VESICULO-DERMATITIS SUUM (SWINE VESICULAR DERMATITIS)

WU-CHI TSAI, CHENG-CHOW KUO, YUNG-CHAN CHANG, WEN-PIN CHOW,PEI-YIN SUNG, CHIU-JU WU, CHENG-LEE HO

In January 1953, a foot-and-mouth disease-like or a disease similar to vesicular exanthema was observed in the quarantine houses of Shanghai Abattoirs and spread rapidly over thousands of pigs to be infected. After a relatively short time of systematic study, the results convinced the authors to consider that the disease is an entity other than swine vesicular exanthema or its allied diseases, Vesiculo-dermatitis suum (swine vesicular dermatitis) was suggested to be the name of the disease. Vesiculo-dermatitis suum may be differentiated from the allied diseases by the following aspects listed in the table. Table: differential diagnosis for the allied diseases with veicular syndromes The experimental results may be briefly summarized as follows: 1. Cattle, sheep, goats, rats, white mice and chickens were not susceptible to this disease by scarification which was a reliable method to reproduce infection in swine. By intracranial inoculation, guinea pigs, rabbits, white rats and white mice did not show any visible reactions. 2. Scarification with finely grinded vesicular membranes and vesicular fluid on the internal space of the third digits or on the membranes of lips of the pigs always induced infection with symptoms similar to that of natural cases. 3. All of four pigs fed each with one gram of the infective membranes which induced infections in the control groups by scarification, did not show any reactions. Apparently, the wound is the only entrance of infection. Dogs, rabbits, rats and mice were also not infected by feeding. 4. In majority, the guinea pigs showed vesicles on soles scarified, and a few of the reactors gave secondary vesicles on the soles un-scarified. 5. The causal agent could pass through the Berkefeld candle W. and no growth occurred when inoculated to broth, blood agar and cooked meat anaerobic medium. 6. The intact vesicles on the digits of the infected pigs retained its in-fectivity at least for three weeks when stored at-18°-+5°C. 7. The muscle, bone marrow and lymgh nodes collected from ninteen sick pigs in different stages of the courses, did not show infectivity by scarification on twenty pigs in three succesive experiments, while the vesicles and vesicular fluid of the same pigs definitely induced infections in the control groups. 8. Twenty ml. of convalescent serum of the pigs recovered a week later could not protect the pigs of 15kg in body weight, and seven pigs recovered a week later all resisted the infection by scarification. 9. Both in the laboratory and in the field, the swine vesicular dermatitis did not cause a single death, unless it was complicated with other serious maladies. However, the growth rate of sick pigs was markedly retarded as shown in one experiment: nine infected pigs of 15kg in body weight each gained 2.1kg in average at the end of an interval of 15 days from inoculation to complete recovery, while other 15 healthy pigs of same body weight and fed under the same conditions each gained 4.35kg in average.