Epidemic situation and diagnosis of imported malaria before and after malaria elimination in Nanjing City, Jiangsu Province / 中国血吸虫病防治杂志

Objective To analyze the epidemiological characteristics and diagnosis of imported malaria before and after malaria elimination in Nanjing City of Jiangsu Province, so as to provide the scientific evidence for formulating the malaria control strategy after malaria elimination. Methods Data pertaining to the epidemic situation and individual investigation of malaria in Nanjing City before (from 2012 to 2016) and after malaria elimination (from 2017 to 2020) were captured from the National Notifiable Communicable Disease Reporting System and the Information System for Parasitic Diseases Control and Prevention and were analyzed statistically. Results A total of 178 malaria cases were reported in Nanjing City from 2012 to 2020, and all were imported cases. There were 99 malaria cases reported before malaria elimination in Nanjing City, including 78 cases with Plasmodium falciparum malaria (78.79%), 5 cases with P. vivax malaria (5.05%), 10 cases with P. ovale malaria (10.10%), 3 cases with P. malariae malaria (3.03%) and 3 cases with mixed infections (3.03%), and 79 malaria cases reported after elimination, including 63 cases with P. falciparum malaria (79.75%), 5 cases with P. vivax malaria (6.33%), 9 cases with P. ovale malaria (11.39%), 2 cases with P. malariae malaria (2.53%). There was no significant difference in the proportion of each type of malaria cases in Nanjing City before and after malaria elimination (χ2 =2.400, P > 0.05). Malaria cases mainly acquired Plasmodium infections in African regions, and no significant difference was seen in the proportion of malaria cases returning to Nanjing City from African countries before and after malaria elimination (χ2 = 0.093, P > 0.05). The number of malaria cases peaked in Nanjing City in January and during the period from May to July before elimination, and there was no apparent seasonal variation in the distribution of malaria cases after elimination. The proportion of malaria cases living in Nanjing City was significantly greater after malaria elimination than before elimination (72.15% vs. 55.56%; χ2 = 5.187, P = 0.023). The proportions of businessmen and international students were both 5.05% before malaria elimination, and increased to 15.19% and 13.92% after elimination, respectively (χ2 = 5.229 and 4.229, both P values < 0.05). The percentage of definitive diagnosis of malaria at initial diagnosis was 18.75% in county-level hospitals before malaria elimination and increased to 61.11% after elimination (χ2 = 6.275, P = 0.012), while the proportion of malaria cases with definitive diagnoses in county-level hospitals was 4.04% before malaria elimination and increased to 13.92% after elimination (χ2 = 5.562, P = 0.018). During the period from 2012 to 2020, the proportion of malaria cases with definitive diagnoses within 1 to 3 days post-admission increased from 27.27% in Nanjing City before malaria elimination to 45.57% after elimination (χ2 = 6.433, P = 0.011). Conclusions The epidemic situation of imported malaria remains serious in Nanjing City during the post-elimination stage, and malaria parasite infections predominantly occur in African regions. In addition, there are changes in regional and occupational distributions of malaria cases and the diagnostic capability of malaria increases in county-level hospitals in Nanjing City after malaria elimination. Further improvements in the malaria surveillance system and the diagnostic and treatment capability of malaria in medical institutions at each level are required to consolidate malaria elimination achievements in Nanjing City.

Effect of integrated schistosomiasis control measures on Oncomelania snails in river channels connecting the Yangtze River in Nanjing City / 中国血吸虫病防治杂志

ObjectiveTo evaluate the effectiveness of Oncomelania snails control following the implementation of integrated schistosomiasis control measures in river channels connecting the Yangtze River in endemic areas of Nanjing City. MethodsThe river channels connecting the Yangtze River with snails in Nanjing City were selected as the study pilots. The integrated schistosomiasis control measures implemented in the study pilots were investigated by means of retrospective analyses and field surveys from 1998 to 2019, and the effectiveness of snail control was evaluated. Results Integrated control measures with emphases on environmental improvements including water resource projects for schistosomiasis control were implemented in the study pilots during the period from 1998 to 2019, including river bank concretion with 84.51 km in length, marshland cutting and dredging with 50.41 km in length, building 2 sluices and 3 overflow dams, digging one floodway and snail control with chemical treatment that covered an area of 3 370.80 hm2. No Schistosoma japonicum infection had been detected in snails since the completion of the integrated control measures. In addition, snails had been eliminated in 6 river channels connecting the Yangtze River until 2019, with the snail habitats reducing from 214.33 hm2 to 52.22 hm2 in 10 river channels connecting the Yangtze River and the snail density reducing to below 0.1 snails/0.1 m2 in snail-breeding river channels connecting the Yangtze River. Conclusions The integrated schistosomiasis control measures with emphases on environmental improvements may effectively control snail breeding and spread in rivers connecting the Yangtze River in endemic areas of schistosomiasis; however, the maintenance of the project and snail surveillance and control should be intensified following the completion of the integrated schistosomiasis control measures.

[Evaluation of implementation effect of schistosomiasis control program in Jiangsu Province from 2010 to 2015].

OBJECTIVE: To evaluate the actual effect of the schistosomiasis control program in Jiangsu Province from 2010 to 2015. METHODS: A total of 67 schistosomiasis-endemic counties in 10 cities were selected, and a combination of retrospective investigation and on-site investigation was adopted to collect and record the epidemic data of the counties from 2010 to 2015, and a retrospective survey database of epidemic situation was established. The effects of integrated control strategies with both Oncomelania hupensis snail control and infection source control were evaluated. RESULTS: From 2010 to 2015, 2 465 911 persons who lived in endemic areas were detected for schistosomiasis, with 16 974 positive cases of blood examinations, and 8 positive cases of fecal examinations. Totally 5 145 people with advanced schistosomiasis were treated and 40 460 people with the history of schistosome cercarial-infested water contact received the expanded chemotherapy. A total of 127 636 cattle raised in the endemic areas were detected, and 51 619 cattle (head-times) with the history of cercarial-infested water contact also received the expanded chemotherapy. The area with snails control by molluscicides was 18 604.84 hm2. By the end of 2015, schistosomeinfected snails had not been found and there was no zoological schistosome infection for 5 consecutive years, and in addition, there had been no acute schistosome-infected persons for 6 consecutive years in the whole province. The area with snails dropped to 1 977.18 hm2, with a decreasing rate of 55.24% compared with that in 2010. CONCLUSIONS: After the implementation of the plan for the prevention and control of schistosomiasis in Jiangsu Province (2010-2015), the prevention and control of schistosomiasis has achieved remarkable effects and realized the goal of the plan.

Investigation of Toxoplasma gondii infection among special populations in Nanjing City, Jiangsu Province / 中国血吸虫病防治杂志

Objective To understand the prevalence of Toxoplasma gondii infection among special populations in Nanjing City, so as to provide the reference for formulating the interventions for the prevention and control of T. gondii infections in this population. Methods The HIV/AIDS patients, tumor patients, pregnant women, and people with livestock and poultry breeding or processing works were selected as the study subjects from September to November 2015. The venous blood samples were collected from each participant for detecting IgG and IgM antibodies against T. gondii by ELISA. Results The overall prevalence of T. gondii infection was 10.2% in the study subjects in Nanjing City. The T. gondii infection rates were 12.2%, 11.3%, 4.0%, and 13.0% among the HIV/AIDS patients, tumor patients, pregnant women, and people with livestock and poultry breeding or processing works, respectively, and there was no statistically significant difference among the four groups (χ2 = 5.668, P = 0.130). The prevalence of T. gondii infection was higher in men than in women (15.3% vs. 5.8%; χ2 = 10.213, P = 0.001), and there were significant differences in the prevalence of T. gondii infection in terms of gender (χ2 = 9.501, P = 0.023), education levels (χ2 = 9.850, P = 0.043) or occupations (χ2 = 8.983, P = 0.062). Conclusions The infection rate of T. gondii among the special population in Nanjing City is high. Therefore, the health education intervention should be strengthened in the follow-up work for the special population.

Evaluation of implementation effect of schistosomiasis control program in Jiangsu Province from 2010 to 2015 / 中国血吸虫病防治杂志

Objective To evaluate the actual effect of the schistosomiasis control program in Jiangsu Province from 2010 to 2015. Methods A total of 67 schistosomiasis-endemic counties in 10 cities were selected, and a combination of retrospective investigation and on-site investigation was adopted to collect and record the epidemic data of the counties from 2010 to 2015, and a retrospective survey database of epidemic situation was established. The effects of integrated control strategies with both Oncomelania hupensis snail control and infection source control were evaluated. Results From 2010 to 2015, 2 465 911 persons who lived in endemic areas were detected for schistosomiasis, with 16 974 positive cases of blood examinations, and 8 positive cases of fecal examinations. Totally 5 145 people with advanced schistosomiasis were treated and 40 460 people with the history of schistosome cercarial-infested water contact received the expanded chemotherapy. A total of 127 636 cattle raised in the endemic areas were detected, and 51 619 cattle (head-times) with the history of cercarial-infested water contact also received the expanded chemotherapy. The area with snails control by molluscicides was 18 604.84 hm2. By the end of 2015, schistosomeinfected snails had not been found and there was no zoological schistosome infection for 5 consecutive years, and in addition, there had been no acute schistosome-infected persons for 6 consecutive years in the whole province. The area with snails dropped to 1 977.18 hm2, with a decreasing rate of 55.24% compared with that in 2010. Conclusion After the implementation of the plan for the prevention and control of schistosomiasis in Jiangsu Province (2010–2015), the prevention and control of schistosomiasis has achieved remarkable effects and realized the goal of the plan.

[Investigation of Toxoplasma gondii infection among special populations in Nanjing City, Jiangsu Province].

OBJECTIVE: To understand the prevalence of Toxoplasma gondii infection among special populations in Nanjing City, so as to provide the reference for formulating the interventions for the prevention and control of T. gondii infections in this population. METHODS: The HIV/AIDS patients, tumor patients, pregnant women, and people with livestock and poultry breeding or processing works were selected as the study subjects from September to November 2015. The venous blood samples were collected from each participant for detecting IgG and IgM antibodies against T. gondii by ELISA. RESULTS: The overall prevalence of T. gondii infection was 10.2% in the study subjects in Nanjing City. The T. gondii infection rates were 12.2%, 11.3%, 4.0%, and 13.0% among the HIV/AIDS patients, tumor patients, pregnant women, and people with livestock and poultry breeding or processing works, respectively, and there was no statistically significant difference among the four groups (χ2 = 5.668, P = 0.130). The prevalence of T. gondii infection was higher in men than in women (15.3% vs. 5.8%; χ2 = 10.213, P = 0.001), and there were significant differences in the prevalence of T. gondii infection in terms of gender (χ2 = 9.501, P = 0.023), education levels (χ2 = 9.850, P = 0.043) or occupations (χ2 = 8.983, P = 0.062). CONCLUSIONS: The infection rate of T. gondii among the special population in Nanjing City is high. Therefore, the health education intervention should be strengthened in the follow-up work for the special population.

Investigation of Toxoplasma gondii infection among special populations in Nanjing City, Jiangsu Province / 中国血吸虫病防治杂志

Objective To understand the prevalence of Toxoplasma gondii infection among special populations in Nanjing City, so as to provide the reference for formulating the interventions for the prevention and control of T. gondii infections in this population. Methods The HIV/AIDS patients, tumor patients, pregnant women, and people with livestock and poultry breeding or processing works were selected as the study subjects from September to November 2015. The venous blood samples were collected from each participant for detecting IgG and IgM antibodies against T. gondii by ELISA. Results The overall prevalence of T. gondii infection was 10.2% in the study subjects in Nanjing City. The T. gondii infection rates were 12.2%, 11.3%, 4.0%, and 13.0% among the HIV/AIDS patients, tumor patients, pregnant women, and people with livestock and poultry breeding or processing works, respectively, and there was no statistically significant difference among the four groups (χ2 = 5.668, P = 0.130). The prevalence of T. gondii infection was higher in men than in women (15.3% vs. 5.8%; χ2 = 10.213, P = 0.001), and there were significant differences in the prevalence of T. gondii infection in terms of gender (χ2 = 9.501, P = 0.023), education levels (χ2 = 9.850, P = 0.043) or occupations (χ2 = 8.983, P = 0.062). Conclusions The infection rate of T. gondii among the special population in Nanjing City is high. Therefore, the health education intervention should be strengthened in the follow-up work for the special population.

Evaluation of implementation effect of schistosomiasis control program in Jiangsu Province from 2010 to 2015 / 中国血吸虫病防治杂志

Objective To evaluate the actual effect of the schistosomiasis control program in Jiangsu Province from 2010 to 2015. Methods A total of 67 schistosomiasis-endemic counties in 10 cities were selected, and a combination of retrospective investigation and on-site investigation was adopted to collect and record the epidemic data of the counties from 2010 to 2015, and a retrospective survey database of epidemic situation was established. The effects of integrated control strategies with both Oncomelania hupensis snail control and infection source control were evaluated. Results From 2010 to 2015, 2 465 911 persons who lived in endemic areas were detected for schistosomiasis, with 16 974 positive cases of blood examinations, and 8 positive cases of fecal examinations. Totally 5 145 people with advanced schistosomiasis were treated and 40 460 people with the history of schistosome cercarial-infested water contact received the expanded chemotherapy. A total of 127 636 cattle raised in the endemic areas were detected, and 51 619 cattle (head-times) with the history of cercarial-infested water contact also received the expanded chemotherapy. The area with snails control by molluscicides was 18 604.84 hm2. By the end of 2015, schistosomeinfected snails had not been found and there was no zoological schistosome infection for 5 consecutive years, and in addition, there had been no acute schistosome-infected persons for 6 consecutive years in the whole province. The area with snails dropped to 1 977.18 hm2, with a decreasing rate of 55.24% compared with that in 2010. Conclusion After the implementation of the plan for the prevention and control of schistosomiasis in Jiangsu Province (2010–2015), the prevention and control of schistosomiasis has achieved remarkable effects and realized the goal of the plan.

[Analysis of human intestinal nematode infections in Nanjing City from 2006 to 2015].

OBJECTIVE: To analyze the epidemiological situation of human intestinal nematode infections in Nanjing City from 2006 to 2015, so as to provide the reference for formulating prevention and control measures. METHODS: The surveillance data of human intestinal nematode infections in Nanjing City from 2006 to 2015 were collected and analyzed statistically. RESULTS: From 2006 to 2015, 98 804 person-times of residents were surveyed in Nanjing City, and 465 person-times of residents were detected with intestinal nematode infections. The highest infection rate was in 2006 (1.97%), and the lowest in 2013 and 2015 (both 0.05%). Moreover, the positive rate of human intestinal nematode infections showed a significantly declining trend in total ( χ2 = 552.19, P < 0.001). Meanwhile, the numbers of Ascaris lumbricoides, hookworm and Trichuris trichura cases were 329, 98 and 25 respectively, and the infection rates were 0.33%, 0.10% and 0.03% respectively. Among them, 443 cases had mild infection intensity (98.66%). There were 462 cases of single-infection (99.35%), and 3 of co-infection of two parasites (0.65%). From 2006 to 2015, 92 539 person-times of children under 12 years old were surveyed for Enterobius vermicularis infection and 352 cases were detected with E. vermicularis infection. Moreover, the positive rate showed a significantly decreasing trend in total (χ2 = 147.94, P <0.001). CONCLUSIONS: The control effect of human intestinal nematode infections in Nanjing City is remarkable. However, the surveillance and health education in key groups still should be strengthened, and the prevention and control programs should be adjusted promptly to further consolidating the effectiveness of intestinal nematode disease prevention and control.

[Epidemiological analysis of malaria prevalence in Nanjing City from 2010 to 2015].

OBJECTIVE: To analyze the epidemiological characteristics of malaria in Nanjing City, so as to provide the evidence 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 countries, 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 institutions 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. Therefore, the surveillance work and health education still should be strengthened, so as to reduce the risk of imported malaria.

[Comparison of Schistosoma japonicum development between single sexual infection and double sexual infection in mice and rabbits].

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 larva 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 single 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.

[Endemic situation of schistosomiasis at national surveillance sites in Nanjing City, 2015].

OBJECTIVE: To understand the dynamic endemic situation of schistosomiasis in Nanjing City, 2015, so as to provide evidences for policy-making of schistosomiasis control. METHODS: According to The National Scheme of Schistosomiasis Surveillance (2014), the endemic situation of schistosomiasis was monitored in 11 national surveillance sites in Nanjing. RESULTS: The positive rates of serological (IHA) and stool examinations were 2.97% (97/3 269) and 0 for local residents, and 0.52％ (12/2 298) and 0 for migrant people, respectively. No schistosome-infected livestock was found. Totally 147.295 3 hm2 area with Oncomelania hupensis snails were found, but no schistosome-infected snails were discovered. CONCLUSIONS: The endemic situation of schistosomiasis declines greatly in Nanjing City in 2015. However, the control work still should be strengthened to consolidate the achievements of schistosomiasis control.