Occurrence of influenza A viruses and their antibodies in migratory birds in Finland.

A Finnish material of 455 cloacal specimens from 24 species of small migratory birds and of 54 cloacal specimens from 10 species of waterfowl was investigated for the occurrence of A type influenza virus. Influenza A virus was isolated in only one specimen, originating from a mallard (Anas platyrhynchos). Parallely, yolk material from 109 waterfowl representing 9 species was investigated for the occurrence of influenza A antibodies by complement fixation and immunodiffusion tests.

Experimental maedi infection in sheep. 2. Antibody response.

All 4 sheep inoculated via the respiratory tract with 7×10 TCID50 af maedi M88 strain developed complement fixing (CF) antibodies within 3 months after inoculation, and a gradual rise in CF titers was found during the first year. The antibody titers have been maintained, though with some fluctation, through the following year, and the titers vary from 64 to 256. Virus neutralizing activity against maedi M88 strain was detected in the sera of all intrapulmonarily inoculated sheep within 8 months after inoculation.

Experimental maedi infection in sheep. 1. Detection of virus, clinical course, histopathology.

Eight sheep were inoculated with Icelandic maedi strain M 88; 2 sheep served as control sheep and were in close contact with the inoculated ones. Four of the sheep were inoculated via the respiratory tract with 7×10 TGID50 of strain M88 and the other 4 intracerebrally with 5×10 TGID50 of the same strain. Maedi M88 strain was isolated from peripheral blood leukocytes of all inoculated sheep.

The effect of air ionization on the air-borne transmission of experimental Newcastle disease virus infections in chickens.

The effect of artificial air-ionization on air-borne transmission of Newcastle disease virus (NDV) infection in chickens was studied in an isolated system consisting of two side-by-side cages with solid walls and a wire-gauze roof. During a 3-week observation period more than 90% of the uninoculated indicator chickens, housed in one of the cages, contracted the virus shed to the air by the NDV-inoculated, diseased birds in the neighbouring cage. This air-borne transmission of NDV was completely prevented by increasing the ion concentration in the test room by a constant negative corona discharge above the wire-gauze roof.