Viruses, Plagues, and History by Oldstone Michael B. A.;

Author:Oldstone, Michael B. A.;
Language: eng
Format: epub
Publisher: Oxford University Press, Incorporated
Published: 2010-01-14T16:00:00+00:00

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Lassa Fever

The family name of Lassa fever virus, the arenaviruses (1), stems from arenosus—Latin for sandy—because of the virus’s characteristic fine granules seen by electron microscopy. Like its relatives, Lassa fever virus causes persistent infection in the host, that is, a long-term infection that does not directly kill. Persistent infection, in general, does little harm to its animal host because the two have evolved a near-symbiotic relationship, usually over the host’s lifespan. The natural host of an arenavirus is often restricted to a single kind of rodent. The rodent host carries these viruses in its blood and passes them in its urine. It is by contact with such excretions from the rodent that humans become infected. Although no chronic or persistent arenavirus infections have been found in humans, Lassa fever virus has been isolated from the urine of patients as late as one month after the onset of acute disease. Since no insects are known to transmit this disease, its spread to humans occurs only when humans come in close contact with the infected rodents in their natural habitat.

Lassa fever was first recognized in West Africa in 1969 but likely has existed in that region for much longer. The natural carrier is the rodent called Mastomys natalensis (multimammate mouse). In Africa, Lassa fever has struck natives, travelers on business, missionaries, and tourists. However, the cases that have provoked international fear are the several explosive hospital outbreaks. An example of the direct and continuous transmission of Lassa fever to five health-care workers is the following initial report of the disease by John Frame and colleagues in 1970 (2–4):

Ms. Laura Wine, a nurse working in the small mission hospital, Church of the Brethren, in Lassa, Nigeria, was in good health until about January 12, 1969, when she complained of a backache. On January 20th, she reported a severe sore throat, but the physician who examined her found no signs to account for her discomfort. The next day, she complained that she could hardly swallow; she had several small ulcers in her throat and mouth, an oral temperature of 100°F, and bleeding from body orifices and hospital-induced needle puncture wounds. By January 24th, she was suffering from sleepiness and some slurring of speech; late in the day she appeared increasingly drowsy. On January 25th, she was flown to Bingham Memorial Hospital in Jos, Nigeria. She died on January 26th after several convulsions.

A 45-year-old staff nurse, Ms. Charlotte Shaw, at the Bingham Memorial Hospital in Jos, Nigeria, was on night call when Ms. Wine was admitted on January 25th. Ms. Shaw had cut her finger earlier picking roses for another patient. As part of her nursing care, Ms. Shaw used a gauze dressing on that finger to clear secretions from the patient’s mouth. Only afterward did she wash and apply antiseptic to the small cut on her finger. Nine days later Ms. Shaw had a chill with headache, severe back and leg pains and mild sore throat, a clinical picture similar to that of Ms.

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