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Background: Mass screening and treatment (MSAT) for malaria elimination lacks an ideal diagnostic tool to allow sensitive and affordable test of the target population in the field. This study evaluated whether Capture and Ligation Probe-PCR (CLIP-PCR) could be used in a field MSAT in Laiza City, Myanmar. Methods: On day 0, two dried blood spots were collected from each participant. On day 1, all samples were screened for Plasmodium in a 20 m2 laboratory with workbench, a biosafety cabinet, a refrigerator, a benchtop shaking incubator and a qPCR machine, by four technicians using CLIP-PCR with sample pooling, at a health clinic of the Chinese bordering town of Nabang. On day 2, all positives were followed up and treated. Results: Of 15,038 persons (65% of the total population) screened, 204 (1.36%) were CLIP-PCR positives. Among them, 188, 14, and 2 were infected with Plasmodium vivax, Plasmodium falciparum, and P. vivax/P. falciparum mix, respectively. The testing capacity was 538 persons/day, with a cost of US$0.92 /person. The proportion of submicroscopic infection was 64.7%. All positive individuals received treatment within 72 h after blood collection. Conclusion: Using CLIP-PCR in MSAT in low transmission settings can support the malaria elimination efforts in the China-Myanmar border region. [ABSTRACT FROM AUTHOR]

Introduction: Malaria importation can be caused by cross-border movement either of both people and anopheline mosquitoes. However, there still lacks robust evidence of imported malaria caused by Plasmodium spp. infected anopheles along international border areas (border-spill malaria). The objectives of this study were to confirm whether an outbreak of Plasmodium vivax malaria is border-spill malaria and assess the effects of China's public health response along China-Myanmar border. Methods: Epidemiological, parasitological and entomological investigations were conducted to investigate the outbreak of border-spill malaria. Meanwhile, comprehensive interventions were carried out to prevent further transmission and reintroduction of malaria. Results: Rapid diagnostic testing, microscopy and polymerase chain reaction were performed and the infections were confirmed as P. vivax. A total of 22 (9.21%) of 239 workers contracted P. vivax during the outbreak. Multivariate logistic regression analysis identified that the distance of worker shelters in China within 300 meters to the internally displaced person (IDP) camps in Myanmar was a risk factors associated with malaria infection (adjusted odds ratio 7.5920; 95% confidence interval, 2.6079–22.1013; P = 0.0002). After comprehensive interventions, malaria transmission was successfully interpreted and prevented at the project site till the completion of project on 14 January 2020, and recurrence of P. vivax malaria was not detected by the end of 2020. Conclusion: This study provided robust evidence of border-spill malaria along China-Myanmar border. Malaria parasite reservoir and distance travelled by female anopheline mosquitoes are two determinants for border-spill malaria. The public health response to the outbreak indicates that the malaria surveillance and response system works well in preventing reintroduction of malaria. However, prevention of border-spill malaria is still a major challenge in the Yunnan border area, China. [ABSTRACT FROM AUTHOR]

Background: Cross-border malaria in Laiza City of Myanmar seriously affected Yingjiang County of China and compromised reaching the goal of malaria elimination by 2020. Since 2017, a pilot project on 3 + 1 strategy of joint cross-border malaria prevention and control was carried out for building a malaria buffer in these border areas. Here, 3 were the three preventive lines in China where different focalized approaches of malaria elimination were applied and + 1 was a defined border area in Myanmar where the integrated measures of malaria control were adopted.Methods: A 5-year retrospective analysis (2015 to 2019) was conducted that included case detection, parasite prevalence and vector surveillance. Descriptive statistics was used and the incidence or rates were compared. The annual parasite incidence and the parasite prevalence rate in + 1 area of Myanmar, the annual importation rate in Yingjiang County of China and the density of An. minimus were statistically significant indictors to assess the effectiveness of the 3 + 1 strategy.Results: In + 1 area of Myanmar from 2015 to 2019, the averaged annual parasite incidence was (59.11 ± 40.73)/1000 and Plasmodium vivax accounted for 96.27% of the total confirmed cases. After the pilot project, the annual parasite incidence dropped 89% from 104.77/1000 in 2016 to 12.18/1000 in 2019, the microscopic parasite prevalence rate dropped 100% from 0.34% in 2017 to zero in 2019 and the averaged density of An. Minimus per trap-night dropped 93% from 1.92 in June to 0.13 in September. The submicroscopic parasite prevalence rate increased from 1.15% in 2017 to 1.66% in 2019 without significant difference between the two surveys (P = 0.084). In Yingjiang County of China, neither indigenous nor introduced case was reported and 100% cases were imported from Myanmar since 2017. The averaged annual importation rate from 2015 to 2019 was (0.47 ± 0.15)/1000. After the pilot project, the annual importation rate dropped from 0.59/1000 in 2016 to 0.28/1000 in 2019 with an overall reduction of 53% in the whole county. The reduction was 67% (57.63/1000 to 18.01/1000) in the first preventive line, 52% (0.20/1000 to 0.10/1000) in the second preventive line and 36% (0.32/1000 to 0.22/1000) in the third preventive line. The averaged density of An. Minimus per trap-night in the first preventive line dropped 94% from 2.55 in June to 0.14 in September, without significant difference from that of + 1 area of Myanmar (Z value = - 1.18, P value = 0.24).Conclusion: The pilot project on 3 + 1 strategy has been significantly effective in the study areas and a buffer zone of border malaria was successfully established between Laiza City of Myanmar and Yingjiang County of China. [ABSTRACT FROM AUTHOR]

Yingjiang County, which is on the China-Myanmar border, is the main focus for malaria elimination in China. The epidemiological characteristics of malaria in Yingjiang County were analysed in a retrospective analysis. A total of 895 malaria cases were reported in Yingjiang County between 2013 and 2019. The majority of cases occurred in males (70.7%) and individuals aged 19-59 years (77.3%). Plasmodium vivax was the predominant species (96.6%). The number of indigenous cases decreased gradually and since 2017, no indigenous cases have been reported. Malaria cases were mainly distributed in the southern and southwestern areas of the county; 55.6% of the indigenous cases were reported in Nabang Township, which also had the highest risk of imported malaria. The "1-3-7" approach has been implemented effectively, with 100% of cases reported within 24 h, 88.9% cases investigated and confirmed within 3 days and 98.5% of foci responded to within 7 days. Although malaria elimination has been achieved in Yingjiang County, sustaining elimination and preventing the re-establishment of malaria require the continued strengthening of case detection, surveillance and response systems targeting the migrant population in border areas.

A retrospective case-control study was conducted to identify risk factors for border malaria in a malaria elimination setting of Yunnan Province, China. The study comprised 214 cases and 428 controls. The controls were individually matched to the cases on the basis of residence, age, and gender. In addition, statistical associations are based on matched analyses. The frequencies of imported, male, adult, and vivax malaria cases were respectively 201 (93.9%), 194 (90.7%), 210 (98.1%), and 176 (82.2%). Overnight stay in Myanmar within the prior month was independently associated with malaria infection (odds ratio [OR] 159.5, 95% confidence interval [CI] 75.1-338.9). In particular, stays in lowland and foothill (OR 5.5, 95% CI 2.5-11.8) or mid-hill (OR 42.8, 95% CI 5.1-319.8) areas, or near streamlets (OR 15.3, 95% CI 4.3-55.2) or paddy field or pools (OR10.1, 95% CI 4.4-55.8) were found to be independently associated with malaria. Neither forest exposure nor use of vector control measures was associated with malaria. In conclusion, travel to lowland and foothill or mid-hill hyperendemic areas, especially along the waterside in Myanmar, was found to be the highest risk factor for malaria. In considering the limitations of the study, further investigations are needed to identify the major determinants of malaria risk and develop new strategies for malaria elimination on China-Myanmar border., (© The American Society of Tropical Medicine and Hygiene.)

Background: Artemisinin-based combination therapy (ACT) is the recommended first-line treatment of falciparum malaria in all endemic countries. Artemisinin resistance in Plasmodium falciparum has been confirmed in the Greater Mekong subregion (GMS). Dihydroartemisinin-piperaquine (DAPQ) is the most commonly used ACT in China. To understand the DAPQ sensitivity of P. falciparum, DAPQ resistance was monitored in vivo along the China-Myanmar border from 2007 to 2013., Methods: Eligible patients with mono-infections of P. falciparum were recruited to this study after obtaining full informed consent. DAPQ tablets for different categories of kg body weight ranges were given once a day for three days. Patients were followed up for 42 days. Polymerase chain reaction (PCR) was conducted to distinguish between re-infection and recrudescence, to confirm the Plasmodium species. The data were entered and analysed by the Kaplan-Meier method. Treatment outcome was assessed according to the WHO recommended standards., Results: 243 patients were completed valid follow-up. The fever clearance time (FCT) and asexual parasite clearance times (APCT) were, respectively, 36.5 ± 10.9 and 43.5 ± 11.8 hours, and there was an increasing trend of both FCT (F = 268.41, P < 0.0001) and APCT (F = 88.6, P < 0.0001) from 2007 to 2013. Eight (3.3%, 95% confidence interval, 1.4-6.4%) patients present parasitaemia on day three after medication; however they were spontaneous cure on day four. 241 (99.2%; 95% CI, 97.1-99.9%) of the patients were adequate clinical and parasitological response (ACPR) and the proportions of ACPR had not changed significantly from 2007 to 2013 (X(2) = 2.81, P = 0.7288)., Conclusion: In terms of efficacy, DAPQ is still an effective treatment for falciparum malaria. DAPQ sensitivity in P. falciparum had not significantly changed along the China-Myanmar border of Yunnan Province, China. However more attentions should be given to becoming slower fever and parasite clearance.