Dihydroartemisinin-piperaquine efficacy in Plasmodium falciparum treatment and prevalence of drug-resistant molecular markers along China-Myanmar border in 2014-2023.

OBJECTIVES: The study aims to monitor dihydroartemisinin-piperaquine (DHA-PPQ) efficacy in Plasmodium falciparum and detect molecular markers associated with its resistance. METHODS: The World Health Organization's standard protocol for therapeutic efficacy studies (TES) was performed from 2014 to 2018; integrated drug efficacy surveillance (iDES) was performed from from 2019 to July 2023. Molecular markers were detected by polymerase chain reaction. The association between gene mutations and delayed parasite clearance was analysed by multivariate logistic regression analysis. RESULTS: A total of 226 P. falciparum patients were enrolled in the TES from 2014 to 2018, and 26 patients with P. falciparum from Africa were recruited in the iDES from 2019 to July 2023. The PCR-adjusted clinical and parasitological cure rate was 93.7% (95% CI: 92.6-99.5%) in the TES and 96.2% (95% CI: 80.4-99.9%) in the iDEs. Twelve mutants and an overall 55.0% prevalence of pfK13 mutations were detected. Of them, G533S, C447R, C447S, N458Y, C469Y, and A676D were first detected out along the China-Myanmar border. Referred to the wild strain, adjusted odds ratios of treatment failure for G533S, N458Y, and P574L by 42 days were 7.54 (95% CI: 1.605-45.86), 13.68 (95% CI: 1.95-130.72), and 89.00 (95% CI: 1.98-2482.1), respectively. CONCLUSION: The efficacy of DHA-PPQ from 2014 to 2018 declined in comparison with 2003 to 2013, but it is still effective for treatment of P. falciparum malaria. Results of the iDES indicate a risk of artemisinin resistance in Africa. G533S, N458Y, and P574L are associated with delayed parasite clearance and treatment failure.

In vivo monitoring of dihydroartemisinin-piperaquine sensitivity in Plasmodium falciparum along the China-Myanmar border of Yunnan Province, China from 2007 to 2013.

BACKGROUND: Artemisinin-based combination therapy (ACT) is the recommended first-line treatment of falciparum malaria in all endemic countries. Artemisinin resistance in Plasmodium falciparum has been confirmed in the Greater Mekong subregion (GMS). Dihydroartemisinin-piperaquine (DAPQ) is the most commonly used ACT in China. To understand the DAPQ sensitivity of P. falciparum, DAPQ resistance was monitored in vivo along the China-Myanmar border from 2007 to 2013. METHODS: Eligible patients with mono-infections of P. falciparum were recruited to this study after obtaining full informed consent. DAPQ tablets for different categories of kg body weight ranges were given once a day for three days. Patients were followed up for 42 days. Polymerase chain reaction (PCR) was conducted to distinguish between re-infection and recrudescence, to confirm the Plasmodium species. The data were entered and analysed by the Kaplan-Meier method. Treatment outcome was assessed according to the WHO recommended standards. RESULTS: 243 patients were completed valid follow-up. The fever clearance time (FCT) and asexual parasite clearance times (APCT) were, respectively, 36.5 ± 10.9 and 43.5 ± 11.8 hours, and there was an increasing trend of both FCT (F = 268.41, P < 0.0001) and APCT (F = 88.6, P < 0.0001) from 2007 to 2013. Eight (3.3%, 95% confidence interval, 1.4-6.4%) patients present parasitaemia on day three after medication; however they were spontaneous cure on day four. 241 (99.2%; 95% CI, 97.1-99.9%) of the patients were adequate clinical and parasitological response (ACPR) and the proportions of ACPR had not changed significantly from 2007 to 2013 (X(2) = 2.81, P = 0.7288). CONCLUSION: In terms of efficacy, DAPQ is still an effective treatment for falciparum malaria. DAPQ sensitivity in P. falciparum had not significantly changed along the China-Myanmar border of Yunnan Province, China. However more attentions should be given to becoming slower fever and parasite clearance.

Monitoring Plasmodium vivax chloroquine sensitivity along China-Myanmar border of Yunnan Province, China during 2008-2013.

BACKGROUND: Plasmodium vivax is the most widespread of the malaria parasites infecting human hosts. In malaria-eliminating settings, both imported and local malaria predominantly occurs in border areas, and most of them are P. vivax. Chloroquine (CQ) is the first-line drug for P. vivax treatment in China. To understand CQ sensitivity in P. vivax, in vivo monitoring of CQ resistance was conducted along the China-Myanmar border from 2008 to 2013. METHODS: Eligible patients with mono-infections of P. vivax were recruited to this study after obtaining full informed consent. CQ tablets for different categories of kg body weight ranges were given once a day for three days. Patients were followed up for 28 days. PCR was conducted to distinguish between re-infection and recrudescence, to confirm the Plasmodium species. The data were entered and analysed by the Kaplan-Meier method. Treatment outcome and sensitivity were classified according to the WHO recommended standards. RESULTS: 603 patients were completed valid follow-up. The fever clearance time and asexual parasite clearance times were, respectively, 22.2 ± 10.2 and 38.1 ± 12.6 hours. 594 (98.5%) patients were adequate clinical and parasitological response (ACPR), and nine (1.5%) patients, who were late clinical failure (LCF) or resistant response level I (RI), were imported from the neighbouring districts of Myanmar. CONCLUSION: In terms of efficacy, CQ is still effective for vivax malaria treatment. Plasmodium vivax CQ sensitivity had not significantly changed along the China-Myanmar border of Yunnan Province, China.

[Field evaluation of SD(BIOLINE) malaria antigen Plasmodium falciparum/Plasmodium vivax rapid test kit].

Four hundred and seventy-five patients with fever within 48 h were detected for Plasmodium using double blind field trials in China-Myanmar border from June to December 2011. The result showed that 202 of 475 were positive by SD(BIOLINE) kits, with 98 positive of Plasmodium falciparum and 104 positive of Plasmodium vivax. By microscope examination, 206 were positive. Taking the result of microscope examination as the reference standard, the general sensitivity and specificity were 98.1% (202/206) and 97.8% (263/269) respectively, and the general coincidence rate of SD(BIOLINE) kits with microscopy was 97.9% (465/475). The sensitivity and specificity of P. falciparum were 99.0% (98/99) and 97.8% (263/269) respectively, and the coincidence rate of SD(BIOLINE) with microscopy was 98.1% (361/368). The sensitivity and specificity of P. vivax were 97.2% (104/107) and 100% (269/269), and the coincidence rate of SD(BIOLINE) with microscopy was 99.2% (373/376). Therefore, the test results of SD(BIOLINE) are stable with a high specificity and sensitivity.

[Efficacy of compound dihydroartemisinin/piperaquine in treatment of uncomplicated falciparum malaria in Myanmar].

OBJECTIVE: To observe the therapeutic efficacy of compound dihydroartemisinin-piperaquine for treatment of uncomplicated falciparum malaria in Myanmar. METHODS: From 2007 to 2008, patients aged 6 to 60 years with uncomplicated P. falciparum infection and parasite density 500 to 200 000 parasites/microl were enrolled following an informed consent. A three-day course of total 8 tablets compound dihydroartemisinin-piperaquine was administered to an adult (each tablet containing 40 mg of dihydroartemisinin and 320 mg of piperaquine phosphate), dosage for children was based on ages (details in the treatment regimen) . The indices including fever subsiding time, parasite clearance time, asexual parasite clearance time and adverse clinical responses were observed and collected on days 7, 14, 21, and 28 after treatment. RESULTS: A total of 134 patients completed the treatment. The mean fever subsiding time and mean asexual parasite clearance time were (25.5 +/- 2.8) h and (39.5 +/- 7.8) h respectively. Asexual parasite clearance rate was 100% on day 7. Four cases recrudesced on day 28 and 16 cases had slight adverse clinical responses such as uncomfortable gastrointestinal tract, headache, nausea, vomit and diarrhea, which disappeared as soon as drug withdrawal. CONCLUSION: The compound dihydroartemisinin/piperaquine shows a sound efficacy in treating uncomplicated falciparum malaria