Low Efficacy of Single-Dose Albendazole and Mebendazole against Hookworm and Effect on Concomitant Helminth Infection in Lao PDR

Parasitic worms remain a public health problem in developing countries. Regular deworming with the drugs albendazole and mebendazole is the current global control strategy. We assessed the efficacies of a single tablet of albendazole (400 mg) and mebendazole (500 mg) against hookworm in children of southern Lao PDR. From each child, two stool samples were examined for the presence and number of hookworm eggs. Two hundred children were found to be infected. They were randomly assigned to albendazole (n = 100) or mebendazole (n = 100) treatment. Three weeks later, another two stool samples were analyzed for hookworm eggs. Thirty-two children who were given albendazole had no hookworm eggs anymore in their stool, while only 15 children who received mebendazole were found egg-negative. The total number of hookworm eggs was reduced by 85.3% in the albendazole and 74.5% in the mebendazole group. About one third of the children who were co-infected with the Asian liver fluke Opisthorchis viverrini were cleared from this infection following albendazole treatment and about one forth in the mebendazole group. Concluding, both albendazole and mebendazole showed disappointingly low cure rates against hookworm, with albendazole performing somewhat better. The effect of these two drugs against O. viverrini should be studied in greater detail

Helminth and Intestinal Protozoa Infections, Multiparasitism and Risk Factors in Champasack Province, Lao People's Democratic Republic

Multiparsitism is a general public health concern in tropical countries, and is of particular importance in the Mekong River basin of Southeast Asia. Here, we report results obtained from an in-depth study of hepato-biliary and intestinal multiparasitism and associated risk factors in three settings of the most southern province of Lao People's Democratic Republic. Multiple species intestinal parasite infections were very common: more than 80% of the study participants harbored at least two and up to seven different intestinal parasites concurrently. Of particular concerns are the high prevalence of the liver fluke Opisthorchis viverrini (64.1%) and the moderate prevalence of the blood fluke Schistosoma mekongi (24.2%), as these fluke infections are responsible for severe hepato-biliary morbidity, including the bile duct cancer cholangiocarcinoma. Hookworm was the most common nematode infection (76.8%). We conclude that given the very high prevalence rates of parasite infections and the extent of multiparasitism, regular deworming is warranted and that this intervention should be coupled with health education and improved assess to clean water and adequate sanitation to consolidate morbidity control and ensure long-term sustainability

Two-year longitudinal survey reveals high genetic diversity of Schistosoma mansoni with adult worms surviving praziquantel treatment at the start of mass drug administration in Uganda

Background: A key component of schistosomiasis control is mass drug administration with praziquantel. While control interventions have been successful in several endemic regions, mass drug administration has been less effective in others. Here we focus on the impact of repeated praziquantel treatment on the population structure and genetic diversity of Schistosoma mansoni. Methods: We examined S. mansoni epidemiology, population genetics, and variation in praziquantel susceptibility in parasites isolated from children across three primary schools in a high endemicity region at the onset of the Ugandan National Control Programme. Children were sampled at 11 timepoints over two years, including one week and four weeks post-praziquantel treatment to evaluate short-term impacts on clearance and evidence of natural variation in susceptibility to praziquantel. Results: Prevalence of S. mansoni was 85% at baseline. A total of 3576 miracidia larval parasites, isolated from 203 individual children, were genotyped at seven loci. Overall, genetic diversity was high and there was low genetic differentiation, indicating high rates of parasite gene flow. Schistosome siblings were found both pre-treatment and four weeks post-treatment, demonstrating adult worms surviving treatment and natural praziquantel susceptibility variation in these populations at the beginning of mass drug administration. However, we did not find evidence for selection on these parasites. While genetic diversity decreased in the short-term (four weeks post-treatment), diversity did not decrease over the entire period despite four rounds of mass treatment. Furthermore, within-host genetic diversity was affected by host age, host sex, infection intensity and recent praziquantel treatment. Conclusions: Our findings suggest that praziquantel treatments have short-term impacts on these parasite populations but impacts were transient and no long-term reduction in genetic diversity was observed. High gene flow reduces the likelihood of local adaptation, so even though parasites surviving treatment were observed, these were likely to be diluted at the beginning of the Ugandan National Control Programme. Together, these results suggest that MDA in isolation may be insufficient to reduce schistosome populations in regions with high genetic diversity and gene flow

Efficacy and safety of mefloquine, artesunate, mefloquine-artesunate, tribendimidine, and praziquantel in patients with Opisthorchis viverrini: a randomised, exploratory, open-label, phase 2 trial

BACKGROUND: Praziquantel is the only drug available for treatment of Opisthorchis viverrini, although in-vivo studies point to activity of mefloquine, artesunate, and tribendimidine against this liver fluke. We aimed to assess the efficacy and safety of these drugs compared with that of praziquantel in patients with O viverrini infection. METHODS: We did a randomised open-label trial between February and April, 2010, in the Saysetha district, Attapeu Province, Laos. Eligible patients were school children aged 10-15 years who had O viverrini infections. Patients were randomly assigned to one of five different treatment groups by use of a computer-generated randomisation code. We assessed efficacy as cure rate and egg reduction rate in intention-to-treat and per-protocol analyses. The trial was registered with Current Controlled Trials, ISRCTN23425032. RESULTS: 125 children were randomly assigned: 25 received mefloquine, 24 artesunate, 24 mefloquine-artesunate, 27 tribendimidine, and 25 praziquantel. 19 patients were lost to follow-up. In the intention to treat analysis, 14 patients receiving praziquantel were cured compared with none with mefloquine, one with artesunate (odds ratio 0·03, 95% CI 0·004-0·29), one with mefloquine-artesunate (0·03, 0·004-0·29), and 19 with tribendimidine (1·87, 0·60-5·85). Egg reduction rate was 98·4% for praziquantel, 30·2% for mefloquine (egg reduction-rate ratio 1·61, 95% CI 0·21-0·72), 31·5% for artesunate (0·43, 0·23-0·80), 41·3% for mefloquine-artesunate (0·60, 0·31-1·10), and 99·3% for tribendimidine (1·00, 0·44-2·30). Most adverse events were mild or moderate and affected all treatment groups; serious adverse events-vertigo, nausea, vomiting, and anxiety-were reported only by patients taking mefloquine or mefloquine-artesunate. INTERPRETATION: Tribendimidine seems to be at least as efficacious as the drug of choice, praziquantel, for the treatment of O viverrini infections; both drugs were well tolerated. Mefloquine, artesunate, and mefloquine-artesunate did not show an effect. Tribendimidine should be further investigated with large clinical trials. FUNDING: Swiss National Science Foundation, University of Basel

Three cases of intestinal capillariasis in Lao People's Democratic Republic

Capillaria philippinensis is a rare zoonotic intestinal parasite that emerged in the 1960s. The outcome of intestinal capillariasis may be fatal if untreated in due time. We report three cases of intestinal capillariasis in Lao People's Democratic Republic (Lao PDR). The three patients were unrelated previously healthy young men (24, 26, and 27 years of age) with no underlying disease or immune depression. They had chronic diarrhea, abdominal pain, edema, and severe weight loss. Two of them acquired the infection in Thailand; the other patient had no travel history outside Lao PDR. All patients were seen several times in different hospitals before the diagnosis was made. All had concurrent parasite infections: Giardia lamblia, Entamoeba histolytica, Strongyloides stercoralis, Opisthorchis viverrini, and hookworm. The patients frequently consumed uncooked fish. After treatment with albendazole (400 mg/day for 21-30 days) all patients recovered. In Lao PDR, consumption of raw small freshwater fish is common. Therefore, the possibility of a capillariasis outbreak should be considered