title: Studies on the transmission potential of filariasis in controlled areas of Henan Province.
abstract: OBJECTIVE
  To study the regular pattern of growth and declination or the transmission potential of filariasis after the disease was basically (the microfilarial rate was lower than 1%) in Henan Province in 1987.
  
  
  METHODS
  According to the distribution of filaria species and original microfilarial rate, in 7 surveillance sites in 7 counties (cities) the etiology and mosquito vector surveys were carried out continuously during 1988-1995 and no control measurement for pathogen was taken.
  
  
  RESULTS
  Ten residual microfilaremias became negative gradually in the first 6 years and no new microfilaremias occurred during 1988-1995. During 1993 to 1995, the microfilaremias rate of population in the sites was 0. The natural infection rates of filarial larvae in vector mosquito were 0.1%-0. During the 8 years, 15 vector mosquitos were positive with a total of 18 filarial larvae which were all of first or second-stage larvae. The C. pipiens pallens was the main vector, the second was A. sinensis, with a small number of C. fatigans and A. anthropophagus. The man-biting rates of mosquitoes for outdoor sleepers fluctuated greatly, the highest one was 360.6 mosquitoes/person per night and the lowest, 7.2. The man-biting rates of mosquitoes for sleepers inside mosquito-net was about 1 mosquito/person per night. The proportion of multiparous mosquitoes also fluctuated more greatly, the highest one was 88.1% and the lowest 27. 2% According to the data described above, the man-biting rate of vector mosquito which contained filarial L3 was 0.
  
  
  CONCLUSIONS
  The results suggested that after the microfilarial rate was lower than 1%, the residual microfilaremias became negative gradually in 3-6 years, and the transmission of the disease was blocked. Therefore, in the areas where filariasis was basically controlled, elimination of the disease was attainable within sight.
authors.affiliation: Health and Anti-epidemic Center of Henan Province, Zhengzhou, China.
authors.forename: B
authors.initials: B
authors.lastname: Xu
authors.forename: Z
authors.initials: Z
authors.lastname: Cui
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Chang
authors.forename: Q
authors.initials: Q
authors.lastname: Zhao
authors.forename: Q
authors.initials: Q
authors.lastname: Huang
authors.forename: X
authors.initials: X
authors.lastname: Lin
mesh_terms: D000818:Animals; D002681:China / Q000453:epidemiology; D009033:Culicidae / Q000469:parasitology*; D004605:Elephantiasis, Filarial / Q000453:epidemiology / Q000635:transmission*; D005260:Female; D005368:Filariasis / Q000453:epidemiology / Q000635:transmission*; D007299:Insect Bites and Stings; D007303:Insect Vectors / Q000469:parasitology; D008137:Longitudinal Studies; D008297:Male; D008842:Microfilariae; D014958:Wuchereria bancrofti