OBJECTIVETo compare the applicability of the SYBR Green-I assay with the standard schizont maturation assay, for determination of sensitivity of Plasmodium vivax (P. vivax) to chloroquine and a new antifolate WR 99210.

METHODSThe study was conducted at Mae Tao Clinic for migrant workers, Tak Province during April 2009 to July 2010. A total of 64 blood samples (1 mL blood collected into sodium heparinized plastic tube) were collected from patients with mono-infection with P. vivax malaria prior to treatment with standard regimen of a 3-day chloroquine. In vitro sensitivity of P. vivax isolates was evaluated by schizont maturation inhibition and SYBR Green-I assays.

RESULTSA total of 30 out of 64 blood samples collected from patients with P. vivax malaria were successfully analyzed using both the microscopic schizont maturation inhibition and SYBR Green-I assays. The failure rates of the schizont maturation inhibition assay (50%) and the SYBR Green-I assay (54%) were similar (P=0.51). The median IC10s, IC50s and IC90s of both chloroquine and WR99210 were not significantly different from the clinical isolates of P. vivax tested. Based on the cut-off of 100 nM, the prevalences of chloroquine resistance determined by schizont maturation inhibition and SYBR Green-I assays were 19 and 11 isolates, respectively. The strength of agreement between the two methods was very poor for both chloroquine and WR99210.

CONCLUSIONSOn the basis of this condition and its superior sensitivity, the microscopic method appears better than the SYBR Green-I Green assay for assessing in vitro sensitivity of fresh P. vivax isolates to antimalarial drugs.

Antimalarials ; pharmacology ; Chloroquine ; pharmacology ; Humans ; Inhibitory Concentration 50 ; Malaria, Vivax ; parasitology ; Organic Chemicals ; Parasitemia ; parasitology ; Parasitic Sensitivity Tests ; Plasmodium vivax ; drug effects ; isolation & purification ; Schizonts ; drug effects

OBJECTIVE: To preliminarily investigate the prevalence of HIV co-infection in patients with malaria in Mae Sot District, Tak Province of Thailand. METHODS: The study was a retrospective study on blood samples collected from a total of 256 patients with malaria (all species and severity) who attended Mae Tao clinic for migrant workers, Tak Province during 2005-2007 (148 samples) and 2010-2012 (108 samples). Malaria diagnosis was performed based on microscopic examination of patients' blood smears. Chemiluminescent microparticle immunoassay and gel particle passive agglutination were employed for the detection of HIV antigen in patients' plasma. RESULTS: Plasmodium falciparum (P. falciparum) and Plasmodium vivax (P. vivax) are the two predominant malaria species with the ratio of about 1: 1 to 1.5:1. Most of the P. falciparum cases were presented with acute uncomplicated signs and symptoms with highest parasitemia of 1 045 000 asexual parasites/μL bloods. The prevalence of malaria and HIV co-infection during 2005-2007 was 1.35% (2/148 cases, 1 each for P. falciparum and P. vivax co-infection), but was increased to 2.78% (3/108 cases, 2 and 1 for P. falciparum and P. vivax co-infection, respectively) during 2010-2012. CONCLUSIONS: The increasing trend of prevalence of malaria and HIV co-infection in Mae Sot, Tak province was of a great concern on either pharmacodynamics or pharmacokinetics aspect. The study in a larger numbers of malaria patients in different endemic areas throughout the country with different time periods is underway.