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Comparison of novel and standard diagnostic tools for the detection of Schistosoma mekongi infection in Lao People's Democratic Republic and Cambodia.

ABSTRACT: Given the restricted distribution of Schistosoma mekongi in one province in Lao People's Democratic Republic (Lao PDR) and two provinces in Cambodia, together with progress of the national control programmes aimed at reducing morbidity and infection prevalence, the elimination of schistosomiasis mekongi seems feasible. However, sensitive diagnostic tools will be required to determine whether elimination has been achieved. We compared several standard and novel diagnostic tools in S. mekongi-endemic areas.The prevalence and infection intensity of S. mekongi were evaluated in 377 study participants from four villages in the endemic areas in Lao PDR and Cambodia using Kato-Katz stool examination, antibody detection based on an enzyme-linked immunosorbent assay (ELISA) and schistosome circulating antigen detection by lateral-flow tests. Two highly sensitive test systems for the detection of cathodic and anodic circulating antigens (CCA, CAA) in urine and serum were utilized.Stool microscopy revealed an overall prevalence of S. mekongi of 6.4% (one case in Cambodia and 23 cases in Lao PDR), while that of Opisthorchis viverrini, hookworm, Trichuris trichiura, Ascaris lumbricoides and Taenia spp. were 50.4%, 28.1%, 3.5%, 0.3% and 1.9%, respectively. In the urine samples, the tests for CCA and CAA detected S. mekongi infections in 21.0% and 38.7% of the study participants, respectively. In the serum samples, the CAA assay revealed a prevalence of 32.4%, while a combination of the CAA assay in serum and in urine revealed a prevalence of 43.2%. There was a difference between the two study locations with a higher prevalence reached in the samples from Lao PDR.The CCA, CAA and ELISA results showed substantially higher prevalence estimates for S. mekongi compared to Kato-Katz thick smears. Active schistosomiasis mekongi in Lao PDR and Cambodia might thus have been considerably underestimated previously. Hence, sustained control efforts are still needed to break transmission of S. mekongi. The pivotal role of highly sensitive diagnostic assays in areas targeting elimination cannot be overemphasised.

SUBMITTER: Vonghachack Y

PROVIDER: S-EPMC5550959 | biostudies-other | 2017 Aug

REPOSITORIES: biostudies-other

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Project description:BackgroundDiphtheria is a vaccine-preventable disease. When vaccination coverage and population immunity are low, outbreaks can occur. We investigated a diphtheria outbreak in Lao People's Democratic Republic that occurred during 2012-2013 and highlighted challenges in immunization services delivery to children in the country.MethodsWe reviewed diphtheria surveillance data from April 1, 2012-May 31, 2013. A diphtheria case was defined as a respiratory illness consisting of pharyngitis, tonsillitis, or laryngitis, and an adherent tonsillar or nasopharyngeal pseudomembrane. To identify potential risk factors for diphtheria, we conducted a retrospective case-control study with two aged-matched neighborhood controls per case-patient in Houaphan Province, using bivariate analysis to calculate matched odds ratio (mOR) with 95% confidence intervals (CI). Reasons for non-vaccination among unvaccinated persons were assessed.ResultsSixty-two clinical cases of diphtheria and 12 diphtheria-related deaths were reported in seven of 17 provinces. Among case-patients, 43 (69%) were <15years old, five (8%) reported receiving three DTP doses (DTP3), 21 (34%) had received no DTP doses, and 35 (56%) had unknown vaccination status. For the case-control study, 42 of 52 diphtheria case-patients from Houaphan province and 79 matched-controls were enrolled. Five (12%) case-patients and 20 (25%) controls had received DTP3 (mOR=0.4, CI=0.1-1.7). No diphtheria toxoid-containing vaccine was received by 20 (48%) case-patients and 38 (46%) controls. Among case-patients and controls with no DTP dose, 43% of case-patients and 40% of controls lacked access to routine immunization services.ConclusionSuboptimal DTP3 coverage likely caused the outbreak. To prevent continued outbreaks, access to routine immunization services should be strengthened, outreach visits need to be increased, and missed opportunities need to be minimized. In the short term, to rapidly increase population immunity, three rounds of DTP immunization campaign should be completed, targeting children aged 0-14years in affected provinces.

Project description:BACKGROUND: HIV infection is an emerging problem in Laos. We conducted the first prospective study on intestinal parasites, including opportunistic protozoa, in newly diagnosed HIV infected patients, with or without diarrhea. The aims were to describe the spectrum of infections, to determine their prevalence and to assess their associations with diarrhea, CD4 cell count, place of residence and living conditions. METHODOLOGY: One to three stool samples over consecutive days were obtained from 137 patients. The Kato thick smear method, formalin-ethyl concentration and specific stains for coccidia and microsporidia diagnosis were performed on 260 stool samples. Baseline characteristics regarding relevant demographics, place of residence and living conditions, clinical features including diarrhea, were collected using a standardized questionnaire. PRINCIPAL FINDINGS: The 137 patients were young (median age: 36 years) and severely immunocompromised (83.9% at WHO stage 3 or 4, median CD4 cell count: 41/mm3). Diarrhea was present in 43.0% of patients. Parasite infection was found in 78.8% of patients, infection with at least two species in 49.6%. Prevalence rates of protozoan and helminth infections were similar (54.7% and 58.4% respectively). Blastocystis sp. was the most frequent protozoa (26.3%). Cryptosporidium sp., Cytoisospora belli and microsporidia, found at low prevalence rates (6.6%, 4.4%, 2.9%, respectively), were described for the first time in Laos. Cryptosporidium sp. was associated with persistent diarrhea. Strongyloides stercoralis was the most prevalent helminth following Opisthorchis viverrini (20.4% and 47.5% respectively). The most immunocompromised patients, as assessed by a CD4 count ≤ 50 cells/mm3, were more likely to be infected with intestinal parasites. CONCLUSIONS/SIGNIFICANCE: HIV infection was mainly diagnosed at an advanced stage of immunosuppression in Lao patients. Intestinal parasite infections were highly prevalent regardless of their diarrheal status. Opportunistic infections were reported. Improving the laboratory diagnosis of intestinal parasite infections and the knowledge on their local risk factors is warranted.

Project description:BackgroundHospital-acquired infections (HAIs) are significant public health issues, especially in low-and middle-income countries (LMICs). Hand hygiene and low-level disinfection of equipment practices among healthcare workers are some of the essential measures to reduce HAIs. Various infection prevention and control (IPC) interventions to reduce HAI incidence have been developed. However, effective interventions have not been well developed in the LMICs context. Therefore, this protocol aims to develop, pilot, and assess the feasibility and acceptability of an IPC intervention in Cambodia and the Lao People's Democratic Republic.MethodsThis study will consist of four phases guided by the Medical Research Council (MRC) Framework. Three hospitals will be purposely selected - each from the district, provincial, and national levels - in each country. The gap analysis will be conducted in Phase 1 to explore IPC practices among healthcare workers at each hospital through desk reviews, direct observation of hand hygiene and low-level disinfection of equipment practices, in-depth interviews with healthcare workers, and key informant interviews with stakeholders. In Phase 2, an IPC intervention will be developed based on the results of Phase 1 and interventions selected from a systematic literature review of IPC interventions in LMICs. In Phase 3, the developed intervention will be piloted in the hospitals chosen in Phase 1. In Phase 4, the feasibility and acceptability of the developed intervention will be assessed among healthcare workers and representatives at the selected hospitals. National consultative workshops in both countries will be conducted to validate the developed intervention with the national technical working groups.DiscussionThe MRC Framework will be employed to develop and evaluate an intervention to reduce HAIs in two LMICs. This theoretical framework will be used to explore the factors influencing hand hygiene compliance among healthcare workers. The gap analysis results will allow us to develop a comprehensive IPC intervention to reduce HAI incidence in Cambodia and Lao People's Democratic Republic. Findings from this protocol will feed into promising IPC interventions to reduce HAI incidence in other resource-limited settings.Clinical trial registrationClinicalTrial.Gov, identifier NCT05547373.

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Comparison of novel and standard diagnostic tools for the detection of Schistosoma mekongi infection in Lao People's Democratic Republic and Cambodia.

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