中国黑热病流行学的现状(综述)

Present Epidemiological Situation of Visceral Leishmaniasis in China

关于中国黑热病流行学的论述,50年代以来已有不少报告,其中具有代表性的有王兆俊(1957),柴君杰(1963)、熊光华等(1974) 和管立人等(1976)的报告。他们均分别论述了我国黑热病流行特征和类型。至于近15年来关于我国黑热病流行学的现状尚缺乏系统的总结。作者自60年代初开始即连续在我国西北。

Visceral leishmaniasis or kala-azar was one of the important parasitic diseases in China. It was prevalent in 16 provinces and autonomous regions, and about 530,000 people were estimated to be infected with this disease before 1958. A large scale control of leishmaniasis such as the mass treatment of patients, the elimination of reservoir host (dog) and the wide spraying of insecticides had been done in the endemic areas in Shangdon, Northern Jiangsu,North-ern Anhwui, Henan, Hebei and eastern Shaanxi. After the control measures taken, the majority of patients had been cured in the last year of the 60's and no new cases were reported from the endemic areas. In China the vast knowledge accumulated from the investigations of kala-azar demonstrated that leishmaiasis mainly distributed in the country plain and was transmitted by the endophily sandfly (P.chinensis) from man to man. Dogs were rarely infected with this disease or served as the reservoir host. Beginning from the 60's, the investigation and control program were conducted in the part of Northwest China. During the period of 11 years from 1980-1990,about 2287 new cases of kala-azar were found from the mountainous and desert regions, including Xinjiang, Gansu, Sichuan, Inner Mongolia, Northern Shananxi. However, it was estimated that about 120 cases of kala-azar were missed in record at Tarim desert, Xinjiang per year. A natural nidus of visceral leishmaniasis had been fround in Tarim desert of Xinjiang. As shown by the epidemiological and entomological investigations, over 91% patients were below 2 years old in age recorded since 1964. In those regions, leishmaniasis was very sporadic and no inter-transmission occurred. This disease was characterized by a relatively short incubation period from 15-90 days, acute onset with a high fever, rapid enlargement of spleen and the pathogen hardly detected in bone marrow smears. In the desert area, P. wui was a typical wild species of sandfly, it was found that 18 out of 300(6.0%) P.wul were naturally infected with promastigotes of which were found in the esophagus of 12 infected sandflies and in 4 of them were extended to the pharynx. Five isolates of promastigotes were obtained from these infected sandflies each of these isolates was identified as L. donovani by the inoculated in an experimetal animals,after two months the inoculated animals became infected and L. d. bodies were found in the viscera, bone-marrow, lymphmodes and skin. There was marked alargement of the spleen. It was realized that thebehaviour of these isolates was identical with that of L.d. inoculated in normal Cricetulus barabeusis. Recently, the promastigotes, also isolates from these infected sadflies were identified as L.donovani by dot blot hybridization with photobiotin labelled k-DNA (Lu Hong-gang andHu Xiao-su 1988). The records indicated that the patients were mainly discovered from the end of the sandfly season till the coming March. The endemic area were usually found in the uncultivated desert, and people alwasys infected after they entered the desert for reclamation. There was no visceral leishmaniasis to be found in the sandfly season. Obviously, the source of promastigotes in the infected fly might be sure in the wild animals. P. wui was an optimum vector in the desert where human kala-azar was sporadic, therefore, the epzoonotic foci of visceral leishmaniasis firmly believed to be exist in the desert area. In Inner Mongolia,the similar focus had been found in Ejin Banner desert in 1972. An another desert focus of visceral leishmaniasis was discovered in Turpan County, Xinjiang, where the transmitted vactor was proved to be P.alexandri. In the euzoonotic foci, a large number of wild animal were examined, but no reservoir host had been found so far. In the mountainous regions, especially in Northern Gansu and Northwest Sichuan, dogs were the main reservoir host, and the incidence of visceral leishmaniasis in dog was consistetly high and was recognized as the canine source of leishmaniasis. P. chinensis (wild species) was naturally inf