Gametocyte prevalence and risk factors of P. falciparum malaria patients admitted at the Hospital for Tropical Diseases, Thailand: a 20-year retrospective study.

BACKGROUND: The incidence of malaria in Thailand has dramatically declined over the past two decades, and the goal is to eliminate malaria by 2025. Despite significant progress, one of the key challenges to malaria elimination are undetected gametocyte carriers. Human migration adds complexity to the malaria situation, as it not only sustains local transmission but also poses the risk of spreading drug-resistant parasites. Currently, no study has assessed the prevalence of gametocytes across multiple years in Plasmodium falciparum malaria patients in Thailand, and the risk factors for gametocyte carriage have not been fully explored. METHODS: Medical records of all P. falciparum malaria patients admitted from January 1, 2001 to December 31, 2020 at the Hospital for Tropical Diseases, Thailand, were retrospectively examined and a total of 1962 records were included for analysis. Both P. falciparum parasites and gametocytes were diagnosed by microscopy. A regression model was used to evaluate predictors of gametocyte carriage. RESULTS: The study demonstrated gametocyte prevalence in low malaria transmission areas. Nine risk factors for gametocyte carriage were identified: age between 15 and 24 years [adjusted odds ratio (aOR) = 1.96, 95% confidence interval (CI) 1.18-3.26], Karen ethnicity (aOR = 2.59, 95% CI 1.56-4.29), preadmission duration of fever > 7 days (aOR = 5.40, 95% CI 3.92-7.41), fever on admission (> 37.5 °C) (aOR = 0.61, 95% CI 0.48-0.77), haemoglobin ≤ 8 g/dL (aOR = 3.32, 95% CI 2.06-5.33), asexual parasite density > 5000-25,000/µL (aOR = 0.71, 95% CI 0.52-0.98), asexual parasite density > 25,000-100,000/µL (aOR = 0.74, 95% CI 0.53-1.03), asexual parasite density > 100,000/µL (aOR = 0.51, 95% CI 0.36-0.72), platelet count ≤ 100,000/µL (aOR = 0.65, 95% CI 0.50-0.85, clinical features of severe malaria (aOR = 2.33, 95% CI 1.76-3.10) and dry season (aOR = 1.41, 95% CI 1.10-1.80). An increasing incidence of imported transnational malaria cases was observed over the past two decades. CONCLUSIONS: This is the first study to determine the prevalence of gametocytes among patients with symptomatic P. falciparum malaria, identify the risk factors for gametocyte carriage, and potential gametocyte carriers in Thailand. Blocking transmission is one of the key strategies for eliminating malaria in these areas. The results might provide important information for targeting gametocyte carriers and improving the allocation of resources for malaria control in Thailand. This study supports the already nationally recommended use of a single dose of primaquine in symptomatic P. falciparum malaria patients to clear gametocytes.

Mimicking platelet indices in patients with malaria and dengue hemorrhagic fever: characteristics and clinical applications.

BACKGROUND: Although platelet indices are routinely available using automated blood cell counters, the clinical applications of these parameters for malaria and dengue hemorrhagic fever (DHF) have not been substantially implemented. We conducted this study to investigate the potential role of platelet indices as a prognostic marker in adult patients with Plasmodium vivax malaria, Plasmodium falciparum malaria, and DHF admitted to the Hospital for Tropical Diseases, Bangkok, Thailand. METHODS: We enrolled 219 eligible patients, comprising 96 with P. falciparum malaria, 71 with P. vivax malaria, and 52 with DHF. We evaluated the study groups' baseline clinical features and alterations of platelet indices during the first 4 days of admission. RESULTS: Upon admission, the initial laboratory findings showed no statistically significant difference in platelet count (PC), plateletcrit (PCT), or platelet distribution width (PDW) between patients with P. vivax and P. falciparum; however, mean platelet volume (MPV) was significantly higher in patients with P. falciparum. Comparisons of the initial platelet indices in malaria and DHF showed that only PC and PCT were significantly lower in DHF. Although MPV in DHF tended to be lower than in malaria, a statistically significant difference was observed only with P. falciparum. Moreover, the results also showed no significant alterations in the platelet indices among the study groups during the first 4 days of admission. CONCLUSIONS AND RECOMMENDATIONS: Clinical presentations of DHF and malaria are nonspecific and may overlap with other common tropical diseases. Alterations of initial platelet indices may be investigated in P. vivax and P. falciparum malaria mimicking DHF. Although a significant reduction in PC and PCT in DHF might be a clue for differential diagnosis of malaria, the use of MPV and PDW might be impractical. We suggest that appropriate laboratory diagnoses for malaria and dengue infections are still needed for the differential diagnosis of acute febrile patients who have a risk of malaria or dengue infections. To clarify the clinical utility of platelet indices in patients with dengue and malaria, further studies are required that particularly include patients with different severities, geographical areas, and levels of health care settings.

Pfcrt genotypes and related microsatellite DNA polymorphisms on Plasmodium falciparum differed among populations in the Greater Mekong Subregion.

Malaria morbidity and mortality have decreased gradually in the Greater Mekong Subregion (GMS). Presently, WHO sets a goal to eliminate malaria by 2030 in the GMS. However, drug-resistant malaria has been reported from several endemic areas. To achieve the goal of elimination, the status of the emergence and spread of drug resistance should be monitored. In this study, the genotype of the Plasmodium falciparum chloroquine (CQ) resistance transporter gene (pfcrt) and 6 microsatellite DNA loci flanking the gene were examined. P. falciparum isolates (n = 136) was collected from malaria patients in Thailand (n = 50, 2002-2005), Vietnam (n = 39, 2004), Laos (n = 15, 2007) and Cambodia (n = 32, 2009). Amino acid sequences at codons 72-76 on the gene were determined. All of the isolates from Thailand were CQ-resistant (CVIET), as were all of the isolates from Cambodia (CVIET, CVIDT). Thirteen of the 15 isolates (87%) from Laos were CQ-resistant (CVIET, CVIDT), whereas the other 2 (13%) were CQ-susceptible (CVMNK). In contrast, 27 of the 39 isolates (69%) from Vietnam were CQ-susceptible (CVMNK), whereas the other 12 (31%) were CQ-resistant (CVIET, CVIDT, CVMDT) or mixed (CVMNK/CVIDT). The mean of expected heterozygosity of the microsatellite loci was 0.444 in the Thai population, 0.482 in the Cambodian population, and 0.734 in the Vietnamese population. Genetic diversity in the Thai population was significantly lower than that in the Vietnamese population. These results suggested that chloroquine selective pressure on P. falciparum populations is heterogeneous in the GMS. Therefore, further examination to understand the mechanisms behind the emergence and spread of drug-resistant malaria are needed.

Plasma levels of Galectin-9 reflect disease severity in malaria infection.

BACKGROUND: Galectin-9 (Gal-9) is a ß-galactoside-binding lectin that interacts with sugar moieties on glycoproteins and glycolipids of cells and pathogens. Gal-9 is known as an immune modulator that induces cell death via interaction with T cell immunoglobulin and mucin domain-3 (Tim3), a co-inhibitory receptor, and it inhibits production of several pro-inflammatory cytokines (TNF, IL-6 and IL-1α) and enhances production of IL-10. To understand the immune pathology of malaria, the Gal-9 in plasma was measured. METHODS: Plasma samples and clinical parameters were obtained from 50 acute malaria cases (nine severe and 41 uncomplicated cases) from Thailand at three time points: day 0, day 7 and day 28. Gal-9 levels were determined by ELISA. A total of 38 species of cytokines and chemokines were measured using a BioPlex assay. RESULTS: Gal-9 levels were higher at day 0 compared to day 7 and day 28 (P < 0.0001). Gal-9 levels were also higher in severe malaria (SM) cases compared to uncomplicated (UM) cases at day 0 and day 7 (923 vs 617 pg/mL; P = 0.03, and 659 vs 348 pg/mL; P = 0.02 respectively). Median Gal-9 levels were higher in patients with blood urea nitrogen to creatinine ratio (BUN/creatinine) ≥20 (mg/dL) than in patients with BUN/creatinine <20 (mg/dL) at day 0 (817.3 vs 576.2 pg/mL, P = 0.007). Gal-9 was inversely significantly correlated with chloride levels in both SM and UM cases (r s = -0.73 and r s = -0.46, respectively). In both UM and SM cases, Gal-9 was significantly associated with pro- and anti-inflammatory cytokines and chemokines such as TNF, IL-6, IFN-α2, IFN-γ, IL-1Ra and IL-10. These correlations were observed at day 0 but disappeared at day 28. CONCLUSIONS: Gal-9 is released during acute malaria, and reflects its severity. This elevation of Gal-9 in acute malaria infection raises the possibility of its role in termination of the immune response by binding to Tim-3, a receptor of Gal-9.

Evaluation of Efficacy of Chloroquine for Plasmodium Vivax Infection Using Parasite Clearance Times: A 10-Year Study and Systematic Review.

INTRODUCTION: Chloroquine, in combination with primaquine, is used as the firstline treatment for uncomplicated P. vivax malaria in Thailand. In view of the declining efficacy of chloroquine in many P. vivax endemic areas, the possibility of emergence of chloroquine- resistant P. vivax in Thailand is a concern. The aim of this study was to assess the trends in therapeutic efficacy of chloroquine and primaquine for the treatment of uncomplicated P. vivax malaria and to assess the utility of parasite clearance times as a measure of efficacy. MATERIALS AND METHODS: This study consisted of: 1) review of medical records of patients who were hospitalised for a period during their treatment for uncomplicated P. vivax malaria at the Hospital for Tropical Diseases, Bangkok, Thailand between 2004 and 2013. Treatment consisted of chloroquine (1500 mg base administered over 3 days) or chloroquine (as before) plus primaquine (15 to 30 mg base/daily for 14 days from day 2); and 2) systematic review of the literature in English to assess current standards in the reporting of parasite clearance times. RESULTS: The 28-day cure rate was 99.1%. The range of median parasite clearance time over the 10-year period was 46 to 59 hours, and there was statistical evidence for an increasing trend in parasite clearance times between 2009 and 2013. Heterogeneity was noted among previous chloroquine efficacy studies in the measurement and reporting of parasite clearance. CONCLUSION: The treatment of P. vivax infection with a combination of chloroquine and primaquine has remained efficacious in Thailand. Increasing rates of parasite clearance in a population over time may be a useful early warning mechanism for the emergence of chloroquine resistance. The utility of monitoring time-trends in parasite clearance to detect resistance may be enhanced if parasite clearance measurements are standardised.

A Phase 3, Double-Blind, Randomized Study of Arterolane Maleate-Piperaquine Phosphate vs Artemether-Lumefantrine for Falciparum Malaria in Adolescent and Adult Patients in Asia and Africa.

BACKGROUND: Artemisinins, which are derived from plants, are subject to risk of supply interruption due to climatic changes. Consequently, an effort to identify a new synthetic antimalarial was initiated. A fixed-dose combination of arterolane maleate (AM), a new synthetic trioxolane, with piperaquine phosphate (PQP), a long half-life bisquinoline, was evaluated in patients with uncomplicatedPlasmodium falciparummalaria. METHODS: In this multicenter, randomized, double-blind, comparative, parallel-group trial, 1072 patients aged 12-65 years withP. falciparummonoinfection received either AM-PQP (714 patients) once daily or artemether-lumefantrine (A-L; 358 patients) twice daily for 3 days. All patients were followed up until day 42. RESULTS: Of the 714 patients in the AM-PQP group, 638 (89.4%) completed the study; of the 358 patients in the A-L group, 301(84.1%) completed the study. In both groups, the polymerase chain reaction corrected adequate clinical and parasitological response (PCR-corrected ACPR) on day 28 in intent-to-treat (ITT) and per-protocol (PP) populations was 92.86% and 92.46% and 99.25% and 99.07%, respectively. The corresponding figures on day 42 in the ITT and PP populations were 90.48% and 91.34%, respectively. After adjusting for survival ITT, the PCR-corrected ACPR on day 42 was >98% in both groups. The overall incidence of adverse events was comparable. CONCLUSIONS: AM-PQP showed comparable efficacy and safety to A-L in the treatment of uncomplicatedP. falciparummalaria in adolescent and adult patients. AM-PQP demonstrated high clinical and parasitological response rates as well as rapid parasite clearance. CLINICAL TRIALS REGISTRATION: India. CTRI/2009/091/000101.

Incidence of potential rabies exposure among Japanese expatriates and travelers in Thailand.

BACKGROUND: Rabies has become a forgotten and neglected disease in Japan. In 2006, there was a slight increase in social awareness of rabies when Japan had two reported cases of human rabies, originating in the Philippines. Although the number of Japanese either traveling or living in other Asian countries has been increasing, the exact risk of this population contracting rabies is unknown. Thus, this study utilized a questionnaire to investigate the incidence of rabies exposure, as well as the knowledge, attitude, and practice toward rabies prevention among Japanese expatriates and travelers in Thailand. METHODS: Japanese travelers and expatriates were asked questions related to knowledge, attitude, practice toward rabies risk, and experiences of potential rabies exposure such as animal bites, licks, and scratches. Questionnaires were either completed at the Bangkok Suvarnabhumi International Airport and other tourist areas or distributed within Japanese associations in Thailand. RESULTS: A total of 1,208 questionnaires from Japanese expatriates and 590 from Japanese travelers were collected and analyzed. We found high incidence rates of potential exposure events among these populations. In particular, Japanese travelers had the highest incidence rate compared to previous studies of international travelers in Thailand. While expatriates' incidence rates of animal bites, licks, and scratches were 1.7, 6.9, and 1.8/1,000 person-months, travelers have much higher incidence rates of 43.1, 136.1, and 33.0/1,000 person-months. Generally, travelers, compared to expatriates, tended to have less accurate knowledge and less often had the pre-exposure prophylaxis vaccination. Moreover, survey answers indicated that 55.0% of expatriates and 88.9% of travelers who were bitten would not seek proper treatment. CONCLUSIONS: Since rabies is a preventable disease as long as one has the appropriate knowledge, attitude, and practice, it is essential to promote prevention activities for the Japanese population in Thailand to avert serious consequences of this disease.

Transient lesion in the splenium of the corpus callosum in acute uncomplicated falciparum malaria.

Patients with acute uncomplicated Plasmodium falciparum malaria have no evident neurologic disorder, vital organ dysfunction, or other severe manifestations of infection. Nonetheless, parasitized erythrocytes cytoadhere to the endothelium throughout their microvasculature, especially within the brain. We aimed to determine if 3 Tesla magnetic resonance imaging studies could detect evidence of cerebral abnormalities in these patients. Within 24 hours of admission, initial magnetic resonance imaging examinations found a lesion with restricted water diffusion in the mid-portion of the splenium of the corpus callosum of 4 (40%) of 10 male patients. The four patients who had a splenial lesion initially had evidence of more severe hemolysis and thrombocytopenia than the six patients who had no apparent abnormality. Repeat studies four weeks later found no residua of the lesions and resolution of the hematologic differences. These observations provide evidence for acute cerebral injury in the absence of severe or cerebral malaria.

Risk factors of shock in severe falciparum malaria.

The objective of this study was to determine the risk factors for the development of shock in adult patients admitted with severe falciparum malaria. As an unmatched case-control study, the records of patients who were admitted to the Bangkok Hospital for Tropical Diseases, Thailand, between the years 2000-2010, were reviewed. One hundred patients with severe falciparum malaria and shock, and another 100 patients with severe malaria but without shock were studied. Demographics, presenting symptoms, physical observations, and laboratory data of these patients were analyzed. Five risk factors for the development of shock were identified: female gender (OR 6.16; 95% CI 3.17-11.97), red cell distribution width (RDW) >15% (adjusted OR 2.90; 95% CI 1.11-7.57), anorexia (adjusted OR 2.76; 95% CI 1.03-7.39), hypoalbuminemia (adjusted OR 2.19; 95% CI 1.10-4.34), and BUN-creatinine ratio >20 (adjusted OR 2.38; 95% CI 1.22-4.64). Diarrhea was found to be a protective factor (adjusted OR 0.33; 95% CI 0.14-0.78). Metabolic acidosis was only weakly correlated to mean arterial blood pressure on admission (r(s) = 0.23). Female gender was the strongest risk factor for the development of shock. We concluded that female gender, RDW >15%, anorexia, hypoalbuminemia, and BUN-creatinine ratio >20 were risk factors of shock development in severe falciparum malaria.

Sexual behavior of foreign backpackers in the Khao San Road area, Bangkok.

Travelers play a role in the spread of sexually transmitted diseases, including HIV because of having unprotected sex. We studied the incidence of casual sex among foreign backpack tourists in the Khao San Road area of Bangkok, Thailand. We also evaluated their attitudes about sexual health and their actual practices. A cross sectional study was conducted using a self-administered, anonymous questionnaire. The target population was backpackers aged > or =18 years, from Europe, North America and Australia. In total, 415 questionnaires were filled out and analyzed. Sixty-four percent of participants were male, the overall median age was 27 years and the mean duration of stay was 14.6 days. One hundred seven respondents (25%) had casual sex while staying in Thailand; of these, 55% always used condoms. The selection of sex partner influenced the use of condoms. The highest rate of condom use was among backpackers who had sex with sex workers (63%), while those who had sex with their travel partners had the lowest rate of condom use (35.6%). One-fourth of backpackers in our study had casual sex during their trip. Their attitudes towards safe sex practices were not ideal. Methods to change attitudes and behavior about unprotected sex need to be explored in this population.

Chronic hepatitis B prognostic markers other than pre-treatment viral load predicted composite treatment outcome.

INTRODUCTION: Chronic hepatitis B (CHB) is a globally common infectious disease. Its clinical course is complicated. In Southeast Asia, nucleos(t)ide analogues (NA) are commonly used drugs for CHB treatment. Composite treatment outcome has often been used in CHB clinical practice, but rarely predicted epidemiologically. This study aimed to compare the composite treatment outcome between CHB patients with low and high treatment-naïve viral load, and to identify its predictors METHODOLOGY: This retrospective cohort study followed up 95 CHB patients on NA treatment for a year. Composite treatment outcome was defined as undetectable HBV DNA level, ALT normalization and, HBeAg clearance in the case of HBeAg-positive patients. Multinomial logistic regression analysis was applied to analyze the significant treatment response predictors. RESULTS: Complete composite treatment outcome was achieved by 52% of CHB patients with an initial viral load < 6.5 log 10 copies /ml, but 31% of those had an initial viral load ≥ log 6.5 log 10 copies /ml. Outcome was predicted by HBeAg negativity (adjusted relative risk ratio, aRRR = 11.1, 95 % confidence interval, CI 3-41.3) and ALT normalization within the sixth month of therapy (aRRR = 6.7, CI 1.8-24.9). An elevation of ALT to more than 1.5 times the normal value (40 IU/ml) can lead to an incomplete response on NA therapy (aRRR = 6.2, CI 1.5-26.6.) CONCLUSION: Routine clinical markers other than pre-treatment viral load predicted composite CHB outcome on NA Therapy.

Factors associated with cerebral malaria.

We conducted a retrospective unmatched case-control study using the medical records of patients admitted to the Hospital for Tropical Diseases, Mahidol University, Bangkok, Thailand to investigate factors associated with cerebral malaria. The records of 137 patients with severe Plasmodium falciparum without cerebral malaria and 35 patients with cerebral malaria hospitalized during 1997-2005 were reviewed and compared. Ten factors associated with cerebral malaria were identified: pulmonary edema [odds ratio (OR)= 13.8; 95% confidence interval (CI): 1.3-143.2], splenomegaly (OR=3.7; 95% CI: 1.3-44.7), fever (OR=3.3; 95% CI: 1.7-14.3), day 1 malarial density < or = 249,999/microl (OR=1.6; 95% CI: 1.1-14.6), day 2 malarial density < or =249,999/microl (OR=3.4; 95% CI: 1.3-35.1), dyspnea (OR=1.4; 95% CI: 1.2-12.1), hepatomegaly (OR=1.8; 95% CI: 0.2-12.1), being a referred patient (OR=1.3; 95% CI: 1.0-2.2), a higher systolic blood pressure (OR=1.2; 95% CI: 1.0-2.1) and a higher body mass index (OR=1.6; 95% CI: 1.0-2.6). Pulmonary edema was the strongest factor associated with cerebral malaria in our study. Clinicians who treat patients with severe Plasmodium falciparum malaria should be aware these factors are associated with cerebral malaria.

Schizontemia as an indicator of severe malaria.

We conducted this study to determine if the finding of schizontemia could be used as an indicator of severe falciparum malaria. We enrolled 250 patients with severe falciparum malaria and 250 patients with umcomplicated falciparum malaria into the study. Severe falciparum malaria was defined following World Health Organization criteria (2010). Of the 250 patients with severe falciparum malaria, 99 (39.6%) had schizontemia on admission. Of the 250 patients with uncomplicated falciparum malaria, 0 (0%) had schizontemia (p<0.05). Schizontemia was also found to be significantly correlated with parasite density, severe malaria, impaired consciousness, pulmonary edema, hypoglycemia, jaundice and hemoglobinuria (p<0.05). Schizontemia may be considered as an indicator of severe malaria.

Activation of nuclear factor kappa B in peripheral blood mononuclear cells from malaria patients.

BACKGROUND: Malaria parasites and their products can activate a specific immune response by stimulating cytokine production in the host's immune cells. Transcription nuclear factor kappa B (NF-κB) is an important regulator for the control of many pro-inflammatory genes, such as interleukin-1 (IL-1) and tumor necrosis factor (TNF). The activation and expression of NF-κB p65 in peripheral blood mononuclear cells (PBMCs) of malaria patients were investigated and correlated with the levels of IL-10 and TNF to study the nature of NF-κB p65 and its linkage to inflammatory cytokines. METHODS: The sample group comprised 33 patients admitted with malaria caused by Plasmodium vivax (n = 11), uncomplicated Plasmodium falciparum (n = 11), and complicated Plasmodium falciparum (n = 11). Peripheral blood was collected at admission and on day 7 for PBMC isolation. Healthy subjects were used as a control group. The expressions of NF-κB p65 in the PBMCs from malaria patients and the plasma levels of IL-10 and TNF were measured by using enzyme-linked immunosorbent assay (ELISA). The immunofluorescence technique was used to determine NF-κB nuclear translocation. RESULTS: At admission, patients with P. vivax and uncomplicated P. falciparum had significantly elevated phospho-NF-κB p65 levels in the PBMCs compared with those of healthy controls. However, patients with complicated P. falciparum malaria had decreased levels of phospho-NF-κB p65. On day 7 post-treatment, significantly increased phospho-NF-κB p65 was found in the PBMCs of patients with complicated P. falciparum, compared with healthy controls. The plasma level of IL-10 was elevated in day 0 in patients with complicated P. falciparum malaria and was found to be negatively correlated with phospho-NF-κB p65 level (rs = -0.630, p = 0.038). However, there was no correlation between phospho-NF-κB p65 expression and TNF level in patients with complicated P. falciparum malaria. CONCLUSIONS: This is the first report demonstrating alterations in NF-κB p65 activity in the PBMCs of malaria patients. The altered lower features of NF-κB p65 in the PBMCs of patients with complicated P. falciparum at admission could be due to a suppressive effect of high IL-10 associated with complicated P. falciparum malaria.

Arterolane maleate plus piperaquine phosphate for treatment of uncomplicated Plasmodium falciparum malaria: a comparative, multicenter, randomized clinical trial.

BACKGROUND: Artemisinin-based combination therapy is the first-line treatment for uncomplicated falciparum malaria. This study assessed the antimalarial efficacy and safety of a combination of 150 mg of arterolane maleate and 750 mg of piperaquine phosphate (AM-PQP) in comparison to Coartem (artemether and lumefantrine) in patients with acute uncomplicated P. falciparum malaria. METHODS: In this open-label, randomized, multicentric, parallel group clinical trial, 240 patients were randomized to receive AM-PQP (160 patients) or Coartem (80 patients). Patients with P. falciparum monoinfection and initial parasite densities ranging from 1000 to 100 000 asexual parasites/µL of blood were followed for 28 days. Polymerase chain reaction-corrected adequate clinical and parasitologic response on day 28, parasite clearance time, and fever clearance time were evaluated. RESULTS: A total of 151 (94.4%) of 160 patients in the AM-PQP group completed the trial, while 77 (96.3%) of 80 patients in the Coartem group completed the trial. No treatment failure was noted in the AM-PQP group, while one patient receiving Coartem failed treatment on day 28. There was no difference in the median parasite clearance time (30 hours in both groups) or median fever clearance time (24 hours in both groups) after administration of the 2 study treatments. CONCLUSIONS: The available data support the evaluation of a drug combination in a larger population as a fixed-dose combination. Clinical Trials Registration. CTRI/2007/091/000031.

Use of buffy coat thick films in detecting malaria parasites in patients with negative conventional thick films.

OBJECTIVE: To determine the frequency of malaria parasite detection from the buffy coat blood films by using capillary tube in falciparum malaria patients with negative conventional thick films. METHODS: Thirty six uncomplicated falciparum malaria patients confirmed by conventional thick and thin films were included in the study. The patients were treated with artemisinin combination therapy at Hospital for Tropical Diseases, Bangkok, Thailand for 28 day. Fingerpricks for conventional blood films were conducted every 6 hours until negative parasitemia, then daily fingerpricks for parasite checks were conducted until the patients were discharged from hospital. Blood samples were also concurrently collected in 3 heparinized capillary tubes at the same time of fingerpricks for conventional blood films when the prior parasitemia was negative on thin films and parasitemia was lower than 50 parasites/200 white blood cells by thick film. The first negative conventional thick films were compared with buffy coat thick films for parasite identification. RESULTS: Out of 36 patients with thick films showing negative for asexual forms of parasites, buffy coat films could detect remaining 10 patients (27.8%) with asexual forms of Plasmodium falciparum. CONCLUSIONS: The study shows that buffy coat thick films are useful and can detect malarial parasites in 27.8% of patients whose conventional thick films show negative parasitemia.

Observation of genotype C infected chronic hepatitis B patients in clinical practice.

INTRODUCTION: Hepatitis B virus (HBV) genotype C is prevalent in many areas of the world including Thailand and Southeast Asia. It is a strong risk for hepatocellular carcinoma (HCC) by evidence. We aimed to describe the baseline clinical information of treatment naïve genotype C infected chronic hepatitis B (CHB) patients and to describe the treatment response by surrogate outcome markers in genotype C infected CHB patients after one year of nucleos(t)ide analogues (NA) treatment METHODOLOGY: Thirty-four genotype C CHB patients were studied at the Hospital for Tropical Diseases, Bangkok, including 12 patients treated with lamivudine, 11 with telbivudine, 8 with adefovir, and 3 with entecavir. Serum HBV DNA levels, serum alanine amino transferase ( ALT ) levels, HBeAg status, and alpha-feto protein (AFP) levels were recorded at the start and after twelve months of ongoing treatment. HBV genotyping was performed by line-probe assay. RESULTS: About half of the patients (58.8%) were HBeAg positive. Mean HBV viral load was 6.53 + 1.15 log10 copies per ml at baseline and reduced to 3.63 + 1.3 log10 copies per ml after one year of NA treatment. Serum HBV DNA levels became undetectable in 47.1 % of the patients and serum ALT was normalized in 23.5 % of the patients. CONCLUSION: Most of the genotype C patients were aged above 40 years. More than half of the genotype C infected patients did not achieve virological response and biochemical remission. Among the CHB patients, genotype C infected patients are a high priority group for intervention.

Evaluation of the NOW Malaria Immunochromatographic Test for Quantitative Diagnosis of Falciparum and Vivax Malaria Parasite Density.

The NOW® Malaria Test, an immunochromatographic test (ICT), was evaluated to determine its ability to quantitatively detect malaria parasites using 100 blood samples from Thailand, including 50 Plasmodium falciparum (Pf) infections and 50 P. vivax (Pv) infections. Intensities of the thickness of the visible bands of the positive ICT were compared with the parasite densities. In cases of Pf infection, the intensities of both HRP-2 bands (T1 bands: Pf specific bands) and aldolase bands (T2 bands: pan-Plasmodium bands) correlated with the parasite densities. The intensities of T2 bands in Pf positive samples showed better correlation with the parasite densities than the T1 bands. In the cases of Pv infection, the intensities of T2 bands were also well correlated with parasite density. These results suggest that the ICT is useful not only for rapid detection of malaria parasites but also for estimating parasite density.

Factors associated with acute renal failure in falciparum malaria infected patients.

To identify factors associated with acute renal failure among patients with severe falciparum malaria (MARF), we studied 189 severe malaria patients admitted to the Hospital for Tropical Diseases, Faculty of Tropical Medicine, Mahidol University, in Bangkok, Thailand. Among these, 63 had MARF, and 126 did not. Baseline clinical demographics and laboratory variables were evaluated with univariate analysis. Logistic regression was used to ascertain adjusted odds ratios. By univariate analysis, factors associated with MARF included male gender, fever duration > 4 days, patients who lived in a non-endemic area prior to malaria infection, body mass index > 18.5 kg/m(2), oliguria, abdominal pain, impaired consciousness, jaundice, anemia, liver enlargement, total white blood cell count > 10x10(9)/1, total bilirubin > 3 mg/dl, aspartate aminotransferase > 120 U/l, alanine aminotransferase > 120 U/l, albumin < 3 g/dl, fever clearance time >72 hours, and parasite clearance time > 72 hours. A hemoglobin > 10 g/dl, patients living in a malaria endemic area, non-oliguria on the day of admission, and splenomegaly were negatively associated with MARF. After multivariate logistic regression, oliguria during the first 24 hours of admission and a history of living in a nonendemic area prior to malarial infection were factors associated with MARF. We conclude the most significant factors associated with MARF were oliguria on the day of admission and living in a non-endemic area prior to malaria infection.