Investigation and control of a Plasmodium falciparum malaria outbreak in Shan Special Region II of Myanmar along the China-Myanmar Border from June to December 2014.
BACKGROUND
From 2007 to 2013, intensive control measures reduced malaria burden by 90 % along the China-Myanmar border. However, despite these measures a P. falciparum malaria outbreak was reported in the Shan Special Region II of Myanmar in June of 2014.


METHODS
Epidemiological, parasitological and entomological investigations were performed. Dihydroartemisinin piperaquine (DAPQ) was immediately administered to treat parasite positive individuals. Long lasting insecticidal nets (LLIN), indoor residual spraying (IRS) with insecticides and behavior change communication (BCC) were also provided for outbreak control. An embedded efficacy study was conducted evaluating DP. Molecular genotyping via polymerase chain reaction (PCR) was performed on the Kelch gene on chromosome 13.


RESULTS
All infections were identified as Plasmodium falciparum by RDT and microscopy. Two fatalities resulted from the outbreak. The attack rate was 72.8 % (67/92) and the incidence density rate was 14.2 per 100 person-weeks. The positive rate of rapid diagnostic test (RDT) was 72.2 % (65/90) and microscopically-determine parasite rate 42.2 % (38/90). Adjusted odds ratio (OR) of multivariate logistic regression analysis for aged <15 years, 15-45 years, inappropriate treatment from a private healer and lack of bed nets were 13.51 (95 % confidence interval, 2.21-105.89), 7.75 (1.48-44.97), 3.78 (1.30-46.18) and 3.21(1.21-15.19) respectively. In the six surrounding communities of the outbreak site, positive RDT rate was 1.2 % (4/328) and microscopically-determine parasite rate 0.6 % (2/328). Two light traps collected a total of 110 anopheline mosquitoes including local vectors, An. minimus, An. sinensis and An. maculates. After intensive control, the detection of malaria attacks, parasites and antigen were reduced to zero between July 1 and December 1, 2014. The cure rate of P. falciparum patients at day 42 was 94.3 % (95 % CI, 80.8-99.3 %). The PCR did not detect K13-propeller mutations.


CONCLUSIONS
Imported P. falciparum caused the outbreak. Age, seeking inappropriate treatment and lack of bed nets were risk factors for infection during the outbreak. P. falciparum was sensitive to treatment with DAPQ. The integrated measures controlled the outbreak and prevented the spread of P. falciparum effectively. The results of this study indicate that malaria control on the China-Myanmar border, especially among special populations, needs further collaboration between China, Myanmar and international societies.
Yunnan Institute of Parasitic Diseases, Yunnan Provincial Center of Malaria Research, Yunnan Provincial Collaborative Innovation Center for Public Health and Disease Prevention and Control, Yunnan Provincial Key Laboratory of Vector-borne Diseases Control and Research, Puer, 665000, China.
Hui
H
Liu
Yunnan Institute of Parasitic Diseases, Yunnan Provincial Center of Malaria Research, Yunnan Provincial Collaborative Innovation Center for Public Health and Disease Prevention and Control, Yunnan Provincial Key Laboratory of Vector-borne Diseases Control and Research, Puer, 665000, China. xjw426@163.com.
Jian-Wei
JW
Xu
Yunnan Institute of Parasitic Diseases, Yunnan Provincial Center of Malaria Research, Yunnan Provincial Collaborative Innovation Center for Public Health and Disease Prevention and Control, Yunnan Provincial Key Laboratory of Vector-borne Diseases Control and Research, Puer, 665000, China. yanghenglin2014@126.com.
Heng-Lin
HL
Yang
National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, 200025, China.
Mei
M
Li
Wa State Department of Health, Pangsang, Shan Special Region II, Myanmar.
Cheng-De
CD
Sun
Yunnan Institute of Parasitic Diseases, Yunnan Provincial Center of Malaria Research, Yunnan Provincial Collaborative Innovation Center for Public Health and Disease Prevention and Control, Yunnan Provincial Key Laboratory of Vector-borne Diseases Control and Research, Puer, 665000, China.
Yi-Jie
YJ
Yin
Wa State Office of Health Poverty Action, Pangsang, Shan Special Region II, Myanmar.
Zhi-Liang
ZL
Zheng
Wa State Office of Health Poverty Action, Pangsang, Shan Special Region II, Myanmar.
Guang-Yun
GY
Zhang
Menglian Center for Disease Control and Prevention, Menglian, 665800, China.
Ai-Shui
AS
Yu
Menglian Center for Disease Control and Prevention, Menglian, 665800, China.
Yong-Hui
YH
Yang
Menglian Center for Disease Control and Prevention, Menglian, 665800, China.
Chun-Hui
CH
Li
Wa State Center for Disease Control and Prevention, Pangsang, Shan Special Region II, Myanmar.
Shui
S
Ai
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000962:Antimalarials / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D009033:Culicidae / Q000469:parasitology; D004196:Disease Outbreaks; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D016778:Malaria, Falciparum / Q000188:drug therapy / Q000453:epidemiology / Q000469:parasitology* / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D002052:Myanmar / Q000453:epidemiology; D010963:Plasmodium falciparum / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D014195:Travel; D055815:Young Adult
D000962:Antimalarials
Chinese-Myanmar border; Control; Investigation; Malaria outbreak; Plasmodium falciparum