Studies on the Influenza, particularly the Influenza A/Asia/57 among Infantile Grips

I. Epidemiological and serological investigations

Abstract

CF test for influenza A and HI test for A/Asia/57 and A/Kojiya/52 were carried out with 442 paired samples of sera obtained from infants suffering from grip from April. 1957 to May 1958;
The results were as follows:
1) A/Asia/57 was isolated in 106 A/Kojiya/52 belonging to the strains hitherto known in two cases.
2) A/Asia/57 occurring since May 1957, demonstrated two peaks in June and Nevember in this year and then gradually decreased till next April.
Two cases were caused by Kojiya strain, one in January and the other in February-1958.
All age groups including one case of newborn were involved, demonstrating a tendency of predominance in school boys.
4) Compared with HI, a significant increase of CF antibody titer was in many cases recognized till 2 weeks of illness. No significant rise of CF antibody titer was noticed in sucklings and when noticed, fell in 6 out of 7 cases to the value of acute stage by 120 days of illness.
5) HI antibody titer rose more slowly than that of CF and 7 out of 10 cases; demonstrated the fall to 32 x by 150 days of illness.
6) A significant rise of cold hemagglutination value was observed only in 2.8% of A/Asia/57 cases.