Objective To investigate the prevalence of key human intestinal helminth infections in Yongxing County, Hunan Province, China, so as to provide a scientific basis for parasitic disease prevention and control. Methods An administrative village each from five townships (located in the eastern, western, southern, northern, and central regions, respectively) was randomly selected in Yongxing County, Hunan Province from 2016 to 2020. At least 200 permanent residents ≥3 years old were surveyed at each surveillance point every year. The intestinal worm eggs were examined by using the Kato-Katz technique. The hookworm species was identified by using filter paper culture. The pinworm eggs were examined by using the anal swab method with a transparent tape for children aged 3 to 9 years. WPS Excel 2021 software was used to establish the database, and SPSS 20.0 software was used to conduct statistical analysis. The infection rate was compared using the Chi-squared test. Results A total of 5 066 persons were examined for worms in feces, with a rate of key intestinal worm infections of 2.68% (136 cases). The infection rates for roundworms, hookworms, pinworms, whipworms, and liver flukes were 1.99%, 0.24%, 0.20%, 0.18%, and 0.08%, respectively. No co-infection was detected. The results of 12 hookworm larvae culture samples were all Necator americanus. The anal swab test detected a pinworm infection rate of 0.33% among a total of 1 500 children aged 3 to 9 years. The overall key intestinal worm infection rates from 2016 to 2020 were 4.08%, 1.97%, 3.24%, 1.10%, and 3.00%, respectively. Conclusion The key human intestinal worm infection rate is at a low epidemic level in Yongxing County, Hunan Province, but the infection factors still exist. It is necessary to strengthen categorical surveillance and promotion and education of parasitic disease prevention and control knowledge.

Objective To provide a scientific basis for the control of local imported malaria by laboratory diagnosis and epidemiological analysis of a case of transfusion-introduced falciparum malaria. Methods The medical records of the patient and epidemiological information of both the patient and the blood donor were collected and analyzed. The blood sample of the patient was analyzed by microscopy, malaria rapid diagnostic test (RDT), and nested polymerase chain reaction (nested PCR). Results The patient had no history of tour in malaria epidemic area and history of malaria infection, but had a history of blood transfusion. Peripheral blood smear of the patient showed the presence of Plasmodium falciparum and both the results of RDT and nested PCR were positive for P. falciparum only. Follow-up study showed that the blood donor of the patient had a history of visiting the malaria-endemic area and being diagnosed with malaria. The blood sample RDT of the donor was positive for P. falciparum only, but the microscopic examination was P. falciparum negative. Conclusion The patient was a case of transfusion-introduced falciparum malaria. It is suggested that malaria screening before blood donation should be conducted to prevent the occurrence of transfusion-introduced falciparum malaria cases.

Objective To analyze the quality of malaria blood smears of febrile patients in Chenzhou city in order to provide a scientific basis for the standardization of blood test. Methods According to the technical solutions to eliminate malaria of 2011 edition, more than 3% Plasmodium negative blood smears and all Plasmodium positive blood smears were reviewed monthly from 2015 to 2017. The quality of blood smear preparation, staining, cleanliness and detection results were reviewed by malaria microscopic examination staff. The descriptive epidemiological method was used to analyze the data. The Chi square test was used to compare the rates, and P<0.05 was statistically significant. Results A total of 9 806 malaria blood tests among febrile patients were carried out in Chenzhou city in 3 years. Plasmodium negative blood smears were reviewed in the number of 518, accounting for 5.29% of all Plasmodium negative blood smears, with the production qualified rate of 77.80%, the staining pass rate of 89.58%, the cleanliness pass rate of 95.17%. No missed detection was found in Plasmodium negative blood smear review. Nine (9) Plasmodium positive blood smears were rechecked, accounting for 100% of all Plasmodium positive blood smears, and the qualified rate of production, staining and cleanliness all were 88.89%. One Plasmodium classification error was found in Plasmodium positive blood slides review. There were statistically significant differences among each county in the production qualified rates, the staining pass rates and cleanliness pass rates ( χ ²=87.286, 80.636, 81.023, all P<0.001). There were no statistically significant differences among each year in the production qualified rates and cleanliness pass rates ( χ ²=3.484, 1.941, both P>0.05). There were statistically significant differences among each year in the staining pass rates ( χ ²=6.521, P=0.038). Conclusion The production and staining of Plasmodium blood smears should be further standardized in Chenzhou in the future, the training and quality control of Plasmodium microscopy should be further strengthened to improve the quality and the accuracy of microscopic examination for malaria diagnosis.

Objective To provide a scientific basis for the prediction, prevention and control of dengue fever epidemic by studying dengue virus infection in mosquitoes, vector species density, and antibody level of dengue virus in human populations. Methods The descriptive epidemiological method was used for statistical analysis on vector monitoring and dengue antibody level in healthy human populations in Chenzhou from 2008 to 2013. Results In total, 789 healthy persons were tested from 2008 to 2013 and the IgG positive rate against dengue virus was 5.32%. As to vectors, 842 of Aedes albopictus were collected. The density of Ae. albopictus was 0.22/h. The highest density of adult Ae. albopictus among different habitats was in park with 0.31/h. The container index (CI) of the larvae was 10.33, with the highest CI in August (12.70) and in waste recycling centers (18.50). The mosquito and oviposition positive index (MOI) was 6.92% and the highest MOI was in park with 10.82%. Eighteen groups of Ae. albopictus tested negative for dengue virus. Conclusion There was no dengue fever virus in adult Aedes mosquitoes in Chenzhou, however, there were natural transmitting vector and dengue fever antibody for healthy populations. Surveillance, prevention, and control of dengue fever should be strengthened gradually.

【Abstract】 Objective To develop a molecular technology to assay human blood index of Anopheline mosquito which could substitute for the traditional immunological method. Methods A pair of specific primer were designed according to the sequence of human rDNA, and the human blood in Anopheline mosquito was identified by polymerase chain reaction （PCR）. Meanwhile, the DNA extracted from the blood of pig, cattle, goat, mouse and the mosquito without bloodsucking were detected to verify the specificity  of  the  method.  And the DNA extracted from the mosquitoes after its bloodsucking for different time （such as 1 h, 6 h, 12 h, 18 h, 24 h, 27 h, 30 h, 33 h, 36 h, 40 h, 44 h, 48 h） were detected to determine the sensitivity of the method. Results The specific PCR product （519 bp） was amplified from the DNA extracted from human blood.  No specific PCR product was found either from the blood of other animals or from the mosquitoes without bloodsucking. The specific bands were produced from all the mosquitoes within bloodsucking for 24 h. After bloodsucking for 27 h, 30 h, 33 h and 36 h, only 4, 4, 2, 1 mosquito could produce specific bands in the total of 5 tested mosquitoes, respectively. No specific PCR product was amplified after feeding for 40 h. Logistic regression analysis indicated there was a negative correlation between the bloodsucking time and the quantity of positive mosquitoes detected by PCR after bloodsucking for 24-40 h （P＜0.01）. Conclusion The PCR method developed in this study could identify human blood in Anopheles sinensis within bloodsucking for 24 h accurately， which could replace the traditional immunological method.