Risk assessment of malaria in land border regions of China in the context of malaria elimination

Abstract

BackgroundCross-border malaria transmission poses a challenge for countries to achieve and maintain malaria elimination. Because of a dramatic increase of cross-border population movement between China and 14 neighbouring countries, the malaria epidemic risk in China’s land border regions needs to be understood.MethodsIn this study, individual case-based epidemiological data on malaria in the 136 counties of China with international land borders, from 2011 to 2014, were extracted from the National Infectious Disease Information System. The Plasmodium species, seasonality, spatiotemporal distribution and changing features of imported and indigenous cases were analysed using descriptive spatial and temporal methods.ResultsA total of 1948 malaria cases were reported, with 1406 (72.2%) imported cases and 542 (27.8%) indigenous cases. Plasmodium vivax is the predominant species, with 1536 malaria cases occurrence (78.9%), following by Plasmodium falciparum (361 cases, 18.5%), and the others (51 cases, 2.6%). The magnitude and geographic distribution of malaria in land border counties shrunk sharply during the elimination period. Imported malaria cases were with a peak of 546 cases in 2011, decreasing yearly in the following years. The number of counties with imported cases decreased from 28 counties in 2011 to 26 counties in 2014. Indigenous malaria cases presented a markedly decreasing trend, with 319 indigenous cases in 2011 reducing to only 33 indigenous cases in 2014. The number of counties with indigenous cases reduced from 26 counties in 2011 to 10 counties in 2014. However, several bordering counties of Yunnan province adjacent to Myanmar reported indigenous malaria cases in the four consecutive years from 2011 to 2014.ConclusionsThe scale and extent of malaria occurrence in the international land border counties of China decreased dramatically during the elimination period. However, several high-risk counties, especially along the China–Myanmar border, still face a persistent risk of malaria introduction and transmission. The study emphasizes the importance and urgency of cross-border cooperation between neighbouring countries to jointly face malaria threats to elimination goals.

Epidemiology of Imported Infectious Diseases, China, 2005–2016

“…Many infectious diseases, such as P. vivax malaria, dengue fever, influenza A(H1N1), epidemic hemorrhagic fever, JE, chikungunya, Lyme disease, scrub typhus, and VL, are found frequently in the indigenous population of China, but some are found more often as imported diseases, such as P. falciparum malaria, yellow fever, Zika virus, and MERS. Imported P. falciparum malaria is a major obstacle to achieving malaria elimination in China (12)(13)(14). This study showed that malaria was the most frequent imported infectious disease during 2005-2016, and Yunnan was the province with the greatest number of cases of imported malaria, which was consistent with other relevant studies in China (15)(16)(17).…”

“…The reason for the large number of imported cases is that Yunnan Province has long international borders with Myanmar, Laos, Vietnam, and other countries of the Greater Mekong Subregion that show a high incidence of malaria (16). The persons who cross these borders to enter or leave China increase opportunities for infectious diseases to be imported from adjacent countries (3,14,18,19), especially from Myanmar (12,13,20). P. falciparum malaria was imported mainly from Ghana and P. vivax malaria mainly from Asia, which was consistent with Zhou's findings (5).…”

“…All these factors have resulted in an increased number of malaria and other mosquitoborne diseases (26). Therefore, the main challenges of eliminating P. falciparum malaria are curtailing border malaria and imported cases from Myanmar and countries in Africa (6,14). Cooperation between China and neighboring countries has played an important role in improving malaria control at cross-border areas and should be further strengthened.…”

Malaria in China: a longitudinal population-based surveillance study

“…The proportion of malaria deaths attributed to P. falciparum was 87.7% and 6.8% by P. vivax. These results were consistent with other reports [19,[21][22][23].…”

Protecting the gains of malaria elimination in China

“…Moreover, the malaria vector mosquitos still thrive with the potential to transmit any imported cases that may be missed. This situation is additionally challenged by the complicated ecological settings along the Yunnan border areas, neighboring three malaria endemic countries: Lao People's Democratic Republic, Myanmar, and Vietnam [1][2][3], as well as the importation of cases from Chinese workers returning from outside the region, such as from Africa. Estimates of these imported cases exceed over 2500 per year and have impacted almost all provinces of China over the past decade.…”