Comparison of the tropisms of six strains of Newcastle disease virus in chickens following aerosol infection.

virus from the air of a poultry house,1 the spread of the infection to chickens separated from diseased birds except for air they breathed, and the signs of coughing and rales quite common to the disease suggest that the respiratory tract is an important route of infection in chickens. Entrance of infection occurs by other channels since the chicken has been found to be susceptible by various routes of inoculation.2'3 Chickens inoculated intramuscularly, intravenously or intranasally develop Newcastle disease, yet the course of the infection and sometimes the outcome is not the same as in chickens acquiring the disease by natural exposure to the virus.3-5 The simulation of natural infection