gums, nose and elsewhere. In 1972, deafness was reported to occur from the disease, and similar reports have been made since, but none have contained audiometric evaluation of the level of hearing loss. Sudden hearing loss is a condition that has been associated with viral infections, but little is known about the natural history of this condition. Lassa fever provides a unique opportunity to follow the natural history of sudden hearing loss subsequent to viral infection. A four-month study of Lassa fever patients was undertaken using three different approaches. One study examined hearing levels in hospitalized adult Lassa fever patients, who were tested at time of discharge and again two weeks later. A second study examined the incidence of sudden deafness among patients with previous Lassa virus infection. The last study examined patients with sudden deafness for immunological signs of prior Lassa fever. The results demonstrate that the level of sudden sensorineural deafness in patients who have had Lassa fever far exceeds the degree found after any other known viral infection. Approximately one third of all such patients experience a significant hearing loss, and approximately two thirds have at least some degree of hearing loss. Lassa fever appears to be responsible for a significant percentage of hearing loss within the areas of the epidemic. Antiviral therapy does not appear to afford any protection for hearing loss in these patients. (Consumer Summary produced by Reliance Medical Information, Inc.)

Diagnosis, Causes of, Complications and side effects, Deafness

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Lassa fever in the United States: investigation of a case and new guidelines for management

Article Abstract:

Lassa fever is an endemic virus-induced fever that was first identified in northeastern Nigeria. The disease is spread by the urine of a rat (Mastomys natalensis) and by person-to-person contact. The incubation period of the virus ranges from 7 to 18 days. It is estimated that there are approximately 300,000 human infections and 5,000 deaths per year. While common in endemic areas, the last known case of lassa fever in the United States occurred in 1976. The present report documents a case history and the diagnosis and containment of lassa fever in the United States. The patient was a 43-year-old black engineer, who before his death from the disease resided within the United States. The patient had returned to his native Nigeria to attend the death of this mother (probably as a result of lassa fever), and two days after returning home was stricken developed a flu-like illness with a high temperature, chills, sore throat, and muscle pain. Despite antibiotic therapy his condition worsened, and he was plagued by headaches, inability to eat, and bloody diarrhea. Approximately two weeks after he became ill, the patient's liver enzyme tests became markedly pathologic, revealing elevation of aspartate aminotransferase. He was hospitalized, isolated with a working diagnosis of hepatitis presumed to be a result of yellow fever. Because of his recent travel and symptoms, a diagnosis of lassa fever was made on the day following hospital admission. The patient soon died, despite intensive medical support. The diagnosis was confirmed by autopsy and the virus was identified by objective laboratory procedures. A group of 102 individuals had significant contact with the patient during a period of time when he was considered to be highly contagious for the disease. Individuals at high risk due to contact were given the antiviral agent ribavirin for 10 days; there were no further infections. The public health issues of the case and the precautions and guidelines of management are also considered in depth. Physicians must be aware to the possibility of infections that are not encountered in the United States, particularly when the individual has a history of foreign travel. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Nigeria, Disease transmission, Ribavirin, Arenaviruses

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Lymphocytic choriomeningitis outbreak associated with nude mice in a research institute

Article Abstract:

Research personnel who handle laboratory animals infected with lymphocytic choriomeningitis virus (LCMV) may have a risk of developing lymphocytic choriomeningitis. Lymphocytic choriomeningitis is an inflammation of the membranes surrounding the brain that is caused by LCMV. Of 31 laboratory personnel who worked with LCMV-infected mice at a research institute, seven were infected with LCMV, and one had a probable LCMV infection. Infected employees were more likely to clean the cages of infected mice or change their bedding and water than non-infected employees who worked with the mice. At the time of the outbreak of LCMV infections in research personnel, the number of experiments involving LCMV-infected mice increased, and the duration of experiments was increased from three to four weeks to three to four months.

Risk factors, Diseases, Meningitis, Medical research personnel, Medical researchers

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