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Ribas A, Jollivet C, Morand S, Thongmalayvong B, Somphavong S, Siew CC, Ting PJ, Suputtamongkol S, Saensombath V, Sanguankiat S, Tan BH, Paboriboune P, Akkhavong K, Chaisiri K. Intestinal Parasitic Infections and Environmental Water Contamination in a Rural Village of Northern Lao PDR. Korean J Parasitol 2017; 55:523-532. [PMID: 29103267 PMCID: PMC5678468 DOI: 10.3347/kjp.2017.55.5.523] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 07/20/2017] [Accepted: 08/14/2017] [Indexed: 12/02/2022]
Abstract
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.
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Affiliation(s)
- Alexis Ribas
- Section of Parasitology, Department of Biology, Healthcare and the Environment, Faculty of Pharmacy and Food Sciences, University of Barcelona, Barcelona, Spain
| | - Chloé Jollivet
- CIRAD Animal et Gestion Integree des Risques, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand
| | - Serge Morand
- CNRS-CIRAD, Faculty of Veterinary Technology, Kasetsart University, Bangkok, Thailand
| | | | - Silaphet Somphavong
- Centre Christophe Merieux du Laos, Vientiane, Lao People's Democratic Republic
| | - Chern-Chiang Siew
- Detection and Diagnostic Laboratories, DSO National Laboratories, Singapore
| | - Pei-Jun Ting
- Detection and Diagnostic Laboratories, DSO National Laboratories, Singapore
| | - Saipin Suputtamongkol
- Department of Anthropology, Faculty of Social Sciences, Thammasart University, Bangkok, Thailand
| | - Viengsaene Saensombath
- Internal Medicine Division, Luangprabang Provincial Hospital, Laos People's Democratic Republic
| | - Surapol Sanguankiat
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Boon-Huan Tan
- Detection and Diagnostic Laboratories, DSO National Laboratories, Singapore
| | - Phimpha Paboriboune
- Centre Christophe Merieux du Laos, Vientiane, Lao People's Democratic Republic
| | - Kongsap Akkhavong
- National Institute of Health, Vientiane, Lao People's Democratic Republic
| | - Kittipong Chaisiri
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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Teo ECY, Tan BH, Purdy MA, Wong PS, Ting PJ, Chang PEJ, Oon LLE, Sue A, Teo CG, Tan CK. Hepatitis E in Singapore: A Case-Series and Viral Phylodynamics Study. Am J Trop Med Hyg 2017; 96:922-928. [PMID: 28093535 DOI: 10.4269/ajtmh.16-0482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AbstractThe incidence of hepatitis E in Singapore appears to be increasing. A retrospective case-series study of patients diagnosed with hepatitis E in a tertiary hospital from 2009 to 2013 was conducted. Of 16 cases, eight (50%) were solid-organ transplant recipients (SOTRs), and 14 (88%) were found infected by genotype 3 hepatitis E virus (HEV-3). Bayesian inferences based on HEV subgenomic sequences from seven cases suggest that HEV-3 strains were introduced to Singapore as two principal lineages. Within limitations of the study, it can be inferred that one lineage, in the 3efg clade, emerged about 83 years ago, probably originating from Japan, whereas the other, in the 3abchij clade, emerged about 40 years ago, from the United States. Establishment and subsequent transmissions of strains from these two lineages likely contribute to the current endemicity of hepatitis E in Singapore.
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Affiliation(s)
| | | | - Michael A Purdy
- Division of Viral Hepatitis, Centers for Disease Control and Prevention, Atlanta, Georgia
| | | | | | - Pik-Eu Jason Chang
- Department of Gastroenterology and Hepatology, Singapore General Hospital, Singapore.,Duke-NUS Medical School, National University of Singapore, Singapore
| | | | - Amanda Sue
- Division of Viral Hepatitis, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Chong-Gee Teo
- Division of Viral Hepatitis, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Chee-Kiat Tan
- Department of Gastroenterology and Hepatology, Singapore General Hospital, Singapore.,Duke-NUS Medical School, National University of Singapore, Singapore
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Lee VJ, Tan CH, Yap J, Cook AR, Ting PJ, Loh JP, Gao Q, Chen MI, Kang WL, Tan BH, Tambyah PA. Effectiveness of pandemic H1N1-2009 vaccination in reducing laboratory confirmed influenza infections among military recruits in tropical Singapore. PLoS One 2011; 6:e26572. [PMID: 22053196 PMCID: PMC3203898 DOI: 10.1371/journal.pone.0026572] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2011] [Accepted: 09/29/2011] [Indexed: 11/19/2022] Open
Abstract
Background Limited information is available about pandemic H1N1-2009 influenza vaccine effectiveness in tropical communities. We studied the effectiveness of a pandemic H1N1 vaccination program in reducing influenza cases in Singapore. Methods A surveillance study was conducted among military personnel presenting with febrile respiratory illness from mid-2009 to mid-2010. Consenting individuals underwent nasal washes, which were tested with RT-PCR and subtyped. A vaccination program (inactivated monovalent Panvax H1N1-2009 vaccine) was carried out among recruits. A Bayesian hierarchical model was used to quantify relative risks in the pre- and post-vaccination periods. An autoregressive generalised linear model (GLM) was developed to minimise confounding. Results Of 2858 participants, 437(15.3%), 60(2.1%), and 273(9.6%) had pandemic H1N1, H3N2, and influenza B. The ratio of relative risks for pandemic H1N1 infection before and after vaccination for the recruit camp relative to other camps was 0.14(0.016,0.49); for H3N2, 0.44(0.035,1.8); and for influenza B, 18(0.77,89). Using the GLM for the recruit camp, post-vaccination weekly cases decreased by 54%(37%,67%, p<0.001) from that expected without vaccination; influenza B increased by 66 times(9–479 times, p<0.001); with no statistical difference for H3N2 (p = 0.54). Conclusions Pandemic vaccination reduced H1N1-2009 disease burden among military recruits. Routine seasonal influenza vaccination should be considered.
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Affiliation(s)
- Vernon J Lee
- Biodefence Centre, Ministry of Defence, Singapore, Singapore.
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Lee VJ, Yap J, Cook AR, Tan CH, Loh JP, Koh WH, Lim EAS, Liaw JCW, Chew JSW, Hossain I, Chan KW, Ting PJ, Ng SH, Gao Q, Kelly PM, Chen MI, Tambyah PA, Tan BH. A clinical diagnostic model for predicting influenza among young adult military personnel with febrile respiratory illness in Singapore. PLoS One 2011; 6:e17468. [PMID: 21399686 PMCID: PMC3047544 DOI: 10.1371/journal.pone.0017468] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 01/28/2011] [Indexed: 11/19/2022] Open
Abstract
Introduction Influenza infections present with wide-ranging clinical features. We aim to
compare the differences in presentation between influenza and non-influenza
cases among those with febrile respiratory illness (FRI) to determine
predictors of influenza infection. Methods Personnel with FRI (defined as fever≥37.5°C, with cough or sore
throat) were recruited from the sentinel surveillance system in the
Singapore military. Nasal washes were collected, and tested using the
Resplex II and additional PCR assays for etiological determination.
Interviewer-administered questionnaires collected information on patient
demographics and clinical features. Univariate comparison of the various
parameters was conducted, with statistically significant parameters entered
into a multivariate logistic regression model. The final multivariate model
for influenza versus non-influenza cases was used to build a predictive
probability clinical diagnostic model. Results 821 out of 2858 subjects recruited from 11 May 2009 to 25 Jun 2010 had
influenza, of which 434 (52.9%) had 2009 influenza A (H1N1), 58
(7.1%) seasonal influenza A (H3N2) and 269 (32.8%) influenza
B. Influenza-positive cases were significantly more likely to present with
running nose, chills and rigors, ocular symptoms and higher temperature, and
less likely with sore throat, photophobia, injected pharynx, and
nausea/vomiting. Our clinical diagnostic model had a sensitivity of
65% (95% CI: 58%, 72%), specificity of
69% (95% CI: 62%, 75%), and overall accuracy of
68% (95% CI: 64%, 71%), performing significantly
better than conventional influenza-like illness (ILI) criteria. Conclusions Use of a clinical diagnostic model may help predict influenza better than the
conventional ILI definition among young adults with FRI.
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Affiliation(s)
- Vernon J Lee
- Biodefence Centre, Ministry of Defence, Singapore, Singapore.
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