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Background: Prevalence of Opisthorchis viverrini, Schistosoma mekongi and soil-transmitted helminths (STH) remains high in Lao People's Democratic Republic (Lao PDR), despite control efforts including mass-drug administration, education and communication campaigns. New approaches are required to advance helminth control., Methods: An ecohealth study was conducted on two Mekong islands in Southern Laos. Demographic and behavioural data were collected by questionnaire. Human and animal reservoir stools were examined. Bithynia spp. and Neotricula aperta snails were examined using shedding. Fresh water fish were examined using digestion technique. Multivariate random-effects analysis was used to find risk factors associated with helminth infections., Results: Human infection rates with O. viverrini, hookworm, S. mekongi, Trichuris trichiura, Ascaris lumbricoides and Taenia spp. were 60.7%, 44.1%, 22.2%, 4.1%, 0.6% and 0.1%, respectively. Heavy intensity infections were 4.2%, 3.6% and 1.8% for O. viverrini, S. mekongi and hookworm, respectively. O. viverrini and S. mekongi infection rates among dogs and cats were 25.0% and 14.7%, respectively. Of the cats tested, 53.1% were infected with O. viverrini. Prevalence of O. viverrini and S. mekongi in snails was 0.3% and 0.01%, respectively. Overall prevalence of O. viverrini infection in fresh water fish was 26.9%, with the highest infection rates occurring in Hampala dispa (87.1%), Cyclocheilichthys apogon (85.7%) and Puntius brevis (40.0%). Illiteracy and lower socioeconomic status increased the risk of O. viverrini infection, while those aged 10-16 years and possessing latrines at home were less likely to be infected. Household dogs and cats that consumed raw fish were significantly and positively associated with O. viverrini infection of the household members. For S. mekongi, children under 9 years old were exposed significantly to this infection, compared to older age groups., Conclusions: There is a pressing need to design and implement an integrated helminth control intervention on the Mekong Islands in southern Lao PDR. Given the highly dynamic transmission of O. viverrini, S. mekongi, STH and extended multiparasitism, annual mass-drug administration is warranted along with environmental modifications, health education and improved access to clean water and adequate sanitation to consolidate morbidity control and move towards elimination., Trail Registration Number: Our findings presented here are from a cross-sectional study, therefore, it has not been registered.

Intestinal parasitic infections are common in Lao People's Democratic Republic (Lao PDR). We investigated the accuracy of the Kato-Katz (KK) technique in relation to varying stool sampling efforts, and determined the effect of the concurrent use of a quantitative formalin-ethyl acetate concentration technique (FECT) for helminth diagnosis and appraisal of concomitant infections. The study was carried out between March and May 2006 in Champasack province, southern Lao PDR. Overall, 485 individuals aged ≥6 months who provided three stool samples were included in the final analysis. All stool samples were subjected to the KK technique. Additionally, one stool sample per individual was processed by FECT. Diagnosis was done under a light microscope by experienced laboratory technicians. Analysis of three stool samples with KK plus a single FECT was considered as diagnostic 'gold' standard and resulted in prevalence estimates of hookworm, Opisthorchis viverrini, Ascaris lumbricoides, Trichuris trichiura and Schistosoma mekongi infection of 77.9%, 65.0%, 33.4%, 26.2% and 24.3%, respectively. As expected, a single KK and a single FECT missed a considerable number of infections. While our diagnostic 'gold' standard produced similar results than those obtained by a mathematical model for most helminth infections, the 'true' prevalence predicted by the model for S. mekongi (28.1%) was somewhat higher than after multiple KK plus a single FECT (24.3%). In the current setting, triplicate KK plus a single FECT diagnosed helminth infections with high sensitivity. Hence, such a diagnostic approach might be utilised for generating high-quality baseline data, assessing anthelminthic drug efficacy and rigorous monitoring of community interventions., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: Helminthiasis is a public health concern in Lao People's Democratic Republic (Lao PDR, Laos). This study aimed to understand helminth infection and associated risk factors in relation to existing local knowledge, attitudes and practices regarding worm infections in endemic communities., Methods: A cross-sectional survey was conducted in 10 randomly selected villages in Saravane district, Southern Laos. Two stool samples obtained from 574 members (aged ≥2 years) of selected households were examined using the Kato Katz method. Household heads (n = 130) were interviewed. Eight focus group discussions (FGDs) and direct observations were performed. Uni- and multivariate logistic regression analyses were conducted to predict infection. Content analysis was conducted for qualitative data., Results: The prevalence of Opisthorchis viverrini, hookworm, Trichuris trichiura, Ascaris lumbricoides and Taenia sp. was 88.7%, 86.6%, 32.9%, 9.8% and 11.5%, respectively. Most individuals were co-infected with O. viverrini and hookworm. More men had multiple helminth infections than did women. Only one-third of household heads had heard about liver fluke before, of which 59.2% associated it with eating raw fish dish. Among the soil-transmitted helminths, roundworm was the most well known (70.8%) but was attributed to raw food consumption (91.3%). Eating raw fish was a common practice (75.4%); few households possessed a latrine (16.1%); less than half of the study participants mentioned health benefits from latrine use and personal hygiene. Focus group discussion participants had a low level of awareness of worm infections; more men liked eating raw fish than did women; some disliked using latrines because they were not used to it and because of their bad smell. Poor personal and village hygiene practices were observed., Conclusions: This study highlights a high helminth infection rate and poor community awareness of worm infections and associated risk factors. Only a sound awareness of worm infection and the underlying risk factors may prevent infection and re-infection after treatment.

A field survey studying intestinal parasites in humans and microbial pathogen contamination at environment was performed in a Laotian rural village to identify potential risks for disease outbreaks. A parasitological investigation was conducted in Ban Lak Sip village, Luang Prabang, Lao PDR involving fecal samples from 305 inhabitants as well as water samples taken from 3 sites of the local stream. Water analysis indicated the presence of several enteric pathogens, i.e., Aeromonas spp., Vibrio spp., E. coli H7, E. coli O157: H7, verocytotoxin-producing E. coli (VTEC), Shigella spp., and enteric adenovirus. The level of microbial pathogens contamination was associated with human activity, with greater levels of contamination found at the downstream site compared to the site at the village and upstream, respectively. Regarding intestinal parasites, the prevalence of helminth and protozoan infections were 68.9% and 27.2%, respectively. Eight helminth taxa were identified in fecal samples, i.e., 2 tapeworm species (Taenia sp. and Hymenolepis diminuta), 1 trematode (Opisthorchis sp.), and 5 nematodes (Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis, trichostrongylids, and hookworms). Six species of intestinal protists were identified, i.e., Blastocystis hominis, Cyclospora spp., Endolimax nana, Entamoeba histolytica/E. dispar, Entamoeba coli, and Giardia lamblia. Questionnaires and interviews were also conducted to determine risk factors of infection. These analyses together with a prevailing infection level suggested that most of villagers were exposed to parasites in a similar degree due to limited socio-economic differences and sharing of similar practices. Limited access to effective public health facilities is also a significant contributing factor. [ABSTRACT FROM AUTHOR]

Background: Among the common soil-transmitted helminth infections, hookworm causes the highest burden. Previous research in the southern part of Lao People's Democratic Republic (Lao PDR) revealed high prevalence rates of hookworm infection. The purpose of this study was to predict the spatial distribution of hookworm infection and intensity, and to investigate risk factors in the Champasack province, southern Lao PDR. Methodology: A cross-sectional parasitological and questionnaire survey was conducted in 51 villages. Data on demography, socioeconomic status, water, sanitation, and behavior were combined with remotely sensed environmental data. Bayesian mixed effects logistic and negative binomial models were utilized to investigate risk factors and spatial distribution of hookworm infection and intensity, and to make predictions for non-surveyed locations. Principal Findings: A total of 3,371 individuals were examined with duplicate Kato-Katz thick smears and revealed a hookworm prevalence of 48.8%. Most infections (91.7%) were of light intensity (1-1,999 eggs/g of stool). Lower hookworm infection levels were associated with higher socioeconomic status. The lowest infection levels were found in preschool-aged children. Overall, females were at lower risk of infection, but women aged 50 years and above harbored the heaviest hookworm infection intensities. Hookworm was widespread in Champasack province with little evidence for spatial clustering. Infection risk was somewhat lower in the lowlands, mostly along the western bank of the Mekong River, while infection intensity was homogeneous across the Champasack province. Conclusions/Significance: Hookworm transmission seems to occur within, rather than between villages in Champasack province. We present spatial risk maps of hookworm infection and intensity, which suggest that control efforts should be intensified in the Champasack province, particularly in mountainous areas. Author Summary: Hookworm is a parasitic worm that can infect the human intestine. Infections are common in low- and middle-income tropical and subtropical countries, particularly where sanitation conditions are poor. Control programs aim at preventing heavy infection intensities, which are associated with morbidity. The aim of this study was to investigate risk factors for hookworm infection and intensity, and to predict their distribution in the Champasack province, southern Lao People's Democratic Republic. We found that almost half of the 3,371 people examined were infected with hookworms. Better-off people had a lower risk and intensity of infection. Females showed lower prevalence and intensity of hookworm infection than males, except women aged 50 years and above, who were the most heavily infected. Preschool-aged children had the lowest infection levels. Hookworm transmission appeared to occur within, rather than between villages. Hookworm infections are widespread in the Champasack province, with homogeneous infection intensity and somewhat lower infection risk west of the Mekong River, which offers higher living conditions. Hookworm control should be intensified in the Champasack province, particularly in the mountainous areas. [ABSTRACT FROM AUTHOR]

Background: Schistosomiasis and opisthorchiasis are of public health importance in Southeast Asia. Praziquantel (PZQ) is the drug of choice for morbidity control but few dose comparisons have been made. Methodology: Ninety-three schoolchildren were enrolled in an area of Lao PDR where Schistosoma mekongi and Opisthorchis viverrini coexist for a PZQ dose-comparison trial. Prevalence and intensity of infections were determined by a rigorous diagnostic effort (3 stool specimens, each examined with triplicate Kato-Katz) before and 28–30 days after treatment. Ninety children with full baseline data were randomized to receive PZQ: the 40 mg/kg standard single dose (n = 45) or a 75 mg/kg total dose (50 mg/kg+25 mg/kg, 4 hours apart; n = 45). Adverse events were assessed at 3 and 24 hours posttreatment. Principal Findings: Baseline infection prevalence of S. mekongi and O. viverrini were 87.8% and 98.9%, respectively. S. mekongi cure rates were 75.0% (95% confidence interval (CI): 56.6–88.5%) and 80.8% (95% CI: 60.6–93.4%) for 40 mg/kg and 75 mg/kg PZQ, respectively (P = 0.60). O. viverrini cure rates were significantly different at 71.4% (95% CI: 53.4–84.4%) and 96.6% (95% CI: not defined), respectively (P = 0.009). Egg reduction rates (ERRs) against O. viverrini were very high for both doses (>99%), but slightly lower for S. mekongi at 40 mg/kg (96.4% vs. 98.1%) and not influenced by increasing diagnostic effort. O. viverrini cure rates would have been overestimated and no statistical difference between doses found if efficacy was based on a minimum sampling effort (single Kato-Katz before and after treatment). Adverse events were common (96%), mainly mild with no significant differences between the two treatment groups. Conclusions/Significance: Cure rate from the 75 mg/kg PZQ dose was more efficacious than 40 mg/kg against O. viverrini but not against S. mekongi infections, while ERRs were similar for both doses. Trial Registration: Controlled-Trials.com ISRCTN57714676 Author Summary: Parasitic worm infections are of public health importance in Southeast Asia. Particularly, the blood-dwelling Schistosoma mekongi worm, which is acquired by skin contact with the infectious cercariae in freshwater, can lead to liver enlargement. An infection with Opisthorchis viverrini is obtained by consumption of undercooked freshwater fish, and this infection increases the risk of developing cholangiocarcinoma. A single oral dose of 40 mg/kg praziquantel is recommended for mass treatment of schistosomiasis and opisthorchiasis, while at the individual level, a total dose of 75 mg/kg divided into three doses, is currently common practice to treat O. viverrini infection. Diagnosis is based on stool examination under a microscope for detection of worm eggs, but is limited by the low sensitivity of the widely used Kato-Katz technique. In this study, we showed that a 75 mg/kg total dose of praziquantel (50 mg/kg+25 mg/kg given 4 hours apart) cleared significantly more O. viverrini infections than a single 40 mg/kg dose, but no difference was observed for S. mekongi. Solicited adverse event profiles were mainly mild and similar in both groups. Repeated stool examination before and after treatment was essential for an accurate assessment of drug efficacy in terms of cure rate, but showed no effect on assessing egg reduction rates. [ABSTRACT FROM AUTHOR]

Background: Detailed investigations of multiparasitism are scarce in the Mekong River basin. We assessed helminth (trematode, nematode, and cestode), and intestinal protozoa infections, and multiparasitism in random population samples from three different eco-epidemiological settings in Champasack province, southern Lao People's Democratic Republic (Lao PDR), and determined underlying risk factors. Methodology: Two stool samples were collected from 669 individuals aged $6 months over consecutive days and examined for helminth infections using the Kato-Katz method. Additionally, one stool sample per person was subjected to a formalin-ethyl acetate concentration technique for diagnosis of helminth and intestinal protozoa infections. Questionnaires were administered to obtain individual and household-level data pertaining to behavior, demography and socioeconomic status. Risk factors for hepato-biliary and intestinal parasitic infections and multiparasitism were determined using multiple logistic regressions analyses. Principal Findings: Multiple species intestinal parasite infections were common: 86.6% of the study participants harbored at least two and up to seven different parasites concurrently. Regarding nematode infections, hookworm was the most prevalent species (76.8%), followed by Ascaris lumbricoides (31.7%) and Trichuris trichiura (25.0%). Regarding trematodes, Opisthorchis viverrini and Schistosoma mekongi infections were found in 64.3% and 24.2% of the participants, respectively. Infections with intestinal protozoa were rare. Conclusions/Significance: There is a pressing need to intensify and sustain helminth control interventions in the southern part of Lao PDR. Given the high prevalence with nematode and trematode infections and the extent of multiparasitism, preventive chemotherapy is warranted. This intervention should be coupled with health education and improved access to clean water and adequate sanitation to consolidate morbidity control and enhance sustainability. [ABSTRACT FROM AUTHOR]