Comparison of the effectiveness before and after the adjustment of schistosomiasis control strategies in Nanjing City / 预防医学

Objective@#To compare the effectiveness before and after the adjustment of schistosomiasis control strategies in Nanjing City, so as to provide the evidence for improving schistosomiasis control interventions.@*Methods@#The prevalence of Schistosomasis japonicum infections in humans, livestock, Oncomelania hupensis and sentinel mice was collected in Nanjing City from 1993 to 2018, and the prevalence of S. japonicum infections in humans, livestock, sentinel mice and O. hupensis, and the areas of snail habitats, areas of infected snail habitats and snail control areas were compared before (1993-2004) and after (2005-2018) the adjustment of schistosomiasis control strategies to evaluate the effectiveness.@*Results@#The prevalence of S. japonicum infections in humans, livestock, O. hupensis and sentinel mice was 0.77% and 0.02% (χ2=6 430.634, P<0.001), 0.46% and 0.01% (χ2=344.401, P<0.001), 0.19% and 0.11% (χ2=239.685, P<0.001), and 34.35% and 1.56% (χ2=1 856.286, P<0.001) in Nanjing City before and after the adjustment of schistosomiasis control strategies, respectively. The median areas (interquartile range) of snail habitats, infected snail habitats and snail control were 4 175.37 (1 301.65) and 2 366.44 (885.27) hm2 (Z=-3.755, P<0.001), 870.49 (1 001.75) and 0 (158.89) hm2 (Z=-3.654, P<0.001) and 1 383.23 (793.57) and 5 031.94 (629.11) hm2 (Z=-4.320, P<0.001) in Nanjing City before and after the adjustment of schistosomiasis control strategies, respectively.@*Conclusions@#After the adjustment of schistosomiasis control strategies, remarkable effects on schistosomiasis control has achieved in Nanjing City, where the transmission of schistosomiasis was interrupted. Nevertheless, the strategy requires to be continued and improved to move towards elimination of schistosomiasis in Nanjing City.

The surveillance of iodine deficiency disorders in Nanjing after the adjustment of iodized salt standard / 中华地方病学杂志

Objective To master the current status of iodine nutrition of people in Nanjing after the adjustment of iodized salt standard,and to provide scientific basis for reasonable iodine supplementation and strategies for iodine nutrition control.Methods The probability proportional to size (PPS) sampling method was employed in the investigation.We firstly selected 30 streets in the whole city,and then chosen 50 children aged 8-10 years from each of 30 primary schools respectively,which was selected from 30 different streets to examine the size of thyroid gland by palpation and B-type ultrasound.We also collected urine and edible salt samples from 12 children aged 8-10 years from each primary school,to detect their urinary and salt iodine content.Moreover,20 pregnant women and 10 lactating women were picked out from each of 30 schools nearby to detect their urinary and salt iodine content.We also conducted a unique questionnaire survey in 30 fifth-grade students selected from each of 30 schools,and 5 housewives selected from these schools nearby to understand their knowledge of iodine deficiency disorders.Results The thyroid palpate swelling rate was 0.33％(5/1 500) in 1 500 children aged 8-10.The medians of urinary iodine level were 220.5 μg/L in 362 school-age children,196.7 μg/L in 600 pregnant women and 152.0 μg/L in 300 lactating women.A total of 1 260 samples of edible salt were tested.The coverage rate of iodized salt and the consumption rate of eligible iodized salt were 99.7％ (1 256/1 260) and 96.9％ (1 221/1 260),respectively.The mean iodine content of edible salt was (24.5 ± 4.5) mg/kg.A total of 900 fifth-grade students and 150 housewives were surveyed for health knowledge of iodine,and the eligible rate was 83.2％ (2 246/2 700) and 91.6％ (412/450),respectively.Conclusions After the adjustment of iodized salt content,iodine nutrition level of people in Nanjing has maintained appropriately.However,health education should be further strengthened.Improving the awareness rate of iodine deficiency knowledge,and guiding scientific iodine consciousness are our serious task in the future.

Comparison of Schistosoma japonicum development between single sexual infection and double sexual infection in mice and rabbits / 中国血吸虫病防治杂志

Objective To observe the development of Schistosoma japonicum after single sexual infection and double sexual infection respectively. Methods A single Oncomelania hupensis snail was infected by a single schistosome miracidium. The lar?va were induced and released from the snail after 60?day incubation at 26℃. The mice were infected by the larva(single sexual infection)and dissected 40 days after the infection. All the worms were collected and the sex of the larvae was determined by the sex of the adult worms. Then,the mice and rabbits were infected by single sex of larvae(single sexual infection)and double sex of larvae(double sexual infection)respectively. The mice and the rabbits were dissected 40 days after the infection. All the worms were collected and measured under a microscope. Results All the male or female worms were collected from the mice and rabbits after single sexual infection. There were three main forms of worms after dissection of double sexual infection of mice and rabbits:folded mature male and female,male or female. Few folded male and immature female were found. Only the double sexual larva infected mice or rabbits had schistosome eggs in the liver and the liver had typical schistosome egg nodules. The sin?gle sexual larva infected mice or rabbits had no schistosome eggs or schistosome egg nodules in the liver tissues. The single male larva could develop to worms with the testis,and with a little smaller size compared to the mature folded male,while the single sexual infection female worm could not develop to the mature stage with much thinner and smaller compared to the mature folded female. Conclusions The male or female worms from single sexual infection are smaller than those from double sexual infection (mature worms?folded male and female). So it is necessary to check single sex worms in vessels of intestinal mucosa thoroughly in the sentinel mice when no schistosome eggs were found in the liver.

Epidemiological analysis of malaria prevalence in Nanjing City from 2010 to 2015 / 中国血吸虫病防治杂志

Objective To analyze the epidemiological characteristics of malaria in Nanjing City,so as to provide the evi?dence for further formulating and adjusting the malaria prevention and control strategy. Methods The data of malaria situation, malaria cases and epidemiological investigations were collected from the Internet Reporting System in Nanjing City from 2010 to 2015 and analyzed statistically. Results A total of 137 confirmed malaria cases were reported in Nanjing City from 2010 to 2015,including 102 falciparum malaria cases(74.45%),33 vivax malaria cases(24.09%),one ovale malaria case(0.73%) and one quartan malaria case(0.73%). Among the 137 malaria cases,126 cases(91.97%)were imported from foreign coun?tries,2 cases(1.46%)were infected locally,and nine cases(6.57%)were imported from other provinces in China. Among the 126 overseas imported cases,117 cases were imported from African countries and 9 from Asian countries. These malaria cases were majorly young men working as migrant workers,laborers and technical persons. About 19.30%of the cases went to hospital on onset day,and 55.65%were confirmed by medical institutions as malaria in the same day. The majority of diagnosis institu?tions were municipal hospitals(74.45%). Conclusions The number of malaria cases in Nanjing City is declining year by year. The local infections are eliminating gradually. However,the situation of imported malaria from overseas is still serious. There?fore,the surveillance work and health education still should be strengthened,so as to reduce the risk of imported malaria.

Development of oil lens-based fully automatic microscopy graphics scanning system and its preliminary application in diagnosis of malaria / 中国血吸虫病防治杂志

Objective To establish an automatic microscope scanning system based on the oil-lens for replacing the traditional manual microscopy reading of blood films to improve the efficiency and the detection rate of Plasmodium.Methods The system consisted of an optical microscope,digital camera,control software and general computer-based component.The system and professional persons read the blood films with single-blind method,everyone read 10 blood samples(100 fields of vision per blood film),and the time and results of reading were recorded.Results The system had the function of automatic displacement and focus,automatic scanning and storage,automatic back-bit and reset,annotation,and automatic counting,reporting and printing.The system can increased the speed of reading films by 30.58%,and improved the accuracy by 13.33%.Conclusion The automatic microscope scanning system can improve the speed and accuracy of reading films and the operation is simple.

Effect of schistosomiasis control in Bianmin River of Nanjing City / 中国血吸虫病防治杂志

Objective To evaluate the effect of comprehensive control for schistosomiasis with emphasis on environmental modification in the Bianmin River water system of Nanjing City.so as to provide scientific evidence for making up further control measures in this water system.Methods Schistosome infections of Oncomelania snails in the waterway.sentinel mice in water and neighbouring human were investigated longitudinally from 1998 to 2007,and the changes of huaman infection rates in differentyears,the infection rates of sentinel mice and snails in different settings were analyzed and compared.Results A total of 77 395 snails collected from the Bianmin River water system were dissected from 1998 to 2007,and among them,27 snails were infected with Schistosoma japonicum,with a total snail infection rate of 0.03%.A total of 61 039 snails collected from the neighbouring marshland which connected to the Yangtze River wore dissected,and among them,257 were infected with S.japonicum,with a total snail infection rate of 0.42%,and there was a significant difference compared with that in the water system(χ~2=248.55,P<0.01).After the protection works in the waterway,the infection rates of sentinel mice in the water system decreased from 69.68% in 1998 to 17.50% in 2001.with a reduction rate of 74.89%.Two years afterthe clearance ofmarshlandinthewaterway,no infected sentinel mouse was found.The infection rates of residents from 1998 to 2007 were 1.96%,1.37%,1.34%,1.60%,0.30%, 0.26%,0.16%,0.10%,0.04% and 0,respectively,andthe rates declined year by year afterthecomprehensive control.Conclusions The control measures based on the elimination of snail habitats in the waterway that is connected to the Yangtze River have achieved obvious effect.However,the clearance of the re-emerging snail habitats should be carried out termly to consolidate the control effect.

Scanning electron microscopy of Schistosoma nanjingi / 中国血吸虫病防治杂志

Objective To examine the tegmental structure of Schistosoma nanjingi using scanning electron microscopy. Methods Adult schistosomes were obtained from infected rabbits with cercariae shedding from Oncomelania snails, which were infected with miracidia of Schistosoma nanjingi. The adult schistosomes were fixed with 4% glutaradehyde, and then, the samples were prepared with the conventional procedures and the schistosomes were examined with a scanning electron microscope (SX-40). Results There were two types of male and female adult worms. For the big male worm, there were big spines and deep cavity on the surface of middle back and some small spines on the surface of middle abdomen; for the small male worm, there were many small spines on the surface of whole back and abdomen. As the big female worm, there were some small spines on the whole tegumental surface. As the small female worm, there were some small spines on the surface of back and abdomen, but the shape of spines was different between the spines of back and abdomen. On the tail surface of the small female worm, there were two types of spines. The spoke-like acetabulum was found. The sensory organelle papillae with or without cilia were found on the tegmental surface of both male and female woems. Conclusion The tegmental structure of Schistosoma nanjingi is much different from that of Schistosoma japonicum.

Observation on development of Schistosoma japonicum in Oncomelania hupensis / 中国血吸虫病防治杂志

Objective To observe the development of Schistosoma japonicum in Oncomelania hupensis. MethodsOncomelania snails were infected heavily with miracidia of S.japonicum and the snails were dissected in different time. The mothersporocysts, daughtersporocysts and cercariae were collected, fixed with Bouin's fluid, dyed with carminic stain, enveloped with neutral gum and examined. ResultsThe neural rings were found in 1-24 hours old mothersporocysts and disappeared in 2 days. In the mothersporocysts, germinal cells increased and developed to germ balls. One germ ball developed to one daughtersporocyst. In daughtersporocysts, there were germ balls of different development stages and at last they developed into cercariae. ConclusionThe development process from the miracidium to mothersporocyst, to daughtersporocyst, to cercaria is observed.