The follwing was an outlook of the epidemic of acute glomerulonephritis among F primary School children in Toyama Prefecture, November, 1970.
The number of absentee at the school, ordinarily about 20, increased gradually from the end of October and reached a maximum of 94 on November 24. More than half of the total number of patients (32 out of 58) fell ill within the month of November, athough sporadic cases had occurred in other months; 4 in June, 8 in July, 1 in September, 6 in October, 5 in December and 2 in January. These nephritis cases were often preceded by the upper respiratory tract disorders with pyrexia, cough, pharyngitis and other symptoms. A survey on the individual physical conditions carried out on November 27 revealed that still many children were showing the upper respiratory tract disorders.
One hundred and seventy six children, most of them showing the upper respiratory tract disorders were chosen and their swabs were examined for hemolytic streptococci. Group and type identifications, in case hemolytic streptococcus strains were isolated, were performed by both micro agar-gel diffusion and capillary precipitation techniques using acid-extracted antigens. Serological examinations were conducted using paired sera with regard to and streptolysin 0 levels.
Sixty two out of 176 children examined were the carriers of group A streptococci and more than 80% of them were the carriers of type 12 strains.
There was a significant difference in the distribution of ASO titers between the type 12 strain carrier and the non-carrier group, the former showing much higher ASO titers (24 out of 32 in the first, and 24 out of 28 in the second examination showed titers of 333 or more) than those of the latter group (only 17 out of 48 in the first, and 12 out of 38 in the second examination showed titers of 333 or more). Among 7 children whose ASO titers were 166 or less, but were the carriers of type 12 strains in the first examination, 5 exhibited significantly increased ASO levels after 3 weeks.
These results clearly indicated that the epidemic of acute glomerulonephritis followed the upper respiratory tract disorders caused by the group A type 12 hemolytic streptococci.
Results of group and type identifications obtained by micro agar-gel diffusion coincided very well with those by capillary precipitation. However, the following advantages over the latter technique could be pointed out. 1) Typing sera could be used directly without absorption of coexisting anti group A polysaccharide antibodies, since the precipitin line formed by the anti M type specific protein antibodies was clearly dissociated from that formed by the antibodies against the polysaccharide. 2) Reading was easier and more reliable. 3) quantity of each antiserum required for the reaction (0.02ml for 4 to 6 antigens to be examined) was less than that for the capillary precipitation.
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