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.

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.

[Detection effect of an automatic identification system of Schistosoma japonicum miracidia].

OBJECTIVE: To evaluate the effect of an automatic identification system of Schistosoma japonicum miracidia, and compare it with the traditional eye detection method in the simulation field. METHODS: A total of 260 fecal samples were collected from schistosomiasis non-endemic areas, and the test sample bottles containing schistosome miracidia were prepared according to different experimental needs. Thirty fecal samples for the sensitivity test were separately added with five fresh miracidia per sample, and then the mixed samples were detected by two experienced technicians (with more than 15 years' traditional test experience) or the automatic system. The positive detection rates were compared between the two methods. Thirty fecal samples for repetition test were separately added with ten fresh miracidia per sample, and then the mixed samples were detected separately with the automatic identification system by two experienced technicians. The results were compared between two persons. The two methods including the automatic identification system and the traditional eye detection method were carried out blindly with totally 200 samples in the simulation field. There were three groups (each with 30 samples) : Group 1 with more than 21 fresh miracidia, Group 2 with 6 to 20 fresh miracidia, and Group 3 with 1 to 5 fresh miracidia. The other 110 samples were as a negative group. The detection time, accuracy, missed detection rate, and false detection rate of the two methods were statistically compared. RESULTS: The positive detection rates of the 30 positive samples were 43.33% and 33.33% by the two technicians with the traditional eye detection method, respectively, while the detection rate was 80.00% by the automatic identification system, and the difference was statistically significant (χ2 = 7.05, χ2 = 12.97, both P < 0.01). Thirty positive samples were detected by the two technicians using the same automatic identification system, and the positive detection rates of the two were 96.67% and 86.67%, respectively, with no significant difference (χ2 = 0.27, P > 0.05). The experiments showed that the correct detection rate of the positive samples was 98.00% by the automatic identification system, which was higher than 79.75% by the traditional eye detection method. The detection time of the automatic identification system was shortened by half compared with that of the traditional eye detection method. The missed detection rate, and false detection rate of the automatic identification system were 2.22% and 1.82%, respectively, which were much lower than 35.56% and 7.73% of the traditional eye detection method. CONCLUSIONS: Compared with the traditional eye detection method, the automatic identification system of S. japonicum miracidia has the advantages of high sensitivity, good repeatability, short detection time, high accuracy, low missed detection rate, and low false detection rate. It can be used in the field and clinical detection in replacement of the traditional eye detection method.

[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.

Detection effect of an automatic identification system of Schistosoma japonicum miracidia / 中国血吸虫病防治杂志

To evaluate the effect of an automatic identification system of Schistosoma japonicum miracidia, and compare it with the traditional eye detection method in the simulation field.A total of 260 fecal samples were collected from schistosomiasis non-endemic areas, and the test sample bottles containing schistosome miracidia were prepared according to different experimental needs. Thirty fecal samples for the sensitivity test were separately added with five fresh miracidia per sample, and then the mixed samples were detected by two experienced technicians (with more than 15 years’ traditional test experience) or the automatic system. The positive detection rates were compared between the two methods. Thirty fecal samples for repetition test were separately added with ten fresh miracidia per sample, and then the mixed samples were detected separately with the automatic identification system by two experienced technicians. The results were compared between two persons. The two methods including the automatic identification system and the traditional eye detection method were carried out blindly with totally 200 samples in the simulation field. There were three groups (each with 30 samples) : Group 1 with more than 21 fresh miracidia, Group 2 with 6 to 20 fresh miracidia, and Group 3 with 1 to 5 fresh miracidia. The other 110 samples were as a negative group. The detection time, accuracy, missed detection rate, and false detection rate of the two methods were statistically compared.The positive detection rates of the 30 positive samples were 43.33% and 33.33% by the two technicians with the traditional eye detection method, respectively, while the detection rate was 80.00% by the automatic identification system, and the difference was statistically significant (χ2 = 7.05, χ2 = 12.97, both P < 0.01). Thirty positive samples were detected by the two technicians using the same automatic identification system, and the positive detection rates of the two were 96.67% and 86.67%, respectively, with no significant difference (χ2 = 0.27, P > 0.05). The experiments showed that the correct detection rate of the positive samples was 98.00% by the automatic identification system, which was higher than 79.75% by the traditional eye detection method. The detection time of the automatic identification system was shortened by half compared with that of the traditional eye detection method. The missed detection rate, and false detection rate of the automatic identification system were 2.22% and 1.82%, respectively, which were much lower than 35.56% and 7.73% of the traditional eye detection method.Compared with the traditional eye detection method, the automatic identification system of S. japonicum miracidia has the advantages of high sensitivity, good repeatability, short detection time, high accuracy, low missed detection rate, and low false detection rate. It can be used in the field and clinical detection in replacement of the traditional eye detection method.

[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.