positive prevalence and smear positive prevalence in countryside were all higher than that of city and town; and they were 2.4, 2.7 and 2.8 times higher than city.

Situation in provinces, municipalities and regions: The prevalence of pulmonary tuberculosis in countryside was higher than in city in 25 provinces, municipalities and regions. There were only two provinces namely Hunan (one city point) and Henan (two city points) whose prevalence in city was higher than in countryside. Concerning smear positive prevalence, the prevalence in countryside was higher in city in 24 provinces, municipalities and regions. In three province and regions i.e. Hunan (one city point), Ningxia (4 city points) and Guangxi (three city points) the smear positive prevalence in city was higher than in countryside.

　

5. Morbidity in Minority Area

Among 928 investigation points in the country, 109 points were minority points i.e. the majority of inhabitant in the point belongs to one minority.

In these 109 minority investigation points, 18 minorities were involved. A total of 1,189 active pulmonary tuberculosis cases were detected among 171,741 examined population. Among them, 354 cases were bacteriological positive patients and 282 cases were smear positive patients.

The prevalences of active pulmonary tuberculosis among these 18 minorities were 162-1990/100,000 and the average prevalence was 700/100,000. The bacteriological positive prevalences were 59-829/100,000 and averaged 208/100,000. The smear positive prevalences were 47-580/100,000 and averaged 165/100,000. All these average prevalences were higher than that of the national prevalences.

Among 18 minorities, six of them (Hani, Tong, Yao, Buyi, Yi and Shui) have only one or two investigation points in their locality and it is, therefore, unadvisable to compare their morbidity with the national morbidity. Among other 12 minorities who have three or more points in their locality, seven of them have a bacteriological positive prevalence higher than the national bacteriological positive prevalence (164/100,000, unweighted) i.e. Uygur(373/100,000), Tujia(320/100,000), Menggu(277/100,000), Li(262/100,000), Hui(232/100,000), Miao(226/100,000), Hasake(194/100,000). Chaoxian had the lowest bacteriological positive prevalence (61/100,000) and Bai followed (71/100,000).

Seven minorities had data of morbidity in 1979 for comparison. The smear positive prevalence increased in five minorities. Based on the magnitude of tuberculosis in 1 979, the smear positive prevalence raised in five minorities i.e. Hui, Uygur, Menggu, Miao and Yi and their percentage of increase were 54%, 33%, 14%, 12% and 10% respectively.

　

?　TUBERCULIN TESTING AND INFECTION RATE

　

1. Positive Rate of Tuberculin Testing

(1) Positive Rate of PPD Reaction

Situation in the country: The sample population of children under 14 years old in all 928 investigation points involved 415,779. The eligible population for PPD testing numbered 408,670 and 394,085 were actually examined. The examination rate of the testing was 96.4%. The PPD reaction was identified in 365,481 children and the percentage of identification of the testing was 92.7%.

85434 children had a diameter of induration≧6mm. The positive rate of PPD testing was 23.4%. The positive rates in 1 year, 7 years and 14 years children were 19.1 %, 21.4% and 31.3% respectively. The positive rate increased with the increase in age after seven years (Tables 4).

　

　

(2) BCG Scar Rate and Positive Rate of Tuberculin Testing

201,098 children had BCG scar and 72,714 of them had a positive reaction of PPD testing; the positive rate of children with BCG scar was thus 36.2%. Among 164,383 children without BCG scar, 12,720 children had positive reaction of PPD testing; the positive rate of children without BCG scar was only 7.7%. The difference was 28.5% (Table 5).

　

　

Difference between city and countryside: In city, the positive rate among children who had BCG scar was 40.3% higher than those children who had no BCG scar; but the figure was 24.0% in countryside (Table 5). In city, the strong positive (≧15mm,≧20mm) rate among children who had BCG scar was 0.6 time (8.7/4.9; 2.4/1.5) higher than the children in countryside. The strong positive (≧15mm,≧20mm) rate among children in city who had no BCG scar was more than one time (4.2/1.9; 1.6/0.7) higher than the children in countryside.

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