抄録
Equine paratyphoid is still prevalent in Hokkaido. Agglutination Reaction is most widely used method of diagnosis, however, its interpretation in relation to the titre that may be observed is often difficult because of frequent presence of animals showing the intermediate titre such as 1 : 800∿1 : 1600. The present standard of titre is considered to be positive at 1 : 1280 and suspicious at 1 : 640. Owing to differences in technique, the titre of different laboratories may not be identical. Thus diagnosis by agglutination test is not easy. The present authors carried out the following described experiments to gain some information on the present status of the diagnosis of this disease. Salm. abortus-equi with a dose of 7.3 million bacilli was administered perorally into 8 foals aging 6∿7 months (except one foal, 19 months old). All of them were infected and some animals showed typical symptoms and some slight. One foal died of sepsis 13 days after infection. Throughout the course of the sickness, initial stage-evolution of disease-, convalescence, the rise and fall of agglutinins, precipitins and complement-fixing antibodies were observed. Furthermore blood samples were taken from almost all horses in the village of Kaminokuni where equine paratyphoid is prevalent, and the above three serum reactions were observed on these 519 sera. The results may by summarized as follows : 1. At an initail stage of infection precipitin appears a little later or simultaneously with agglutinin and complement-fixing antibody rises later than the former (Tab. 3,Fig. 2∿5). 2. In the developing stage of infection the titres of the three kinds of antibodies rise to a maximum which is usually attained between the 14th and 25th day after inoculation. However, the amount of antibody produced in response to infection varies with the slightness or severity of the symptoms. Usually the titre is low when the symptoms are slight (Tab. 3). 3. In the convalescent stage, the antibodies begin to fall. The preciptin falls most rapidly and disappears very soon. The complement-fixing antibody disappears later than the former or persists with a low titre. The agglutinin falls gradually but does not return to the titre of pre-infection (Tab. 3,Fig. 2∿5). 4. It should be noted that the abortion bacilli could not be detected from the foals slaughtered when precipitin titre sunk to zero. On the contrary, the bacilli were detected from a mesenteric lymph nodules and kidney of two foals out of three which were killed when precipitin still persisted (Tab. 2). 5. The authors carried out the above three tests with 519 sera of horses in Kaminokuni Village where equine paratyphoid is prevalent. The number of animals that possess agglutinin titre higher than 1 : 3200 is largest in an age group of 2 years. However, the proportion of the animals that possess intermediate titre of 1 : 800∿1 : 1600 increases with increasing age. At an age group of 5 years and over, this proportion had risen to 74.6 per cent (Tab. 4). 6. When an agglutinin titre is 1 : 6400 or over, the other two serum reactions show also high titre. In these animals, the infection seems to be still in active stage (Tab. 4). 7. The discrepancy between the three serum reactions increases with the fall of agglutinin titre. At a titre of 1 : 800∿1 : 1600,the majority of horses sera showed negative precipitation and complement fixation test (Tab. 5). From the above mentioned data, a titre of 1 : 6400 or over is rarely met with except as the result of an active infection and it is usually regarded as evidence of equine paratyphoid. However, in many cases possessing low titres less than 1 : 3200,the discrepancy between the 3 tests increases with the fall of agglutinin titre. Because of the lack of acceptable agglutinin titre standard which determines the diagnoses of active infection, it is impossible to arrive at a diagnosis when an agglutinin titre shows an intermediate value such as 1 : 800&ac
Equine paratyphoid is still prevalent in Hokkaido. Agglutination Reaction is most widely used method of diagnosis, however, its interpretation in relation to the titre that may be observed is often difficult because of frequent presence of animals showing the intermediate titre such as 1 : 800∿1 : 1600. The present standard of titre is considered to be positive at 1 : 1280 and suspicious at 1 : 640. Owing to differences in technique, the titre of different laboratories may not be identical. Thus diagnosis by agglutination test is not easy. The present authors carried out the following described experiments to gain some information on the present status of the diagnosis of this disease. Salm. abortus-equi with a dose of 7.3 million bacilli was administered perorally into 8 foals aging 6∿7 months (except one foal, 19 months old). All of them were infected and some animals showed typical symptoms and some slight. One foal died of sepsis 13 days after infection. Throughout the course of the sickness, initial stage-evolution of disease-, convalescence, the rise and fall of agglutinins, precipitins and complement-fixing antibodies were observed. Furthermore blood samples were taken from almost all horses in the village of Kaminokuni where equine paratyphoid is prevalent, and the above three serum reactions were observed on these 519 sera. The results may by summarized as follows : 1. At an initail stage of infection precipitin appears a little later or simultaneously with agglutinin and complement-fixing antibody rises later than the former (Tab. 3,Fig. 2∿5). 2. In the developing stage of infection the titres of the three kinds of antibodies rise to a maximum which is usually attained between the 14th and 25th day after inoculation. However, the amount of antibody produced in response to infection varies with the slightness or severity of the symptoms. Usually the titre is low when the symptoms are slight (Tab. 3). 3. In the convalescent stage, the antibodies begin to fall. The preciptin falls most rapidly and disappears very soon. The complement-fixing antibody disappears later than the former or persists with a low titre. The agglutinin falls gradually but does not return to the titre of pre-infection (Tab. 3,Fig. 2∿5). 4. It should be noted that the abortion bacilli could not be detected from the foals slaughtered when precipitin titre sunk to zero. On the contrary, the bacilli were detected from a mesenteric lymph nodules and kidney of two foals out of three which were killed when precipitin still persisted (Tab. 2). 5. The authors carried out the above three tests with 519 sera of horses in Kaminokuni Village where equine paratyphoid is prevalent. The number of animals that possess agglutinin titre higher than 1 : 3200 is largest in an age group of 2 years. However, the proportion of the animals that possess intermediate titre of 1 : 800∿1 : 1600 increases with increasing age. At an age group of 5 years and over, this proportion had risen to 74.6 per cent (Tab. 4). 6. When an agglutinin titre is 1 : 6400 or over, the other two serum reactions show also high titre. In these animals, the infection seems to be still in active stage (Tab. 4). 7. The discrepancy between the three serum reactions increases with the fall of agglutinin titre. At a titre of 1 : 800∿1 : 1600,the majority of horses sera showed negative precipitation and complement fixation test (Tab. 5). From the above mentioned data, a titre of 1 : 6400 or over is rarely met with except as the result of an active infection and it is usually regarded as evidence of equine paratyphoid. However, in many cases possessing low titres less than 1 : 3200,the discrepancy between the 3 tests increases with the fall of agglutinin titre. Because of the lack of acceptable agglutinin titre standard which determines the diagnoses of active infection, it is impossible to arrive at a diagnosis when an agglutinin titre shows an intermediate value such as 1 : 800&ac
