Key actions
Table 1 shows the key actions that have significant impact on border malaria control and elimination in Yunnan.
Table 1
Key actions of malaria control and elimination along international border in Yunnan, China, 2002-2021
Year
|
Actions and results
|
2002
|
An underreported malaria survey among a sample of 30580 people was conducted across Yunnan. Results indicated that mean underreported rate of malaria cases was as high as 88.8% in Yunnan, and the underreported rate was more than 90% (range 90.1 -97.8%) in the border areas [15].
|
2003
|
In January, the first round of the China’s Global Fund to fight AIDS, Tuberculosis and Malaria (GFATM) malaria program was rolled out in 25 border counties.
|
2005
|
On 7th June, the first collaborative document of cross border malaria control was signed between China and Myanmar [17].
|
2007
|
In July, the sixth round of the China’s GFATM malaria program on cross border malaria control was launched in China’s 12 border counties and Myanmar’s four special regions [19].
|
2010
|
On 1st July, the national malaria elimination action was launched across China including Yunnan’s 25 border counties [21].
|
2012
|
On 1st January, the tenth round of the China’s GFATM malaria program on cross border malaria control was rolled out in China’s seven border counties and Myanmar’s five special regions [19].
|
2013-2014
|
The tenth round of the China’s GFATM malaria program on cross border malaria control stopped in China on 31st December 2013. The second phase of the project was consolidated into the Myanmar’s GFATM project from 1st January, 2014 [19].
|
2014-2016
|
There was a slight resurgence of malaria incidence in Myanmar’s Kachin Special Region II (KR2) and Shan Special Region II (Wa State) which led to the increase of imported cases of malaria into Yunnan [27, 28].
|
2014
|
China and Myanmar collaboratively controlled the outbreak of Plasmodium falciparum in Wa State and prevented malaria importation into China [28].
|
2014
|
The impact evaluation of cross China-Myanmar border malaria control program during 2007-2013 was carried out. Results indicated that the malaria burden was reduced by 95% in China’s 19 border counties based on the API and by 90% in Myanmar’s five special regions based on the malaria parasite prevalence [19].
|
2016
|
The last indigenous malaria case of China was reported from Yingjiang county on China-Myanmar border, on 17 April 2016 [23].
|
2017-2019
|
China and Myanmar collaboratively controlled the resurgence of malaria incidence in the malaria hot spot of Laiza and nearby areas, KR2, Myanmar. The number of malaria cases was reduced from 2080 cases in 2016 to 274 cases in 2019 in Laiza and nearby area.
|
2018
|
In March, the Yunnan health and Family Planning Commission released “The notification on further standardizing malaria elimination work and process” to clear the responsibility of general health service in malaria surveillance.
|
2019
|
In January, the “3+1” strategy for border malaria elimination and preventing reintroduction of malaria transmission was developed and formulated.
|
2020
|
In January, Yunnan passed the national technical assessment of malaria elimination. In June, Yunnan passed the finally national assessment of malaria elimination.
|
2021
|
In May, The WHO Malaria Elimination Certification Panel conducted field assessment in Yunnan and visited two border counties, Menglian and Yingjiang, for national malaria elimination certification.
|
2005-
|
“The joint malaria control project along China–Myanmar Border" regularly exchanges information and conducts some activities of malaria control since 2005 [23].
|
Control, 2003-2013
In 2003, the first year of this case study, a total of 15431 confirmed malaria cases were reported across Yunnan, in which 10349 (67.1%), mean API of 17.10 per 10000 person-years were reported in the 25 border counties (Additional file 1). A survey of underreported malaria cases reported that the mean underreported rate was 88.8% across Yunnan, and 9 0.0% in the border areas in 2002 (Table 1) [15]. Based on the survey of underreported malaria cases, it was estimated that there were about 100 thousand malaria cases in the border area in 2003. Facing hyperendemicity, approach of “one village, one strategy” that was developed and started in Yunnan in early 1990s was continuously carried out during phase 2003-2013. This strategy categorized all natural villages into four types each year based on malaria incidence in last three years. The definitions and interventions for each type of natural village were listed in Table 2 [16]. To solve problems of high morbidity, specificity and complexity, the strategy of natural village-based stratification and interventions was still conducted in the border county with high malaria burden from 2010 to 2013. Meanwhile, the county-based stratification and interventions documented in “Action plan of China malaria elimination (2010–2020)” were also used for malaria detection and response. During this phase, the API was successfully reduced to 13.54 per 10000 person-years in 2006, followed by 2.26 per 10000 person-years in 2010 and then 0.62 per 10000 person-years in 2013 (Additional file 1). The significant reduction of malaria burden made possible to fully orientate malaria programme from control to elimination in Yunnan.
Table 2
Malaria area stratification and interventions in border areas, Yunnan, 2003-2013
Tier
|
definition
|
Interventions
|
Type 1
|
A village API ≥1%, or malaria clinical attack rate ≥10% last year
|
1) Mass drug administration for radical cure and preventive treatment;
2) Presumptive treatment of all febrile patients for malaria;
3) Two rounds of indoor residual spraying (IRS) or dipping bed nets with pyrethroid insecticides.
|
Type 2
|
A village API <1%, or malaria clinical attack rate<10% last year, but there are indigenous cases in last 3 years.
|
1) Radical cure treatment of people with malaria attack history in last 2 years;
2) Presumptive treatment of suspected malaria cases and febrile patients without clear causes for malaria
3) One rounds of IRS or dipping bed nets with pyrethroid insecticides.
|
Type 3
|
A village without indigenous cases, only imported cases in last 3 years
|
1) Radical cure treatment of people with malaria attack history in last 2 years;
2) Presumptive treatment of suspected malaria cases and febrile patients without clear causes for malaria;
3) IRS with pyrethroid insecticides to malaria patient’s and neighbouring houses
|
Type 4
|
A village without any malaria cases in last 3 years
|
Cross border collaboration between China and Myanmar, 2005-2013
China and Myanmar signed “The agreement of cross border malaria control” on 7th June 2005 [17]. Supporting from the International Collaboration Department of National Health Commission (the former Ministry of Health) of China, Yunnan has carried out “The joint malaria control project along China–Myanmar Border" since 2005 [18]. Due to the limited investment, this project can only focus on personnel training and communication. Under the agreement framework, YIPD and Health Poverty Action (HPA, the former Health Unlimited) that is a UK-based nongovernment organization successfully applied for and implemented the sixth and tenth round of GFATM Malaria projects along China-Myanmar border from 2007 to 2013. The two GFATM projects obtained a total budget of US$ 32,512,550. China allocated a total of US$ 17,196,071 (52.9%) to the HPA for control activities in the border areas of Myanmar. When cars, drugs, bed nets and other equipment were included, more than 70% of the two grants received by China centre for disease control and prevention (CDC) were used in Myanmar. The two GFATM projects distributed a total of 52257 long-lasting insecticidal bed nets, performed 1101979 parasite-based tests (RDTs or microscopy) for malaria, and administered a total of 472356 treatment courses including 277329 courses for preventive treatments and 195027 courses for clinical treatments. Health education activities were meanwhile conducted to promote these interventions for malaria vector and parasite control. These interventions successfully reduced the malaria burden by 90% in five special regions of Myanmar, decreasing malaria parasite prevalence from 13.6% (95% CI, 12.7-14.6%) in March, 2008, to 1.5% (95% CI, 1.2 - 2.0%) in November, 2013. The hyperendemic areas in Myanmar’s border areas were reduced to only three main malaria hot spots by 2013, namely, Laiza and nearby areas in Kachin Special Region II (KR2), Salween River Valley in Shan Special Region II and Small Golden Triangle in Shan Special Region IV. The malaria burden was reduced by 95% in 19 China’s counties bordering with Myanamr, decreasing the API from 19.6 per 10000 person-years in 2006 to 0.9 per 10 000 person-years in 2013. The reduced malaria burden along China-Myanmar border significantly contributed to the success of malaria elimination in China. For example, only 518 imported malaria cases were detected in Yunnan in 2013 [14, 19].
Elimination, 2014-2016
Malaria elimination is a set of labor-intensive interventions, which requires a universal coverage of malaria case surveillance and rapid response to malaria foci [13, 14]. Chinese ‘‘1-3-7’’ strategy requests reporting of malaria cases within one day, confirmation and investigation of malaria cases within three days, and an appropriate public health response to prevent further transmission within seven days [20]. The WHO recommends that elimination phase starts in areas where the first programme reorientation has been achieved, and where health facility data show a malaria incidence of less than 1 infection per 1000 people at risk per year, equal to less than 100 new cases per year in a district with a population of 100 000 people [13]. In China, the smallest unit for elimination is a county, most of counties with a population of over one million. The national malaria elimination program therefore recommended that elimination phase started after API < 1 per 10000 person-years. The action plan of China malaria elimination 2010–2020 requested to reduce API to less than 1 per 10000 person-years in each border county of Yunnan by the end of 2015. This goal was actually achieved by 2013 with a mean API of 0. 62 per 10000 person-years across 25 border counties except Tengchong with API 2.0 per 10000 person-years due to imported malaria cases being calculated into the API and imported cases accounting for more than 95% of the total cases in Tengchong (Additional file 1). The WHO guideline of malaria elimination does not recommend involvement of imported malaria cases in calculation of API [13]. In Yunnan, malaria elimination action was fully launched in 25 border counties since 2014.
Yunnan’s 104 inland counties kept the pace with country to start malaria elimination action since 2010. The national standards of county stratification for malaria elimination categorized all counties into four tiers: type 1 was presence of confirmed local case(s) in the last three years, with at least one year having an annual incidence >=1/10,000; type II was presence of confirmed local case(s) in the last three years, annual incidence <1/10,000; type III was no local case for at least three years, only imported cases; and type IV was no history of any local cases, only imported cases [21]. Yunnan categorized its 129 counties into three tiers (no type IV), namely, 19 type I counties with 17 border counties, 55 type II counties with eight border counties, and 55 type III counties based on the national standards in 2010. On the basis of this stratification, every county took malaria elimination as one of the government work objectives, establishing leadership and technical steering team. Intensive surveillance and rapid response were conducted following “The protocol of Yunnan malaria elimination action plan (2010-2020)” [22]. From 2014 to 2016, a total of 341336 febrile patents were tested by microscopy for malaria. Individual and focus epidemiology investigations and responses were conducted to all 1189 malaria cases or foci following the “1-3-7” work approaches [20]. Strengthened malaria surveillance ensured to detect any parasite infections timely and rapid response to prevent further transmission [22]. The transmission of P. falciparum malaria was successfully interrupted since the last locally infected P. falciparum case was reported from Cangyuan County in May 2015, and then the P. vivax malaria transmission was finally interrupted since the last locally infected P. vivax case was reported from Yingjiang County at 17 April 2016 (Additional file 2) [23].
Preventing reintroduction, 2017-2020
The WHO malaria elimination certification standard is that the chain of indigenous malaria transmission by Anopheles mosquitoes has been interrupted nationwide for at least the past three consecutive years, and a country must also demonstrate the capacity to prevent reintroduction. However, Yunnan borders three malaria endemic countries. Imported malaria can be caused by both border crossers and parasite-infected Anopheles mosquitoes which fly over the boundary from endemic areas of neighbouring countries. The threat from Vietnam and Lao PDR is slight. The overall incidence of malaria is low in Vietnam with malaria transmission being interrupted in the north of Vietnam [24]. Malaria control has also made rapid progress towards localised elimination goals in the northern provinces of Laos [25]. Yunnan firstly achieved malaria free for at least three years in Honghe Prefectures with three counties only bordering with Vietnam in 2015 [12], and then Wenshan Prefectures with three counties just bordering with Vietnam in 2016. After interruption of malaria transmission, the national stratification for malaria elimination was not suitable for the actual situation any more. To prevent reintroduction effectively, after carefully considering of malaria hyperendemicity in Myanmar and the specificity of 25 border counties, Yunnan further categorized 25 border counties into three tiers in 2017, namely 12 type A counties, seven type B counties, and six type C counties. Type C counties only border with Vietnam, they do not need additional investment for special interventions. The 12 type A counties need more input of human and financial resources to carry out more intensive interventions. Based on results of 291 Anopheles mosquito mark-release-recapture (MMRR) experiments in 143 localities around the world estimated that the mean distance travelled (MDT) of female Anopheles was not more than 2.5 km [26], assessment of the receptivity and vulnerability for each border community in China and the malaria endemicity within 2.5 km-wide perimeter border areas of Myanmar along the international border, 16 natural villages were proposed to be in the threat of border-spill malaria that was defined as imported malaria caused by parasite-infected Anopheles from border endemic areas of neighbouring countries in 2018 (Additional file 3). Integrated interventions that include proactive and passive detections for the malaria parasites, enhancement and optimization of vector surveillance, further strengthening of timely detection with high-quality confirmed diagnosis and prompt action based on the surveillance results were carried out in these 16 natural villages [14]. The intensive interventions prevented reintroduction effectively to make sure the national and the WHO malaria free certification in time. Table 3 shows the years of malaria transmission interrupted and malaria free certificated by Yunnan itself for six border prefectures following the national standards of malaria elimination assessment. The China National Health Commission finally assessed and certificated Yunnan malaria free in June 2020. The WHO Malaria Elimination Certification Panel (MECP) visited two border counties, Menglian and Yingjiang, to conduct field assessment for China’s national malaria elimination certification in May 2021. The WHO MECP highly appreciated the infrastructure and equipment, the competence of staff of the health system and supporting organization, the data management and record system during their visits.
Table 3
Time of malaria free certification for eight border prefectures, Yunnan
Prefecture
|
Transmission interrupted
|
Malaria free certificated
|
Bordering with Vietnam only
|
|
|
Honghe
|
2012
|
2015
|
Wenshan
|
2013
|
2016
|
Bordering with Vietnam, Lao PDR and Myanmar
|
XishuangBanna
|
2014
|
2017
|
Puer
|
2016
|
2018
|
Bordering with Myanmar only
|
|
|
Baoshan
|
2014
|
2017
|
Lincang
|
2016
|
2018
|
Nujiang
|
2016
|
May 2019
|
Dehong
|
2016
|
Sep 2019
|
Cross border collaboration, 2014-2020
China was listed by the World Bank as a mid-high income country in 2012 and was no longer eligible for grants of the GFATM. The second phase of the tenth round of China’s GFATM malaria project was consolidated into the Myanmar’s GFATM project from 2014. The policy change of the GFATM made China no enough resource investing for malaria control in Myanmar’s border areas. Malaria control strategy in Myanmar is different from that of China. For example, Myanmar’s strategy only treats malaria cases with laboratory test positivity, and does not permit treatment for suspected malaria cases with antimalarial drugs; only long lasting insecticidal bed nets (LLINs) can be used for vector control, without indoor spraying with insecticides. A slight malaria resurgence appeared in Myanmar’s border areas since 2014 [27, 28], which led to an increase of imported malaria in Yunnan, from 358 in 2013 to 594 cases in 2015. To solve the increasing threat of malaria importation, Yunnan strengthened collaboration of malaria control with Myanmar, especially Laiza and nearby areas in the KR2. For example, Yunnan provided necessary antimalarial drugs, insecticides and other supplies to the KR2, and sent a technical team from YIPD and Yingjiang County CDC to station in Laiza providing technical assistance. The collaboration and effective interventions reduced the number of malaria cases reported in Laiza and nearby areas from 1936 cases in 2017 followed by 664 cases in 2018 and then 274 cases in 2019. Decreased malaria burden in the KR2 contributed the reduced number of malaria importation in Yingjiang County, from 179 cases in 2017 followed by 106 cases in 2018, and then 92 cases in 2019 and 75 cases in 2020. The cross border collaboration not only helped achieving malaria free and preventing reintroduction, but also reduced the work load of epidemiological investigations and responses to imported malaria in Yunnan.