Intestinal parasitic infections and environmental water contamination in a rural village of northern Lao PDR

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

Epidemiology and serotype distribution of Streptococcus pneumoniae carriage among influenza-like illness cases in metropolitan Vientiane, Lao PDR: a community-based cohort study

BackgroundData on the epidemiology of Streptococcus pneumoniae among influenza-like illness (ILI) cases, particularly in low- and middle-income countries are scarce. This study assessed the prevalence, risk factors and serotype distribution of S. pneumoniae carriage among ILI cases in metropolitan Vientiane, Lao People's Democratic Republic. The 13-valent pneumococcal conjugate vaccine (PCV13) was introduced among infants in October 2013.MethodsActive ILI surveillance was conducted through weekly phone calls in an open community-based cohort study (April 2015–February 2019), involving 5,690 participants from 1,142 randomly selected households. Participants reporting ILI symptoms provided a nasopharyngeal swab and answered a questionnaire. S. pneumoniae and serotype pneumococcal-positive samples were screened by Multiplex PCR assays. Chi-squared tests and generalized linear mixed models were used to test for variables associated with pneumococcal positivity.ResultsAmong 1,621 ILI episodes, 269 (16.6%) tested positive for nasopharyngeal pneumococcal carriage, with the highest prevalence (55.4%) in children under 5 years. Pneumococcal carriage was significantly associated with concurrent detection of Hemophilus influenzae (adjusted odds ratio [aOR]: 6.93; 95% CI: 2.10–22.9) and exposure to household cigarette smoke (aOR: 1.65; 95% CI: 1.07–2.54). PCV13 serotypes accounted for 37.8% of all pneumococcal isolates. Detection of PCV13 serotypes among ILI cases aged under 5 years declined significantly between 2015/16 and 2018/19.ConclusionsCommunity-based surveillance of S. pneumoniae among ILI cases complement surveillance at healthcare facilities to provide a more complete picture of pneumococcal carriage. Our findings contribute also to the growing body of evidence on the effects of PCV13 introduction on circulating serotypes and their potential replacement

HIV Viral Load Testing in Laos

The number of people living with HIV/AIDS in the People’s Democratic Republic of Laos (also known as Laos PDR) is estimated at 13,600 and the number of people in need of antiretroviral therapy at 8,000. Today, around 3,200 HIV infected individuals receive treatment in seven centres throughout the country. Until recently, antiretroviral treated patients were followed-up only on the basis of clinical and immunological criteria. In 2009 the Centre d'Infectiologie Christophe Mérieux in Laos PDR (CICML) signed a collaboration agreement with the national Centre of HIV/AIDS/STI (CHAS) for the implementation of HIV viral load testing (VLT) in the country, leading to the technological transfer of the ANRS generic assay (HIV Generic charge virale, Biocentric, Bandol, France). The introduction of HIV VLT has been accompanied through national HIV workshops every 6 months. From June 2009 to December 2011, HIV viral load has been measured in 1,782 antiretoviral-treated patients. Of these, 97% were on reverse-transcriptase inhibitor -based 1st line regimen. HIV viral load was undetectable (<250 copies/ml) for 1,491 out of 1,782 (84%) antiretroviral-treated patients. Four months after adherence strengthening, HIV viral load became undetectable for 179/247 patients (72.5%) while 68/247 patients (27.5%) remained viremic (median viral load: 4.1 Log10). This report demonstrates the feasibility of setting up an affordable HIV viral load generic test at a national level in Laos PDR. Interestingly, only 16% of antiretroviral-treated patients presented with detectable VL at their first viral load measurement. Importantly, almost two thirds of them have controlled their viral load after strengthening their adherence to treatment.La République démocratique populaire du Laos compterait 13 600 personnes atteintes du VIH/SIDA dont 8000 auraient besoin d’un traitement antirétroviral. Aujourd’hui, environ 3200 individus infectés par le VIH reçoivent un traitement dans sept centres répartis dans tout le pays. Jusqu’à récemment, le suivi des patients traités par antirétroviraux se faisait uniquement sur la base de critères cliniques et immunologiques. En 2009, le Centre d'Infectiologie Christophe Mérieux du Laos (CICML) a signé un accord de collaboration avec le Programme national SIDA du Laos (CHAS) pour la mise en œuvre de tests de détection de la charge virale de VIH (VLT) dans le pays, qui permettra le transfert technologique de la technique générique ANRS (HIV Generic charge virale, Biocentric, Bandol, France). L’introduction du VLT appliqué au VIH s’est faite au travers d’ateliers nationaux sur le VIH tous les 6 mois. De juin 2009 à décembre 2011, la charge virale de VIH a été mesurée chez 1782 patients traités par antirétroviraux. Parmi eux, 97 % prenaient un traitement de première intention à base d’inhibiteur de la transcriptase inverse. La charge virale de VIH était indétectable (<250 copies/ml) chez 1491 des 1782 (84 %) patients traités par antirétroviraux. Quatre mois après renforcement de l’administration du traitement, la charge virale de VIH est devenue indétectable chez 179/247 patients (72,5 %) tandis que 68/247 patients (27,5 %) sont demeurés virémiques (charge virale médiane : 4,1 Log10). Cet article montre la faisabilité de la mise en place d’un test de détection générique de la charge virale de VIH abordable au niveau national au Laos. Il est intéressant de noter que seuls 16 % des patients traités par antirétroviraux ont présenté une charge virale détectable lors de la première mesure. En outre, près des deux-tiers d’entre eux ont pu maîtriser leur charge virale par une meilleure administration du traitement.El número de personas que padecen VIH/SIDA en la República Democrática Popular de Laos (también conocida como RDP Lao) se estima en 13.600, y el número de personas que necesitan un tratamiento antirretroviral es de 8.000. En la actualidad, cerca de 3.200 personas infectadas por el VIH reciben tratamiento en siete centros repartidos por todo el país. Hasta hace poco, el seguimiento de los pacientes tratados con fármacos antirretrovirales dependía exclusivamente de criterios clínicos e inmunológicos. En el 2009, el Centro de Infectología Christophe Mérieux de PDR Lao (CICML) suscribió un acuerdo de colaboración con el Centro Nacional de VIH/SIDA/ITS (CHAS) para la implantación del estudio de la carga viral del VIH (VLT, por sus siglas en inglés) en el país, lo que comportaría la transferencia de la tecnología del ensayo genérico ANRS (carga viral genérica del VIH, Biocentric, Bandol, Francia). La introducción del estudio de la carga viral del VIH se ha visto respaldada por la realización de varios talleres nacionales sobre el VIH cada 6 meses. Desde junio de 2009 a diciembre de 2011 se ha medido la carga vírica del VIH de 1.782 pacientes tratados con antirretrovirales. El 97 % de ellos seguía un régimen antirretroviral de primera línea basado en inhibidores de la transcriptasa inversa. No se detectó carga viral del VIH (<250 copias/ml) en 1.491 de 1.782 (84 %) de los pacientes tratados con antirretrovirales. Cuatro meses después del fortalecimiento de la adherencia, no se detectó carga viral del VIH en 179 de 247 pacientes (72,5 %) mientras que 68 de 247 pacientes (27,5 %) seguían siendo virémicos (carga viral media: 4,1 Log10). Este informe demuestra la viabilidad de elaborar un estudio genérico de la carga viral del VIH económico a nivel nacional en la RDP Lao). Cabe destacar que solamente el 16 % de los pacientes tratados con antirretrovirales presentaron una carga viral detectable en su primera medición de la carga viral. Es significativo que casi dos terceras partes de ellos hayan conseguido controlar su carga viral después de fortalecer su adherencia al tratamiento

Correction: "Epidemiology and aetiology of influenza-like illness among households in metropolitan Vientiane, Lao PDR": A prospective, community-based cohort study.

[This corrects the article DOI: 10.1371/journal.pone.0214207.]

Pooling samples to increase testing capacity with Xpert Xpress SARS-CoV-2 during the Covid-19 pandemic in Lao People's Democratic Republic.

The COVID-19 pandemic created the need for large-scale testing of populations. However, most laboratories do not have sufficient testing capacity for mass screening. We evaluated pooled testing of samples, as a strategy to increase testing capacity in Lao PDR. Samples of consecutive patients were tested in pools of four using the Xpert Xpress SARS CoV-2 assay. Positive pools were confirmed by individual testing, and we describe the performance of the test and savings achieved. We also diluted selected positive samples to describe its effect on the assays CT values. 1,568 patients were tested in 392 pools of four. 361 (92.1%) pools were negative and 31 (7.9%) positive. 29/31 (93.5% (95%CI 77-99%) positive pools were confirmed by individual testing of the samples but, in 2/31 (6.5%) the four individual samples were negative, suggesting contamination. Pools with only one positive sample had higher CT values (lower RNA concentrations) than the respective individual samples, indicating a dilution effect, which suggested an increased risk of false negative results with dilutions >1:10. However, this risk may be low if the prevalence of infection is high, when pools are more likely to contain more than one positive sample. Pooling saved 67% of cartridges and substantially increased testing capacity. Pooling samples increased SARS-CoV-2 testing capacity and resulted in considerable cartridge savings. Given the need for high-volume testing, countries may consider implementation of pooling for SARS-CoV-2 screening

"Epidemiology and aetiology of influenza-like illness among households in metropolitan Vientiane, Lao PDR": A prospective, community-based cohort study.

Respiratory diseases are a major contributor to morbidity and mortality in many tropical countries, including Lao PDR. However, little has been published regarding viral or bacterial pathogens that can contribute to influenza-like illness (ILI) in a community setting. We report on the results of a community-based surveillance that prospectively monitored the incidence of ILI and its causative pathogens in Vientiane capital in Lao PDR. A cohort of 995 households, including 4885 study participants, were followed-up between May 2015 and May 2016. Nasopharyngeal swabs, throat swabs, and sputum specimens were collected from ILI cases identified through active case-finding. Real-Time PCR was used to test nasopharyngeal swabs for 21 respiratory pathogens, while throat and sputum samples were subjected to bacterial culture. Generalized linear mixed models were used to assess potential risk factors for associations with ILI. In total, 548 episodes of ILI were reported among 476 (9.7%) of the study participants and 330 (33.2%) of the study households. The adjusted estimated incidence of ILI within the study area was 10.7 (95%CI: 9.4-11.9) episodes per 100 person-years. ILI was significantly associated with age group (p<0.001), sex (p<0.001), and number of bedrooms (p = 0.04) in multivariate analysis. In 548 nasopharyngeal swabs, the most commonly detected potential pathogens were Streptococcus pneumoniae (17.0%), Staphylococcus aureus (11.3%), influenza A (11.1%; mostly subtype H3N2), rhinovirus (7.5%), and influenza B (8.0%). Streptococci were isolated from 42 (8.6%) of 536 throat swabs, most (27) of which were Lancefield Group G. Co-infections were observed in 132 (24.1%) of the 548 ILI episodes. Our study generated valuable data on respiratory disease burden and patterns of etiologies associated with community-acquired acute respiratory illness Laos. Establishment of a surveillance strategy in Laos to monitor trends in the epidemiology and burden of acute respiratory infections is required to minimize their impact on human health

The surveillance of viral hepatitis B and C in Lao PDR : from routine analysis toward to research of biomarkers by metabolomics methods

Les travaux exposés dans cette thèse sont le reflet d'années d'efforts consacrées à la mise en place de diagnostics de qualités des hépatites virales au Laos au sein du Centre d'infectiologie Lao Christophe Mérieux (CILM), dont je suis aujourd'hui la directrice scientifique. En introduction, nous avons tenu à présenter les caractéristiques socio-économiques du Laos et ses défis sanitaires pour atteindre les Millennium Development Goals, qui guident les politiques publiques de pays en situation de développement. Nous avons jugé important de souligner ces points tout comme la présentation du CILM pour faire comprendre au lecteur le contexte de réalisation de ce travail. C'est grâce à une bio-banque riche de plus de 7,000 échantillons biologiques de patients infectés par les virus des hépatites virales B et C, que nous avons pu poser la question de recherche clé de cette thèse : Comment évoluent les hépatites virales chez les patients reçus depuis une dizaine d'années au CILM ? Cette question en a fait émerger une deuxième concernant la qualité du diagnostic dans les centres de soins à Vientiane. Ainsi, nous nous sommes intéressés aux kits de diagnostic rapide de l'hépatite B utilisés dans les structures de soins de Vientiane, comparés au standard utilisé dans notre laboratoire. Ces travaux, qui ont donné lieu à la publication de 2 articles (un troisième article a été soumis), jouent un rôle capital pour le pays, car ils donnent des axes d'intervention aux autorités de santé publique laotiennes pour combattre ce fléau. Nous avons choisi une présentation dichotomique des hépatites virales avec une partie dédiée aux hépatites B et une partie dédiée à l'hépatite C en raison de l'émergence d'une troisième question de recherche plus fondamentale. Il s'agit du risque de développement du cancer du foie chez les patients infectés, risque différent suivant que l'on est porteur d'une hépatite B ou d'une C. En effet, les outils diagnostiques pour déterminer la magnitude de ce risque sont peu ou pas accessibles pour les patients au Laos. [...]The work presented in this thesis reflects many years of effort to devoted the implementation of quality diagnostics of viral hepatitis in Laos at the Centre d'infectiologie Lao Christophe Mérieux (CILM), of which I am now the scientific director. In the introduction, we wanted to present the socio-economic characteristics of Laos and its health challenges in order to achieve the Millennium Development Goals (MDG), which guide public policies in developing countries. We felt it was important to highlight these points as well as the presentation of the CILM to help the readers to understand the context in which this work was carried out. It is thanks to a bio-bank with more than 7,000 biological samples from patients infected with viral hepatitis B and C viruses, that we were able to ask the key research question of this thesis: What is the evolution of patients infected by viral hepatitis B/C who have been follow the viral load at CILM for the past ten years or so? This question raised a second one concerning the quality of diagnosis in health centres in Vientiane. For example, we were interested in the rapid diagnostic kits for hepatitis B used in Vientiane's health facilities, compared to the standard used in our laboratory. This work, which has resulted in the publication of 2 articles (a third article has been submitted), plays a crucial role for the country, as it provides Laotian public health authorities with a focus for action to combat this scourge

Surveillance des hépatites virales B-C au Laos : de l'analyse de routine à la recherche de biomarqueurs par métabolomique

The work presented in this thesis reflects many years of effort to devoted the implementation of quality diagnostics of viral hepatitis in Laos at the Centre d'infectiologie Lao Christophe Mérieux (CILM), of which I am now the scientific director. In the introduction, we wanted to present the socio-economic characteristics of Laos and its health challenges in order to achieve the Millennium Development Goals (MDG), which guide public policies in developing countries. We felt it was important to highlight these points as well as the presentation of the CILM to help the readers to understand the context in which this work was carried out. It is thanks to a bio-bank with more than 7,000 biological samples from patients infected with viral hepatitis B and C viruses, that we were able to ask the key research question of this thesis: What is the evolution of patients infected by viral hepatitis B/C who have been follow the viral load at CILM for the past ten years or so? This question raised a second one concerning the quality of diagnosis in health centres in Vientiane. For example, we were interested in the rapid diagnostic kits for hepatitis B used in Vientiane's health facilities, compared to the standard used in our laboratory. This work, which has resulted in the publication of 2 articles (a third article has been submitted), plays a crucial role for the country, as it provides Laotian public health authorities with a focus for action to combat this scourge.Les travaux exposés dans cette thèse sont le reflet d'années d'efforts consacrées à la mise en place de diagnostics de qualités des hépatites virales au Laos au sein du Centre d'infectiologie Lao Christophe Mérieux (CILM), dont je suis aujourd'hui la directrice scientifique. En introduction, nous avons tenu à présenter les caractéristiques socio-économiques du Laos et ses défis sanitaires pour atteindre les Millennium Development Goals, qui guident les politiques publiques de pays en situation de développement. Nous avons jugé important de souligner ces points tout comme la présentation du CILM pour faire comprendre au lecteur le contexte de réalisation de ce travail. C'est grâce à une bio-banque riche de plus de 7,000 échantillons biologiques de patients infectés par les virus des hépatites virales B et C, que nous avons pu poser la question de recherche clé de cette thèse : Comment évoluent les hépatites virales chez les patients reçus depuis une dizaine d'années au CILM ? Cette question en a fait émerger une deuxième concernant la qualité du diagnostic dans les centres de soins à Vientiane. Ainsi, nous nous sommes intéressés aux kits de diagnostic rapide de l'hépatite B utilisés dans les structures de soins de Vientiane, comparés au standard utilisé dans notre laboratoire. Ces travaux, qui ont donné lieu à la publication de 2 articles (un troisième article a été soumis), jouent un rôle capital pour le pays, car ils donnent des axes d'intervention aux autorités de santé publique laotiennes pour combattre ce fléau. Nous avons choisi une présentation dichotomique des hépatites virales avec une partie dédiée aux hépatites B et une partie dédiée à l'hépatite C en raison de l'émergence d'une troisième question de recherche plus fondamentale. Il s'agit du risque de développement du cancer du foie chez les patients infectés, risque différent suivant que l'on est porteur d'une hépatite B ou d'une C. En effet, les outils diagnostiques pour déterminer la magnitude de ce risque sont peu ou pas accessibles pour les patients au Laos. [...

The Threat of Multiple Liver Carcinogens in the Population of Laos: A Review

International audienceLaos is a landlocked country in South East Asia, ranking fifth for primary liver cancer incidence worldwide. Risk factors that might explain this worrying situation are poorly known. We conducted a review of the literature concerning the etiologies of terminal liver diseases in Laos. A double infectious burden with hepatitis B and C viruses and the liver fluke Opisthorchis viverrini seems to be the main cause of the high liver cancer incidence. Moreover, it was also suggested that mutagenic substances frequently found in tobacco, alcoholic beverages, fermented fish, and mold-contaminated cereals or nuts, which are all substances heavily consumed by Lao people, lead to the accumulation of DNA mutations in the liver cell genome causing tumor processes. However, the respective proportions of liver cancer cases attributable to each category of infections and substances consumed, as well as the histological nature of the neoplasia are still not precisely documented in Laos. The international medical and scientific communities as well as public health stakeholders should urgently consider the alarming situation of liver health in Laos to stimulate both research and subsequent implementation of prevention policies