Khampheng Phongluxa

Low efficacy of single-dose albendazole and mebendazole against hookworm and effect on concomitant helminth infection in Lao PDR

Background Albendazole and mebendazole are increasingly deployed for preventive chemotherapy targeting soil-transmitted helminth (STH) infections. We assessed the efficacy of single oral doses of albendazole (400 mg) and mebendazole (500 mg) for the treatment of hookworm infection in school-aged children in Lao PDR. Since Opisthorchis viverrini is co-endemic in our study setting, the effect of the two drugs could also be determined against this liver fluke. Methodology We conducted a randomized, open-label, two-arm trial. In total, 200 children infected with hookworm (determined by quadruplicate Kato-Katz thick smears derived from two stool samples) were randomly assigned to albendazole (n = 100) and mebendazole (n = 100). Cure rate (CR; percentage of children who became egg-negative after treatment), and egg reduction rate (ERR; reduction in the geometric mean fecal egg count at treatment follow-up compared to baseline) at 21–23 days posttreatment were used as primary outcome measures. Adverse events were monitored 3 hours post treatment. Principal Findings Single-dose albendazole and mebendazole resulted in CRs of 36.0% and 17.6% (odds ratio: 0.4; 95% confidence interval: 0.2–0.8; P = 0.01), and ERRs of 86.7% and 76.3%, respectively. In children co-infected with O. viverrini, albendazole and mebendazole showed low CRs (33.3% and 24.2%, respectively) and moderate ERRs (82.1% and 78.2%, respectively). Conclusions/Significance Both albendazole and mebendazole showed disappointing CRs against hookworm, but albendazole cured infection and reduced intensity of infection with a higher efficacy than mebendazole. Single-dose administrations showed an effect against O. viverrini, and hence it will be interesting to monitor potential ancillary benefits of a preventive chemotherapy strategy that targets STHs in areas where opisthorchiasis is co-endemic. Clinical Trial Registration Current Controlled Trials ISRCTN29126001

PCR Diagnosis of Opisthorchis viverrini and Haplorchis taichui Infections in a Lao Community in an Area of Endemicity and Comparison of Diagnostic Methods for Parasitological Field Surveys

ABSTRACT Opisthorchiasis is a major public health problem in Southeast Asia. Affected individuals often have mixed infections with the liver fluke Opisthorchis viverrini and minute intestinal flukes such as Haplorchis taichui. The usual methods of diagnosing these infections involve the demonstration of fluke eggs in stool samples under light microscopy, but sensitivity and specificity are low. We developed two PCR tests that detect and discriminate between O. viverrini and H. taichui infections. PCR tests were validated by stool samples from purged individuals. We then applied the PCR tests to estimate the prevalence of O. viverrini and H. taichui infections from a random sample of individuals selected from a community in an area of endemicity in Khong District, Laos. PCR results were compared with those from the Kato-Katz (KK) method and the formalin-ether concentration technique (FECT). When validated with purge results, PCR tests of O. viverrini and H. taichui had sensitivities of 93.7% (95% confidence interval [CI], 85.8 to 97.9%) and 73.3% (95% CI, 60.3 to 83.9%) and could detect as little as 0.75 pg DNA and 1.32 ng DNA, respectively. The PCR-determined community prevalences of O. viverrini and H. taichui infections were 63.9% (95% CI, 54.1 to 72.9%) and 30.6% (95% CI, 22.1 to 40.2%), respectively. Using PCR as the gold standard to detect O. viverrini, three KK thick smears performed comparably well, whereas one KK smear and FECT were poorer (sensitivities of 91.4% [95% CI, 81.0 to 97.1%,], 62.3% [95% CI, 49.8 to 73.7%], and 49.3% [95% CI, 37.0 to 61.6%], respectively). PCR may be a valuable and sensitive diagnostic tool, particularly for low-intensity O. viverrini and H. taichui infections.

Subtle to severe hepatobiliary morbidity in Opisthorchis viverrini endemic settings in southern Laos.

Evidence of severe hepatobiliary morbidity associated with Opisthorchis viverrini liver fluke infection including cholangiocarcinoma (CCA) is scarce in Laos although O. viverrini infection is highly prevalent. We assessed hepatobiliary morbidity using abdominal ultrasonography (US) in O. viverrini adult patients in Saravan province, Southern Laos. A random sample of 431 O. viverrini patients from 10 villages underwent abdominal US. Mild, moderate and markedly advanced periductal fibrosis was diagnosed in 7.0%, 66.5%, and 17.0% of patients, respectively. Normal liver parenchyma was seen in only 9.5% of patients. Presence of gall stones (13.2%), sludge (1.4%), gall wall thickening (1.2%), bile duct dilatation (1.6%), fatty liver (12.0%), kidney stones (8.6%) and cysts (7.9%) were diagnosed in considerable frequencies. In five patients (1.2%) hepatobiliary lesions suggesting CCA were diagnosed. Tumour markers, i.e. Interleukin-6, plasminogen activator inhibitor and carbohydrate antigen 19-9 were within normal range. The number of CCA suspected liver masses and hepatobiliary morbidity diagnosed among clinically asymptomatic adult patients in O. viverrini endemic area presents a major public health concern in Laos. However, definitive diagnosis of Opisthorchis-related severe sequelae including CCA is urgently needed to gauge the burden of this deadly disease in Laos.

Perceived illness drives participation in mass deworming campaigns in Laos

Multiple helminth infections are very common in communities of southern Laos. Preventive chemotherapy in combination with health education is the mainstay of control. We assessed the knowledge, perceptions and practices of rural communities related to endemic helminthiasis and their control during a mass drug administration (MDA) campaign. Short interviews with household heads (n=192), direct observations and discussions with attendees of MDAs, and in-depth interviews with local opinion leaders (n=21) were carried out. Quantitative and qualitative data analysis was performed. Results showed that opinion leaders and villagers were well aware of the importance of attending MDA. Leaders perceived the effectiveness of MDA against severe schistosomiasis and appreciated that it was provided for free and in their village. They encouraged villagers to attend it. Anticipated adverse events of praziquantel was a barrier for participation. A majority of leaders purchased deworming tablet (mebendazole, albendazole) in a local pharmacy for deworming when MDA is absent in their villages (19/21). Most leaders (20/21) had a good knowledge on severe schistosomiasis though only a few of them (5/21) described its cause correctly. They knew little about the disease consequences of liver fluke (3/21) and soil-transmitted helminth (4/21) infections but more about their causes. A high risk for worm infection was observed: consumption of raw or insufficiently cooked fish (100%), frequent physical contacts with Mekong River water (76.0%) and low number of latrines (14.5%). In conclusion, MDA is widely accepted in affected communities. Avoiding severe schistosomiasis was the main motivation to comply. Participation rates increased significantly with drugs provided free of charge in the villages. Better knowledge on the consequences of worm infections and on its modes of transmission will foster the distribution and acceptance of appropriate preventive treatment and other measures in helminth-endemic communities. Where multiple infections require several drugs for MDA, preceding health education and information about MDA and its benefits are a prior condition.

Efficacy of Moxidectin Versus Ivermectin Against Strongyloides stercoralis Infections: A Randomized, Controlled Noninferiority Trial

Background Infections with Strongyloides stercoralis are of considerable public health relevance. Moxidectin, a well-established drug in veterinary medicine under consideration for regulatory submission for the treatment of onchocerciasis, might serve as an alternative to the widely used ivermectin. Methods We conducted an exploratory, randomized, single-blind trial to evaluate the efficacy and safety of moxidectin (8 mg) vs ivermectin (200 μg/kg) against S. stercoralis infections. Cure rate (CR) against S. stercoralis was the primary outcome. Safety and efficacy against coinfections with soil-transmitted helminths and Opisthorchis viverrini were secondary outcomes. Noninferiority required the lower limit of the 95% confidence interval (CI) of the differences in CRs not exceed 7 percentage points. Results A total of 127 participants were enrolled and randomly assigned to the 2 treatments whereby 1 participant per arm was lost to follow-up. We observed a CR of 93.7% (59/63) for moxidectin compared to 95.2% (59/62) for ivermectin. Differences between CRs were estimated as -1.5% percentage points (95% CI, -9.6 to 6.5), thus the lower limit of the CI exceeds the noninferiority margin of 7 percentage points. No side effects were observed. CRs against hookworm infection were 57% (moxidectin) and 56% (ivermectin). Low efficacy for both drugs against O. viverrini was observed. Conclusions Moxidectin might be a safe and efficacious alternative to ivermectin for the treatment of S. stercoralis infection, given that only slight differences in CRs were observed. However, noninferiority could not be demonstrated. Larger clinical trials should be conducted once the drug is marketed. Clinical Trials Registration Current Controlled Trials: ISRCTN11983645.

Evaluation of two DNA extraction methods for detection of Strongyloides stercoralis infection

ABSTRACT Strongyloides stercoralis is present worldwide, but its prevalence is still uncertain, mainly due to the lack of sensitivity of diagnostic methods. Molecular techniques are under development, but a standardized protocol is still unavailable. We compared the sensitivity of real-time PCR, using two extraction protocols, with that of the Baermann technique. Samples were collected in the framework of the baseline screening of a randomized clinical trial evaluating moxidectin against S. stercoralis in Lao Peoples Democratic Republic. Two stool samples from each participant were processed by the Baermann method, and one subsample was processed by PCR. DNA was extracted using the QIAamp DNA stool minikit based on the standard protocol for the QIAamp DNA minikit (QIA) and using a modification of the QIA procedure (POL). Subsequently, all extracted samples were analyzed by real-time PCR. Overall, 95 samples were analyzed by the three diagnostic methods. Sixty-nine (72.6%) samples were positive according to the Baermann method, 25 (26.3%) by the QIA method, and 62 (65.3%) by the POL method. The sensitivities were 86% (95% confidence interval [CI], 76.7 to 92.9), 31.0% (95% CI, 21.3 to 42.6), and 78.0% (95% CI, 66.8 to 86.1) for the Baermann, QIA, and POL methods, respectively. The sensitivities calculated for each day of the Baermann method separately were 60% (48.4 to 70.8%) and 64% (52.2 to 74.2%) for days 1 and 2, respectively. In conclusion, the POL method revealed a good performance and was comparable to the Baermann test performed on two stool samples and superior to the Baermann method performed on one stool sample. Additional studies are needed to standardize a PCR protocol for S. stercoralis diagnosis.

Efficacy and safety of praziquantel against light infections of Opisthorchis viverrini: a randomised parallel single blind dose-ranging trial.

Background The liver fluke Opisthorchis viverrini, highly prevalent in Southeast Asia, is an important public health burden, including a risk factor for developing an aggressive bile duct cancer, cholangiocarcinoma, in chronically infected patients. Praziquantel, administered at a single 40 mg/kg dose in preventive chemotherapy programs and 3 × 25 mg/kg for individual treatment, is the drug of choice, yet information on the nature of the dose-response relationship is lacking. Methods We performed a randomized, parallel, single-blind dose-ranging phase 2 trial in the Lao People’s Democratic Republic in O. viverrini–infected adults. Patients were randomly assigned to 30 mg/kg, 40 mg/kg, 50 mg/kg, or 3 × 25 mg/kg praziquantel or placebo. Adverse events were recorded at baseline, 3 hours, and 24 hours posttreatment. Cure rates (CRs) and egg reduction rates (ERRs) were estimated 3 weeks after drug administration using available case analysis. Dose-response curves were predicted using Emax models. Results Two-hundred seventeen O. viverrini–infected patients were assigned to the 5 treatment arms. The majority (94.3%) of patients harbored light infections. The Emax model predicted a high efficacy among the observed dose range. We observed CRs ranging from 92.7% to 95.5% and ERRs >99.5% for all praziquantel treatment groups. Adverse events were mild but higher in the standard treatment group (3 × 25 mg/kg) than in the single-dose treatment arms. Conclusions Single-dose praziquantel appears to be as efficacious as the standard 3 × 25 mg/kg regimen for the treatment of O. viverrini infections, while presenting fewer adverse events. Further studies are necessary in moderate and heavy O. viverrini infections. Clinical Trials Registration Randomized Controlled Trials (ISRCTN77186750).