A review of botulism in China

The epidemiological characteristics and etiology of botulism in China, as well as the distribution of different types of Clostridium botulinum in China, are described. Through 1989, 15 provinces and autonomous regions reported the occurrence of botulism. There were 2861 cases involved in 745 outbreaks. Among the cases 421 died, with a case fatality of 14.7%. The main epidemiological characteristics of botulism in China are: (i) the major foods causing botulism are homemade fermented bean products which accounted for 62.6% of the cases; (ii) the incubation period is longer (3 h-54 days) than that described in the western literature (mostly 2-7 days); (iii) the peak occurrence is from February to May; (iv) the progression of symptoms and signs is slower than that of western cases. All types of C. botulinum, with the exception of type G, have been found in China. The distribution of various types of C. botulinum is significantly different between southern and northern China; this is related to the latitude and is correlated with the prevalence of this disease. Most of the botulism outbreaks occurred above 30 degrees north latitude in northern China and outbreaks rarely occurred below 30 degrees north latitude. Nationwide surveys showed that the average detection rate of C. botulinum spores in soil and foods in the northern parts of China was 14.8%, while it was only 2.5% in the south. C. botulinum types A, B, E, and F, which are involved in human botulism, were frequently found in the North, while types C and D, which are involved only in animal intoxication, were found more frequently in the south.