The virus family Arenaviridae is a diverse group of RNA viruses and includes the etiologic agents of several emerging zoonoses that are characterized by high case-fatality rates.The purpose of this article is to review the major features of the zoonotic arenaviruses from the angles of their taxonomy and classification,epidemiology and ecology,mode of transmission,clinical signs,prevention and control,etc.Which are important for the reason that viruses causing severe disease in humans are re-emerging somewhere the world.

Objective To make the quality control of the tests used in the schistosomiasis survey. Methods A specific new method was proposed to test the independency of three tests in order to control the quality of the survey. Simulated data and real survey data were used to discuss the adaptability of the method. Results The simulated data and the real data both revealed that the new method could be used to test the independency of three tests. Conclusions The new approach can be applied in the quality control of schistosomiasis survey and is of high value for wide application.

A quantitative study on human water contact was carried out in an endemic area of schistosomiasis japonica. The information relating to frequency, duration and intensity of each activities was obtained from 390 persons (93% of all) aged 5-59 and 10 days of each season in 1987 was surveyed by using systematic sampling. Socioeconomic investigation and stool examination were also performed on the same population. It is found that cutting grass and fishing are the most important activities, as well as swimming and bathing. The accumulated index ofexposure is high in spring and summer, low in autumn and rare in winter. The peak contact is 8-12 o'clock in the morning. The reasons of contact are different between males and females. And the peak contact is at teen aged youth. Studies on water contact and socioeconomic factors show that there are more contacts in peasants than in those with other occupations. Rich farmers who has more savings contact less. The contacts seem more frequent in those whose family water supply is from infected water. The stepwise regression analysis shows that the most important factor relating to the infection of schistosomiasis japonica are index B of exposure (accumulation of duration ? intensity). The infected water supply of family and education were two other factors relating to the infection.

Mathematical model has been increasingly applied in the description of the transmission of schistosomiasis, the prediction and selection of schistosomiasis prevention measures, and it has being developed constantly. This paper briefly introduces several typical mathematical models for transmission of schistosomiasis and summarizes their advancements.

Objective To explore the application of amplified fragment length polymorphism (AFLP) in the study of genetic diversity of Oncomelania hupensis. Methods A snail was taken at random from Dali region, Yunnan Province and Yueyang City, Hunan Province respectively, and DNA was drawn with guanidinium thiocyanate and resin et al. Genomic DNA was amplified selectively by the AFLP technique with 64 pairs of primers, and the polymorphism of PCR products was examined by SDS-PAGE. Results The number of AFLP markers was between 5 and 55 for a pair of primers. The average number of a pair of primers was 38.30 (95% CI 36.03-40.57) for the snail from Yunnan Province, and 39.14 (95% CI 36.71-41.57) for the one from Hunan Province. For a pair of primers, the number of amplified polymorphic markers was between 3 and 37, and the polymorphic rate was between 28.6% and 76.2%, the average, 23.67 (95% CI 22.12-25.22) and 47.36%(95 %CI 45.22%-49.50%), respectively. The average similarity between the two populations was 0.69 (95% CI 0.67-0.70). Conclusion The AFLP technique is a new path for classifying Oncomelania hupensis and studying the genetic diversity of it.[

The elimination of Oncomelania hupensis snails is important to schistosomiasis control. Recently,the application of molluscicidal organisms is considered as a safe and efficient method for snail elimination. In order to provide scientific evi?dences for effective control of O. hupensis and schistosomiasis,this paper summarizes the researches of molluscicidal microor?ganisms against O. hupensis.

Objective To observe the survival and multiplication of Legionella pneumophila cocultured with Acanthamoeba polyphaga for setting up the laboratory model of such infections. Methods With the ratio of 1∶1000, Acanthamoeba polyphaga and Legionella pneumophila were cocultured under laboratory condition. We investigated the intracellular growth, survival and multiplication of Legionella pneumophila in Acanthamoeba polyphaga in morphological way by using inverted microscopy,electron microscopy and Giemsa staining of the cover glass picking up from the flask. Results Giemsa staining of the cover glass from the culture flask showed that the vacuoles appeared after 8 h coculture, and became more and bigger with the time. After 24 h, Giemsa staining showed that the bacteria started to accumulate within amoeba. In the anaphase of the coculture, the infected amoeba lacked defined organelle structures and was filled with legionella. The electron microscope revealed the survival of legionella in vacuoles of both trophozoites and cysts, showing different phases of binary fission. Conclusions Legionella pneumophila can survive and multiply in Acanthamoeba polyphaga . The results indicated that live amoeba could be a reservoir host for Legionella pneumophila.

Objective To explore the relati onship between the reliability of information of genetic diversity and sample si ze in morphologic quantitative characteristics of Oncomelania h upensis. Methods Sixty snails ( smooth shell) from Dali City, Yunnan Province and sixty snails (ribbed shell) f rom Yueyang City, Hunan Province were sampled at random, and the morphologic qua ntitative characteristics of the snails were measured, and then the coefficient of variation, proportion of variation between the two groups and Shannon's infor mation index were computed respectively. Results Among 11 indices of morphologic quantitative characteristics, the coefficient of variation of thickness of labra brim was th e largest, and those of ribbed-shell and smooth-shell population were 20.57% and 14.14% respectively, and the next was length of hypo-body whorl, and those of ri bbed-shell and smooth-shell snails were 12.98% and 11.49% respectively. Amon g 11 morphologic quantitative characteristics indices, there were nearly three out of four indices which the coefficients of variation of ribbed-shell snails were m o re than those of smooth-shell population, and the average coefficient of variat i on of ribbed-shell population was also more than those of smooth-shell populat io n. The average Shannon's information indices of ribbed-shell and smooth-shell po pulation were 1.541 and 1.220 respectively, and the former was the bigger. Whe n the sample size was less than 30, the result of genetic diversity gained from th e study was not very reliable, and with the increase of sample size the reliabil ity of the information of genetic diversity was also augmented. When the sample size was more than 55, the result of genetic diversity was reliable. Conclusion In order to get reliable information of genetic variation in the study of morphologic quantitative charac-teristics of Oncomelania hupensis, at least 55 individual s should be investigated for each population.

The paper reviewed the project management model and its evolution in the national schistosomiasis control in China at different stages.The key factors impacting the progress of the control activities were analyzed by introducing the concept of project management,and the principles,i.e.objective management,temporal management,cost-effectiveness management,and quality management,that would have to be complied with in the future control activities were put forward,so as to accelerate the elimination of schistosomiasis in China.

ObjectiveTo investigate the dynamic changes of T helper (Th) responses and hepatic granuloma development during Schistosoma japonicum infection and to evaluate the possible correlation between the Th1/Th2 cytokines and pathological liver damage. MethodsSera from both Schistosoma japonicum infected C57BL/6 mice and uninfected controls were measured for interferongamma (IFN-γ), interleukin (IL)-4 and IL-13 at week 4, 6, 8 and 12 post-infection. At the same time, the splenic Th1/Th2 ratio was examined. The development of liver granulomas in infected mice was also observed and the correlation between the cytokines and granulomas were assessed. Wilcoxon test and Spearman rank correlation test were performed for data analysis. ResultsSerum IFN-γ level in infected mice was (2. 835±0. 049) lgpg/mL at week 4 post infection, which was significantly higher than that in controls [(1. 787 ± 0. 174) lgpg/mL, Z= - 2. 646, P = 0. 008]. Thereafter, the level declined after week 6, but remained higher than controls at the end of 12-week experiment (Z= -2.457, P=0. 014). IL-4 and IL-13 levels did not increase until week 6 (Z=-2. 646,P=0. 008;Z=-2. 646,P=0. 008), and peaked at week 8. After soluble egg antigen (SEA) stimulation, splenic Th1/Th2 ratio in infected mice was 0.5 (95％ CI 0. 2-1.2) at week 8 and 0.3 (95％ CI 0. 3-0.6)at week 12 post infection, both of which were significantly lower than those in uninfected controls (week 8: Z=2. 173, P=0.030; week 12:Z=2.551, P=0.011). Compared with unstimulated splenic cells, splenic Th1/Th2 ratio after SEA stimulation significantly decreased at week 8 (Z=2. 236, P=0. 025) and week 12 (Z=3. 130, P=0.002). Granulomas were first observed in livers at week 6 and the size kept on increasing. A negative correlation between serum IL-13 and the diameter of liver granulomas was discovered at week 12 post infection (r=0. 636, P= 0. 048). Conclusions Th1 response is dominant during the early stage of Schistosoma japonicum infection.However,followed by oviposition, Thl response declines and meanwhile a strong Th2 response gradually develops. Therefore, Th2 response probably plays a role in the development of hepatic granulomas.