Prevalence of Plasmodium vivax VK210 and VK247 subtype in Myanmar.
BACKGROUND
Plasmodium vivax is divided into two subtypes, a dominant form, VK210 and a variant form, VK247. This division is dependent on the amino acid composition of the circumsporozoite (CS) protein. In this study, the prevalence of the VK247 variant form of P. vivax was investigated in Myanmar.


METHODS
The existence of malaria parasites in blood samples was determined by microscopic examination, polymerase chain reaction (PCR) and DNA hybridization assays. To test for antibodies against P. vivax and Plasmodium falciparum in blood samples, an indirect immunofluorescence antibody test (IFAT) was performed using asexual blood antigens. An enzyme-linked immunosorbent assay with synthetic VK210 and VK247 antigens was carried out to discriminate between the P. vivax subtypes.


RESULTS
By thick smear examination, 73 (n=100) patients were single infected with P. vivax, one with P. falciparum and 13 with both species. By thin smear, 53 patients were single infected with P. vivax, eight with only P. falciparum and 16 with both. Most of the collected blood samples were shown to be P. vivax positive (n=95) by PCR. All cases that were positive for P. falciparum by PCR (n=43) were also positive for P. vivax. However, 52 cases were single infected with P. vivax. IFAT showed antibody titres from 1:32 to 1:4,096. Additionally, using specific antibodies for VK210 and VK247, ELISA showed that 12 patients had antibodies for only the VK210 subtype, 4 patients had only VK247 subtype antibodies and 21 patients had antibodies for both subtypes. Using a DNA hybridization test, 47 patients were infected with the VK210 type, one patient was infected with VK247 and 23 patients were infected with both subtypes.


CONCLUSIONS
The proportion of the VK247 subtype in Myanmar was 43.1% (n=25) among 58 positive cases by serodiagnosis and 25.6% (n=24) among 94 positive cases by genetic diagnosis. In both diagnostic methods, the infection status of malaria patients is highly diverse with respect to malaria species, and multiple clonal infections are prevalent in Myanmar. Therefore, the complexity of the infection should be considered carefully when diagnosing malaria in Myanmar.
Kim
Tong-Soo
TS
Division of Malaria and Parasitic diseases, Korea Centers for Disease Control and Prevention, Seoul 122-701, Republic of Korea.
Kim
Hyung-Hwan
HH
Lee
Sun-Sim
SS
Na
Byoung-Kuk
BK
Lin
Khin
K
Cho
Shin-Hyeong
SH
Kang
Yoon-Joong
YJ
Kim
Do-Kyung
DK
Sohn
Youngjoo
Y
Kim
Hyuck
H
Lee
Hyeong-Woo
HW
D000913:Antibodies, Protozoan / Q000032:analysis; D015342:DNA Probes; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D016780:Malaria, Vivax / Q000453:epidemiology* / Q000276:immunology / Q000469:parasitology; D008969:Molecular Sequence Data; D002052:Myanmar / Q000453:epidemiology; D010966:Plasmodium vivax / Q000145:classification / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D015995:Prevalence; D015800:Protozoan Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D016036:Seroepidemiologic Studies; D012698:Serologic Tests
D000913:Antibodies, Protozoan; D015342:DNA Probes; D015800:Protozoan Proteins; C041595:circumsporozoite protein, Protozoan