Abstract: Objective To compare the screening effects of RDT, microscopy and PCR for malaria among residents in low malaria areas and elimination areas, and to investigate the presence of malaria in residents of border Villages in Cangyuan Va County and asymptomatic infections in surrounding areas, providing a basis for preventing re-introduction of malaria after elimination. Methods From August 2020 to March 2021, the fingertip blood of the investigated subjects was collected from three survey sites in the border area between China and Myanmar, namely Banlao Township in Cangyuan Va Autonomous County of Lincang City, Banwai District, Mengmao County, the Second Special Zone of Shan State, Myanmar, Yongmo and Dayan Township, Nandeng Special Zone, the Second Special Zone of Shan State, Myanmar. The malaria parasite antigen detection test kit, malaria parasite microscopic examination, fluorescent quantitative PCR and nested PCR were used to detect the asymptomatic infection of malaria parasites. Results A total of 1 040 blood samples were collected, including 606 from China and 434 from Myanmar, with 506 males and 534 females. Among them, , there were 51 individuals aged 0 to <5 years, 283 aged 5 to < years, 187 aged 15 to < years, 232 aged 30 to <45 years, 205 aged 45 to < years, and 82 aged ≥60 years. All 1 040 people tested negative for plasmodium antigen detection kit. One case of Plasmodium vivax detected by plasmodium microscopic etiology, with a detection rate of 0.10%. One case of P. vivax was also detected by fluorescent quantitative PCR and nested PCR, with a detection rate of 0.10%. Among them, one case of P. vivax was detected in Banwai District, Mengmao County, the Second Special Zone of Shan State, Myanmar, with a detection rate of 0.35%. The detection rates of malaria parasites in Banlao Township in Cangyuan Va Autonomous County of Lincang City, Yunnan Province and Yongmo Township and Dayan Township, Nandeng Special District, the Second Special Zone of Shan State, Myanmar were both 0. The difference in the detection rate of malaria parasites among the three survey sites was not statistically significant (χ2 =2.682, P>0.05). The asymptomatic P. vivax infection was detected in a 6-year-old girl from Banwai District, Mengmao County, the Second Special Zone of Shan State, Myanmar. Conclusions RDT is not suitable for malaria screening in low malaria area and elimination area. Microscopic examination and PCR can be used for malaria screening, but PCR operation is complex and costly. In surrounding areas outside of China, malaria is still prevalent, while there is no source of malaria infection in border villages of Cangyuan Va County. However, there is a risk of importation, and timely and effective measures should be taken to prevent reintroduction and transmission.

Yunnan Province borders with Myanmar, Vietnam, and Laos, the China-Myanmar border area is the key area for prevention of re-establishment from imported malaria after the disease was eliminated in China. Since the malaria elimination action plan was launched in Yunnan Province in 2011, 129 counties (cities, districts) were classified into three categories according to malaria incidence and transmission risk, and different technical strategies and measures were implemented with adaptations to local circumstances. A total of 68 malaria consultation service stations were established on the Chinese side of the China-Myanmar border and 80 malaria prevention and control stations were established on the Myanmar side by Yunnan Province in 2014. Then, the “Three Lines of Defense” strategy was implemented for malaria elimination in the China-Myanmar border area in Yunnan Province during the period from 2015 to 2018, and this strategy was further refined and adjusted to the “3 + 1” strategy for prevention of re-establishment from imported malaria in 2019. Through decades of multifaceted efforts, the malaria elimination goal was achieved in Yunnan Province in June 2021. However, the number of imported malaria cases appeared a tendency towards a rise in Yunnan Province in 2023 and 2024, due to changes in the situation in Myanmar and the gradual resumption of international travel and border crossings following the adjustment of the COVID-19 prevention and control policy in China. The joint malaria prevention and control cooperation between China and Myanmar was initiated with the pilot project for joint malaria prevention and control in the China-Myanmar border area in 2005, and this project was progressed into the joint malaria and dengue fever prevention and control project in parts of the Greater Mekong Subregion border areas in 2010. The threat of overseas malaria epidemics to border areas in Yunnan Province was effectively reduced through implementation of coordination meetings with Myanmar health departments, establishment of efficient information exchange mechanisms, establishment of overseas surveillance sentinel sites, technical training, provision of material supports, joint propagation activities and joint responses to malaria epidemics. This project was incorporated into the Five-Year Plan of Action on Lancang-Mekong Cooperation (2018—2022) in China in 2018, with 5 liaison offices and 20 liaison workstations established in Myanmar, Laos, Vietnam, Cambodia, and Thailand, and 21 cross-border malaria surveillance sites assigned in border areas of Myanmar, Laos and Vietnam, and a long-term malaria prevention and control cooperation mechanisms was established through meetings, training, propagation, and joint investigations. Currently, Yunnan Province is poised to engage in more extensive and in-depth cooperation with neighboring countries, including malaria diagnosis and treatment techniques, drug and vaccine research and development, talent cultivation, information sharing, cross-border human health services, and health promotion, under the guidance of the Five-Year Plan of Action on Lancang-Mekong Cooperation (2023—2027).

Objective To investigate the awareness of malaria-related knowledge, the use of mosquito nets and their influencing factors among residents in Banlao Township, Cangyuan County, Yunnan Province.. Methods In August 2020, 19 settlement sites in Banlao Township, Cangyuan County, Lincang City, Yunnan Province were selected as study areas, and permanent residents at ages of 10 years and older were enrolled for a questionnaire survey, including residents’ demographics, family economic status, malaria control knowledge and use of mosquito nets. In addition, the factors affecting the use of mosquito nets in the night prior to the survey were identified using multivariate logistic regression analysis. Results A total of 320 questionnaires were allocated, and all were recovered (a 100% recovery rate). There were 316 valid questionnaires, with an effective recovery rate of 98.75%. The 316 respondents included 152 men and 164 women and 250 Chinese respondents and 66 foreign respondents. The awareness of clinical syndromes of malaria was significantly higher among Chinese residents (71.60%) than among foreign residents (50.00%) (χ² = 11.03, P < 0.01), and the proportions of Chinese and foreign residents sleeping under mosquito nets were 46.00% and 69.70% on the night prior to the survey, respectively (χ² = 11.73, P < 0.01). Multivariate logistic regression analysis identified ethnicity group and type of residence as factors affecting the use of mosquito nets in the night prior to the survey. Conclusions The awareness of malaria control knowledge, the coverage and the use of mosquito nets were low among residents in Banlao Township, Cangyuan County, Yunnan Province. Targeted health education is recommended to improve the awareness of malaria control knowledge and self-protection ability. In addition, improving the allocation of long-lasting mosquito nets and health education pertaining to their uses and increasing the proportion of using mosquito nets correctly is needed to prevent re-establishment of imported malaria.