title: Neorickettsia sennetsu as a Neglected Cause of Fever in South-East Asia.
abstract: Neorickettsia sennetsu infection is rarely recognized, with less than 100 globally reported patients over the last 50 years. The disease is thought to be contracted by eating raw fish, a staple of many South-East Asian cuisines. In 2009, the first patient with sennetsu was identified in the Lao PDR (Laos), raising the question as to how common this organism and related species are in patients presenting with fever. We investigated the frequency of N. sennetsu infection at hospitals in diverse areas of Laos. Consenting febrile hospital inpatients from central (Vientiane: n = 1,013), northern (Luang Namtha: n = 453) and southern (Salavan: n = 171) Laos were screened by PCR for N. sennetsu, if no previous positive direct diagnostic test was available. A PCR-restriction fragment length polymorphism assay was developed to differentiate between N. sennetsu, Ehrlichia chaffeensis and Anaplasma phagocytophilum. To allow more detailed studies of N. sennetsu, culture was successfully established using a reference strain (ATCC VR-367), identifying a canine-macrophage cell line (DH82) to be most suitable to visually identify infection. After screening, N. sennetsu was identified and sequence confirmed in four (4/1,637; 0.2%) Lao patients. Despite the previously identified high seroprevalence of N. sennetsu antibodies in the Lao population (~17%), acute N. sennetsu infection with sufficient clinical signs to prompt hospitalization appears to be rare. The reservoir, zoonotic cycle and pathogenicity of N. sennetsu remain unclear and require further investigations.
authors.affiliation: Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, University of Oxford, Oxford, England, United Kingdom.
authors.forename: Sabine
authors.initials: S
authors.lastname: Dittrich
authors.affiliation: Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic.
authors.forename: Weerawat
authors.initials: W
authors.lastname: Phuklia
authors.affiliation: Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, University of Oxford, Oxford, England, United Kingdom; Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Gareth D H
authors.initials: GD
authors.lastname: Turner
authors.affiliation: Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic.
authors.forename: Sayaphet
authors.initials: S
authors.lastname: Rattanavong
authors.affiliation: Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic.
authors.forename: Vilada
authors.initials: V
authors.lastname: Chansamouth
authors.affiliation: Departments of Pathology, Microbiology and Immunology University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Dumler
authors.affiliation: Nuffield Department of Clinical Laboratory Science, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom.
authors.forename: David J P
authors.initials: DJ
authors.lastname: Ferguson
authors.affiliation: Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, University of Oxford, Oxford, England, United Kingdom; Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Paris
authors.affiliation: Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, University of Oxford, Oxford, England, United Kingdom.
authors.forename: Paul N
authors.initials: PN
authors.lastname: Newton
mesh_terms: D000711:Anaplasmataceae Infections / Q000453:epidemiology / Q000382:microbiology*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D004285:Dogs; D005334:Fever / Q000097:blood / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D007812:Laos / Q000453:epidemiology; D008264:Macrophages / Q000382:microbiology; D058069:Neglected Diseases / Q000097:blood / Q000453:epidemiology / Q000382:microbiology*; D041101:Neorickettsia sennetsu / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D012150:Polymorphism, Restriction Fragment Length; D011446:Prospective Studies
chemical_list: D000907:Antibodies, Bacterial