| Hemorrhagic fever with renal syndrome (HFRS) belongs to naturally acquired diseases, which is originated by Hantaviruses and harms people's health and lives. A large number of HFRS cases are widely distributed throughout the world with severe pathogenetic conditions and high death rates. Shandong province is one of the gravest epidemic areas of HFRS in China, of which the number of cases accounts for one third of that nationwide all the time. Totally 287882 cases were reported in Shandong province from 1974～2004, and the epidemic process durng this time can be described as follows: highly sporadic → local epidemic → outbreak → extensive epidemic. Although prevention and treatment of HFRS has been performed for many years and it was true that incidence level did decline to some extents, the incidence of HFRS in 21 Shandong province shows obvious characteristic of spatial heterogeneity, due to disparate epidemic factors and diverse ephasises on prevention and treatment work between different places, which can be summarized that most cases of HFRS centered in few counties. Twelve counties (cities, districts) invluding Yiyuan, Yishui, Mengyin, Qingzhou, Linqu, Junan, Pingyi, Feixian, Sishui, Changle, Lanshan and Yinan become the major epidemic areas in Shandong province, where the annual incidence rates all surpass 30/100,000 and together local patients account for 39.38% of those in Shandong province in 2000.There were 14872 new HFRS cases in 1999 and 10220 cases in 2000, accounting for 32.78% and 29.32% of total national HFRS cases respectively. Such numbers topped all provinces in China. Owning to reasons discussed above, in order to study intervention strategies and measures, and to control epidemic situation rapidly, we chose twelve counties (cities, districts), which obtained more than 30 HFRS cases per 100,000 residents, as trial loci. Using experimental epidemiological methods and integrated intervention model, which are mainly utilized to immune residents and eliminate mice, we discuss epidemical effects and economic benefits of integrated intervention model for the purpose of offering theories, methods and bases for establishing HFRS intervention model.Results from this study showed that::1. Although the HFRS incidence level of Shandong province differed from 1974to 2005, it showed a periodic variation of 8~10 years. The first epidemic period was from 1974 to 1981 and HFRS incidence level reached its peak in 1980; the second epidemic period was from 1982 to 1988, and the second peak appeared during 1984 to 1988; the third epidemic period was from 1989 to 2000 accompanied with the third peak appeared in 1995. According to the periodic regularity above, the fourth period would begin in 2001, and the fourth peak would be predicted to appear around 2005. After the integrated control model was put into practice, the number of HFRS cases was decreasing, the annual incidence rate declined to 6.76 Per 10 million, and the highly predictable peak around 2005 didn't appear.2. During intervention period, in residential areas of all monitoring points, the total rodent density and rodent Density of kinds were all controlled less than 5%. The total index of HFRS carrier and indexes of HFRS carrier of kinds were also controlled below 0.03. Each year, sewer rat and Mus musculus are predominant rat species in residential areas. In 2001, 2003, 2004 sewer rat has a higher index of HFRS carrier; however in 2004, 2005 mus musculus has a higher index of HFRS carrier significantly. Meanwhile in 2004, Apodemus agrarius's index of HFRS carrier was also high. These features indicate that, due to the intervention of deratization and change of ecological environment, the population structure of host rodents and index of HFRS carrier have changed in residential areas. 3. Since the integrated control model was carried out, the annual incidence rate has shown an evident downward tendancy in each trial county (city, district). At last, the incidence rate of each county decreased to a great extent in the end of intervention duration, when compared with that at the beginning of intervention duration. That is to say HFRS incidence level declined with the fulfiling and consummation of intervening measures. At the end of 2005, the incidence rate declined to 6.76%, and epidemic situation was controlled effectively.4. Integrated interventions in various counties (cities, districts) have positive epidemiological effects on prevention and control of HFRS. The whole effective Index in trial area reached to 4.2978, rate of protect is 72.19%, and the overall effect is favorable.5. During the intervention duration, the total cost (including the rodenticide, rodenticide grain bait , vaccines, insecticides, the investigation of density, laboratory testing, transportation, working hours, etc.) of the integrated intervention model is 7.5048 million yuan. The total saving expenditure resulted from the reduced number of patients (including hospitalization expenditure and the cost for therapies, payments for nutrition, charges on patients who missing work, accompanying fees of family members, the cost of case investigations, etc.) is 57.6671 million yuan, and benefit / cost ratio is 7.68. All the achievements of interventions above indicate high economic efficiency and favorable social benefits.Conclusions:1. Since the integrated control model was carried out, the annual incidence rate in each trial county (city, district) has decreased evidently, and the number of natural villages involved in HFRS has also declined. The incidence rate of each county (city, district) decreased to a great extent in the end of intervention duration (2005), when compared to that at the beginning of intervention duration (2001). At the end of 2005, the incidence rate in entire trial area declined to 14.41/100,000. From what we discussed above, we can conclude that the integrated intervention model of HFRS is a effective method to solve the problem of high incidence rate of HFRS in Shandong province and play an important role in keep HFRS mobidity rate steadily decline in Shandong province.2. Since the integrated control model was carried out, the population structure of host rodents and index of HFRS carrier has changed, due to the cooperation of deratization, change of ecological environment, and other involved factors.3. Integrated interventions of counties (cities, districts) have positive epidemiological effects on prevention and control of HFRS. The whole effective indexreached to 4.2978, rate of protect is 72.19%, and the overall effect is favorable.4. The integrated intervention model achieved high economic and social benefits, and the benefit / cost ratio is 7.68.
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