Efficacy and Safety of a Naphthoquine-Azithromycin Coformulation for Malaria Prophylaxis in Southeast Asia: A Phase 3, Double-blind, Randomized, Placebo-controlled Trial.

BACKGROUND: A prophylactic antimalarial drug that is both effective for protection and improves compliance is in high demand. METHODS: We conducted a randomized, placebo-controlled, double-blinded phase 3 trial to evaluate the 1:1 fixed-dose combination of naphthoquine-azithromycin (NQAZ) for safety and protection against Plasmodium infections in villages along the China-Myanmar border. A total of 631 residents, 5-65 years of age, were randomized into the drug group (n = 319) and the placebo group (n = 312) to receive NZAQ and placebo, respectively, as a single-dose monthly treatment. Follow-ups were conducted weekly to monitor for adverse events and malaria infections. RESULTS: Of the 531 subjects completing the trial, there were 46 and 3 blood smear-positive Plasmodium infections in the placebo and treatment groups, respectively. For the intent-to-treat analysis, the single-dose monthly NQAZ treatment had 93.62% protective efficacy (95% confidence interval [CI]: 91.72%-95.52%). For the per-protocol analysis, NQAZ treatment provided a 93.04% protective efficacy (95% CI: 90.98%-95.1%). Three smear-positive cases in the NQAZ group were all due to acute falciparum malaria. In comparison, NQAZ treatment provided 100% protection against the relapsing malaria Plasmodium vivax and Plasmodium ovale. The treatment group had 5.6% of participants experiencing transient elevation of liver aminotransferases compared with 2.2% in the placebo group (P > .05). CONCLUSIONS: Monthly prophylaxis with NQAZ tablets was well tolerated and highly effective for preventing Plasmodium infections. It may prove useful for eliminating P. vivax in areas with a high prevalence of glucose-6-phosphate dehydrogenase deficiency in the population. CLINICAL TRIALS REGISTRATION: ChiCTR1800020140.

Randomized, Double-Blind, Placebo-Controlled Studies to Assess Safety and Prophylactic Efficacy of Naphthoquine-Azithromycin Combination for Malaria Prophylaxis in Southeast Asia.

New prophylactic drugs against malaria infections are urgently needed. We conducted randomized, double-blind, placebo-controlled, phase 2 trials of a new antimalarial drug combination, naphthoquine-azithromycin (NQAZ), to determine its safety and protective efficacy in a low-endemicity area of Southeast Asia. In the first trial, 127 healthy volunteers were randomized to receive two single doses of either 400 mg of NQAZ (200 mg of each drug), 800 mg of NQAZ (400 mg of each drug), or placebo on day 0 and day 30. Weekly follow-ups were performed for 2 months, and physical and clinical laboratory exams were done during the second and eighth week. Both drug regimens were well tolerated, without any serious adverse events. Four adverse events (transient and slight elevations of serum transaminase concentrations) were found only in the two drug-treated groups and thus might be drug-related. In the second trial, 353 volunteer villagers were randomized into the same three groups as in the first trial, and malaria infections were followed for a month. For the intention-to-treat analysis, both regimens offered greater than 90% prophylactic efficacies against all malaria infections. When the analysis was done according to parasite species, 400 mg and 800 mg NQAZ provided 81.63 and 90.59% prophylactic efficacies, respectively, against Plasmodium falciparum infections, whereas both offered 100% prophylactic efficacy against Plasmodium vivax and Plasmodium ovale These trials showed that NQAZ had a good safety profile, and monthly single doses of 400 mg or 800 mg for adults offered excellent prophylaxis against malaria infections, especially the two relapsing species.

[Species Identification and Sequence Analysis of Plasmodium spp. in Border Areas of Yunnan Province by 18S rRNA-based Nested PCR]

Objective: To analyze blood samples from patients with falciparum malaria and vivax malaria in border areas of Yunnan Province, using 18S rRNA-based nested PCR, and compare 18S rRNA sequences. Methods: Blood or filter blood samples with positive microscopic results for Plasmodium falciparum or P. vivax infection were collected from Laza, Nankajiang, Mangdong and Nawei of Myanmar, and from Mengla, Tengchong and Yingjiang of Yunnan Province between 2004 and 2011. 18S rRNA-based nested PCR was conducted on the samples, and PCR products were sequenced and blasted. Phylogenetic tree was constructed using the neighbor-joining method with MEGA software (version 6.06). Results: Microscopic examination revealed P. falciparum infection in 256 samples and P. vivax infection in 219 samples. The 18S rRNA-based PCR further confirmed P. falciparum infection in 242 samples, P. vivax infection in 176 samples, and mixed infection in 57 samples. The consistency rate was 81.7% （388/475） between microscopic and PCR results. The inconsistency rate significantly correlated with parasite density （Spearman's r=-0.408， P<0.05）. Sequence alignment revealed 11 and 10 homologous sequences for P. falciparum and P. vivax 18S rRNA gene, comprising 2.9%（6/205） and 22.5%（27/120） variable sites, respectively. The 18S rRNA of P. falciparum clustered with that from Cameroon（GenBank accession number KC428742）, but was distantly related with the S-type 18S rRNA from the Netherlands （U36465） and Brazil （U36466 and U36467）. The 18S rRNA of P. vivax clustered with A-type 18S rRNA from Thailand （U07367）, but was distantly related with the C-type 18S rRNA from Thailand（U07368）. Conclusion: Nested PCR revealed mixed infection in 57 samples among those identified with single infection by microscopy. There is no significant difference in 18S rRNA sequence in seven counties/cities in Yunnan Province.

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.

Artemisinin-naphthoquine combination versus chloroquine-primaquine to treat vivax malaria: an open-label randomized and non-inferiority trial in Yunnan Province, China.

BACKGROUND: Plasmodium vivax is the main malaria parasite in China, and China is now making efforts to eliminate malaria by 2020. Radical cure of vivax malaria is one of challenges for malaria elimination. The purpose is to evaluate the efficacy and safety of artemisinin-naphthoquine (ANQ) versus chloroquine-primaquine (CQ-PQ) in treatment of vivax malaria in Yunnan Province, China. METHODS: An open-label randomized and non-inferiority design, eligible patients with monoinfections of P. vivax were randomly assigned to receive either a total target dose of ANQ 24.5 mg/kg (naphthoquine 7 mg/kg and artemisinin 17.5 mg/kg), once a day for three days, or a total CQ dose of 24 mg base/kg, once a day for three days plus a PQ dose of 0.45 mg base/kg/day, once a day for eight days. Patients were followed up for one year. The difference in efficacy between ANQ and CQ-PQ was compared via Wilson's test. RESULTS: By day 42, the number of patients free of recurrence was 125 (98.4%; 95% Confidence interval, 94.4-99.8%) for ANQ arm and 123 (96.1%; 95%CI, 91.1-98.7%) for CQ-PQ, and non-significant (P = 0.4496). By day 365, the number was 101 (79.5%; 95%CI, 71.8-85.9%) for ANQ and 106 (82.8%; 95%CI, 75.1-88.9%) for CQ-PQ, and non-significant (P = 0.610). So the proportions of patients free of recurrence had no significant difference between ANQ and CQ-PQ groups by day 28, 42 and 365; compared with CQ-PQ, the side effect of ANQ was mild. CONCLUSION: ANQ is non-inferior to CQ-PQ in terms of patients free of recurrence, and safer than CQ-PQ.

[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.

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.

[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

Use of bed nets and factors that influence bed net use among Jinuo Ethnic Minority in southern China.

BACKGROUND: Insecticide-treated nets (ITNs) are an integral part of vector control recommendations for malaria elimination in China. This study investigated the extent to which bed nets were used and which factors influence bed net use among Jinuo Ethnic Minority in China-Myanmar-Laos border areas. METHODS AND FINDINGS: This study combined a quantitative household questionnaire survey and qualitative semi-structured in-depth interviews (SDI). Questionnaires were administered to 352 heads of households. SDIs were given to 20 key informants. The bed net to person ratio was 1∶2.1 (i.e., nearly one net for every two people), however only 169 (48.0%) households owned at least one net and 623 (47.2%) residents slept under bed nets the prior night. The percentages of residents who regularly slept under nets (RSUN) and slept under nets the prior night (SUNPN) were similar (48.0% vs. 47.2%, P>0.05), however the percentage correct use of nets (CUN) was significantly lower (34.5%, P<0.0001). The annual cash income per person (ACIP) was an independent factor that influenced bed net use (P<0.0001), where families with an ACIP of CNY10000 or more were much more likely to use nets. House type was strongly associated with bed net use (OR: 4.71, 95% CI: 2.81, 7.91; P<0.0001), where those with traditional wood walls and terracotta roofs were significantly more likely to use nets, and the head of household's knowledge was an independent factor (OR: 5.04, 95% CI: 2.72, 9.35; P<0.0001), where those who knew bed nets prevent malaria were significantly more likely to use nets too. CONCLUSIONS: High bed net availability does not necessarily mean higher coverage or bed net use. Household income, house type and knowledge of the ability of bed nets to prevent malaria are all independent factors that influence bed net use among Jinuo Ethnic Minority.