title: Causes of non-malarial fever in Laos: a prospective study.
abstract: 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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  Wellcome Trust, WHO-Western Pacific Region, Foundation for Innovative New Diagnostics, US Centers for Disease Control and Prevention
authors.forename: Mayfong
authors.initials: M
authors.lastname: Mayxay
authors.forename: Josée
authors.initials: J
authors.lastname: Castonguay-Vanier
authors.forename: Vilada
authors.initials: V
authors.lastname: Chansamouth
authors.forename: Audrey
authors.initials: A
authors.lastname: Dubot-Pérès
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Paris
authors.forename: Rattanaphone
authors.initials: R
authors.lastname: Phetsouvanh
authors.forename: Jarasporn
authors.initials: J
authors.lastname: Tangkhabuanbutra
authors.forename: Phouvieng
authors.initials: P
authors.lastname: Douangdala
authors.forename: Saythong
authors.initials: S
authors.lastname: Inthalath
authors.forename: Phoutthalavanh
authors.initials: P
authors.lastname: Souvannasing
authors.forename: Günther
authors.initials: G
authors.lastname: Slesak
authors.forename: Narongchai
authors.initials: N
authors.lastname: Tongyoo
authors.forename: Anisone
authors.initials: A
authors.lastname: Chanthongthip
authors.forename: Phonepasith
authors.initials: P
authors.lastname: Panyanouvong
authors.forename: Bountoy
authors.initials: B
authors.lastname: Sibounheuang
authors.forename: Koukeo
authors.initials: K
authors.lastname: Phommasone
authors.forename: Michael
authors.initials: M
authors.lastname: Dohnt
authors.forename: Darouny
authors.initials: D
authors.lastname: Phonekeo
authors.forename: Bouasy
authors.initials: B
authors.lastname: Hongvanthong
authors.forename: Sinakhone
authors.initials: S
authors.lastname: Xayadeth
authors.forename: Pakapak
authors.initials: P
authors.lastname: Ketmayoon
authors.forename: Stuart D
authors.initials: SD
authors.lastname: Blacksell
authors.forename: Catrin E
authors.initials: CE
authors.lastname: Moore
authors.forename: Scott B
authors.initials: SB
authors.lastname: Craig
authors.forename: Mary-Anne
authors.initials: MA
authors.lastname: Burns
authors.forename: Frank
authors.initials: F
authors.lastname: von Sonnenburg
authors.forename: Andrew
authors.initials: A
authors.lastname: Corwin
authors.forename: Xavier
authors.initials: X
authors.lastname: de Lamballerie
authors.forename: Iveth J
authors.initials: IJ
authors.lastname: González
authors.forename: Eva Maria
authors.initials: EM
authors.lastname: Christophel
authors.forename: Amy
authors.initials: A
authors.lastname: Cawthorne
authors.forename: David
authors.initials: D
authors.lastname: Bell
authors.forename: Paul N
authors.initials: PN
authors.lastname: Newton
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003141:Communicable Diseases / Q000150:complications* / Q000453:epidemiology; D005260:Female; D005334:Fever / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D007812:Laos / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012621:Seasons; D055815:Young Adult
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