Surveillance on the Vivax Malaria in Endemic Areas in the Republic of Korea Based on Molecular and Serological Analyses

Abstract

<i>Plasmodium vivax</i> reemerged in 1993. It has been sustained for more than 25 years and become one of the important indigenous parasitic diseases in northern and western parts of the Republic of Korea near the demilitarized zone. In particular, relapse is a significant concern for the control of malaria, as short- and long-term incubation periods vary among those infected in Korea. In this study, the prevalence of asymptomatic carriers was examined among residents of high endemic areas of vivax malaria during nonseasonal transmission of mosquitoes. Blood samples from 3 endemic regions in northwestern Korea were evaluated by microscopic examination, rapid diagnostic testing, and nested PCR to identify asymptomatic patients carrying malaria parasites in the community. However, no positive malaria case among residents of endemic areas was detected. Additionally, serological analysis was carried out to measure antibodies against 3 antigenic recombinant proteins of <i>P. vivax</i>, merozoite surface protein 1-19, circumsporozoite surface protein-VK210, and liver-stage antigen (PvLSA-N), by the protein array method. Interestingly, seropositivity of sera between previous exposure and samples without exposure to malaria was significantly higher using the PvLSA-N antigen than the other antigens, suggesting that PvLSA-N can be used as a serological marker to analyze the degree of exposure for malaria transmission in endemic areas. This indicates a very low asymptomatic carrier prevalence during the nonmalaria season in the endemic areas of Korea.

Using Serological Markers for the Surveillance of Plasmodium vivax Malaria: A Scoping Review

“…It was commonly found that the inclusion of multiple Plasmodium antigens improved detection capacity [ 60 , 73 , 78 , 80 , 81 , 85 , 89 , 90 ]; however, mixed conclusions were drawn on the three most commonly used antigens. Pv MSP1-19 was deemed both useful [ 23 , 34 , 55 , 69 , 77 , 92 , 93 ] and uninformative [ 94 ] as an antigen to indicate exposure to P. vivax . Pv AMA1 was found to be both suitable [ 47 , 55 ] and ambiguous [ 94 ].…”

“…Kattenberg et al [ 63 ] found Pv AMA1 to only be useful for long-term changes in exposure, as opposed to identifying recent exposure. Pv CSP was deemed both apt [ 35 , 57 , 66 , 92 ] and imprecise [ 52 , 74 , 80 , 93 , 95 ] for the identification of P. vivax exposure. Other issues compounded this difficulty in antigen selection, including the existence of polymorphisms for some proteins [ 56 , 88 ].…”

“…In summary, serosurveillance is an incredibly promising tool that requires further refinement and standardisation. Various combinations of serological exposure markers should be explored to identify panels that are suited for various transmission contexts [ 38 , 85 ]; these panels should then be validated with respect to both the relevant transmission context and surveillance system [ 44 , 83 , 93 , 94 , 112 ]. This process has begun in some instances [ 41 ] and should be extended to other serological marker panels.…”

Recent Spatial and Temporal Trends of Malaria in Korea

“…Malaria is one of the oldest diseases, and its influence has probably been greater than that of any other infectious agents [ 5 ]. Caused by the Plasmodium species of protozoan parasites, malaria is a major public health burden worldwide [ 6 ]. P. falciparum is the most prevalent malaria parasite in Africa, and it is the greatest menace because of its high mortality rate [ 7 ].…”

“…P. falciparum is the most prevalent malaria parasite in Africa, and it is the greatest menace because of its high mortality rate [ 7 ]. P. vivax is less lethal than P. falciparum , but more prevalent in Korea [ 6 ]. It was eradicated from Korea late 1970s, but re-emerged 1993 and continued prevalent despite the ongoing national eradication program [ 8 ].…”