[Evaluation of malaria elimination surveillance in Liyang City from 2010 to 2016].

OBJECTIVE: To evaluate the effect of malaria elimination monitoring in Liyang City, so as to provide the evidence for formulating control strategies and measures of malaria elimination.

METHODS: The monitoring data about the epidemic situation, blood tests of feverish patients and epidemiology investigation of individual malaria patients in Liyang City from 2010 to 2016 were collected and analyzed by the descriptive epidemiology method.

RESULTS: From 2010 to 2016, there were 67 malaria cases in total. Totally 39 196 feverish patients had blood tests for Plasmodium , and 65 of them showed positive and the positive rate was 0.17%. The other 2 cases of microscopy negative were treated with anti-malarial drugs by themselves after the onset of fever, and no Plasmodium was detected in the microscopy, but the tests with malaria rapid diagnostic kit (RDTs) were positive. Among all the 67 cases, there were 49 falciparum malaria cases, 13 ovale malaria cases and 5 vivax malaria cases. All the 67 malaria cases were imported, and the number of cases from Africa was 63 (94.03%). Totally 97.01% (65/67) of the malaria patients were male and most of them were young adults. The patients aged 30 to 49 years accounted for 73.13% (49/67) and 80.60% (54/67) of them were farmers. There were malaria cases in all the 10 towns of the city, and the time of onset had no obvious seasonal characteristics. The timely rate of case report, timely rate of blood film review, standardized treatment rate, epidemiological case investigation rate, and epidemic focus investigation and disposal rate were all 100%. There were 18 076 people with the active case investigation, but no malaria parasite positive carriers were found. The mosquito vector monitoring was performed with the methods of mosquito trap lamp and human bait half night trap, and 187 and 78 Anopheles mosquitoes were captured respectively, and all the parasites were Anopheles sinensis . A total of 88 person-times were performed for the Plasmodium examinations with microscopy and RDTs (one blood sample, two detections) in Liyang City Center for Disease Prevention and Control from 2012 to 2016, and 35 person-times were positive, including 28 person-times of Plasmodium falciparum and 7 person-times of P. ovale , and there was no statistically significant difference between the detection rates of P. falciparum , and P. ovale (adjusted χ 2 = 0.05, P > 0.05). There were 34 RDTs positive cases, including 14 cases of malignant malaria, and 17 cases of malignant malaria or mixed infections of P. falciparum with other three kinds of Plasmodium parasites, and 3 cases of single infection or mixed infections of other three kinds of Plasmodium parasites, and there was a statistically significant difference among them in the positive RDTs detection rates (adjusted χ 2 = 13.75, P < 0.05).

CONCLUSIONS: There are still imported malaria cases and there is the risk of malaria retransmission in Liyang City. Therefore, it is necessary to strengthen the malaria surveillance work and the management of infectious sources, so as to consolidate the achievements of malaria elimination in the future.