title: An outbreak investigation of scrub typhus in Western Province, Solomon Islands, 2014.
abstract: OBJECTIVE
  To identify the etiology and risk factors of undifferentiated fever in a cluster of patients in Western Province, Solomon Islands, May 2014.
  
  
  METHODS
  An outbreak investigation with a case control study was conducted. A case was defined as an inpatient in one hospital in Western Province, Solomon Islands with high fever (> 38.5 °C) and a negative malaria microscopy test admitted between 1 and 31 May 2014. Asymptomatic controls matched with the cases residentially were recruited in a ratio of 1:2. Serum samples from the subjects were tested for rickettsial infections using indirect micro-immunofluorescence assay.
  
  
  RESULTS
  Nine cases met the outbreak case definition. All cases were male. An eschar was noted in five cases (55%), and one developed pneumonitis. We did not identify any environmental factors associated with illness. Serum samples of all five follow-up cases (100%) had strong-positive IgG responses to scrub typhus. All but one control (10%) had a moderate response against scrub typhus. Four controls had low levels of antibodies against spotted fever group rickettsia, and only one had a low-level response to typhus group rickettsia.
  
  
  CONCLUSIONS
  This outbreak represents the first laboratory-confirmed outbreak of scrub typhus in the Western Province of Solomon Islands. The results suggest that rickettsial infections are more common than currently recognized as a cause of an acute febrile illness. A revised clinical case definition for rickettsial infections and treatment guidelines were developed and shared with provincial health staff for better surveillance and response to future outbreaks of a similar kind.
authors.affiliation: Clinical Research Department, Faculty of Tropical and Infectious Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.; Hospital for Tropical Diseases, University College London Hospitals NHS Trust, London, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Marks
authors.affiliation: Office of the WHO Representative in Solomon Islands, Honiara, Solomon Islands.; Ministry of Health and Medical Services, Honiara, Solomon Islands.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Joshua
authors.affiliation: Helena Goldie Hospital, Munda, Solomon Islands .
authors.forename: Jenny
authors.initials: J
authors.lastname: Longbottom
authors.affiliation: Helena Goldie Hospital, Munda, Solomon Islands .
authors.forename: Katherine
authors.initials: K
authors.lastname: Longbottom
authors.affiliation: Office of the WHO Representative in Solomon Islands, Honiara, Solomon Islands.; Ministry of Health and Medical Services, Honiara, Solomon Islands.
authors.forename: Alison
authors.initials: A
authors.lastname: Sio
authors.affiliation: National Referral Hospital, Honiara, Solomon Islands .
authors.forename: Elliot
authors.initials: E
authors.lastname: Puiahi
authors.affiliation: Ministry of Health and Medical Services, Honiara, Solomon Islands .
authors.forename: Greg
authors.initials: G
authors.lastname: Jilini
authors.affiliation: Australian Rickettsial Reference Laboratory, Geelong, Australia .
authors.forename: John
authors.initials: J
authors.lastname: Stenos
authors.affiliation: Ministry of Health and Medical Services, Honiara, Solomon Islands .
authors.forename: Tenneth
authors.initials: T
authors.lastname: Dalipanda
authors.affiliation: Office of the WHO Representative in Solomon Islands, Honiara, Solomon Islands .
authors.forename: Jennie
authors.initials: J
authors.lastname: Musto
mesh_terms: D000293:Adolescent; D000328:Adult; D004196:Disease Outbreaks; D005334:Fever / Q000453:epidemiology / Q000209:etiology; D006801:Humans; D008297:Male; D008542:Melanesia; D012282:Rickettsia Infections / Q000150:complications / Q000453:epidemiology; D012612:Scrub Typhus / Q000453:epidemiology* / Q000635:transmission*