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Mayxay M.,Lao Oxford Mahosot Hospital Wellcome Trust Research Unit LOMWRU | Mayxay M.,Health Science University | Mayxay M.,University of Oxford | Castonguay-Vanier J.,Lao Oxford Mahosot Hospital Wellcome Trust Research Unit LOMWRU | And 38 more authors.
The Lancet Global Health | Year: 2013

Background: Because of reductions in the incidence of Plasmodium falciparum malaria in Laos, identification of the causes of fever in people without malaria, and discussion of the best empirical treatment options, are urgently needed. We aimed to identify the causes of non-malarial acute fever in patients in rural Laos. Methods: For this prospective study, we recruited 1938 febrile patients, between May, 2008, and December, 2010, at Luang Namtha provincial hospital in northwest Laos (n=1390), and between September, 2008, and December, 2010, at Salavan provincial hospital in southern Laos (n=548). Eligible participants were aged 5-49 years with fever (≥38°C) lasting 8 days or less and were eligible for malaria testing by national guidelines. Findings: With conservative definitions of cause, we assigned 799 (41%) patients a diagnosis. With exclusion of influenza, the top five diagnoses when only one aetiological agent per patient was identified were dengue (156 [8%] of 1927 patients), scrub typhus (122 [7%] of 1871), Japanese encephalitis virus (112 [6%] of 1924), leptospirosis (109 [6%] of 1934), and bacteraemia (43 [2%] of 1938). 115 (32%) of 358 patients at Luang Namtha hospital tested influenza PCR-positive between June and December, 2010, of which influenza B was the most frequently detected strain (n=121 [87%]). Disease frequency differed significantly between the two sites: Japanese encephalitis virus infection (p=0·04), typhoid (p=0·006), and leptospirosis (p=0·001) were more common at Luang Namtha, whereas dengue and malaria were more common at Salavan (all p<0·0001). With use of evidence from southeast Asia when possible, we estimated that azithromycin, doxycycline, ceftriaxone, and ofloxacin would have had significant efficacy for 258 (13%), 240 (12%), 154 (8%), and 41 (2%) of patients, respectively. Interpretation: Our findings suggest that a wide range of treatable or preventable pathogens are implicated in non-malarial febrile illness in Laos. Empirical treatment with doxycycline for patients with undifferentiated fever and negative rapid diagnostic tests for malaria and dengue could be an appropriate strategy for rural health workers in Laos. Funding: Wellcome Trust, WHO-Western Pacific Region, Foundation for Innovative New Diagnostics, US Centers for Disease Control and Prevention. © 2013 Mayxay et al. Source

Komada K.,National Center for Global Health and Medicine | Sugiyama M.,Research Center for Hepatitis and Immunology | Vongphrachanh P.,National Center for Laboratory and Epidemiology | Xeuatvongsa A.,National Immunization Program | And 6 more authors.
International Journal of Infectious Diseases | Year: 2015

Background: There is limited information regarding the prevalence of hepatitis B in Lao PDR, where the hepatitis disease burden is substantial. Thus, reliable seroprevalence data is needed for the disease, based on probability sampling. Methods: A stratified, multistage, cluster sampling survey of hepatitis B surface antigen (HBsAg) positivity among children aged 5-9 years and their mothers aged 15-45 years was conducted. Participants were selected randomly from the central region of Lao PDR via probability-proportional-to-size sampling. Blood samples were collected onto filter paper and subsequently analyzed using a chemiluminescent microparticle immunoassay. Results: A total of 911 mother-and-child pairs were collected; the seroprevalence of HBsAg was estimated to be 2.1% (95% confidence interval 0.8-3.4%) among children and 4.1% (95% confidence interval 2.6-5.5%) in their mothers after taking into account the sampling design and the weight of each sample. The children's HBsAg positivity was positively associated with maternal infection and being born in a non-health facility, while the maternal infection status was not associated with any background characteristic. Conclusions: Lao PDR has a relatively lower HBsAg prevalence in the general population compared to surrounding countries. To ensure comparability to other countries and to future data, rapid field tests are recommended for a nationwide prevalence survey. © 2015 The Authors. Source

Khamphaphongphane B.,National Center for Laboratory and Epidemiology | Ketmayoon P.,National Center for Laboratory and Epidemiology | Ketmayoon P.,Centers for Disease Control and Prevention | Lewis H.C.,World Health Organization | And 8 more authors.
Influenza and other Respiratory Viruses | Year: 2013

Information on influenza virology and epidemiology from Lao PDR is limited and the seasonal patterns of influenza have not been previously described. Objectives To describe epidemiological and virologic characteristics of influenza in Lao PDR to recommend public health interventions, including improvements in surveillance and response. Patients/Methods We performed a descriptive analysis of samples taken from patients with influenza-like-illness (ILI) (fever >38°C with cough and/or sore throat) presenting at seven sentinel hospitals in three regions of Lao PDR, January 2008-December 2010. A nasopharyngeal (NP) swab or combined nasal with oropharyngeal swab was collected from patients with ILI. Samples were tested for influenza by either Luminex RVP, conventional reverse transcriptase PCR (RT-PCR) (January 2008-2009), or by real-time PCR (rRT-PCR) using US CDC reagents (February 2009 onward). Results Of 2346 samples tested from patients with ILI, 523 (22%) were positive for influenza. The median age of those positive was 12years (range, <1-60year). The percentage of samples that were influenza positive was similar over the 3years (20-23%). Each year 3-4 types/subtypes cocirculated with differing predominant type/subtype. Influenza was detected year-round with the highest proportion of positive specimens in the 3rd and 4th quarter. Conclusions Similar to other countries in the region, we found that influenza is present year-round and has a peak activity from July to December. Dominant types or subtypes vary by year. A large proportion of patients with ILI are not influenza positive. ILI surveillance is critical for weighing disease burden, both morbidity and mortality, against the costs of advancing influenza vaccine delivery strategy. © 2012 Blackwell Publishing Ltd. Source

Hiscox A.,London School of Hygiene and Tropical Medicine | Hiscox A.,Institute Pasteur du Laos | Winter C.H.,National Center for Laboratory and Epidemiology | Vongphrachanh P.,National Center for Laboratory and Epidemiology | And 11 more authors.
American Journal of Tropical Medicine and Hygiene | Year: 2010

A large-scale cross-sectional seroprevalence study of dengue (DEN) and Japanese encephalitis (JE) was conducted in Khammouane province, Lao PDR, as part of the initial baseline health impact assessment of the Nam Theun 2 hydroelectric dam construction project. Health surveys were performed between May 2007 and February 2008 with serum samples collected from healthy individuals involved in the resettlement program of 16 villages (total surveyed population 4,369). Hemagglutination inhibition assay using flavivirus antigens (DENV1, DENV3, and JEV) performed on 1,708 plasma specimens revealed 30.4% (519) cross-reactive positives, and 10% (172) and 1.3% (22) positives to JEV or DENV, respectively. Entomological surveys conducted during the rainy season of 2008 indicated the presence of competent flavivirus vectors (Culex vishnui group and Aedes albopictus), although Aedes aegypti was not found. Continued surveillance and investigation is warranted to assess the clinical disease burden of flaviviruses in this area that is undergoing rapid ecological and demographic change. Copyright © 2010 by The American Society of Tropical Medicine and Hygiene. Source

Sithivong N.,National Center for Laboratory and Epidemiology | Morita-Ishihara T.,Japan National Institute of Infectious Diseases | Vongdouangchanh A.,National Center for Laboratory and Epidemiology | Phouthavane T.,National Center for Laboratory and Epidemiology | And 11 more authors.
Emerging Infectious Diseases | Year: 2011

A cholera outbreak in Laos in July 2010 involved 237 cases, including 4 deaths. Molecular subtyping indicated relatedness between the Vibrio cholerae isolates in this and in a 2007 outbreak, uncovering a clonal group of V. cholerae circulating in the Mekong basin. Our finding suggests the subtyping methods will affect this relatedness. Source

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