title: Evaluation of circumsporozoite protein of Plasmodium vivax to estimate its prevalence in the Republic of Korea: an observational study of incidence.
abstract: BACKGROUND
  Plasmodium vivax re-emerged in 1993. Although the number of infections has been steadily decreasing, it is likely to continue to affect public health until it is eradicated. The aim of this study is to measure anti-circumsporozoite protein (CSP) antibody and compare malaria prevalence. As to understand the prevalence, an epidemiology study has to be conducted in the Republic of Korea.
  
  
  METHODS
  A total of 1,825 and 1,959 blood samples were collected in 2010 and 2011, respectively, from the inhabitants of Ganghwa and Cheorwon counties. The antibody titers of the inhabitants were measured by enzyme-linked immunosorbent assay (ELISA) using recombinant protein purified from Escherichia coli transformed with a CSP gene-inserted pET-28a(+) expression vector. Microscopic examination was performed to identify malaria parasites.
  
  
  RESULTS
  The annual parasite incidence (API) in Ganghwa decreased from 4.28 in 2010 to 2.23 in 2011, and that in Cheorwon decreased from 1.88 in 2010 to 1.15 in 2011. The antibody-positive CSP rate in these areas also decreased from 18.14% (331/1825) in 2010 to 15.36% (301/1959) in 2011. Pearson analysis showed a strong correlation between the API and the antibody-positive CSP rate in these areas (r = 1.000, P < 0.01). The intensity of the immune responses of the inhabitants of Cheorwon, as measured by the mean optical density, decreased from 0.9186 ± 0.0472 in 2010 to 0.7035 ± 0.0457 in 2011 (P = 0.034), but increased in Ganghwa from 0.7649 ± 0.0192 in 2010 to 0.8237 ± 0.1970 in 2011 (P = 0.006). The immune response increased according to age (r = 0.686, P = 0.041).
  
  
  CONCLUSIONS
  The positive CSP-ELISA rate was closely related to the API in the study areas. This suggests that seroepidemiological studies based on CSP-ELISA may be helpful in estimating the malaria prevalence. Moreover, such studies can be used to establish and evaluate malaria control and eradication programmes in high-risk areas in Korea.
authors: Pyo-Yun
authors: PY
authors: Cho
authors: Sang-Wook
authors: SW
authors: Lee
authors: Seong Kyu
authors: SK
authors: Ahn
authors: Jin Su
authors: JS
authors: Kim
authors: Seok Ho
authors: SH
authors: Cha
authors: Byoung-Kuk
authors: BK
authors: Na
authors: Yun-Kyu
authors: YK
authors: Park
authors: Sung Keun
authors: SK
authors: Lee
authors: Won-Ja
authors: WJ
authors: Lee
authors: Ho-Woo
authors: HW
authors: Nam
authors: Sung-Jong
authors: SJ
authors: Hong
authors: Jhang Ho
authors: JH
authors: Pak
authors: Yoon-Joong
authors: YJ
authors: Kang
authors: Youngjoo
authors: Y
authors: Sohn
authors: Young-Yil
authors: YY
authors: Bahk
authors: Han-Ik
authors: HI
authors: Cho
authors: Departments of Parasitology, Inha University School of Medicine, Incheon 400-712, Republic of Korea. tongsookim@inha.ac.kr.
authors: Tong-Soo
authors: TS
authors: Kim
authors: Hyeong-Woo
authors: HW
authors: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000913:Antibodies, Protozoan / Q000097:blood*; D002648:Child; D003001:Cloning, Molecular; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D016780:Malaria, Vivax / Q000097:blood* / Q000453:epidemiology* / Q000469:parasitology; D008297:Male; D008875:Middle Aged; D010966:Plasmodium vivax / Q000276:immunology / Q000302:isolation & purification*; D015995:Prevalence; D015800:Protozoan Proteins / Q000276:immunology*; D056910:Republic of Korea / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000913:Antibodies, Protozoan; D015800:Protozoan Proteins; C041595:circumsporozoite protein, Protozoan