A retrospective analysis of malaria epidemiological characteristics in Yingjiang County on the China-Myanmar border

Serological surveillance on potential Plasmodium vivax exposure risk in a post-elimination setting

China was declared malaria free in June of 2021. In the post-elimination setting, vigilant surveillance is essential to sustain malaria free status. Serological surveillance has been recognized as an efficient tool for assessing the immunity levels and exposure risk in a population. In this study, a cross-sectional serological survey was conducted in Yingjiang County, China, in August–September, 2021. The study sites were villages along the borders with Myanmar, which have no local transmission since the last indigenous case registered in 2016. A total of 923 participants from six villages were enrolled. The majority was aged > 36 years (56.12%) and 12.46% (115/923) participants had experienced malaria infection at least once. A magnetic- bead-based assay was used to test antibodies against Plasmodium vivax antigen PvMSP-119 to evaluate the prevalence of antibody positive subjects. A reversible catalytic model was used to assess the risk of exposure. The prevalence of anti-PvMSP-119 IgG was 12.84% [95% confidence interval (CI): 9.22%–16.47%], 13.93% (95% CI: 10.11%–17.74%), and 3.57% (95% CI: 1.40%–5.75%) in three different line-of-defense areas, which differed significantly (P < 0.0001). The prevalence of anti-PvMSP-119 IgG increased with age and no statistically significant difference was detected between the sexes. The reversible catalytic model indicated that the seropositive conversion rate and seronegative reversion rate were 0.0042, 0.0034, 0.0032 and 0.0024, 0.0004, 0.0065 in the first-, second-line-of-defense area and total areas, respectively, and the fitted value did not differ significantly from the observed value (P > 0.1). Although this study found the prevalence of antibody-positive subjects and the seroconversion rate in this post-elimination setting were lower than that in transmission setting, the population still had an exposure risk. Serological surveillance should be considered in post-elimination settings to provide valuable information with which to evaluate the risk of malaria re-establishment.

Evolution of anti-malaria policies and measures in P.R. China for achieving and sustaining malaria-free

Malaria is a major public health threat worldwide, and it was also widely prevalent in the history in China, seriously endangering people's health and affecting socioeconomic development. China was certified malaria elimination in 2021 with unremitting efforts since the founding of the People's Republic of China in 1949. This great achievement has been another milestone in the fight against major infectious diseases following the elimination of smallpox, poliomyelitis, leprosy, filariasis, neonatal tetanus and blinding trachoma in China. This paper briefly introduces the malaria burden dynamics and the corresponding malaria transmission risk stratificantions, as well as systematically reviews the evolution of anti-malaria policies and measures from severe epidemic to elimination in China. Meanwhile, five key lessons in malaria control and elimination in China are also briefly summarized. All of the above provide evidences for promoting global malaria eradication and preventing reestablishment of malaria transmission, finally benefit all individuals still suffering from the scourge of malaria.

Prompt and precise identification of various sources of infection in response to the prevention of malaria re-establishment in China

Prompt and precise diagnosis of patients is an essential component of malaria control and elimination strategies, it is even more vital for the prevention of malaria re-establishment in the post elimination phase. After eliminating malaria in China, the strategy for prevention of malaria re-establishment was updated in a timely manner from the elimination strategy focusing on each case/focus to the prevention of re-establishment focusing on timely identification of the source of infection. However, there are numerous challenges, such as the persistent large number of imported malaria cases, the long-term threat of border malaria, unknown levels of asymptomatic infections and Plasmodium falciparum HRP2/3 gene deletions, and the continuous spreading of antimalarial drug resistance. Meanwhile, the detection capacity also need to be further improved to meet the timely detection of all sources of infection, otherwise it is bound to occur introduced malaria cases and malaria re-establishment in the presence of malaria vector mosquitoes. Therefore, it is necessary to continuously strengthen the malaria detection competency at all levels, promote the research and development on the malaria parasitological testing technologies, thus improving the timely detection of various sources of infection, and preventing the re-establishment of malaria.