Monitoring of Plasmodium vivax sensitivity to chloroquine in vitro in Thailand.

The sensitivity of Plasmodium vivax to chloroquine in vitro was investigated in patients admitted to the Bangkok Hospital for Tropical Diseases, Thailand, between September 2001 and May 2002. Of 42 isolates, 34 were successfully tested for parasite sensitivity to chloroquine in vitro; the results showed a significant decrease in sensitivity compared with data published in 1989 and 1995: the IC50 and IC90 were 187.2 and 1217.9 ng/mL blood, respectively, an approximate 4-fold decrease in sensitivity in comparison with other data from the past 2 decades. A number of in vitro tests were performed simultaneously using both WHO microplates and our own laboratory-prepared pre-dosed microplates under the same conditions and there was no significant difference between the results.

Therapeutic effects of chloroquine in combination with quinine in uncomplicated falciparum malaria.

The efficacy and toxicity of oral quinine combined with oral chloroquine were studied in 50 Thai men with uncomplicated falciparum malaria. All were treated for 7 days with quinine sulphate (10 mg salt/kg every 8 h). Twenty-five of the patients, selected at random, were also given oral tetracycline (4 mg/kg four times daily) over the same period and the remainder were given chloroquine (25 mg base/kg over the first 3 days). There were no serious adverse effects. Overall fever-clearance times (FCT) and parasite-clearance times (PCT) in the chloroquine and tetracycline groups were not significantly different, with mean (S.D.) values of 51 (33) and 41 (27) h for FCT and 80 (25) and 83 (21) h for PCT, respectively. Most of the patients (18 in each group) were followed for > or = 2 months. Recrudescence rates (R1) were significantly higher in the chloroquine group than in the tetracycline group (39% v. 6%; P = 0.02), all recrudescences occurring within 4 weeks (18-25 days) of starting treatment. Subsequent parasitaemia with Plasmodium vivax, however, occurred less frequently in the chloroquine group (11%) than in the tetracycline group (33%) (P = 0.11) and took longer to develop in the chloroquine group [51 or 59 days compared with a mean (S.D.) value of 29 (10) days in the tetracycline group; P = 0.01]. Within the chloroquine group, FCT and PCT were both shorter in those with cure than in those with R1 resistance, with mean (S.D.) values of 41 (25) and 70 (33) h for FCT (P = 0.09) and 72 (20) and 100 (18) h for PCT (P = 0.01), respectively. Chloroquine does not potentiate the clinical response to quinine against resistant strains of uncomplicated falciparum malaria, nor does it convey any useful antipyretic effect.

A randomized comparative study of albendazole and thiabendazole in chronic strongyloidiasis.

An open randomized study for comparing the efficacy of albendazole and thiabendazole in chronic strongyloidiasis was done in 1990-1992. All 35 patients with positive stool examinations for Strongyloides stercoralis were divided randomly into two groups. 23 patients (group A) received albendazole (400 mg twice daily for 5 days) and 12 patients (group B) received thiabendazole (1 g twice daily for 5 days). All patients except four patients in group A were admitted in the Hospital for Tropical Diseases for 21 days for monitoring side effects (D0-7) and stool examination (D0, D7, 8, 9, D21, 22, 23). Methods of stool examination included: direct microscopy of saline smear, formalin ether concentration, culture (Harada and Mori method) and larva count (Stool and Sasa method). Cure was defined as negative stool examination done at 21 days after medication by all above methods. The cure rate for group A was 95% (only one failed to clear the parasite at D21) and the cure rate for group B was 100%. But there was no statistical difference between the two. Mild changes of transminases observed in 5/23 patients who received albendazole, but none developed clinical hepatitis.

Microsporidium: modified technique for light microscopic diagnosis.

Microsporiodosis caused by Enterocytozoon bieneusi is one of the opportunistic infections in HIV positive patients with chronic diarrhea. The organism is difficult to diagnose because of its small size, previously the diagnosis of this infection relied on identification of the organism under electron microscope. Until recently, the spores of this organism in stool specimens could be seen under light microscope by using various staining techniques. In this study, the modified trichrome staining technique was used to identify microsporidia spores with characteristic red belt-like stripes. Less time and less reagent are required by this modified technique than the conventional method.

Fansimef for prophylaxis of malaria: a double-blind randomized placebo controlled trial.

At a time when Fansimef, the fixed combination of mefloquine, sulfadoxine and pyrimethamine was considered for prophylaxis of falciparum malaria, a randomized double-blind study comparing the efficacy and tolerability of Fansimef with that of Lariam (mefloquine), Fansidar, chloroquine and placebo in malaria prophylaxis was performed in Thailand from July 1987 to January 1988. The study population of 602 adult males was recruited in Pak Tongchai District, some 360 km North-East of Bangkok, where multiresistant P. falciparum is endemic. All active treatments and placebo were given once weekly for 24 weeks with doses as follows: Fansimef: 125 mg mefloquine + 250 mg sulfadoxine + 12.5 mg pyrimethamine (1 half-strength tablet); Lariam: 125 mg mefloquine (1 half-strength tablet); Fansidar: 500 mg sulfadoxine + 25 mg pyrimethamine; chloroquine; 300 mg. A loading dose of 2 half-strength tablets was given in the Fansimef group in weeks 1 and 2 and in the Lariam group in weeks 1 to 4. The incidence of acute episodes of P. falciparum per 100 person months of prophylaxis was 0.17 each in the Fansimef and the Lariam groups, 1.18 in the Fansidar group, 0.69 in the chloroquine group and 0.64 in the placebo group (differences statistically not significant). Clinically adverse events were reported by 170 subjects (Fansimef 28, Lariam 29, Fansidar 41, choroquine 43, placebo 29; differences statistically not significant). The most frequent adverse events in all groups were headache, sleepiness, dizziness and weakness.(ABSTRACT TRUNCATED AT 250 WORDS)

Fecal egg output in relation to worm burden and clinical features in human opisthorchiasis.

A study of the relation of fecal egg excretion to worm burden and clinical features was carried out in 45 opisthorchiasis patients who had no signs of biliary obstruction. The fecal egg excretion was consistent and correlated with the worm burden. Although there was no definite association between clinical signs and intensity of infection, mild hepatomegaly and thickened wall or dilatation of the gallbladder were found more commonly in heavily infected patients. Eosinophilia was observed more often than previous reports. Concomitant parasitic infections were found in 82% of the patients. After praziquantel treatment, egg counts increased greatly during the first few days then decreased to very low levels in 7 days.

Albendazole in the treatment of strongyloidiasis.

Albendazole was used to treat 30 patients with Strongyloides stercoralis infections. There were 21 males and 9 females, 13 to 68 years of age, who were divided into two groups of 11 and 19, respectively. Repeated pre- and post-treatment stool examinations were done by simple direct smear and formalin-ether concentration, and larval quantitations were done by the Stoll and Sasa's technique. Group I patients were given albendazole in dosages of 400 mg/day in divided doses for 3 days. Group II patients were given similar dosages, but were treated again 7 days later on the same schedule. Patients in Group I were followed for 14 days and those in Group II for 30 days. The cure rates were 73% for Group I and 100% for Group II. Side effects were minimal and transient. Albendazole is recommended for the treatment of strongyloidiasis in dosages of 400 mg/day in divided doses for 3 days with treatment repeated one week later.

Clinical trial of flubendazole on hookworm, Trichuris trichiura and Ascaris lumbricoides infections.

Flubendazole, a parafluoro analoque of mebendazole, was given to 89 service men with hookworm, Trichuris trichiura and Ascaris lumbricoides infections. The drug was given either as two doses of 300 mg at 12 hour interval (regimen A) or as two doses of 300 mg at 24 hour interval (regimen B). At four weeks follow-up the mean percentage egg reduction for hookworm was 88% and 96% in regimen A and B respectively. There were too few cases of Trichuris and Ascaris infection to allow comparison of the two regimens, but flubendazole appeared to be as effective and the single day regimen more convenient than difetasone for trichuriasis and levamisole for ascariasis. Side effects were few, mild and transient.