Assessing the Effect of an Integrated Control Strategy for Schistosomiasis Japonica Emphasizing Bovines in a Marshland Area of Hubei Province, China: A Cluster Randomized Trial

Abstract

IntroductionMore than 80% of schistosomiasis patients in China live in the lake and marshland regions. The purpose of our study is to assess the effect of a comprehensive strategy to control transmission of Schistosoma japonicum in marshland regions.Methodology/Principal FindingsIn a cluster randomized controlled trial, we implemented an integrated control strategy in twelve villages from 2009 through 2011 in Gong'an County, Hubei Province. The routine interventions included praziquantel chemotherapy and controlling snails, and were implemented in all villages. New interventions, mainly consisting of building fences to limit the grazing area for bovines, building safe pastures for grazing, improving the residents' health conditions and facilities, were only implemented in six intervention villages. Results showed that the rate of S. japonicum infection in humans, bovines, snails, cow dung and mice in the intervention group decreased from 3.41% in 2008 to 0.81% in 2011, 3.3% to none, 11 of 6,219 to none, 3.9% to none and 31.7% to 1.7%, respectively (P<0.001 for all comparisons). In contrast, there were no statistically significant reductions of S. japonicum infection in humans, bovines and snails from 2008 to 2011 in the control group (P>0.05 for all comparisons). Moreover, a generalized linear model showed that there was a higher infection risk in humans in the control group than in the intervention group (OR = 1.250, P = 0.001) and an overall significant downward trend in infection risk during the study period.Conclusions/SignificanceThe integrated control strategy, designed to reduce the role of bovines and humans as sources of S. japonicum infection, was highly effective in controlling the transmission of S. japonicum in marshland regions in China.Trial RegistrationChinese Clinical Trial Registry ChiCTR-PRC-12002405.

New scope on the relationship between rotifers and Biomphalaria alexandrina snails

“…Regarding SG II-B, straight line and zigzag swimming motions (1&2) were as detectable as pauses with intermittent spins or irregular onward movements (3&4) throughout the four weeks of shedding. Stationary cercarial pauses (5) were exclusively identified in the first two weeks of shedding in SG II-C even more than the pauses observed with intermittent spins or irregular onward movements (3&4). The latter types 3&4 were seen to even overwhelm the straight line-and zigzag-cercarial swimmings (1&2) in the last two weeks of shedding.…”

“…Seven weeks post-infection, eggs obtained from the intestines and livers of infected mice were exposed to direct sunlight for approximately 30 min to stimulate miracidial hatching. Each snail was individually exposed to [5][6] active, vigorously swarming S. mansoni miracidia in 5 mL of DTW for 2 h, a period sufficient for maximal miracidial penetration [25] .…”

“…Crushed snail-tissues were cautiously removed from their shells, fixed in Bouin's fluid for 5 h, and then transferred to 70% alcohol. Further procedures included dehydration in 100% alcohol, clearing in xylol, then paraffin embedding were followed.…”

“…The infectivity powers of cercariae shed from all exposed snails subgroups (SG II-A,-B,-C) were investigated. A total fo 120 locally bred Swiss albino mice, [4][5][6] weeks old and weighing [20][21][22][23][24][25] g, were infected with 80 S. mansoni cercariae per mouse using the paddling technique [24] . Mice were equally distributed among 4 subsequent subgroups (n=40/subgroup), to be subsequently examined along the 1-4 weeks duration of shedding.…”

“…A number of control strategies, including blocking parasite transmission in snail hosts; have been proved unsuccessful for long-term control of schistosomiasis [4][5][6] . Philodina snails are needed by Schistosoma mansoni (S. mansoni) parasites to be able to complete their life cycle [7] .…”