320 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [II, III
Detailed Report of Work done at the Experimental Station, Pirbright, and at the
Veterinary Laboratory of the Ministry of Agriculture and Fisheries, New Haw,
Weybridge.—ANDREWS, W. H., DOBSON, N., BANNATYNE, T., SIMMINGS, G. B.,
WATKINS, C. V., EVANS, J. T. and DAVIES, G. O.—Fourth Progress Report of the
Foot-and-Mouth Disease Research Committee, Ministry of Agriculture and Fisheries,
Great Britain, pp. 33—140, 24 figs., 9 coloured. London : H. M. Stationery
Office (1931). [Reprinted from the Veterinary Bulletin, Vol. 2, No. 3. March
1932.]
SURVIVAL OF THE VIRUS OF FOOT-AND-MOUTH DISEASE.
Influence of the Hydrogen-ion Concentration on the Survival of Virus in Guinea Pig
Epithelium.—Epithelium was collected from the plantar pads of guinea pigs which had reacted in
24 hours to Virus 1. Discs were cut from these pads and were used as the source of the Virus for
trial. A series of solutions, both M/15 and M/25 were prepared, giving a range of hydrogen-ion
concentrations from pH 6.6 to pH 8.0. The discs were placed in glass stoppered vessels and were
kept in the cold store at —1° C. Discs of epithelium were tested from time to time by intradermal
inoculation of guinea pigs, from the ninth to the one hundred and fifty-second day. From the
forty-ninth to the one hundred and fifty-second day, the virus survived satisfactorily only in those
solutions with reactions of pH 7.6, 7.8, and 8.0. Two further series were tested, one kept in the
cold store and the other in the cool laboratory. In both series of observations the virus survived
longest over the range pH 7.2 to pH 8.0 with the optimum at pH 7.4.
Survival of the Virus in Blood when Dried on Various Substrata.—Blood from reacting
guinea pigs were placed on various substances and allowed to dry in a cool laboratory. The virus
survived on leather, hides and rubber for 80 days, 89 days and 102 days, respectively.
Survival of the Virus in Epithelium when Dried on Various Substrata.—Discs of epithe-
lium from the pads of reacting guinea pigs were placed on various substrata under conditions
similar to the test made with blood. The virus survived 27 days on limed walls, two to three
weeks on wood, glass and brick, and 45 and 46 days on stockinette and hessian.
Survival of the Virus in Guinea Pig Tissues at Chilling Temperature.—Guinea pigs
inoculated with virus 1 reacting + 1 were killed and bled, the carcasses were dressed and the organs
stored at —2° C. The tissues were tested by guinea pig inoculation and the following maximum
periods of survival were recorded:—tendon, 145 days; bone marrow, 107 days; liver, 99 days;
kidney and lungs, 96 days; tongue and fat, 82 days; and heart, 62 days.
Survival of the Virus at Low Temperatures in the Bovine Carcass.—The cattle were infected
by contact with active cases. They were slaughtered at different stages of the infection, but
mostly when the temperature was rising. All the carcasses were kept at "chilling " temperature
(29° F.) and, as in the imported meat trade, the "Offals" were frozen at 15° to 18° F. The
following periods of survival of virus were recorded :—up to 33 days in the tongue and cheek and
in the washings from intact quarter ; up to 49 days in meat wrapping cloths soaked in virulent
blood; and up to 80 days in bone marrow and blood clot, all kept at a temperature of 29° F. Hides
from these cattle, salted and stored in an ordinary loose box, were found to be infective to swine
after 46 days.
DISINFECTION.
Acid and Alkalies.—Many weak acids and acid salts were used in these experiments. Citric
and tartaric acids gave the best results, and solutions of 1:1,000 killed the virus within 30