Rapid diagnostic tests (RDTs) for malaria using antibodies against pan-Plasmodium antigen lactate dehydrogenase (pLDH) are commonly used for malaria diagnosis. The level of malaria parasitemia determined by peripheral blood smears (PBS) correlates with the pLDH concentration in most cases. We report a case of malaria recurrence associated with false-negative RDT results. A 22-year-old male patient was admitted to the Armed Forces Capital Hospital with fever and chills, and was diagnosed with malaria infection. Four days after antimalarial treatment, these symptoms recurred. After admitting to our hospital, doxycycline was administered for 4 days. Even after administration of doxycycline, the malaria parasites in blood smears remained positive, but RDT showed negative results. Therefore, for patients receiving doxycycline, serial blood smear testing should be performed to exclude false-negative malaria RDT results.
Antibodies ; Arm ; Chills ; Diagnosis ; Diagnostic Tests, Routine ; Doxycycline ; Fever ; Humans ; L-Lactate Dehydrogenase ; Malaria ; Male ; Parasitemia ; Parasites ; Recurrence ; Young Adult

In recent years, rapid diagnostic tests (RDTs) have been widely used for malaria detection, primarily because of their simple operation, fast results, and straightforward interpretation. The Asan EasyTest(TM) Malaria Pf/Pan Ag is one of the most commonly used malaria RDTs in several countries, including Korea and India. In this study, we tested the diagnostic performance of this RDT in Uganda to evaluate its usefulness for field diagnosis of malaria in this country. Microscopic and PCR analyses, and the Asan EasyTest(TM) Malaria Pf/Pan Ag rapid diagnostic test, were performed on blood samples from 185 individuals with suspected malaria in several villages in Uganda. Compared to the microscopic analysis, the sensitivity of the RDT to detect malaria infection was 95.8% and 83.3% for Plasmodium falciparum and non-P. falciparum, respectively. Although the diagnostic sensitivity of the RDT decreased when parasitemia was < or =500 parasites/microl, it showed 96.8% sensitivity (98.4% for P. falciparum and 93.8% for non-P. falciparum) in blood samples with parasitemia > or =100 parasites/microl. The specificity of the RDT was 97.3% for P. falciparum and 97.3% for non-P. falciparum. These results collectively suggest that the accuracy of the Asan EasyTest(TM) Malaria Pf/Pan Ag makes it an effective point-of-care diagnostic tool for malaria in Uganda.
Adolescent ; Adult ; Antigens, Protozoan/blood/*isolation & purification ; Child ; Child, Preschool ; Humans ; Malaria, Falciparum/*diagnosis/epidemiology ; Parasitemia ; Point-of-Care Systems ; Predictive Value of Tests ; Reagent Kits, Diagnostic ; Sensitivity and Specificity ; Uganda/epidemiology ; Young Adult

A loop-mediated isothermal amplification (LAMP) assay allows rapid diagnosis of Toxoplasma gondii infection. In the present study, the LAMP assay was evaluated using blood from both naturally and experimentally infected pigs. The sensitivity of the LAMP assay was compared with that of Q-PCR. Both assays detected T. gondii in the blood of experimentally infected pigs, with 100% agreement. In infected blood samples, the parasite was detected as early as 2 days post-infection and reached a peak in 3-5 days. In 216 field serum samples, the detection rates of LAMP and Q-PCR assays were 6.9% and 7.8%, respectively. This result indicates that the sensitivity of the LAMP assay was slightly lower than that of the Q-PCR assay. However, the LAMP may be an attractive diagnostic method in conditions where sophisticated and expensive equipment is unavailable. This assay could be a powerful supplement to current diagnostic methods.
Animals ; Azure Stains ; Biological Assay ; Brain/parasitology ; DNA, Protozoan/*blood/genetics ; Lung/parasitology ; Mice ; Nucleic Acid Amplification Techniques/*veterinary ; Parasitemia ; Real-Time Polymerase Chain Reaction/veterinary ; Sensitivity and Specificity ; Swine ; Swine Diseases/*diagnosis/parasitology ; Toxoplasma/genetics/*isolation & purification ; Toxoplasmosis, Animal/*diagnosis/parasitology

The traditional light microscopy has limitations for precise growth assays of malaria parasites in culture or for assessment of new compounds for antimalarial activity; the speed and high reproducibility of flow cytometry can overcome these limitations. A flow cytometric method using PicoGreen, a DNA-binding fluorochrome, was developed with optimal precision suitable for performing growth assays of low-parasitemia field isolates. In addition, intra- and inter-person reproducibility of the flow cytometric and the microscopic method were compared in order to quantitatively demonstrate the improved precision. RNase treatment contributed to the precision of the flow cytometric measurements by enhancing the signal-to-noise ratios. Coefficients of variation of the method were smaller than 10% for 0.1% or higher parasitemia samples. The intra- and inter-person coefficients of variation of the flow cytometric method were three to six times smaller than those of the microscopic method. The flow cytometric method developed in this study yielded substantially more precise results than the microscopic method, allowing determination of parasitemia levels of 0.1% or higher, with coefficients of variation smaller than 10%. Thus, the PicoGreen method could be a reliable high sensitivity assay for analysis of low parasitemia samples and might be applied to a high throughput system testing antimalarial drug activity.
*Flow Cytometry ; Fluorescent Dyes/chemistry ; Humans ; *Microscopy ; Organic Chemicals/chemistry ; Parasitemia/*diagnosis ; Plasmodium falciparum/*isolation & purification ; Reproducibility of Results ; Ribonucleases/metabolism ; Signal-To-Noise Ratio

Parasitemia characteristics of Plasmodium vivax malaria in temperate regions may differ from those in tropical zones. However, most parasitological and clinical features of P. vivax malaria have been investigated in the latter. In this study, we investigated 383 malaria patients to clarify the parasitemia characteristics of a P. vivax strain in the Republic of Korea (ROK). The mean parasitemia (8,396/microL) was less than half of tropical P. vivax malaria, and multiple invasions of erythrocytes were not rare (53.5% of the patients, 2.4% of the total investigated RBCs), but less than the observations in tropical zones. The intervals between the first symptom onset and diagnosis were significantly longer in gametocyte (+) patients than in gametocyte (-) patients. Only half of the total patients had both genders of gametocytes (191 of 353), and the male gametocyte density (169/microL) was lower than that of P. vivax strains of a previous study. Multiple invasions of erythrocytes and gametocytemia were coincident factors of the degree of anemia in P. vivax malaria. The present findings demonstrate the P. vivax strain in ROK reveals relatively low parasitemia and low male to female gametocyte ratio. The low ratio may be related with low transmission efficacy.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Erythrocytes/parasitology ; Female ; Humans ; Malaria, Vivax/*diagnosis/epidemiology/parasitology ; Male ; Middle Aged ; Parasitemia/*diagnosis/epidemiology/parasitology ; Plasmodium vivax/isolation & purification ; Republic of Korea/epidemiology

Parasitemia characteristics of Plasmodium vivax malaria in temperate regions may differ from those in tropical zones. However, most parasitological and clinical features of P. vivax malaria have been investigated in the latter. In this study, we investigated 383 malaria patients to clarify the parasitemia characteristics of a P. vivax strain in the Republic of Korea (ROK). The mean parasitemia (8,396/microL) was less than half of tropical P. vivax malaria, and multiple invasions of erythrocytes were not rare (53.5% of the patients, 2.4% of the total investigated RBCs), but less than the observations in tropical zones. The intervals between the first symptom onset and diagnosis were significantly longer in gametocyte (+) patients than in gametocyte (-) patients. Only half of the total patients had both genders of gametocytes (191 of 353), and the male gametocyte density (169/microL) was lower than that of P. vivax strains of a previous study. Multiple invasions of erythrocytes and gametocytemia were coincident factors of the degree of anemia in P. vivax malaria. The present findings demonstrate the P. vivax strain in ROK reveals relatively low parasitemia and low male to female gametocyte ratio. The low ratio may be related with low transmission efficacy.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Erythrocytes/parasitology ; Female ; Humans ; Malaria, Vivax/*diagnosis/epidemiology/parasitology ; Male ; Middle Aged ; Parasitemia/*diagnosis/epidemiology/parasitology ; Plasmodium vivax/isolation & purification ; Republic of Korea/epidemiology

BACKGROUND: Examination of peripheral blood smear (PBS) is the gold standard for the diagnosis of malaria; however, its diagnostic utility will be dependent on the examiner's microscopic experience, the quality of the smear, and the degree of parasitemia. Therefore, it is essential to have available a rapid and simple test that is as sensitive and specific as PBS, at a small-middle range medical center, a health care center, and a military hospital in a malaria endemic area. METHODS: Malaria antigen and antibody tests were performed on 120 febrile patients who were requested for complete blood count (CBC) and PBS at two military hospitals from May 2004 to August 2005. RESULTS: Of the 45 patients who were diagnosed with malaria by examination of peripheral blood smears, 42 were positive on both malaria antigen and antibody tests, and 2 were positive on either antigen or antibody test. Only 1 patient was negative on the both test. Furthermore, all 75 patients with negative microscopic examinations also had negative malaria antigen and antibody tests. CONCLUSIONS: The results of this study show that a rapid differential diagnosis of malaria can be made by performing malaria antigen and antibody tests on febrile patients at hospitals in malaria endemic areas. Moreover, the test is simple and convenient enough to be performed without any special equipment or experience.
Blood Cell Count ; Delivery of Health Care ; Diagnosis ; Diagnosis, Differential* ; Fever of Unknown Origin* ; Fever* ; Hospitals, Military ; Humans ; Malaria* ; Malaria, Vivax* ; Parasitemia

Toxoplasma gondii tachyzoites were isolated from the blood of an ocular patient, and have been successfully passaged in the laboratory, for over a year, by peritoneal inoculation in mice. The isolated parasite was designated the Korean Isolate-1 (KI-1) and its characteristics were compared with those of the RH strain, a wellknown virulent strain originating from a child who suffered from encephalitis. The morphology, pathogenicity, infectivity and cell culture characteristics of the KI-1 were similar to those of the RH strain. Both RH and KI-1 antigens were detected by an anti-T. gondii monoclonal antibody (mAb), Tg563, against the major surface protein SAG1 (30 kDa), whereas no reaction was observed against an anti-Neospora caninum mAb, 12B4. The KI-1 was confirmed as an isolate of T. gondii. A long-term laboratory maintenance and characterization of a local T. gondii isolate is reported for the first time in the Republic of Korea.
Animals ; Antigens, Protozoan/analysis ; Female ; Humans ; Korea ; Mice ; Mice, Inbred BALB C ; Microscopy, Electron ; Middle Aged ; Parasitemia/parasitology ; Sarcoma 180 ; Serial Passage ; Specific Pathogen-Free Organisms ; *Toxoplasma/classification/growth & development/isolation & purification/pathogenicity ; Toxoplasmosis, Ocular/*diagnosis/parasitology ; Tumor Cells, Cultured ; Virulence

BACKGROUND: The diagnosis of malaria has been usually made using microscopic examination of Wright stained thin blood films in Korean army. This method is labor-intensive, time consuming and requires the microscopic expertise. Therefore, the alternative techniques, rapid diagnostic test, have been sought for use in Korean army. We performed a comparison of the OptiMAL test with GENEDIA Malaria (P. vivax) Ab Rapid I, II to assess its sensitivity and specificity of Plasmodium vivax malaria. METHODS: Blood specimen were collected from 51 patients who were presented and initially diagnosed for P. vivax by the microscopy of blood smears and from 30 control patients without malaria infection at the Capital Armed Forces General Hospital (CAFGH) between October 2000 and February 2001. Among the 51 patients, we also collected 24 samples from 24 patients at 2 or 3 days after therapy. The OptiMAL test and GENEDIA Malaria (P. vivax) Ab Rapid I, II were performed according to the manufacturer's instructions on all samples respectively. RESULTS: Compared with the blood film, sensitivities and specificities of the OptiMAL test, GENEDIA Malaria (P. vivax) Ab Rapid I and GENEDIA Malaria (P. vivax) Ab Rapid II were 94.1~100% (29/29), 80.4~83.3%, 96.1~96.7% respectively. One case was interpreted as 'undetermined' by OptiMAL test. In 24 patients during therapy, the sensitivities of the OptiMAL test, GENEDIA Malaria (P. vivax) Ab Rapid I and GENEDIA Malaria (P. vivax) Ab Rapid II on 8 specimens with mean 120/microliter parasitemia and 16 specimens with negative parasitemia were 75~43.8%, 87.5~81.3%, 100~100% respectively. CONCLUSION: Our data demonstrated that the sensitivity and specificity of the GENEDIA Malaria (P. vivax) Ab Rapid I were not satisfactory, but the sensitivity and specificity of the OptiMAL test and GENEDIA Malaria (P. vivax) Ab Rapid II were relatively high and useful diagnostic tests for diagnosis of P. vivax in areas like the militaries where laboratory facilities are poor or non-existent.
Arm ; Diagnosis* ; Diagnostic Tests, Routine ; Hospitals, General ; Humans ; Malaria* ; Malaria, Vivax ; Microscopy ; Military Personnel* ; Parasitemia ; Plasmodium vivax* ; Plasmodium* ; Sensitivity and Specificity

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