Lassa fever

Lassa fever: An acute viral infection found in the tropics, especially in West Africa, in countries such as Sierra Leone, Congo (formerly Zaire), Liberia and Nigeria. The disease was discovered in 1969 when two missionary nurses died of it in the village of Lassa, Nigeria. The virus (a member of the virus family Arenaviridae) is a single-stranded RNA virus and is animal-borne (zoonotic). Lassa fever is a grave health concern because it can cause a very severe, potentially fatal illness, is highly contagious and can rapidly spread. The number of Lassa virus infections per year in West Africa has been roughly estimated at 100,000 to 300,000 with 5,000 deaths. The virus has been found in a rodent known as the "multimammate rat" of the genus Mastomys. People can become infected by eating an infected rat or by eating food contaminated by rat excretions. Person-to-person transmission is by direct contact, contamination of skin breaks with infected blood, and aerosol spreads. The first symptoms occur 1-3 weeks after the patient comes into contact with the virus and include inncreasingly high fever, sore throat, cough, eye inflammation (conjunctivitis), facial swelling, retrosternal pain (behind the breastbone), back pain, abdominal pain, vomiting, diarrhea and general weakness lasting for several days. The most common complication of Lassa fever is deafness. Because the symptoms are so varied and nonspecific, clinical diagnosis is often difficult. If the person has traveled to West Africa and has a severe fever within 3 weeks after returning (the incubation period of lassa virus is 1 to 3 weeks), the illness should be reported to a doctor. Medical isolation precautions should be followed, due to the highly contagious nature of Lassa fever. The procedures together are called VHF isolation precautions or barrier nursing methods and include wearing protective clothing such as masks, gloves, gowns, and goggles; using infection control measures such as complete equipment sterilization; and isolating infected patients from contact with unprotected persons until the disease has run its course. Patients may excrete the virus weeks after recovery. Their bodily fluids should therefore be monitored for infectivity before they leave the hospital. The key to treatment is Ribavirin, an antiviral drug. Ribavirin is most effective when given early in the course of the disease. Patients are also given supportive care with fluid balance, oxygen as needed, treatment of any other complicating infections, etc.