• 1

    Spear RC, Seto E, Liang S, Birkner M, Hubbard A, Qiu D, Yang C, Zhong B, Xu F, Gu X, Davis G, 2004. Factors influencing the transmission of Schistosoma japonicum in the mountains of Sichuan Province of China. Am J Trop Med Hyg 70 :48–56.

    • Search Google Scholar
    • Export Citation
  • 2

    Zong B, Xiong ME, Zhao LG, Lai YH, Lai J, Chen L, Yin HZ, Sha KY, Zhang Y, Gu XG, 2001. Investigation of water contamination situation in Qionghai Lake area, Xichang, Sichuan. J Pract Parasitic Dis 9 :97–100.

    • Search Google Scholar
    • Export Citation
  • 3

    The Office of Endemic Disease Control M, 2000. Handbook of Schistosomiasis Control. Shanghai: Shanghai Science & Technology Press.

  • 4

    Laird NM, Ware JH, 1982. Random-effects models for longitudinal data. Biometrics 38 :963–974.

  • 5

    Scott JT, Diakhate M, Vereecken K, Fall A, Diop M, Ly A, De Clercq D, de Vlas SJ, Berkvens D, Kestens L, Gryseels B, 2003. Human water contacts patterns in Schistosoma mansoni epidemic foci in northern Senegal change according to age, sex and place of residence, but are not related to intensity of infection. Trop Med Int Health 8 :100–108.

    • Search Google Scholar
    • Export Citation
  • 6

    Gazzinelli A, Bethony J, Fraga LA, LoVerde PT, Correa-Oliveira R, Kloos H, 2001. Exposure to Schistosoma mansoni infection in a rural area of Brazil. I: water contact. Trop Med Int Health 6 :126–135.

    • Search Google Scholar
    • Export Citation
  • 7

    Li Y, Sleigh AC, Williams GM, Ross AG, Forsyth SJ, Tanner M, McManus DP, 2000. Measuring exposure to Schistosoma japonicum in China. III. Activity diaries, snail and human infection, transmission ecology and options for control. Acta Trop 75 :279–289.

    • Search Google Scholar
    • Export Citation
  • 8

    Ross AG, Yuesheng L, Sleigh AC, Williams GM, Hartel GF, Forsyth SJ, Yi L, McManus DP, 1998. Measuring exposure to S. japonicum in China. I. Activity diaries to assess water contact and comparison to other measures. Acta Trop 71 :213–228.

    • Search Google Scholar
    • Export Citation
  • 9

    Friedman JF, Kurtis JD, McGarvey ST, Fraga AL, Silveira A, Pizziolo V, Gazzinelli G, LoVerde P, Correa-Oliveira R, 2001. Comparison of self-reported and observed water contact in an S. mansoni endemic village in Brazil. Acta Trop 78 :251–259.

    • Search Google Scholar
    • Export Citation
  • 10

    Chandiwana SK, Woolhouse ME, 1991. Heterogeneities in water contact patterns and the epidemiology of Schistosoma haematobium. Parasitology 103 :363–370.

    • Search Google Scholar
    • Export Citation

 

 

 

 

SPATIAL AND TEMPORAL VARIABILITY IN SCHISTOSOME CERCARIAL DENSITY DETECTED BY MOUSE BIOASSAYS IN VILLAGE IRRIGATION DITCHES IN SICHUAN, CHINA

View More View Less
  • 1 Center for Occupational and Environmental Health, School of Public Health, University of California, Berkeley, California; Sichuan Institute of Parasitic Diseases, Chengdu, People’s Republic of China

A mouse bioassay was used monthly over the infection season of 2001 to determine the temporal and spatial variability of schistosome cercarial density in irrigation ditches in five villages in southwestern Sichuan Province in the People’s Republic of China. Analysis of variance showed that approximately half of the variability was due to the village and site within the village, with little contribution from air temperature, weekly average rainfall, or the month within the infection season in which the bioassay was performed. The location-specific variability in these data suggest that epidemiologic studies will generally have low power to detect the influence of water-contact intensity on human parasite burden without taking account of variations in cercarial density at sites of water contact.

Save