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 β-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.

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.

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.

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.

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.

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.

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.

Nucleos(t)ide analogues treatment outcome in genotype B and C chronic hepatitis B

Background:

Hepatitis B genotypes influence the course and severity of the disease.

Aim:

To compare the treatment outcome of chronic hepatitis B genotype B and C patients after treating with nucleos(t)ide analogues for six months.

Patients and Methods:

Forty chronic hepatitis B patients attending the liver clinic of Hospital for Tropical diseases, Bangkok, were studied in retrospective cohort design. Six genotype B patients (15%) and thirty-four genotype C patients (85%) were treated. Serum hepatitis B viral load, serum alanine amino transferase level, HBeAg status and alpha-feto protein level were measured at the time of starting nucleos(t) analogues therapy, and six months later. Besides, achievement of undetectable viral load was assessed in patients with normal serum alanine amino transferase compared to patients with high serum alanine amino transferase level.

Results:

After six months of nucleos (t) analogues treatment, achievement of undetectable hepatitis B viral load was higher in genotype B patients (66.7%) than in genotype C patients (42.4%) (Relative Risk=1.57, 0.79-3.14). Biochemical remission, HBeAg seroconversion and tumor marker levels between the two groups were not significantly different. Moreover, achievement of undetectable hepatitis B viral load was significantly higher in normal alanine amino transferase level (75%) than in patients with high serum alanine amino transferase level (33.3%) on nucleos(t)ide analogue treatment (Relative Risk=2.25, 1.20- 4.20).

Conclusion:

Chronic hepatitis B treatment outcome between genotype B and C were not significantly different. Patients with normalized serum alanine amino transferase level tend to achieve undetectable viral load after nucleoside analogues treatment.

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.

Falciparum malaria parasitemia index for predicting severe malaria

INTRODUCTION

While hyperparasitemia is considered an important indicator for the development of severe malaria, there is currently no consensus on the quantitative definition of hyperparasitemia. This study was conducted to establish a cutoff point for peripheral parasitemia among patients with Plasmodium falciparum malaria, to define severe malaria.

METHODS

The clinical presentations of 200 uncomplicated P. falciparum malaria, and 189 severe P. falciparum malaria, patients, admitted to the Hospital for Tropical Diseases, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand, were analyzed.

RESULTS

A peripheral parasitemia of 0.5% was found to be the optimal cutoff point for defining severe malaria, demonstrating highest sensitivity (85.1%), specificity (62.0%), and accuracy (73.2%).

CONCLUSION

Symptoms of severe falciparum malaria depend on many factors. For the definition of hyperparasitemia in areas of low or seasonal transmission, peripheral parasitemia of 0.5% might be considered a cutoff point for discrimination between severity levels. This value might be useful for the clinical management of malaria, particularly in hypo-endemic areas, unstable transmission areas, and other areas with similar transmission patterns.

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.

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.

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.

Effect of artesunate and mefloquine in combination on the Fridericia corrected QT intervals in Plasmodium falciparum infected adults from Thailand

OBJECTIVE

To ascertain whether mefloquine (MQ) produces electrocardiogram (ECG) changes that could be a risk for Torsades de Pointe (TdP), a potentially malignant, ventricular tachyarrhythmia.

METHODS

We measured the Fridericia corrected QT (QTcF) intervals on 12 lead ECGs on days (D) 0, 3, 7 in Plasmodium falciparum infected adults, treated with oral artesunate (AS) and MQ as a new fixed dose (n = 25) combination or loose tablets (n = 25) over 3 days. Target total doses were 12 mg/kg of AS and 24-25 mg/kg of MQ. MQ concentrations ([MQ]) were measured by HPLC.

RESULTS

All ECG intervals were similar between drug arms and were combined for analysis. Mean QTcF values were 389 (D0), 407 (D3) and 399 (D7) ms (Ps < 0.003 vs. D0); corresponding heart rates and [MQ]s were 83, 67 and 73 beats/minute (Ps ≤ 0.0003 vs. D0) and 0, 3095 and 1721 ng/ml. One male patient (loose arm) had a D3 QTcF 504 ms (D0 406 ms, D7 433 ms). In the modelling of QTcF and JTcF from D0 to D7, significant effects were observed individually for [MQ], temperature and heart rate (HR). The MQ AUC(0-∞) was not a significant factor. Using a manual descending, model building approach to select variables, the HR was the only significant variable (P = 0.001) over time in the model that best explained the changes in the QTcF and JTcF intervals.

CONCLUSIONS

In this small group of patients, slowing heart rates due to malaria resolution best explained the observed increases in the QTcF intervals.

Arterolane, a new synthetic trioxolane for treatment of uncomplicated Plasmodium falciparum malaria: a phase II, multicenter, randomized, dose-finding clinical trial

BACKGROUND

Drug-resistant Plasmodium falciparum malaria necessitates development of novel drugs for treatment.The present study assessed the efficacy and safety of 3 dose levels of arterolane (RBx 11160), a synthetic trioxolane, for treatment of acute uncomplicated falciparum malaria.

METHODS

In this randomized, double-blind, multicenter, parallel-group, dose-finding, phase II trial, 230 patients from 4 centers in Thailand, India, and Tanzania (mainland and Zanzibar) received either 50 mg (n=78), 100mg (n=76), or 200 mg (n=76) of arterolane once daily for 7 days. Patients (aged 13-65 years) with asexual parasite density of 1000-100,000 parasites/microL were included and were followed up for 28 days. The median time to 90% parasite clearance (PC90) was evaluated.

RESULTS

The median PC90 was longer in the group receiving the 50-mg dose (19.4 h), compared with the groups receiving the 100-mg dose (12.8 h) and 200-mg dose (12.6 h) (P < .01). The polymerase chain reaction-corrected adequate clinical and parasitological responses on day 28 were 63%, 71%, and 72% for the groups receiving the 50-mg, 100-mg, and 200-mg doses, respectively, by intention-to-treat analysis (odds ratio, 1.55; 95%confidence interval, 0.78-3.06, for comparison of the 200-mg and 50-mg dose groups). Treatment was generally well tolerated. No patient died or experienced any serious adverse event. Mild complaints were reported in <10%of the patients and were similar in the 3 groups. Biochemistry and hematological analyses did not show any signof drug toxicity in any patient.

CONCLUSION

Arterolane at daily doses of 100 and 200 mg is a rapidly acting, effective, and safe synthetic antimalarial drug, which may potentially represent an alternative to artemisinin derivatives in antimalarial combination therapy.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT00362050.

Long term primaquine administration to reduce Plasmodium falciparum gametocyte transmission in hypoendemic areas

Artemesinin-combination therapies (ACTs) for falciparum malaria reduce gametocyte carriage, and therefore reduce transmission. Artemisinin derivatives act only against young gametocytes, but primaquine acts against mature gametocytes (which are usually present in the circulation at the time the patient presents for treatment). Both artemisnin derivatives and primaquine have short half-lives (less than 1 hour and 8 hours, respectively). Therefore, asexual parasites and young gametocytes may remain after completing ACT. Single dose of primaquine (0.5-0.75 mg base/kg) at the end of ACT can kill only mature gametocytes (if present) but cannot kill young gametocytes (if present). Remaining asexual forms and sequestered young gametocytes remaining after completion of ACT may develop into mature gametocytes 7-15 days later. Some patients have the first appearance of gametocytemia 4-8/day after completion of ACT. Thus, additional doses of primaquine (0.5-0.75 mg base/kg) given 15-18 days after or concurrently with 3 day-ACT respectively or given 15-22 days after or concurrently with 7 day-ACT respectively may be beneficial in killing the remaining mature gametocytes and thus contribute to interruption of P. falciparum gametocyte transmission more affectively than giving only a single dose of primaquine just after completing ACT.

Cruveilhier-Baumgarten syndrome in a cirrhotic patient taking alcohol with Boesenbergia pundurata

Cruveilhier-Baumgarten syndrome (CBS) is a rare complication of cirrhosis. We reported a case of CBS who came to hospital with progressive ascites, jaundice, fever and upper gastrointestinal bleeding. The cause of cirrhosis and hepatitis might be due to alcohol and possibly local Thai herb [Boesenbergia pundurata (Roxb.) Schitr or Krachaidum].

Changes in platelet count in uncomplicated and severe falciparum malaria

This study investigated alterations in platelet counts pre- and post-treatment with artemisinin derivatives in uncomplicated and severe falciparum malaria. Serial platelet counts were taken over 4 weeks for 110 uncomplicated and 110 severe falciparum malaria patients admitted to the Hospital for Tropical Diseases during 2005-2008. On admission, prior to treatment, thrombocytopenia was found in 73.6% of uncomplicated falciparum malaria patients and 90.9% of severe falciparum malaria cases. Platelet levels significantly lower in severe malaria cases. Although initial platelet counts were lower than normal in both study groups, they slowly increased significantly over time, and approached normal levels by several weeks post-treatment. No bleeding was evident during treatment, and none of the patients required a platelet transfusion. Platelet transfusions are not required for malaria patients with thrombocytopenia who have no bleeding.

Factors associated with acute renal failure in severe falciparum [corrected] malaria patients

Acute renal failure (ARF) is a common cause of morbidity and mortality in severe malaria infection. We evaluated factors associated with acute renal failure in severe malaria by comparing patients with severe malaria with and without ARF admitted to the Hospital for Tropical Diseases, Bangkok, Thailand. Nine hundred fifteen severe malaria patients were included in the study, of whom 195 had ARF and 720 did not have ARF. We found jaundice, anemia, hypoalbuminemia, hyponatremia, hyperkalemia, acidosis, leukocytosis, elevated transaminases (SGOT and SGPT) and cerebral malaria, were significantly associated with ARF among patients with severe malaria (p < 0.05). Patients who have ARF and any of these clinical or laboratory manifestations of severe malaria should be monitored and managed properly, since early detection and treatment may reduce morbidity and mortality.

Intravenous ibuprofen (IV-ibuprofen) controls fever effectively in adults with acute uncomplicated Plasmodium falciparum malaria but prolongs parasitemia

Because some febrile patients are unable to swallow or retain oral antipyretic drugs, we carried out a double-blind, placebo-controlled trial in which intravenous ibuprofen (IV-ibuprofen) was given to adults hospitalized with fever associated with acute uncomplicated falciparum malaria treated with oral artesunate plus mefloquine. Thirty patients received IV-ibuprofen 400 mg and 30 received placebo every 6 hours for 72 hours. Reduction in the area above 37.0 degrees C versus time curve was significantly greater for IV-ibuprofen than for placebo during the first 72 hours after first administration. No patients developed severe malaria; parasite clearance was delayed in the patients whose fevers were controlled by IV-ibuprofen (median 37.3 hours versus 23.7 hours in the placebo group [P = 0.0024]). This difference did not appear to be clinically important Adverse events, none considered severe, occurred equally in both groups. IV-ibuprofen was effective and well tolerated in reducing fever in febrile inpatients with malaria.

Primaquine administration after falciparum malaria treatment in malaria hypoendemic areas with high incidence of falciparum and vivax mixed infection: pros and cons

Mixed infections of Plasmodium falciparum and Plasmodium vivax is high (approximately 30%) in some malaria hypoendemic areas where the patients present with P. falciparum malaria diagnosed by microscopy. Conventional treatment of P. falciparum with concurrent chloroquine and 14 days of primaquine for all falciparum malaria patients may be useful in areas where mixed falciparum and vivax infections are high and common and also with mild or moderate G6PD deficiency in the population even with or without subpatent vivax mixed infection. It will be possibly cost-effective to reduce subsequent vivax illness if the patients have mixed vivax infection. Further study to prove this hypothesis may be warranted.

Appropriate time for primaquine treatment to reduce Plasmodium falciparum transmission in hypoendemic areas

Artemesinin-combination therapies (ACT) for falciparum malaria reduce gametocyte carriage, and therefore reduce transmission. Artemisinin derivatives will act against only young gametocytes whereas primaquine acts on mature gametocytes which are present usually in the circulation at the time when the patient presents for treatment. Both artemisinin derivatives and primaquine have short half-lives, less than 1 hr and 7 hr, respectively. Therefore, asexual parasites or young gametocytes remain after completed ACT. A single dose of primaquine (0.50-0.75 mg base/kg) at the end of ACT can kill only mature gametocytes but cannot kill young gametocytes (if present). Remaining asexual forms after completion of ACT course, e.g., artesunate-mefloquine for 3 days, may develop to mature gametocytes 7-15 days later. Thus, an additional dose of primaquine (0.50-0.75 mg base/kg) given 2 weeks after ACT completion may be beneficial for killing remaining mature gametocytes and contribute to more interruption of Plasmodium falciparum transmission than giving only 1 single dose of primaquine just after completing ACT.

Vitamin K injection in spontaneous bleeding and coagulopathy in severe malaria: pros and cons

Not all clinicians give vitamin K to severe malaria patients with systemic bleeding. Vitamin K injections may not be useful to stop bleeding in severe malaria patients with predominant hepatocellular jaundice. However, vitamin K may be justified in bleeding patients who have prolonged fasting of more than 3-7 days, underlying malnutrition, or predominant cholestatic jaundice. The decision to give vitamin K to severe malaria patients with systemic bleeding should be based on underlying diseases, type of jaundice, risk for vitamin K deficiency, and allergy to the drug.

Management of Plasmodium knowlesi malaria without PCR confirmation

Plasmodium knowlesi morphologically resembles P. malariae; PCR assays are able to differentiate between the 2 species correctly. However, PCR is not available in many hospitals in P. knowlesi endemic areas, particularly in Southeast Asia. In places where PCR is not available, anti-malarial drugs for P. malariae or other non-P. falciparum or P. falciparum species are effective against P. knowlesi. Even with a wrong diagnosis of another malaria species by light microscopy instead of P. knowlesi, the antimalarial drugs given are still effective for treating P. knowlesi infection.

Whole blood angiopoietin-1 and -2 levels discriminate cerebral and severe (non-cerebral) malaria from uncomplicated malaria

Background

Severe and cerebral malaria are associated with endothelial activation. Angiopoietin-1 (ANG-1) and angiopoietin-2 (ANG-2) are major regulators of endothelial activation and integrity. The aim of this study was to investigate the clinical utility of whole blood angiopoietin (ANG) levels as biomarkers of disease severity in Plasmodium falciparum malaria.

Methods

The utility of whole blood ANG levels was examined in Thai patients to distinguish cerebral (CM; n = 87) and severe (non-cerebral) malaria (SM; n = 36) from uncomplicated malaria (UM; n = 70). Comparative statistics are reported using a non-parametric univariate analysis (Kruskal-Wallis test or Chi-squared test, as appropriate). Multivariate binary logistic regression was used to examine differences in whole blood protein levels between groups (UM, SM, CM), adjusting for differences due to ethnicity, age, parasitaemia and sex. Receiver operating characteristic curve analysis was used to assess the diagnostic accuracy of the ANGs in their ability to distinguish between UM, SM and CM. Cumulative organ injury scores were obtained for patients with severe disease based on the presence of acute renal failure, jaundice, severe anaemia, circulatory collapse or coma.

Results

ANG-1 and ANG-2 were readily detectable in whole blood. Compared to UM there were significant decreases in ANG-1 (p < 0.001) and significant increases in ANG-2 (p < 0.001) levels and the ratio of ANG-2: ANG-1 (p < 0.001) observed in patients with SM and CM. This effect was independent of covariates (ethnicity, age, parasitaemia, sex). Further, there was a significant decrease in ANG-1 levels in patients with SM (non-cerebral) versus CM (p < 0.001). In participants with severe disease, ANG-2, but not ANG-1, levels correlated with cumulative organ injury scores; however, ANG-1 correlated with the presence of renal dysfunction and coma. Receiver operating characteristic curve analysis demonstrated that the level of ANG-1, the level of ANG-2 or the ratio of ANG-2: ANG-1 discriminated between individuals with UM and SM (area under the curve, p-value: ANG-2, 0.763, p < 0.001; ANG-1, 0.884, p < 0.001; Ratio, 0.857, p < 0.001) or UM and CM (area under the curve, p-value: ANG-2, 0.772, p < 0.001; ANG-1, 0.778, p < 0.001; Ratio, 0.820, p < 0.001).

Conclusions

These results suggest that whole blood ANG-1/2 levels are promising clinically informative biomarkers of disease severity in malarial syndromes.

Use of peroxisome proliferator-activated receptor gamma agonists as adjunctive treatment for Plasmodium falciparum malaria: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Despite the use of potent antimalarial drugs, the fatality rate associated with severe malaria remains high. Adjunctive therapies that target the immunopathological responses to infection may decrease mortality associated with severe malaria. We hypothesized that peroxisome proliferator-activated receptor gamma agonists (eg, rosiglitazone) would modulate the host's innate immune response to malaria and improve outcome.

METHODS

In a randomized, double-blind, placebo-controlled, phase I/II trial of treatment for malaria acquired in Thailand, we investigated the safety, tolerability, and efficacy of rosiglitazone use for parasite clearance and for reducing malaria-induced inflammation. Sequential patients with uncomplicated Plasmodium falciparum malaria were randomly assigned to 1 of 2 groups: 70 patients received rosiglitazone 4 mg twice daily for 4 days, and 70 patients received a placebo twice daily for 4 days. Both groups also received standard antimalarial therapy (ie, a fixed combination of 1000 mg of atovaquone per day for 3 days and 400 mg of proguanil per day for 3 days). Primary efficacy outcomes were 50% and 90% parasite clearance times (PCTs). Secondary outcomes were fever clearance time, levels of inflammatory mediators, blood glucose measurements, aminotransferase levels, admission to intensive care, and subjective tolerability of study drug.

RESULTS

For the 70 patients who received rosiglitazone, parasite clearance from peripheral blood was significantly enhanced, compared with the 70 patients who received a placebo (mean 50% PCT, 19.0 h vs. 24.6 h [p = .029]; mean 90% PCT, 30.9 h vs. 40.4 h [p = .004]). Also, the patients who received rosiglitazone had reduced inflammatory responses to infection, compared with the patients who received a placebo (ie, interleukin-6 levels at 24 h [p < .005] and at 48 h [p = .013] and monocyte chemoattractant protein-1 level at 48 h [p = .05]). There were no significant differences between the 2 groups with regard to safety and tolerability of treatment, and there were no admissions the intensive care unit or deaths.

CONCLUSIONS

The use of rosiglitazone is a well-tolerated adjunct to standard therapy for nonsevere P. falciparum malaria. Treatment with rosiglitazone increased parasite clearance and decreased inflammatory biomarkers associated with adverse malaria outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT00149383 .

Misclassification of drug failure in Plasmodium falciparum clinical trials in southeast Asia

Most trials of antimalarials occur in areas in which reinfections are possible. For Plasmodium falciparum, reinfections are distinguished from recrudescences by polymerase chain reaction analysis of 3 polymorphic genes. However, the validity of this approach has never been rigorously tested. We tested for misclassification in 6 patients from clinical trials in Thailand and Cambodia who were classified as being reinfected by the standard polymerase chain reaction protocol. Using heteroduplex tracking assays and direct DNA sequencing, we found that 5 (83%) of 6 patients were misclassified. Misclassification in this manner overestimates the efficacy of antimalarials and delays the recognition of decreasing therapeutic efficacy, thus delaying potential changes in policy.

Malaria diagnosis: a brief review

Malaria is a major cause of death in tropical and sub-tropical countries, killing each year over 1 million people globally; 90% of fatalities occur in African children. Although effective ways to manage malaria now exist, the number of malaria cases is still increasing, due to several factors. In this emergency situation, prompt and effective diagnostic methods are essential for the management and control of malaria. Traditional methods for diagnosing malaria remain problematic; therefore, new technologies have been developed and introduced to overcome the limitations. This review details the currently available diagnostic methods for malaria.

Differences in genetic population structures of Plasmodium falciparum isolates from patients along Thai-Myanmar border with severe or uncomplicated malaria

BACKGROUND

There have been many reports on the population genetic structures of Plasmodium falciparum from different endemic regions, but few studies have examined the characteristics of isolates from patients with different clinical outcomes. The population genetic structures of P. falciparum isolates from patients with either severe or uncomplicated malaria were examined.

METHODS

Twelve microsatellite DNA loci from P. falciparum were used to assess the population genetic structures of 50 isolates (i.e., 25 isolates from patients with severe malaria and 25 from patients with uncomplicated malaria) collected in the Thai-Myanmar border area between 2002 and 2005.

RESULTS

Genetic diversity and effective population sizes were greater in the uncomplicated malaria group than in the severe malaria group. Evidence of genetic bottlenecks was not observed in either group. Strong linkage disequilibrium was observed in the uncomplicated malaria group. The groups demonstrated significant genetic differentiation (P < 0.05), and allele frequencies for 3 of the 12 microsatellite loci differed significantly between the two groups.

CONCLUSION

These findings suggest that the genetic structure of P. falciparum populations in patients with severe malaria differs from that in patients with uncomplicated malaria. The microsatellite loci used in this study were presumably unrelated to antigenic features of the parasites, but, these findings suggest that some loci may influence the clinical outcome of malaria.

Hyponatraemia and hypokalaemia in adults with uncomplicated malaria in Thailand

In a retrospective study of 1415 patients aged 15 and over, we determined the incidence of clinically important hyponatraemia and hypokalaemia in adults with uncomplicated malaria. On admission, serum concentrations of sodium (135-145 mmol/L) and potassium (3.5-5.0 mmol/L) were found outside these reference ranges in 81% of patients. Severe hypokalaemia (K+ <3.0 mmol/L) and severe hyponatraemia (Na+ <125 mmol/L occurred in 4.4% and 0.6% of the patients, respectively. For hypokalaemia (43%) and hyponatraemia (37%), hypovolaemia, blood urea to creatinine ratio and high serum glucose (>100 mg/dL) were all independent factors (P < 0.001). Other independent predictors for hypokalaemia were Plasmodium vivax infection, female gender; and for hyponatraemia, P. falciparum infection, male gender, concentrations of G-6-PD and serum bicarbonate.

Gametocyte clearance in uncomplicated and severe Plasmodium falciparum malaria after artesunate-mefloquine treatment in Thailand

Artemisinin-based combination therapy (ACT) is currently promoted as a strategy for treating both uncomplicated and severe falciparum malaria, targeting asexual blood-stage Plasmodium falciparum parasites. However, the effect of ACT on sexual-stage parasites remains controversial. To determine the clearance of sexual-stage P. falciparum parasites from 342 uncomplicated, and 217 severe, adult malaria cases, we reviewed and followed peripheral blood sexual-stage parasites for 4 wk after starting ACT. All patients presented with both asexual and sexual stage parasites on admission, and were treated with artesunate-mefloquine as the standard regimen. The results showed that all patients were asymptomatic and negative for asexual forms before discharge from hospital. The percentages of uncomplicated malaria patients positive for gametocytes on days 3, 7, 14, 21, and 28 were 41.5, 13.1, 3.8, 2.0, and 2.0%, while the percentages of gametocyte positive severe malaria patients on days 3, 7, 14, 21, and 28 were 33.6, 8.2, 2.7, 0.9, and 0.9%, respectively. Although all patients were negative for asexual parasites by day 7 after completion of the artesunate-mefloquine course, gametocytemia persisted in some patients. Thus, a gametocytocidal drug, e.g., primaquine, may be useful in combination with an artesunate-mefloquine regimen to clear gametocytes, so blocking transmission more effectively than artesunate alone, in malaria transmission areas.

Dynamic changes in white blood cell counts in uncomplicated Plasmodium falciparum and P. vivax malaria

Total and differential white blood cell (WBC) counts are basic and essential indicators in any type of illness resulting from infection. In malaria, WBC counts are generally characterized as low to normal during treatment. WBC-counts data, before and during treatment with artemisinin derivatives, was gathered for patients with either Plasmodium falciparum or Plasmodium vivax infection (at 28-day follow-up), to investigate dynamic changes in WBC count. We analyzed and compared the WBC counts of 1,310 inpatients presenting with uncomplicated P. falciparum and P. vivax malaria at the Hospital for Tropical Diseases, in Bangkok, Thailand. Before-treatment, a statistically significant negative correlation was found between initial WBC count and highest temperature on admission. Before and during treatment, WBC counts were significantly lower in P. falciparum than P. vivax infection on days 0 and 7, but the numerical difference was small. We also found clinically significantly low WBC counts during the acute stages of both types of malaria, which subsequently normalized by day 28 follow-up. This finding has important clinical implications for the conventional method of estimating parasitemia using an assumed WBC count of 8,000 cells/microL. The most significant finding in our analysis is that WBC counts in acute P. falciparum and P. vivax malaria are significantly lower than previously assumed for estimating malaria-parasite density. However, these abnormalities returned to normal within several weeks after artemisinin-derivative-based treatment.

Defective erythropoietin production and reticulocyte response in acute Plasmodium falciparum malaria-associated anemia

To elucidate the relationship between falciparum malaria-associated anemia and serum erythropoietin (Epo) levels and reticulocyte response during acute malaria infection, 87 adults aged 18-65 years presenting with acute, uncomplicated malaria were examined on enrollment and for 28 days of follow-up. The 87 patients were divided into 2 groups: those with anemia (n = 45) and those without (n = 42). Serum samples were taken on admission (Day 0), then on Days 7, 21, and 28, to measure the reticulocyte count, absolute reticulocyte count, reticulocyte hemoglobin content, and erythropoietin level (Epo). The absolute reticulocyte counts for the anemic patients were significantly higher than for those without anemia on Days 0, 7, 21, and 28. The serum Epo levels for the anemic patients were significantly higher than the non-anemic group only on Day 0 (44.39 +/- 4.06 vs 25.91 +/- 4.86 mlU/ml, p < 0.001). Inadequate Epo production was found in 31.03% (27/87) of patients on Day 0, 37.93% (33/87) on Day 7, 43.67% (38/87) on Day 21, and 39.08% (34/87) on Day 28. These results indicate defective Epo production and reticulocyte response in adult patients suffering from acute P. falciparum malaria, which differs from pediatric patients. Our findings may provide the basis for further study into the choice of therapeutic strategies to treat acute P. falciparum malaria-associated anemia with recombinant human Epo to correct refractory anemia due to malaria.

High-dose primaquine regimens against relapse of Plasmodium vivax malaria

Plasmodium vivax causes debilitating but usually non-lethal malaria in most of Asia and South America. Prevention of relapse after otherwise effective therapy for the acute attack requires a standard daily dose of primaquine administered over 14 days. This regimen has < 90% efficacy in Thailand, and is widely regarded as ineffective because of poor compliance over the relatively long duration of dosing. We evaluated the efficacy, safety, and tolerability of alternative primaquine dosing regimens combined with artesunate among 399 Thai patients with acute, symptomatic P. vivax malaria. Patients were randomly assigned to one of six treatment groups: all patients received artesunate, 100 mg once a day for 5 days. Groups 1-5 then received primaquine, 30 mg a day for 5, 7, 9, 11, and 14 days, respectively. Group 6 received primaquine, 30 mg twice a day for 7 days. The 28-day cure rates were 85%, 89%, 94%, 100%, and 96%, respectively. Treatment of P. vivax malaria with artesunate for 5 days followed by high-dose primaquine, 30 mg twice a day for 7 days, was highly effective, well-tolerated, and equivalent or superior to the standard regimen of primaquine therapy.

Predictive score of uncomplicated falciparum malaria patients turning to severe malaria

In acute uncomplicated falciparum malaria, there is a continuum from mild to severe malaria. However, no mathematical system is available to predict uncomplicated falciparum malaria patients turning to severe malaria. This study aimed to devise a simple and reliable model of Malaria Severity Prognostic Score (MSPS). The study was performed in adult patients with acute uncomplicated falciparum malaria admitted to the Bangkok Hospital for Tropical Diseases between 2000 and 2005. Total 38 initial clinical parameters were identified to predict the usual recovery or deterioration to severe malaria. The stepwise multiple discriminant analysis was performed to get a linear discriminant equation. The results showed that 4.3% of study patients turned to severe malaria. The MSPS = 4.38 (schizontemia) + 1.62 (gametocytemia) + 1.17 (dehydration) + 0.14 (overweight by body mass index; BMI) + 0.05 (initial pulse rate) + 0.04 (duration of fever before admission) - 0.50 (past history of malaria in last 1 year) - 0.48 (initial serum albumin) - 5.66. Based on the validation study in other malaria patients, the sensitivity and specificity were 88.8% and 88.4%, respectively. We conclude that the MSPS is a simple screening tool for predicting uncomplicated falciparum malaria patients turning to severe malaria. However, the MSPS may need revalidation in different geographical areas before utilized at specific places.

Efficacy of Artequick versus artesunate-mefloquine in the treatment of acute uncomplicated falciparum malaria in Thailand

To determine the efficacy, safety and tolerability of an alternative short-course, artemisinin-based combination therapy for acute uncomplicated Plasmodium falciparum malaria, we compared Artequick--a fixed-dosed combination of artemisinin (80 mg), piperaquine (400 mg), and primaquine (4 mg), per tablet--with a standard regimen of artesunate-mefloquine. A total of 130 patients were randomly assigned to treatment with an orally administered, once-daily, 3-day regimen of either Artequick (Group A: 3.2 mg/Kg/day of artemisinin, 16 mg/Kg/day of piperaquine, and 0.16 mg/Kg/day of primaquine) or artesunate-mefloquine (Group B: artesunate, 4 mg/Kg/day, with mefloquine, 8 mg/Kg/day). Patients receiving each regimen had a rapid clinical and parasitological response. All treatments were well tolerated, and no serious adverse effects occurred. No significant differences were found in fever- and parasite-clearance times between the two study groups. The 28-day cure rates were similarly high, at 98.5% and 100%, in groups A and B, respectively. We conclude that Artequick was as effective and well tolerated as artesunate-mefloquine and could be used as an alternative treatment for multidrug-resistant Plasmodium falciparum malaria in Southeast Asia.

Dose ranging studies of new artemisinin-piperaquine fixed combinations compared to standard regimens of artemisisnin combination therapies for acute uncomplicated falciparum malaria

To determine the optimum dose of artemisinin-piperaquine combination therapies for acute uncomplicated Plasmodium falciparum malaria, we examined 7 candidate regimens in 411 patients admitted to the Bangkok Hospital for Tropical Diseases. The studies were performed from May 2005 to October 2005 and November 2005 to June 2006. We compared 3-day courses of artesunate-mefloquine, artemether-lumefantrine (Coartem) and of dihydroartemisinin-piperaquine (Artekin) as reference antimalarial treatments, with candidate regimens using 2-3 day courses of artemisinin-piperaquine, Artequick. Initially, patients receiving each of the regimens had a rapid clinical and parasitological response. All treatments were well tolerated and no serious adverse effects occurred. The 28-day cure rates were < 80% for the 2-day treatments with artemisinin-piperaquine at 2.4 mg/kg and 14.4 mg/kg, respectively, in the first study period and artemisinin-piperaquine at 3.2 mg/kg and 16.0 mg/kg, respectively, but > 98% for the 3-day regimens. These results suggest that a 3-day course of artemisinin-piperaquine at 3.2 mg/kg and 16.0 mg/kg, respectively, deserve further evaluation as an alternative treatment for multidrug-resistant P. falciparum malaria.

Clinical efficacy of chloroquine versus artemether-lumefantrine for Plasmodium vivax treatment in Thailand

Chloroquine remains the drug of choice for the treatment of vivax malaria in Thailand. Mixed infections of falciparum and vivax malaria are also common in South-East Asia. Laboratory confirmation of malaria species is not generally available. This study aimed to find alternative regimens for treating both malaria species by using falciparum antimalarial drugs. From June 2004 to May 2005, 98 patients with Plasmodium vivax were randomly treated with either artemether-lumefantrine (n = 47) or chloroquine (n = 51). Both treatments were followed by 15 mg of primaquine over 14 days. Adverse events and clinical and parasitological outcomes were recorded and revealed similar in both groups. The cure rate was 97.4% for the artemether-lumefantrine treated group and 100% for the chloroquine treated group. We concluded that the combination of artemether-lumefantrine and primaquine was well tolerated, as effective as chloroquine and primaquine, and can be an alternative regimen for treatment of vivax malaria especially in the event that a mixed infection of falciparum and vivax malaria could not be ruled out.

Minor liver profile dysfunctions in Plasmodium vivax, P. malaria and P. ovale patients and normalization after treatment

Liver function tests were performed in 61 vivax, 54 malariae and 15 ovale malaria patients who were admitted to Bangkok Hospital for Tropical Diseases between 2001 and 2004. The objective of the study was to evaluate changes in hepatic biochemical indices before and after treatment with artemisinin derivatives. On admission and prior to treatment, hepatic dysfunction was found among the 3 groups. Serum liver function tests and physical examinations were performed weekly during the 28-day follow-up period. Initially elevated serum bilirubin and diminished albumin returned to normal within 2 weeks of treatment. Serum alkaline phosphatase and aminotransferases returned to within normal limits within 3 weeks. We conclude that patients with Plasmodium vivax, P. malariae and P. ovale infections had slightly elevated serum bilirubin, aminotransferase and alkaline phosphatase levels, and hypoalbuminemia. These minor abnormalities returned to normal within a few weeks after treatment with therapies based on artemisinin derivatives.

In vitro antimalarial activity of azithromycin, artesunate, and quinine in combination and correlation with clinical outcome

Azithromycin when used in combination with faster-acting antimalarials has proven efficacious in treating Plasmodium falciparum malaria in phase 2 clinical trials. The aim of this study was to establish optimal combination ratios for azithromycin in combination with either dihydroartemisinin or quinine, to determine the clinical correlates of in vitro drug sensitivity for these compounds, and to assess the cross-sensitivity patterns. Seventy-three fresh P. falciparum isolates originating from patients from the western border regions of Thailand were successfully tested for their drug susceptibility in a histidine-rich protein 2 (HRP2) assay. With overall mean fractional inhibitory concentrations of 0.84 (95% confidence interval [CI]=0.77 to 1.08) and 0.78 (95% CI=0.72 to 0.98), the interactions between azithromycin and dihydroartemisinin, as well as quinine, were classified as additive, with a tendency toward synergism. The strongest tendency toward synergy was seen with a combination ratio of 1:547 for the combination with dihydroartemisinin and 1:44 with quinine. The geometric mean 50% inhibitory concentration (IC50) of azithromycin was 2,570.3 (95% CI=2,175.58 to 3,036.58) ng/ml. The IC50s for mefloquine, quinine, and chloroquine were 11.42, 64.4, and 54.4 ng/ml, respectively, suggesting a relatively high level of background resistance in this patient population. Distinct correlations (R=0.53; P=0.001) between quinine in vitro results and parasite clearance may indicate a compromised sensitivity to this drug. The correlation with dihydroartemisinin data was weaker (R=0.34; P=0.038), and no such correlation was observed for azithromycin. Our in vitro data confirm that azithromycin in combination with artemisinin derivatives or quinine exerts additive to synergistic interactions, shows no cross-sensitivity with traditional antimalarials, and has substantial antimalarial activity on its own.