Aerosol Stability and Respiratory Infectivity of Lassa Virus
ARMY MEDICAL RESEARCH INST OF INFECTIOUS DISEASES FORT DETRICK MD
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The aerosol stability and respiratory infectivity of Lassa virus were assessed. Aerosol stability determinations were performed at 24 C and each of three relative humidities RH 30, 55, and 80. A highly significant difference existed between aerosol stability at 30 RH and stability at 55 and 80 RH. Among all RH, 75.3 of the virus in suspension was airborne and infective at 4 min 75 efficiency. Biological half-life values in aerosol of 54,.6, 21.5, and 17.5 min were determined for RH of 30, 55, and 80, respectively. Infectivity of the Josiah strain of Lassa virus for cynomolgus monkeys and outbred guinea pigs was evaluated using dynamic aerosol equipment. All nine cynomolgus monkeys exposed to various doses were infected and died. For outbred guinea pigs, the LD50 and ID50 values were 10 to the 3.75th power and 10 to the 1.18 power PFU respectively. High titers of infectious virus were recovered from the upper respiratory tract, lungs, and spleen of sequentially killed guinea pigs. Concentrations of virus in the brain and liver were analogous to those in the blood. Transmission, therefore, appeared to occur via the respiratory tract, rather than by direct transport across the cribiform plate to tissues of the central nervous system. Viremia and tissue infection persisted throughout the 30-day study period.
- Medicine and Medical Research