[Malaria situation in the People's Republic of China in 1998].

Notwithstanding there was a flood over the five provinces located at the middle and lower reaches of the Changjiang River, i.e. Hunan, Hubei, Jiangxi, Anhui and Jiangsu, in the summer and autumn of 1998, the prevalence of malaria in these areas was basically stable or slightly decreased as a result of timely implementing active and effective preventive measures. According to the case reporting system, the number of malaria cases of the whole nation totaled 31,319 in 1998, with a mean incidence of 2.53 per a hundred thousand, and 24 deaths. A decrease of 12.0% in incidence was revealed as compared with that in 1997. The county-based reckoning showed that absence of malaria cases or drop of the incidence to lower than 1@10000 was reported from areas in 2,774 counties with a coverage of 1.2016 billion people; areas with 30.6 million people distributed in 75 counties showed an incidence of 1.1-10@10000, and areas with 6.50 million people distributed in 27 counties showed an incidence of 10.1@10000-100@10000. Of the 17 provinces, autonomous regions and municipalities (P/A/M) where major malarious areas are located, 6 showed more or less increase in malaria incidence, particularly noteworthy for Hainan and Yunnan Provinces, where 5,043 and 12,988 malaria cases were reported respectively, accounting for 57.6% of the national total. However, the actual number of malaria cases of the two provinces was estimated to be ten folds the number of the reported cases. Malaria surveillance was performed in areas covering 1,298 counties in 17 P/A/M with a coverage of 589 million people. Blood examination on febrile patients for 8,712,454 man/time detected 27,090 cases positive for malaria parasite, showing a mean positive rate of 0.31%, of which the number of falciparum malaria cases was 4,042 (including mixed infections with vivax malaria, the same below), a proportion of 14.9% of the total parasite positives was exhibited. Altogether 597,111 targeted people, inhabitants in epidemic spots and migratory people were also examined, 4,326 people were found to be positive for malaria parasites, showing a mean parasite rate of 0.72%, while falciparum malaria carriers were noted as 748 among them. As a whole, the endemicity of falciparum malaria was still confined to 47 counties of Hainan and Yunnan Provinces. Imported falciparum malaria cases were reported in 84 counties of 15 P/A/M (including non-endemic areas of Hainan and Yunnan), whereas no introduced falciparum malaria cases were recorded. The distribution of malaria did not show conspicuous changes in recent years. The prevalence was most severe in mountainous regions in Hainan with Anopheles dirus as the major vector, followed by areas south to 25 degrees N.L. where An. minimus distributed and areas between 25 degrees N.L. with An. anthropophagus as the vector. The three mentioned anopheline species were distributed in areas where more than 200 million people resided, the number of malaria cases amounted to 90% odd of the national total, the prevalence of malaria was unstable there, and focal outbreaks were often reported. Nevertheless, in areas only distributed with An. sinensis, the endemicity of malaria was stable, and its incidence has been reduced to less than 0.1@10000.