An open randomized clinical trial of Artekin vs artesunate-mefloquine in the treatment of acute uncomplicated falciparum malaria.

Malaria remains a major cause of morbidity and mortality in tropical countries and subtropical regions in the world. Southeast Asia has the most resistant malaria parasites in the world, which has limited treatment options in this region. In response to this situation, short-course artemisinin-based combination therapies (ACTs) have been developed. The combination of dihydroartemisinin (DHA) and piperaquine (PQP) in the form of Artekin has been developed as an alternative to established combinations, such as artesunate-mefloquine, primarily to reduce treatment costs and toxicity. We conducted a study comparing a standard treatment for acute uncomplicated falciparum malaria (artesunate 4 mg/kg/day together with mefloquine 8 mg/kg/day oral route once a day for 3 days) (Group A) and a combination of dihydroartemisinin 40 mg and piperaquine 320 mg in the form of Artekin given once a day for 3 days (Group B) to determine safety, efficacy, and tolerability. One hundred and eighty patients were randomly enrolled at the ratio of 1:2 into groups A:B. All patients had rapid initial clinical and parasitological responses. There were no significant differences in fever clearance time or parasite clearance time between both groups. The 28-day cure rates were high, at 100% and 99%, in groups A and B, respectively. We conclude that Artekin was as effective and well-tolerated as artesunate-mefloquine, and can be used alternatively as the current treatment for multidrug-resistant P. falciparum malaria.

Assessment of therapeutic efficacy of chloroquine for vivax malaria in Thailand.

Chloroquine-resistant Plasmodium vivax has been reported in some Asian countries. In 2003, 161 patients infected with vivax malaria were treated according to the Thai National Drug Policy, with oral chloroquine (approximately 25 mg base/kg body weight, administered over 3 days) followed by primaquine on day 28 (15 mg daily for 14 days). All the patients were initially cured after chloroquine treatment, clearing their parasitemias within 7 days. Only one patient presented with parasitemia at 28 days. These data indicate that chloroquine is still effective for the treatment of patients with vivax malaria in Thailand.

Cryptococcal meningitis in human immunodeficiency virus (HIV)-positive and HIV-negative patients.

This study compared clinical manifestations, blood biochemistry and cerebrospinal fluid (CSF) results of HIV-positive and HIV-negative patients with cryptococcal meningitis. We collected 57 cases of cryptococcal meningitis from cytological specimens submitted to the Department of Tropical Pathology, Faculty of Tropical Medicine. Pertinent clinical data were analyzed retrospectively in 47 cases for clinical manifestations, laboratory features and outcomes of 38 HIV-positive and 9 HIV-negative patients. Headache was the most common symptom seen in all cases, of which 70.2% occurred with fever. CSF examination of both groups revealed elevated opening pressure. Increased CSF protein and depressed CSF glucose levels were seen in HIV-negative cases, which differed from HIV-positive cases, where a slight change was noted. CSF pleocytosis in HIV-positive patients was variable. Forty-eight percent of HIV-positive patients had CSF leukocyte counts below 20 cells/ mm3. None was found in the HIV-negative patients. Specific treatments with amphotericin B and fluconazole were given. Five fatal cases of cryptococcal meningitis were noted, all of which were HIV-positive. There were statistically significant differences in blood neutrophils, blood eosinophils, CSF leukocyte counts, CSF neutrophils, CSF lymphocytes, CSF glucose, and CSF total protein, in HIV-positive and HIV-negative patients (p = 0.050, p = 0.022, p = 0.002, p = 0.016, p = 0.047, p = 0.031, p = 0.009, respectively).

An open randomized clinical trial of Artecom vs artesunate-mefloquine in the treatment of acute uncomplicated falciparum malaria in Thailand.

The efficacy and safety of Artecom were assessed in an open randomized trial in adults presenting with acute, uncomplicated Plasmodium falciparum malaria in Thailand. Three hundred and fifty-two patients were randomly enroled at the ratio of 2:1 into group A:B and received Artecom (group A) and the standard combination of artesunate and mefloquine (group B) respectively. All patients had rapid initial clinical and parasitological responses. There were no significant differences in fever clearance time and parasite clearance time between the two groups. The 28-day cure rates were high as 97% in both groups. Artecom was effective and well-tolerated as artesunate-mefloquine, the current treatment in this area of multidrug-resistant P. falciparum malaria.

Effect of primaquine standard dose (15 mg/day for 14 days) in the treatment of vivax malaria patients in Thailand.

Primaquine (8-aminoquinoline), the only effective drug to prevent relapses of the persistent liver forms of Plasmodium vivax and Plasmodium ovale, can induce hemolytic anemia in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. The severity varies considerably among affected individuals. Three hundred and sixty-four Plasmodium vivax cases (342 G6PD-normal and 22 G6PD-deficient) were given a 3-day course of chloroquine (total dose 1,500 mg) followed by primaquine 15 mg a day for 14 days and completed a 28-day follow-up. All G6PD-deficient patients were male; there were no relapses or serious adverse events during the study. Although a significant decrease in hematocrit levels and an increase in the percent reduction of hematocrit levels were observed on day 7 (34.9+/-5.0 vs 26.7+/-5.4; (-1.2)+/-14.4 vs (-24.5) +/-13.9 respectively) and on day 14 (35.7+/-4.3 vs 30.9+/-3.1; 1.6+/-17.8 vs (-11.0) +/-19.3 respectively) blood transfusion was not required. Daily doses of 15 mg of primaquine for 14 days following a full course of chloroquine when prescribed to Thai G6PD deficient patients where Mahidol variant is predominant, are relatively safe.

Cerebrospinal fluid analysis in eosinophilic meningoencephalitis.

Eosinophilic meningoencephalitis (EME) remains an important neurological disease and is widely distributed in Thailand. We analyzed the cytological specimens of 56 EME cases. Pertinent clinical data were analyzed retrospectively and correlated with the cerebrospinal fluid (CSF)analysis. Headache was the commonest symptom seen in all EME cases. History of raw or partially cooked Pila snail ingestion was elicited from most patients. There was a marked seasonal occurrence between July to January. Patients received specific treatment as supportive therapy, which included spinal taps, analgesics and corticosteroids, was adequate. No fatal cases were seen. The CSF specimens were sorted into two categories: fresh CSF and hematoxylin and eosin (H&E) stained centrifuged CSF sediment. There was a statistically significant difference between the number of eosinophils and lymphocytes of fresh CSF and the H&E stained centrifuged CSF sediment (p = 0.001 and 0.001 respectively). The CSF glucose and the number of eosinophils in both methods were significantly correlated (p = 0.000, p = 0.008 for fresh CSF and the H&E stained centrifuged CSF sediment respectively). Moreover, the number of eosinophils was statistically significant with the protein in the CSF (p = 0.013), and intracranial pressure (ICP) (p = 0.025). Higher yields of eosinophils, especially in the early course of the disease, can readily be detected in the H&E stained centrifuged CSF sediment, whereas fresh specimens were negative. Further tests may increase the sensitivity and specificity of EME diagnostic results.

IgE elevation and anti-plasmodium falciparum IgE antibodies: association of high level with malaria resistance.

The total IgE and anti-Plasmodium falciparum IgE antibodies were determined by enzyme linked immunosorbent assay (ELISA) in 480 children and adults living in malaria endemic area along Thai-Myanmar border, Kanchanaburi Province, western Thailand. Approximately 73.13% of tested individuals had elevated levels of total IgE with a range of 160-998 ng/ml. 20.5% of these IgE were specific to P falciparum blood stage antigens, with a range of 78-353 microg/ml. However, the levels of total IgE were not significantly correlated with those of specific IgE (r = 0.083). The elevation of anti-P falciparum IgE antibodies seems to be age dependent. The prolonged or repeated exposure to malaria parasites is necessary for the induction of specific IgE response as indicated by the finding of a significant correlation between the levels of P falciparum specific IgE and the number of malaria attacks (r = 0.551, p = 0.01). Interestingly, among the specific IgE responders, 20 individuals naturally exposed to malaria but without clinical malaria reported had high levels of both total IgE and anti- P. falciparum IgE antibodies, with mean values of 418.67 mg/ml and 146.25 ng/ml, respectively. It is likely that the antibodies from such specific IgE responders could mediate phagocytosis in vitro.

Lack of association between CSF nitrate and sera nitrate in falciparum malaria infection.

Nitrate levels in CSF and sera from 16 coma and 19 noncoma falciparum malaria patients were determined using nitric oxide colorometric assay. The medians (range lower, upper limits) of nitrate in sera of comatose and noncomatose patients were 0.28 (0.11, 1.24) and 0.23 (0.05, 0.87) microM, respectively. The medians of nitrate level in CSF of coma and noncoma cases were 0.09 (0.01, 0.28) and 0.15 (0, 1.18) microM, respectively. There was no difference of nitrate level in sera and CSF from comatose or noncomatose patients compared to that in normal sera and CSF. The amount of nitrate in sera and CSF of both groups was not significantly correlated with coma depth, parasitemia, parasite clearance time and time to recovery. Contrast to our in vitro study using immunoperoxidase staining, we found inducible nitric oside synthase production by brain endothelial cells during 4-24 hours of coculturing with late stage of P. falciparum infected red blood cells. These results suggests that malaria severity can not be differentiated by nitrate level in body fluid.

Evaluation of a newly developed dipstick test for the rapid diagnosis of scrub typhus in febrile patients.

Scrub typhus is a potentially fatal, febrile disease prevalent in rural Asia. The etiological agent, Orientia tsutsugamushi, is transmitted to humans by the bite of a larval trombiculid mite. No current diagnostic test is sufficiently practical for use by physicians working in rural areas. A new dipstick test using a dot blot immunoassay format has been developed for the serodiagnosis of scrub typhus. We evaluated this test on 83 patients presenting with acute fever of unknown origin at Maharaj Hospital, a tertiary care medical center in Nakhon Ratchasima, Northeast Thailand. The diagnosis of scrub typhus was confirmed in 30 of these patients (36%) by the indirect immunoperoxidase test. The sensitivity of the test was 87% and its specificity was 94%. The dot blot immunoassay dipstick is accurate, rapid, easy to use, and relatively inexpensive. It appears to be the best currently available test for diagnosing scrub typhus in rural areas where this disease predominates.

Can treatment of P. vivax lead to a unexpected appearance of falciparum malaria?

Of 994 patients admitted to the Bangkok Hospital for Tropical Diseases for P. vivax malaria, 104 (10.5%) experienced appearance of Plasmodiumfalciparum following drug treatment for P. vivax . In all patients, P. falciparum parasites were not found by microscopic examination upon admission. The mean time for P. falciparum appearance was 12.6 days after the commencement of chloroquine treatment. Patients experiencing appearance of P. falciparum had significantly lower hematocrit, and greater initial P. vivax parasite counts. We use a mathematical model to explore the consequences of chloroquine treatment of such mixed infections. Both clinical results and features of the model suggest that such "hidden infections" may be quite common, and that the appearance of P. falciparum may be stimulated by treatment of P. vivax.

Is there any artemisinin resistance in falciparum malaria?

We reported two cases of complicated falciparum malaria who had poor response to artesunate with delayed parasite clearance times. They were splenectomized patients who were treated with high doses of artemisinin derivatives. Our cases showed the importance of the spleen in the clearance of malaria parasites and had different clinical outcome, one fatal and one recovery. The host factors, the parasitemia count, the quality of antimalarial chemotherapy and blood level of the antimalarial drugs must be considered in relation to the causes of the delayed clearance of parasitemia.

A randomized clinical trial of combinations of artesunate and azithromycin for treatment of uncomplicated Plasmodium falciparum malaria in Thailand.

Recently, a combination of artesunate and mefloquine has proved effective, although is contraindicated in early pregnancy and young children. Azithromycin, a widely used antibiotic and has antimalarial effects, replace mefloquine as a new alternative antimalarial regimen. Two hundred and two uncomplicated falciparum malaria patients were randomly assigned to 1 of 3 regimens. Patients in group I (n = 68) received artesunate 200 mg once daily for 3 days, group II (n = 67) received artesunate 200 mg together with mefloquine 10 mg/kg on the first 2 days and artesunate 200 mg together with mefloquine 5 mg/kg on the third day, and group III (n = 67) received artesunate 200 mg together with azithromycin 50 mg once daily for 3 days. The 28 day cure rates were 44, 98 and 56%, respectively. The median time to recrudescence was significantly longer in group III. In conclusion, a combination of artesunate and azithromycin might be useful in treating children in whom bacterial and malarial infections may be concomitant. However, further work is required in order to enhance its clinical efficacy.

Absence of knobs on parasitized red blood cells in a splenectomized patient in fatal falciparum malaria.

We present a case report of fatal falciparum malaria of a splenectomized adult Thai patient. The patient developed high peripheral parasitemia and showed signs of severe malaria with multiorgans involvement. Ultrastructure of Plasmodium falciparum-infected red blood cells in a fatal splenectomized patient and pathological features are reported for the first time with special emphasis on the role of the spleen as a modulating cytoadherence phenotype of parasitized red blood cells (PRBC). In this patient, adherence of the PRBC to the vascular endothelium of brain, kidney and lung including blood circulating cells, was noted, despite the absence of knob on the surface of the PRBC.

Guideline in management of severe malaria.

Severe malaria remains a major cause of mortality in the world. Malaria can mimic many diseases and there is no absolute diagnostic clinical features. High index of suspicion is clue for clinical diagnosis. Previous travel history to endemic area should be elicited in all, and in particular, febrile patients. Management of severe malaria needs potent antimalarial drug and intensive care. Artemisinin derivatives can be of altemative use to quinine. Dexamethasone and mannitol have no beneficial value in the management of cerebral malaria. In pulmonary oedema patients whose hydration assessments are difficult to monitor, central venous pressure evaluation may be useful. Acute renal failure patients may need dialysis until uraemic syndrome subsides or patients can void urine. Most severe malaria patients have thrombocytopenia; however, platelet concentrate transfusion is indicated only in patients with systemic bleeding. Morbidity and mortality will be reduced in severe malaria patients with early diagnosis and prompt treatment.

Prognostic significance of skin and subcutaneous fat sequestration of parasites in severe falciparum malaria.

Intradermal blood smear, histopathologic and immunohistologic studies were performed in severe malaria (n=10) and uncomplicated malaria (n=10) patients during positive parasitemia and within 6 hours after negative parasitemia by finger prick smears. Intradermal blood smears showed asexual forms and intraleukocytic pigments when finger prick blood smears showed negative results; however intradermal blood smear did not indicate disease severity within 6 hours after negative parasitemia by finger prick. Histopathologic findings showed 15 fold higher parasitized red blood cells sequestered in vessels of subcutaneous fatty tissue in severe malaria than in uncomplicated malaria (p<0.001) and may indicate disease severity. A panel of polyclonal antibodies against cytokines applied to skin biopsies clearly detected a higher titer against tumor necrosis factor-alpha (TNFalpha) and interleukin-10 (IL-10) in dermal vessels and stratum granulosum respectively, in severe malaria compared with uncomplicated malaria. Results of the study suggest that histopathology and immunohistology of skin and subcutaneous fatty tissue may indicate prognostic severity of malaria and may be associated with focal accumulation of cytokines.

Hidden Plasmodium falciparum infections.

Mixed infection of P. vivax and P. falciparum malaria frequently recorded in field survey. However mixed infection was frequently misdiagnosed as single infection due to low parasite density, difficult species identification and procedure error of microscopic examination. Our previous report showed high rates (32-33%) of P vivax infection following treatment of previously assumed to be only P. falciparum infection. In a study of 992 patients with initial presentation with P. falciparum, we found that 104 (10.5%) of patients had P. falciparum appearing during 28 days in the hospital (ranged 1-28 days) following chloroquine treatment for P. vivax. The potential for P. falciparum appearing following elimination of P. vivax must be considered in malaria treatment.

A clinical trial of combination of artesunate and mefloquine in the treatment of acute uncomplicated falciparum malaria: a short and practical regimen.

The difficulties in treating drug-resistant falciparum malaria in Thailand are compounded by the necessity of giving antimalarials over long periods of time. The resultant fall in patient compliance not only lowers cure rates but also predisposes to the further spread of drug-resistance. Sequential treatment with artesunate given over 5 days followed by mefloquine produced 100% cure rates in previous study, but might not be a suitable regimen for field treatment. We conducted a clinical trial of a combination of artesunate and mefloquine given twice daily for 2 days in 150 patients with acute uncomplicated falciparum malaria. The dose of artesunate (200 mg) and mefloquine (312.5 mg) were given simultaneously in a separate package. All patients were admitted to a hospital in Bangkok for 28 days to exclude re-infection and monitor the possible adverse effects. One hundred and thirty patients completed the study with 28 days follow up. Twenty patients (13%) left the hospital prior to completion of follow-up for reasons unrelated to their treatment. Cure rate was 97% (126/130). There were no RII or RIII failures and all four patients with treatment failures were of the RI type. The mean parasite clearance time and fever clearance time were 46.4 and 42.5 hours, respectively. All patients were tolerated the combination drugs well and there were no serious toxic adverse reactions. The results indicate that combination of artesunate and mefloquine given twice daily for 2 days is effective and well tolerated in patients with acute, uncomplicated falciparum malaria and suitable as an alternative treatment for multidrug resistant falciparum malaria.

Pulmonary edema in cerebral malaria patients in Thailand.

Pulmonary edema is a serious complication of falciparum malaria that usually occurs in association with cerebral malaria, acute renal failure, high parasitemias, or delayed antimalarial treatment. From 1993 to 1996, 120 adult patients admitted to the intensive care unit of the Bangkok Hospital for Tropical Diseases were enrolled in a prospective study to assess the combination of artesunate and mefloquine for the treatment of cerebral malaria. Twenty-five patients (21%) presented with pulmonary edema and a majority developed complications in other organs as well, especially acute renal failure. In most patients (19 of 25), pulmonary edema was noted on the first day of admission and was associated with higher parasitemias and levels of acidemia, than in patients without pulmonary edema. Ten of the 25 patients diagnosed with pulmonary edema developed signs consistent with adult respiratory distress syndrome (ARDS). The mean central venous pressure when pulmonary edema was diagnosed was markedly lower in ARDS than in non-ARDS patients, supporting the argument that fluid imbalance is not essential for malaria-induced lung injury. Seven of 10 patients with ARDS died, 5 within 24 hours of admission, but there were no deaths in the 15 pulmonary edema patients without ARDS. Early diagnosis and prompt treatment remain important principles to reduce the morbidity and mortality associated with complicated falciparum malaria. This report emphasizes that ARDS, when concurrently occurs, is a poor prognostic clinical indicator in cerebral malaria.

Research on new antimalarial drugs and the use of drugs in combination at the Bangkok Hospital for Tropical Diseases.

With the emergence of multidrug resistant falciparum malaria in Thailand, various approaches have been taken. Research on new antimalarial drugs and the use of existing available drugs with modification are urgently needed. New drugs and drugs in combination such as pyronaridine, WR 238605, arteether, dihydroartemisinin, benflumetol atovaquone/proguanil are being evaluated. Drug combinations for the treatment of patients suffering from uncomplicated falciparum malaria include quinine-tetracycline for 7 days, or sequential treatment of artesunate (600 mg given over 5 days) followed by mefloquine (1,250 mg divided into 2 doses 6 hours apart) are recommended. The sequential treatment is highly recommended for those who failed other treatment regimens. Other combinations such as a short course sequential treatment of artesunate (300 mg given over 2.5 days) followed by a single dose of 750 mg mefloquine, or a combination of mefloquine 1,250 mg together with tetracycline 1 g per day or doxycycline 200 mg per day for 7 days are alternative treatment regimens with acceptable cure rates. The simultaneous administration of artesunate and mefloquine, in various doses and duration of treatment, is currently being investigated. Until proven otherwise, the drug combinations are still recommended for all adult patients suffering from acute uncomplicated falciparum malaria contracted in multidrug resistant areas. In severe malaria and malaria in children, the drug combinations need further investigation.

Opisthorchiasis and intestinal fluke infections in northern Thailand.

Four hundred and thirty-one residents from 16 provinces in northern Thailand who had previously been found positive for Opisthorchis viverrini or Opisthorchis viverrini-like eggs were given praziquantel 40 mg/kg. The stool was collected for 4 to 6 times and examined for adult worms. The prevalence of Opisthorchis viverrini in this group was 11.6%. Intestinal flukes, Haplorchis taichui and Haplorchis yokogawai, were predominantly found in 63.11% and 10.44% respectively. Other intestinal flukes (Centrocestus caninus, Echinostoma malayanum, Haplorchis pumilio, Phaneropsolus bonnei, Plagiorchid flukes, Prosthodendrium molenkampi and Stellantchasmus falcatus) were also found in small numbers.