We report a case of vivax malaria that showed ruptured form of merozoite only in the peripheral blood. A 28-year old man was admitted to Korea University hospital because of irregular high fever, chill and abdominal pain. The peripheral blood smear, showed only small merozoites which seemed to have been recently released from schizonts and destroyed remnants form of schizonts and did not show any forms of malaria parasite such as ring forms, mature trophozoites, schizonts, and gametocytes. On acridine orange fluorochrome stain, we could not find any suspected forms of malaria. However, we detected parasite LDH which is specific to Plasmodium vivax. Malaria treatment was done to the patient, and he is now under follow up in local hospital.
Abdominal Pain ; Acridine Orange ; Adult ; Fever ; Follow-Up Studies ; Humans ; Korea ; Malaria ; Malaria, Vivax* ; Merozoites* ; Parasites ; Plasmodium vivax ; Schizonts* ; Trophozoites

Plasmodium vivax merozoite surface protein-1 (PvMSP1) gene codes for a major malaria vaccine candidate antigen. However, its polymorphic nature represents an obstacle to the design of a protective vaccine. In this study, we analyzed the genetic polymorphism and natural selection of the C-terminal 42 kDa fragment within PvMSP1 gene (Pv MSP142) from 77 P. vivax isolates, collected from imported cases of China-Myanmar border (CMB) areas in Yunnan province and the inland cases from Anhui, Yunnan, and Zhejiang province in China during 2009–2012. Totally, 41 haplotypes were identified and 30 of them were new haplotypes. The differences between the rates of non-synonymous and synonymous mutations suggest that PvMSP142 has evolved under natural selection, and a high selective pressure preferentially acted on regions identified of PvMSP133. Our results also demonstrated that PvMSP142 of P. vivax isolates collected on China-Myanmar border areas display higher genetic polymorphisms than those collected from inland of China. Such results have significant implications for understanding the dynamic of the P. vivax population and may be useful information towards China malaria elimination campaign strategies.
China ; Genetic Variation* ; Haplotypes ; Malaria ; Merozoite Surface Protein 1* ; Merozoites* ; Myanmar ; Plasmodium vivax* ; Plasmodium* ; Polymorphism, Genetic ; Selection, Genetic* ; Silent Mutation

Protozoa of the genus Cryptosporidium are small coccidian parasite known to infect the mucosal epithelium of a variety of animals including human, causing fatal course in immunodeficient patients as well as self-limited illness in healthy individuals. Various life cycle stages including trophozoite, meront, merozoite, gametocyte and oocyst in infected mucosa are a diagnostic feature. Electron microscopy (EM) provides sufficient findings for genus and species identification of this parasitic organism. The authors presented scanning and transmission EM findings of Cryptosporidium parvum infection in two children: one with acute lymphoblastic leukemia and the other without any evidence of immune compromise.
Animals ; Child ; Cryptosporidium parvum ; Cryptosporidium* ; Epithelium ; Humans* ; Intestines* ; Life Cycle Stages ; Merozoites ; Microscopy, Electron ; Mucous Membrane ; Oocysts ; Parasites ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; Trophozoites

BACKGROUND: In the Republic of Korea, Plasmodium vivax malaria, which had disappeared since 1984, re-emerged in 1993. Currently, malaria is becoming a serious public health problem in the Republic of Korea. The diagnosis of malaria has relied on microscopic examination such as thin and thick blood smears. However, even for expert microscopists, this test is a laborious and time-consuming procedure. Therefore, the development of a reliable, easy, and convenient diagnostic test is crucial. Recently, the LG malaria anti-PvTM enzyme-linked immunosorbent assay (ELISA) kit for the detection of a specific antibody against the merozoite surface protein (MSP) of P. vivax was developed. The aim of this study was to evaluate the diagnostic kit for P. vivax malaria in the Republic of Korea. METHODS: To determine the usefulness of the LG malaria anti-PvTM as a diagnostic kit for vivax malaria, a total of 59 serum samples from patients with P. vivax malaria were tested. The patients were diagnosed microscopically and the parasitemia index of their blood was calculated. Sera from 203 uninfected healthy blood donors, which were microscopically negative for Plasmodium vivax, were used as negative controls. RESULTS: The sensitivity and specificity of the LG malaria anti-PvTM were 98.31% (58/59) and 98.03% (199/203), respectively. The false-positive and false-negative rates were 1.97% (4/203) and 1.69% (1/59), respectively. CONCLUSIONS: The diagnostic kit, LG malaria anti-PvTM, might be a useful tool for diagnosis and screening of P. vivax malaria in Korea.
Blood Donors ; Diagnosis* ; Diagnostic Tests, Routine ; Enzyme-Linked Immunosorbent Assay ; Humans ; Korea ; Malaria* ; Malaria, Vivax* ; Mass Screening ; Merozoites ; Parasitemia ; Plasmodium vivax* ; Plasmodium* ; Public Health ; Republic of Korea* ; Sensitivity and Specificity

BACKGROUND: Plasmodium vivax circumsporozoite protein (CSP), merozoite surface protein (MSP) and Duffy binding protein (DBP) are functionally important conserved proteins and may have an important role in developing antigens. The aim of this study was to develop recombinant CSP, MSP, and DBP antigens, to evaluate their diagnostic usefulness, and to analyze the prevalence of seroreactivity against P. vivax in five different regions in Korea. METHODS: To construct recombinant CSP, MSP, and DBP antigens from P. vivax, DNA obtained from specimens previously diagnosed as P. vivax was used. To evaluate diagnostic usefulness of recombinant CSP, MSP, and DBP antigens from P. vivax, sera from 45 patients with P. vivax and 48 normal controls including 4 patients with Plasmodium falciparum were used. For the epidemiologic study, a total of 1, 014 serum samples obtained from five different regions in Korea were used. RESULTS: The sensitivity of the IgG antibody against the P. vivax recombinant CSP, MSP, DBP antigens and the antigens mixture of these proteins were 75.6%, 62.2%, 68.9%, and 97.8%, and the specificity were 92.1%, 84.2%, 81.6%, and 97.4%, respectively. The seropositivity against P. vivax recombinant antigens was highest in Cheolwon province. The IgG seropositivity against P. vivax recombinant CSP, MSP and DBP was 2.0%, 1.2%, and 1.5%, respectively. There were no significant differences in seroreactivity against P. vivax between each recombinant protein and each five different regions in Korea. CONCLUSIONS: Newly constructed recombinant CSP, MSP and DBP were useful in the detection of antibodies against the P. vivax antigen.
Antibodies ; Antibody Formation* ; Carrier Proteins* ; DNA ; Epidemiologic Studies ; Humans ; Immunoglobulin G ; Korea ; Merozoites* ; Plasmodium falciparum ; Plasmodium vivax* ; Prevalence ; Sensitivity and Specificity ; Seroepidemiologic Studies

Human infections due to the monkey malaria parasite Plasmodium knowlesi is increasingly being reported from most Southeast Asian countries specifically Malaysia. The parasite causes severe and fatal malaria thus there is a need for urgent measures for its control. In this study, the level of polymorphisms, haplotypes and natural selection of full-length pkmsp8 in 37 clinical samples from Malaysian Borneo along with 6 lab-adapted strains were investigated. Low levels of polymorphism were observed across the full-length gene, the double epidermal growth factor (EGF) domains were mostly conserved, and non-synonymous substitutions were absent. Evidence of strong negative selection pressure in the non-EGF regions were found indicating functional constrains acting at different domains. Phylogenetic haplotype network analysis identified shared haplotypes and indicated geographical clustering of samples originating from Peninsular Malaysia and Malaysian Borneo. This is the first study to genetically characterize the full-length msp8 gene from clinical isolates of P. knowlesi from Malaysia; however, further functional characterization would be useful for future rational vaccine design.
Asian Continental Ancestry Group ; Borneo ; Epidermal Growth Factor ; Genetic Variation ; Haplorhini ; Haplotypes ; Humans ; Malaria ; Malaysia ; Merozoites ; Parasites ; Plasmodium knowlesi ; Selection, Genetic

The discovery and understanding of antigenic proteins are essential for development of a vaccine against malaria. In Plasmodium falciparum, Pf92 have been characterized as a merozoite surface protein, and this protein is expressed at the late schizont stage, but no study of Pv92, the orthologue of Pf92 in P. vivax, has been reported. Thus, the protein structure of Pv92 was analyzed, and the gene sequence was aligned with that of other Plasmodium spp. using bioinformatics tools. The recombinant Pv92 protein was expressed and purified using bacterial expression system and used for immunization of mice to gain the polyclonal antibody and for evaluation of antigenicity by protein array. Also, the antibody against Pv92 was used for subcellular analysis by immunofluorescence assay. The Pv92 protein has a signal peptide and a sexual stage s48/45 domain, and the cysteine residues at the N-terminal of Pv92 were completely conserved. The N-terminal of Pv92 was successfully expressed as soluble form using a bacterial expression system. The antibody raised against Pv92 recognized the parasites and completely merged with PvMSP1-19, indicating that Pv92 was localized on the merozoite surface. Evaluation of the human humoral immune response to Pv92 indicated moderate antigenicity, with 65% sensitivity and 95% specificity by protein array. Taken together, the merozoite surface localization and antigenicity of Pv92 implicate that it might be involved in attachment and invasion of a merozoite to a new host cell or immune evasion during invasion process.
Animals ; Computational Biology ; Cysteine ; Fluorescent Antibody Technique ; Humans ; Immune Evasion ; Immunity, Humoral ; Immunization ; Malaria ; Merozoites* ; Mice ; Parasites ; Plasmodium falciparum ; Plasmodium vivax* ; Plasmodium* ; Protein Array Analysis ; Protein Sorting Signals ; Schizonts ; Sensitivity and Specificity